key: cord-0077693-f7mt02oa authors: nan title: 15th National Congress of the Italian Association of Nuclear Medicine and Molecular Imaging (AIMN): Rimini (Italy), May, 12–15, 2022 date: 2022-05-03 journal: Clin Transl Imaging DOI: 10.1007/s40336-022-00492-x sha: 2ca7013c4f7366df3327e052b4ae78c2ccbb8f11 doc_id: 77693 cord_uid: f7mt02oa nan Background-aim: PET imaging can be affected by respiratory motion artifacts that can cause image distortions and inaccurate information regarding tracer uptake, tumor shape and volume. To overcome this issue, different strategies can be applied, including respiratory gating techniques. As an alternative to traditional gating techniques that involve the use of external sensors able to track the breathing cycle, faster and deviceless approaches have recently been developed. Data-driven gating techniques (DDG) offer hardware-free motion detection and correction, easy to implement in the clinic as a default process. The aim of the study was to evaluate the impact of fully automatic motion correction on the clinical routine and on PET image quality as well. Methods: In order to evaluate the DDG feasibility, we decided to apply this technique to all FDG and DOTATOC whole body PET studies performed over 2 months. The images were acquired using a digital PET/CT scanner (Discovery MI 5-Ring Detector, GE Healthcare) after injection of 2 MBq/kg 18 F-FDG or 68 Ga-DOTA-TOC. Prospective DDG was applied using patient diaphragm to target the field of view (FOV) and motion correction was triggered automatically when the detected respiratory signal exceeded a set threshold (R value C 15), at which point the scan time for that bed position was doubled. A total of 442 patients were retrospectively analyzed (414 FDG and 28 DOTATOC) and for each patient a PET data set was reconstructed where DDG was enabled (PETDDG) and where DDG was not enabled (PETnoDDG) as well. All PET images were evaluated by an expert Nuclear Medicine physician who rated the general image quality, motion effects and the impact of PETDDG on lesion detectability. In the FOV where DDG correction lesions were assessed for changes in SUV max and metabolic tumor volume (MTV). The lesion volumes were obtained using auto contour volume of interest (VOI) delineation with a 41% of SUV max threshold. Statistical significance was considered for p values below 0.0001 using Wilcoxon's signed rank test. Results: In 309/442 patients (70%) a significative respiratory movement was detected and DDG was automatically applied resulting in an increase of about 2.5 min for each acquisition. Out of these 309 PETDDG studies, 7% resulted in new findings with potential change of further clinical management, 15% resulted in a better lesion definition, 12% no difference in image quality was found compared to PETnoDDG, while in 66% no finding was present in DDG FOV. By applying DDG, a mean 18% increase in the SUV max was achieved, as compared to the non-gated images (P \ 0.0001). In addition, a mean 17% decrease in MTV in gated as compared to non-gated images was estimated (P \ 0.0001). Conclusions: Likewise to motion-tracking devices, DDG increased lesion detectability and changed management in a significant number of patients. Unlike motion-tracking devices, DDG provided reliable fully automatic motion correction in clinical routine with a negligible impact from the point of view of feasibility, making the hypothesis of its implementation in clinical routine very promising. Background-Aim: Quantification of myelin loss in MS remains challenging. PET imaging with b-amyloid ligands is emerging as a molecular imaging technique targeting quantitative measurement of myelin content changes in MS. Available pioneering data have to date focused on measurement of standard uptake value ratio (SUVr) and distribution volume ratio (DVR) at equilibrium or in late static standard PET imaging (i.e. after 90 min). Based on the proposed amyloid PET traces affinity to myelin, we evaluated the value of early PET dynamic images followed by late acquisition to elucidate the biologic underpinnings of amyloid PET signal in MS. Methods: 95 white matter lesions in eleven MS patients (6 primaryprogressive (PPMS), 5 relapsing-remitting (RRMS), age 43.2 ± 10.8 years) recruited in a prospective trial founded by the Italian Ministry of Health were included in these preliminary analyses. Lesions were segmented using 3 T MRI. Baseline [18F]Florbetaben PET (early dynamic acquisition of the first 30 min and late steady state acquisition 90-110 min p.i.) were analyzed. After PET normalization on the cerebellum, SUVratio in the individual lesions and in the contralateral normal appearing white matter (NAWM) was measured in late and early PET images. Lesions sizeeffect on PET signal was also assessed. Early frames were submitted to a principal component analysis (PCA). Late lesional and NAWM SUVr and PCA scores, were compared and correlated among themselves and with T1/T2 ratio, a proxy measure of myelin loss (linear regression and Bland-Altmann plot). Results: Two PCAs explained 90% of variance of early dynamic tracer profile. PCA1 corresponded to a positive and constant vector (likely reflecting local tracer uptake overtime), while PCA2 loads showed a descending trend overtime (possibly better capturing plaques dynamic nature). SUVratio and early PCA2 were significantly lower in lesions compared to NAWM (p \ 0.001). Both in lesions and in NAWM, late static SUVratio and PCA2 (but not PCA1) correlated with T1/T2 ratio values (p \ 0.001). Conclusions: We confirmed previous pioneering data suggesting that late steady state amy-PET images are able to capture demyelination in MS lesions. However, tracer kinetic over time seems to open a further window on the capability of amyloid PET to assess myelin dynamics in MS lesions (which might go beyond the intensity uptake reflected by SUVratio). Reproducibility of SUV-ratio (SUVR) dependent and independent methods for semiquantification of amyloid pet included in Dolab platform OP13 Brain 123I-ioflupane SPECT and 18F-FDG PET combined use in movement and cognitive associated diseases of recent appearence Background-Aim: Parkinson's Disease (PD) and Atypical Parkinsonian Syndromes (APS) share many phenotypic manifestations creating clinical challenges. A relevant role in the differential diagnosis of PD and APS is played by [ 18 F]FDG PET, as metabolic patterns of regional glucose metabolism of these nosological entities are different and disease-specific. Artificial intelligence (AI)-based framework might represent an optimal imaging-biomarker to classify PD, APS and healthy controls (HC). We aimed to create [ 18 F]FDG PET predictive model using Random Forest (RF) classifier to distinguish parkinsonian patients. Methods: A retrospective study was conducted on a multi-centre cohort consisted of 150 patients (mean age 70 ± 7; 80 female) including 29 iPD patients and other atypical parkinsonian syndromes, such as Multiple System Atrophy (MSA, n = 37), Progressive Supranuclear Palsy (PSP, n = 43), Corticobasal Degeneration (CBD, n = 29) and Lewy Body Dementia (LBD, n = 12). A healthy control dataset of n = 153 subjects (mean age 60.1 ± 14; 66 female) provided by the AIMN Neurology Study-Group was included. All [ 18 F]FDG PET/CT scans were proceeded using SPM12. An atlasbased cortical/subcortical regional standardized uptake ratio (SUVr) were generated using MarsBaR toolbox. A supervised learning model, based on RF algorithm was developed to train the disease classifier (Tidymodels, RStudio). The dataset was split into training (80%) and testing (20%) particles. RF stabilization with 500 trees and five-fold cross-validation was carried out. The prediction model was applied to classify, first, the diseased patients and controls, and second, the iPD and atypical PD patients. The prediction performance of a model was validated while considering the overall accuracy, area under curve (AUC), sensitivity and specificity. Results: The RF model, incorporating basal ganglia and thalamus, showed excellent classification efficiency distinguishing the diseased patients and control group, with an accuracy of 92%, AUC of 0.94, sensitivity of 91% and specificity of 92% in the test-dataset. The classification accuracy of iPD from other atypical parkinsonian syndromes was achieved to 76%, and AUC 0.89 in the test dataset with the model embedding both subcortical and cortical regions. The caudate, putamen and globus pallidus showed significantly higher weight of diagnostic importance than cortical regions. Conclusions: The [ 18 F]FDG PET/CT based RF prediction model shows excellent diagnostic performance classifying diseased patients from controls and iPD patients from other parkinsonian syndromes. 123I-Ioflupane brain SPECT (I-SPECT) and brain parenchyma sonography (BPS) combined use in movement disorder diagnosis the usefulness of I-SPECT and BPS combined use in patients with movement disorders. Methods: We retrospectively evaluated 28 consecutive patients with recent appearance of movement disorder symptoms. Seventeen/28 cases (group A) underwent both I-SPECT and BPS procedures; I-SPECT was processed by qualitative (QL) and quantitative (QN) analyses (cut-off value: 3.3). BPS was carried out by a phased-array ultrasound system with 2-2.5 MHz transducer through the periauricular acoustic bone windows (hyperecogenicity cut off: 0.20 cm2). Six/28 cases (group B) underwent BPS alone because physical patients conformation, while 3/28 patients (group C) were investigated only by I-SPECT since ultrasound window were nonassessable. The remaining 2/28 cases were excluded from the study for patient cooperation lack. Results: Group A: 11/17 cases showed at both QL and QN I-SPECT tracer uptake reduction at least in one basal ganglia nucleus and BPS evidenced SN hyperecogenicity classifying the patients as affected by PD. Two/17 cases had normal tracer uptake at both QL and QN I-SPECT with normal BPS values, too; one of these patients were classified as VP because MRI vascular foci, and the other one as ET. Two/17 cases had at both QL and QN I-SPECT pathological basal ganglia tracer uptake and normal SN echogenicity at BPS, thus being considered as PSP. One/17 cases had normal I-SPECT at QL but slight reduction at QN in one putamen with pathological SN at BPS and was classified as PD. The remaining 1/17 cases with both QL and QN normal results at I-SPECT was classified as ET, despite uncertain abnormal BPS results. Group B: 4/6 patients showed BPS hyper echogenic values and were diagnosed as PD in 2 cases, IP in one, while the diagnosis was uncertain in the remaining one; 2/6 cases had normal BPS and were classified as PSP in one case and uncertain in the other. Group C: 3/3 patients had tracer reduction at QL and QN and were classified as PD. Conclusions: The present study confirmed that I-SPECT and BPS combined use could lead to a more appropriate movement disorder diagnosis, in particular when clinical signs are inconclusive. Our future efforts should be directed to specify whether the two combined techniques could be useful in movement disorder differential diagnosis, especially in the early stages but also in the prodromal phases. For this preliminary study, patient number is relatively small, but the casuistry is progressively increasing in order to provide useful support to the conclusions that emerged from this study. Results: 260 subjects with suggestive motor and non-motor symptoms appeared in less than 1 year were analyzed. Mean age at baseline was 66 ± 9.8 years, with males being slightly more numerous than females (147 vs 113). Clinical diagnosis after 3 years of follow-up was PD in 143 patients and non-PD in 117 patients. Diagnostic odds ratio (OR) with 95% confidence interval (CI) was calculated for both 123I-FP-CIT and 123I-mIBG. 123I-FP-CIT OR was 0.98 (95% CI 0.93-1.03) for right C/O (p = 0.55); 0.98 (95% CI 0.93-1.03) for right P/O (p = 0.46); 0.97 (95% CI 0.91-1.02) for left C/O (p = 0.28) and 0.97 (95% CI 0.91-1.02) for left P/O (p = 0.25). 123I-mIBG OR was 0.22 (95% CI 0.19-0.26) for eH/M and 0.29 (95% CI 0.25-0.32) for lH/M (p = 0.001). ROC curves showed an AUC value of 0.954 for both eH/M and lH/M. Conclusions: This retrospective multicenter study showed that 123I-mIBG scintigraphy has higher positive predictive value than 123I-FP-CIT scintigraphy in early onset PD. The combined use of these molecular imaging studies does not seem mandatory. In fact, at this stage of disease the evaluation of the cardiac sympathetic nerve fibers integrity seems to offer a greater contribute to clinicians for the diagnosis of neurodegenerative motor disorder. Inhomogeneity of retrospective neurology molecular imaging data in multicenter studies. how to address the problem? Background-Aim: The NeuroArtP3 project (NET-2018-12366666) is a 3-year multi-site research co-funded by the Italian Ministry of Health. It brings together clinical and computational Centers operating in the field of neurology, including neurodegenerative diseases. The core objectives of the project are (1) to harmonize the collection of data across the participating centers, (2) to structure standardized disease-specific datasets and (3) to advance knowledge on diseases trajectories through machine learning analysis. In this study we have explored the feasibility to meaningfully apply a categorical scale to Dopamine Transporter (DaT) SPECT data deriving from two Centers. Methods: Retrospective DaT SPECT data were considered from 85 patients affected by Parkinson's disease (PD) performing the test as per the diagnosis standard procedure. In December 2021, data were collected from the Genoa and the Trento neurological-nuclear medicine units. DaT SPECT was acquired with different 2-head, parallelhole gamma camera (Millenium VG G.E. Healthcare in Genoa and E-Cam dual head Siemens in Trento). Due to the heterogeneity of image quality (pixel dimensions, filters, reconstruction algorithms), a semi-quantitative analysis with one of the available software is unfeasible. We thus explored the reliability of use a 5-point scale scoring system, that has recently been adopted in the Standard Operating Procedure by the Italian Virtual Neuroscience network (visual analysis: 0 = normal, 1 = reduced uptake in one putamen, 2 = in both putamen, 3 = in all nuclei, 4 = in nuclei of one side only). Results: The sample included 40 PD patients of Genoa (mean age 71.9 ± 6.0) and 45 PD patients of Trento (mean age 60.1 ± 9.5) (p \ 0.01). Genoa's group scores ranged from 1 to 4 (score 1 = 4 pts; score 2 = 25 pts; score 3 = 9 pts; score 4 = 2 pts; mean 2.225 ± 0.697 SD) while Trento's ranged from 1 to 3 (score 1 = 3 pts; score 2 = 36 pts; score 3 = 6 pts; score 4 = 0 pts; mean 2.045 ± 0.428). The scoring distribution was similar between the centers despite a significant difference in age, thus it will be blindly repeated by presenting Genoa patients to Trento nuclear medicine physicians, and vice versa. Conclusions: Sharing comparable data is key to promote quality and reliability results of solid research based on considerable amount of data. However, this implies proper harmonization of data across different centers, especially due to different equipment and postprocessing software. The issue has been managed by using a discrete visual scale, to be cross-validated by presenting scans collected in one center to specialists both from the same center and the other, blind to the clinical conditions while aware of the diagnosis. Further research is needed to understand the impact of this approach when trying to address the inhomogeneity of datasets. The unexpected relation between aortic stenosis and 99MTC-DPD bone scintigraphy: the CT-SCAN calcium score? Background-Aim: Technetium-99m-labelled 3,3-diphosphono-1,2propanodicarboxylic acid (99mTc-DPD) bone scintigraphy is well recognized as an important tool of the diagnostic work up of transthyretin (ATTR) cardiac amyloidosis (CA). The mechanism behind the high sensitivity and specificity of 99mTc-DPD scintigraphy has not been settled, but it has been suggested that the high calcium content in ATTR amyloid facilitates binding to phosphate in the radiotracer. Consequently there is a concern that the presence of high quantity of calcium in the heart (such as patients with calcified aortic stenosis) might give a false positive DPD scan in the planar image. Methods: We retrospectively enrolled fifty-five patients with a diagnosis of severe aortic stenosis (AS) who underwent 99mTc-DPD bone scintigraphy because they had a suspicion of Cardiac Amyloidosis (CA). Out of 55, thirty-three patients who also underwent CTscan for the evaluation of calcium content were selected for the final analysis. CT-aortic valve calcium was valued and quantified by an experienced operator for both groups. None of the patients had a laboratory test suspicion for AL amyloidosis. We divided the patients in two group based on the result of the scintigraphy: 12 patients had positive 99mTc-DPD bone scintigraphy (we called this group ''ASpos''), 21 patients had negative bone scintigraphy (we called this group ''AS-Neg''). AS-Pos patients had a median age of 85.5 years (vs. 82) with only one female patient (vs. 8 in the AS-Neg group). Results: A statistically significant difference between AS-Pos and AS-Neg groups was observed in calcium score (3345 vs.4785 Hounsfield units, P 1/4 0.037) calcium volume (2411 vs. 3626 mm2, P 1/4 0.03) and calcium mass (687 vs. 1147 g, P 1/4 0.023) with the AS-Neg group paradoxically having higher CT-scan calcium values. Conclusions: Contrary to expectations CT-aortic valve calcium scores were significatively lower in AS patients with concomitant positive DPD scan in comparison to patients with negative DPD scan. Therefore low calcium score in patients with AS might be a red flag for the concomitant presence of a positive DPD scan and consequently ATTR CA. Although the results are statistically significant, considering the small sample size, further and larger studies are needed to validate the results. Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 Background-Aim: The aim of the study was to evaluate the prognostic differences of myocardial 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy results between females and males in patients with heart failure (HF). The study was conducted to elucidate if the different gender physiology could reflect differences in arrhythmic events (AE) prediction. Methods: The study population was identified by patients with HF prior to implantable cardioverter-defibrillator (ICD) implantation. A dual head gamma camera and a low energy parallel hole high resolution collimator were used. Planar anterior thoracic images and single photon emission computed tomography (SPECT) images were acquired at 15 and 25 min after tracer injection. Region of interest were manually drawn over the heart and the upper mediastinum and we calculated Early and late heart-to-mediastinum ratios (eHM, lHM) and myocardial washout rate WR in early and late images. Early and late summed SPECT scores (ESS, LSS) were calculated. A univariate analysis was conducted taking into account age, body mass index (BMI), males rate, comorbidities (diabetes, dyslipidemia, chronic renal failure, chronic obstructive pulmonary disease), smoke habits, administered treatment (ACE-inhibitors, a and b-blockers, potassiumsparing diuretics, calcium antagonists, sartans, amiodarone and digitalis), ESS, LSS, eHM, lHM, WR and ejection fraction (EF). Also a multivariate analysis was conducted in general population and separately for women and man, taking into account age, administered treatment, ESS, lHM, EF, the presence of coronary artery disease (CAD). Results: 306 consecutive patients (247 males) were enrolled, 115 had AE with a median follow-up of 85 months. In general population at univariate analysis ESS (HR = 1.023 CI 95% 1.008-1.039; p = 0.003) and LSS (HR = 1.02 CI 95% 1.005-1.035; p = 0.009) have been established as risks factors for AE. Moreover, eHM (HR = 0.326 CI 95% 0.143-0.742; p = 0.008) and lHM (HR = 0.215 CI 95% 0.094-1.002; p = 0.001) were protective factor in the prediction of AE, with AUC of 0.625 and 0.645 respectively. Age (p = 0.004, HR = 1.025) and gender were significant. For female, no MIBG parameters gained statistical significance in AE prediction (p [ 0.05). Male group data results were similar to the total population, and slightly better (eHM AUC = 0.677; lHM AUC = 0.693). Moreover, the overall survival in males was superior to females, and the risk of AE in males was inferior to females. At multivariate analysis only EF (p = 0.056, HR = 0.971), gender, and gender associated to age (p = 0.042) were significant. Conclusions: MIBG represents a valid tool for AE prediction in male patients: ESS and LSS are risk factors while eHM and lHM are protective factors. In general population as eHM and lHM increases, the risk of AE diminishes, while as ESS and LSS increases the risk of AE increases. MIBG showed lower specificity and sensibility in long term analysis and in estimation of AE risk in females, maybe due to the female smaller population. Axillary lymph node hypermetabolism (ALNH) related to COVID-19 vaccination in cancer patients undergoing 18F-FDG PET/CT: a single centre study on 500 cases Nuclear Medicine Unit. University of Sassari. Italy. 2 Unit of Infectious Diseases. University of Sassari. Italy Background-Aim: The aim of the present study was to investigate the occurrence and characteristics of axillary lymph node hypermetabolism (ALNH) after COVID-19 vaccination in a large series of cancer patients undergoing 18F-FDG PET/CT. Methods: We retrospectively reviewed a consecutive series of 500 cancer patients (267 males and 233 females, aged 22-91 years, mean age: 64.9 years) who underwent 18F-FDG PET/CT after COVID-19 vaccination (period: March-October 2021). Twenty of these patients were studied twice for a total of 520 PET/CT studies; 135/520 studies were carried out after the first dose of vaccine and the remaining 385/520 studies after the second dose. All FDG PET/CT studies were acquired at the same nuclear medicine Centre according to standardized acquisition procedure protocols, using a Discovery 710 system (GE Healthcare). PET images were analysed both qualitatively and semiquantitatively calculating SUV max at the level of hypermetabolic lymph nodes. Results: ALNH ipsilateral to COVID-19 vaccination was observed in 176/520 studies (33.8%). Among the 176 positive studies, HALN was considered vaccine-related (Group 1) in 130/176 cases (74%), metastatic (Group 2) in 34/176 cases (19.3%) and equivocal (Group 3) in the remaining 12/176 cases (6.8%). SUV max was 3.5 ± 2.21 in Group 1, 8 .95 ± 5.83 in Group 2 and 3.912 ± 1.66 in Group 3 (p \ 0.0001). Among the 130 Group 1 cases, 31 were studied after vaccine dose 1 (subgroup 1A) and 99 after vaccine dose 2 (subgroup 1B) with SUV max equal to 3.12 ± 1.72 in the former subgroup and 3.62 ± 2.34 in the second subgroup (p = 0.27). Furthermore, in the subgroup 1A, SUV max was 3.68 ± 2.01 in the first week after vaccination, 2.76 ± 1.57 in the second week and 2.52 ± 1.2 in the third week (p = 0.567), while in the subgroup 1B the corresponding SUV max values were 5.51 ± 3.03, 3.81 ± 2.01 and 3.17 ± 1.96 (p \ 0.001). After third week post-vaccination, FDG lymph node avidity was observed in 2/31 subgroup 1A cases and in 27/99 subgroup 1B cases. Conclusions: In our series, the overall prevalence of vaccine-related ALNH was 25% (130/520). Vaccine-related hypermetabolic lymph nodes showed a significantly lower SUV max than that observed in metastatic lymph nodes. Equivocal findings were seen in \ 7% of cases. No statistically significant difference in SUV max was seen after dose 1 and dose 2 vaccinations. However, after the second vaccination, the SUV max was statistically higher in the first week rather than later. Finally, FDG lymph node uptake may persist beyond the third week, mainly after the second vaccination. Background-Aim: While there's a wide literature on CT abnormalities in COVID-19 sequelae, the role of lung perfusion scintigraphy have been scarcely investigated. Recent findings reported lung microvascular and endothelial alterations in patients recovered from COVID-19 without pulmonary embolism, presenting persistent dyspnea (POST-COVID). We compared perfusion scintigraphy and CT findings of these patients with dyspneic subjects in whom lung scintigraphy excluded pulmonary embolism (NON-COVID). In POST-COVID patients, the correlation between lung perfusion scintigraphic findings and (1) CT abnormalities, and (2) clinical/ biochemical parameters were also assessed. Methods: 24 POST-COVID and 33 NON-COVID patients who underwent lung perfusion scintigraphy for dyspnea from March 2020 to December 2021 were retrospectively enrolled. High-resolution chest CT performed 15 days before/after lung perfusion scintigraphy were available in 15/24 POST-COVID and 15/33 NON-COVID patients. From scintigraphic images counting rates for upper, middle, and lower fields were calculated in order to compute their ratio with total lung counts (UTR, MTR, and LTR, respectively) for both right and left lungs (RL and LL, respectively). CT images were analyzed using a semi-automated segmentation algorithm of 3D Slicer ( http://www.slicer.org), obtaining total, infiltrated and blood vessels' volumes, in order to calculate the infiltration rate (IR) and vascular density (VD). White blood cells, platelets, PT, INR, PTT, fibrinogen, and D-dimer of 15/24 POST-COVID patients were also collected from blood tests performed before the lung perfusion scintigraphy. Results: POST-COVID patients with persistent dyspnea showed reduced LTR (RL 22.4% ± 6.6%; LL 24.7% ± 3.1%) and higher MTR (RL 55.2% ± 5.2%; LL 49.1% ± 3.3%) compared to non-COVID patients (RL-LTR 29.6% ± 6.0%, p \ 0.0001; LL-LTR 28.3% ± 4.6%, p = 0.001; RL-MTR 47.3% ± 4.2%, p \ 0.0001; LL-MTR 47.3% ± 3.0%, p = 0.036), while UTR resulted bilaterally superimposable between the two groups. Similar IR and VD values at CT imaging were documented bilaterally in both groups. In POST-COVID patients, no significant correlations between lung perfusion scintigraphy and CT findings were observed. Correlation analysis indicated D-dimer levels as associated with UTR (Pearson's r = 0.664; p = 0.007) and MTR (Pearson's r = -0.555; p = 0.032), while no parameter significantly associated with LTR was observed. Conclusions: Lung perfusion scintigraphy can reveal reduced perfusion rates of lower pulmonary fields in POST-COVID patients with persistent dyspnea in the absence of pulmonary embolism, independently from CT abnormalities, infection duration and coagulation biomarkers. Although mechanisms underlying these findings need to be supported by pathological lung tissue examination, lung nonthrombotic microvascular and endothelial dysfunction may be involved. [18F]FDG PET/CT semiquantitative index as imaging biomarker of active inflammation in LVV At correlation analysis, TVS and SUV-ratio were not significantly associated with inflammatory biomarkers. However, when patients were grouped according to a progressive TVS severity score (minimal, mild, moderate, severe) higher levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were found in more severe TVS groups. Multiple linear regression analysis using multiple clinical predictor variables and TVS as a response variable showed that fever is a significant predictive factor for disease severity. In the subgroup of patients with a baseline and follow-up study, ANOVA showed that there is a significant difference in TVS between the two scan (within subject contrast, p \ 0.05) and borderline significance in ANA positive group (between subject contrast, p = 0.06). Conclusions: In conclusion, TVS appears to be a reliable score for stratifying patients with LVV. TVS allows to manage patients with severe vasculitis as well as to evaluate the response to therapy, thus providing indication for proper adaptive treatment. provides information about the presence and the extent of the infection, as compared to other imaging (e.g. trans thoracic/esophageal cardiac echocardiography). However, incidental findings, suspicious for asymptomatic CIEDI, may be detected during FDG-PET/CT scan in oncological patients (pts), thus leading to misinterpretations. Moreover, standardization of semi-quantitative parameters and extrapolation of cut-off values predictive of CIEDI are still lacking in the literature. The aim of this study was to assess the performance of FDG-PET/CT in detecting incidental pocket and lead uptakes in asymptomatic pts and to identify FDG-PET/CT predictors of CIEDI. Methods: This study was approved from the Ethical Committee of our Centre (UNEXPET-TC study). Between 2016 and 2019, FDG PET/CT of CIED pts were retrospectively retrieved and classified as follows: Group 1 (G1): pts referred from our Hospital to PET/CT for cancer or for suspected infection not related to the CIED; Group 2 (G2): pts referred to PET/CT for suspected CIEDI; expert nuclear medicine physicians blindly reviewed the scans with regard to the presence of FDG uptakes in the pocket and/or in the extracardiac leads, according to visual analysis (VI, i.e. visually suspicious findings) and by reporting standardized uptake values (SUV), liver and blood pool target-to-background ratios (TBR), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). An up-to-6 months follow-up investigating CIEDI events (antibiotic treatment only, AT or lead extraction, LE) was also performed. Results: Overall, 400 FDG PET/CT were included (G1 = 243; G2 = 157). Overall sensitivity and specificity for CIEDI (AT ? LE), according to VI were 83% and 78% in G1 and 83% and 73% in G2, respectively. According to the report, sensitivity and specificity resulted 50% and 95% in G1 and 59% and 86% in G2, respectively. Sensitivity and specificity improved for both groups, if LE was considered as the only CIEDI event. ROC analysis identified similar performances for SUV max , liver TBR and bloodpool TBR in detecting CIEDI in G1 (AUCs 0.859; 0865; 0.866 respectively, all p-values \ 0.0001). For each parameter, high specific cut-off values were identified in G1, resulted good predictors of LE event at Kaplan-Meier curves: SUV max = 2.6 (sens 71%, spec 89%; p = 0.001); blood pool TBR = 1.9 (sens 68%, spec 90%; p = 0.003); liver TBR = 1.3 (sens 69% spec 89%; p = 0.003). Moreover, pts with pocket and/or lead SUV max [ liver parenchyma had a higher risk of LE at 6 months (p = 0.007). Conclusions: Incidental FDG PET/CT findings in asymptomatic CIED pts are frequently underestimated although not rarely related to subtle CIEDI. By introducing high-specific SUV cut-off values, a considerable impact on patient management is expected. Background-Aim: Interictal positron emission computed tomography (PET/CT) with 18fluorodeoxyglucose (FDG) is routinely used for the imaging and pre-operatory planning of patients affected by pharmaco-resistant focal epilepsy. However, a detection rate (DR) of 50-60% for epileptogenic focus (EF), visualized as a hypometabolic area at PET/CT, has been reported in previously published papers. Digital PET/CT (dPET/CT), based on silicon-photomultipliers (SiPMs), has been recently introduced with relevant impact on DR in oncological and non-oncological fields. Our aim was to retrospectively assess diagnostic performance of dPET/CT with respect to traditionally used device (i.e. analogue PET/CT, aPET) for the detection of EF in patients with focal epilepsy. Methods: Two cohorts, each one encompassing 11 patients submitted to brain FDG PET/CT during presurgical workup of focal epilepsy, were enrolled, closely matched as possible for clinical characteristics. The first cohort underwent aPET/CT (discovery ST, GE, Milwaukee, WI, USA) between January 2018 and November 2019, while the second cohort was submitted to dPET/CT (Biograph Vision 450, Siemens Healthcare; Erlangen, Germany) between January 2020 to September 2021. In both cohorts, PET/CT scans were evaluated by 3 experienced nuclear medicine physicians by utilizing a 4-point visual score (i.e. modified Paldino method). Two-tailed Student's test and Fisher exact test were applied to analyze differences among groups, with significance at p \ 0.05. Results: Mean age resulted in 13 ± 4 and 13.2 ± 5.4 years for patients submitted to dPET and aPET, respectively, without significant differences among groups (p = 0.9). In the aPET cohort, EF was detected in 5 out of 11 subjects (DR 45.4%) and correlated with clinical data (i.e. MRI/EEG) in all cases, the average visual score resulted in 1.8 ± 1.2. In dPET cohort, EF was identified in 9 out 11 subjects (81.8%) and corresponded to clinical data in all cases, with an average visual score of 3.2 ± 1.0. As far as it concerns DR, there was no significant difference among the 2 cohorts at p = 0.5. The visual scores derived from dPET was meaningfully higher than that of aPET at p \ 0.05. Conclusions: Comparing with traditional aPET, dPET resulted in an increased, though not significantly, detection and a meaningfully more accurate delineation of EF in patients with focal epilepsy. Background-Aim: Recent developments in sentinel lymph node (SLN) and in radio occult lesion localization (ROLL) suggest the need for a multi-modal contrast agent providing a better pre-surgical imaging via PET and an intra-operative mapping via fluorescence detection. For this reason, we have studied a trimodal SLN/ROLL targeting agent (99mTc-68Ga-ICG) with commercially available kits of macroaggregated or nanocolloidal albumin (MA/NC-HSA). The aim of this study was to optimise the labelling and tagging of these two radiopharmaceuticals and assess their yields and stability. Methods: Radiolabelling: commercially available kits of MAA and NC-HSA particles are used for radiolabelling with 68Ga and 99mTc. A buffered solution of 68Ga-chloride is added to the MAA/NC kit previously dissolved in 2 mL saline. The 68Ga-MAA/NC suspension is incubated in a heat block at 75°C for 30 min. Then 99mTc Pertechnetate in saline is added to the labelling vial, incubated at room temperature for 20 min. Fluorescent tagging. A vial of ICG Pulsion Ò (25 mg) is dissolved in 5 mL water. 100 lL of this ICG solution was added to the 68Ga-99mTc-ICG-MAA/NC-HSA vial (incubation at room temperature for 5 min). Quality control: the radiochemical purity (RP) after radiolabelling was assessed with ITLC, mobile phases MetOH:H 2 O 85:15 and tribasic-citrate solution 0.1 M, pH 6 for 99mTc and 68Ga respectively. Fluorescent purity was measured by the same iTLC method (MetOH:H 2 O 85:15) scanned with a PDE (PhotoDynamicEye) probe. Results: The RP for the 68Ga and 99mTc labelled MAA and NC was C 97%. without significant radioactivity at the solvent front (99mTc pertechnetate and free or hydroxylated 68Ga) with the respective mobile phases. Fluorescent purity was affected by a variable amount (5-20%) of unbound dye. Additional in vitro stability tests of the hybrid imaging agent assessed with DTPA challenge, dilution test and incubation in human plasma confirmed the compound stability. Polycarbonate membrane (50-30 nm pore size, Nuclepore) filtration confirmed the absence of agglutination of NC after labelling procedure. Conclusions: This first attempt shows the possibility to obtain a SPET/PET/fluorescence imaging agent starting from commercially available kit, with a simple procedure and no additional pre-or postpurification steps. PET imaging with 68Ga could provide a quantitative pre-operative map for surgical planning with a better spatial resolution and the possibility to predict signal intensity during surgery. Comparison between 75-selenium homocholic acid taurine (SEHCAT) scintigraphy and clinical response to cholestyramine in patients affected by chronic diarrhoea: a pilot study Background-Aim: 75-Selenium homocholic acid taurine (SeHCAT) scintigraphy is the gold standard for the diagnosis of bile acid malabsorption (BAM). Recent papers showed that up to one third of patients with chronic functional diarrhoea had a short-term response to cholestyramine, clinically confirming BAM. However, cholestyramine is not yet included among first line therapies for functional diarrhoea. It is unknown whether also patients with diarrhoea and negative SeHCAT test can benefit from cholestyramine. This study aims to investigate the relationship between SeHCAT results and clinical response to cholestyramine in patients affected by chronic diarrhoea. Methods: From February to December 2021, patients with chronic diarrhoea attending our Gastroenterology outpatient clinic were prospectively proposed to undergo SeHCAT test followed by a trial of cholestyramine 8 g/day regardless from SeHCAT results. SeHCAT uptake values \ 15% were considered positive. Preliminary clinical response to cholestyramine was evaluated at 1, 3, 6 months. Results: 48 patients were proposed for the study, but only 35 (30 F; mean age 44 ± 14 years) accepted (7 refused the scan and 6 to take cholestyramine). Three patients were affected by an organic disease (1 Crohn's disease with ileal involvement, 1 coeliac disease with persistent diarrhoea despite histological response to a strict glutenfree diet, and refractory coeliac disease). 11/35 had a positive SeH-CAT test and 29 of these 35 patients were evaluated at 1 month. 10 had a positive SeHCAT and a complete response to cholestyramine, 13 had a negative test but responded to therapy, and 6 had negative test and no response to cholestyramine (sensitivity 43.5%, specificity 100%, VPP 100%, VPN 31.6%, diagnostic accuracy 55.2%). Clinical response to cholestyramine persisted over follow-up at 3 months (8 pts with positive SeHCAT and full response) and 6 months (4 patients with positive SeHCAT and clinical response and 5 with response despite negative SeHCAT). Conclusions: Our preliminary data show that cholestyramine is effective in the vast majority of patients with diarrhoea, regardless from presence of perturbations of biliary salt circulation confirmed by SeHCAT scintigraphy. [18F]FDG PET/CT in HNSCC: a head-to-head between visual point-scales and the added value of multi-modality imaging G. Santo 1 , A. R. Pisani 1 , C. Ferrari 1 , A. Branca 1 , C. Altini 1 , G. Rubini 1 1 Section of Nuclear Medicine, DIM, University ''Aldo Moro'', Bari, Italy Background-Aim: Head and neck squamous cell carcinoma (HNSCC) represents the 6th leading cancer worldwide. In most cases patients present a locally advanced disease at diagnosis and chemoradiotherapy (CRT) is considered the standard of care. Nowadays, [18F]FDG PET/CT is a validated tool in post-treatment evaluation, with a high level of evidence. However, in order to standardize imaging response, several visual scales have been proposed with none of them approved yet. The study aim is a head-to-head comparison between the diagnostic performance of the Hopkins criteria, Deauville score (both 5-point scales) and the new proposed Cuneo score (a 6-point scale), to establish their prognostic role. Secondly, we investigate the possible added value of semiquantitative analysis and morphological data. Methods: We performed a retrospective analysis on histologically proven locally advanced HNSCC patients candidate to curative-intent non-surgical treatment, who underwent baseline and response assessment [18F]FDG PET/CT. Post-treatment scans were reviewed according to Hopkins, Deauville, and Cuneo criteria, assigning a score to the primary tumor site and lymph nodes. Then, a per-patient final score for each scale was chosen, corresponding to the highest score between the two sites. Score 1-3 for Hopkins and Deauville and 1-4 for Cuneo criteria were considered as metabolic response. Sensitivity, specificity, PPV, NPP, and overall accuracy were calculated for each score considering any evidence of locoregional progression in the first 3 months as the gold standard. In addition, SUV max as well as the product of diameters of the lymph node with the highest uptake at post-treatment scan, if present, were calculated. Kaplan Meier and Cox proportional hazards regression analyses were performed to select potential prognostic factors for PFS and OS. Results: A total of 43 patients (median age 57 years; M:F = 32:11) were included. The most frequent primary tumor site was the oropharynx (19/43). The median time between the end of treatment and PET/CT was 5 months (range 2-11). The median time between diagnosis and the last follow-up was 48 months (range 7-153). Sensitivity, specificity, PPV, NPV and accuracy were 87%, 86%, 76%, 92% and 86% for Hopkins score, whereas 93%, 79%, 70%, 96%, and 84% for Deauville score, respectively. Conversely, the Cuneo score reached the highest specificity and PPV (93% and 78%, respectively) but the lowest sensitivity (47%), NPV (76%), and accuracy (77%). Each scale significantly correlated with PFS (p \ 0.0001) and OS (Hopkins p = 0.05; Deauville p = 0.001; Cuneo p = 0.002). The multivariate analysis revealed the Cuneo criteria (HR 0.271, 95% CI 0.082-0.892, p = 0.032) and the product of diameters (HR 1.004, 95% CI 1.0-1.009, p = 0.051) as prognostic factors for PFS. Conclusions: According to our preliminary results, each visual score statistically correlated with prognosis thus demonstrating the reliability of point-scale criteria in HNSSC. The novel Cuneo score showed the highest specificity but the lowest sensibility compared to Hopkins and Deauville criteria. Moreover, combining visual analyses with morphological data extracted from PET/CT could support the evaluation of doubtful cases. The emerging role of [18F]FDG PET/CT in monitoring lymphoid organs activation and irae in the era of immunotherapy G. Santo 1 , A. Branca 1 , C. Ferrari 1 , N. C. Merenda 1 , N. Maggialetti 2 , G. Rubini 1 1 Section of Nuclear Medicine, DIM, University ''Aldo Moro'', Bari, Italy. 2 Section of Radiodiagnostics, DSMBNOS, University ''Aldo Moro'', Bari, Italy Background-Aim: Immune checkpoint inhibitors (ICI) have revolutionized the therapeutic landscape of different cancers. For therapy success, a systemic antitumor response involving primary and secondary lymphoid organs is required, which can lead to immunerelated adverse events (IRAE) as an index of immune-response upregulation. Interestingly, patients treated with ICIs who develop an IRAE have been shown to have reduced risk of death and progression. The study aim is to evaluate the predictive role of [18F]FDG PET/CT in the early immune organs activation and/or IRAE detection and their impact on treatment efficacy. The second goal is to investigate the prognostic value of baseline inflammation biomarkers and PET parameters. Methods: This single-center retrospective study analyzed patients treated with ICI for advanced cancer who underwent [18F]FDG PET/ CT before and after the immunotherapy initiation. Each IRAE detected on the first restaging PET images was reported. SUV max of lymphoid organs (spleen, liver to spleen ratio-LSR-and bone marrow-BM) were extracted from baseline and first restaging PET scans. Moreover, inflammation biomarkers (ANC, ALC, AMC, PLT as well as neutrophiles/lymphocyte ratio-NLR-, monocyte/lymphocyte ratio-MLR-, and platelet/lymphocyte ratio-PLR) before ICI initiation were collected. Objective response was considered as complete or partial response, according to the imaging modality available for each patient. The relation between the detection of IRAE as well as metabolic activation of lymphoid organs and objective response to ICI was assessed by using Chi-square and Fisher's exact test. A multivariate prediction model was developed using Cox Model for OS (p \ 0.05). Results: Thirty-five patients (mean age 65 y, range 44-85) affected by lung cancer or melanoma (28:7) were eligible. Median follow-up was 19 months (range 4-65 months). Twelve patients (34%) experimented objective response to ICI. At least one IRAE was detected at the first restaging PET images in 11 (31%) patients (8 responders, 3 no-responders). A significant correlation between IRAE detection and objective response was observed (p = 0.004), with a higher incidence of IRAE in responders. In multivariate analyses, the increased of PLR (HR 114.0, 95% CI 6.3-2057.9, p = 0.001), the bone marrow SUVmax [ 2.0 (HR 5.7, 95% CI 1.1-28.9, p = 0.036), as well as the decrease of baseline AMC (HR 0.05, 95% CI 0.006-0.41, p = 0.005) resulted associated with a shorter OS. Basing on BM SUV max and AMC, the study population was stratified into three groups: good prognosis (BM SUV max Background-Aim: Immune checkpoint inhibitors (ICIs) proved to have a significant survival benefit and improved tolerability profile in a variety of tumors, including melanoma. However, about 40% of patients do not respond to ICIs and severe adverse events may occur. An accurate pre-therapy prediction of response is difficult due to the lack of reliable biomarkers and the possible atypical radiological response patterns. The identification of 18F FDG PET/CT parameters as indicators of ICIs efficacy could potentially be useful to predict clinical benefit and to adjust therapy regimens. The aim of this study is thus to evaluate the correlation between quantitative PET/CT parameters defined before the beginning of ICIs and the response to treatment and patient outcome in advanced stage melanoma. Methods: We retrospectively analyzed 38 patients with diagnosis of advanced stage melanoma (stage IV), treated with either Nivolumab or Pembrolizumab in any line from 2016 to 2021 who underwent a basal 18F FDG PET/CT scan within 3 months before the beginning of ICIs. Basal PET parameters (whole-body metabolic tumor volume-wMTV, total lesion glycolysis-wTLG, highest standardized uptake volume maximum, mean and peak-SUV max , SUV mean and SUV peak ) as well as clinical parameters (neutrophil/lympocyte ratio-NLR, presence of metastasis, BRAF mutation) were considered for each patient. We then investigated the association between these parameters and response to ICI and survival. Results: In the univariate analysis, lower basal NLR was associated with better response (p = 0.002) and survival (p = 0.012) as well as absence of metastatic disease. Among PET/CT parameters, higher SUV max , MTV and TLG correlated with worse PFS, while no relation was found with OS. No relation was found between SUV mean and SUV peak and efficacy outcomes. A trend of association was found between survival and MTV (p = 0.073) and TLG (p = 0.068), whereas response to ICI was significantly associated with all quantitative PET parameters: SUV max (p = 0.029), SUV mean (p = 0.054), SUV peak (p = 0.03), MTV (p = 0.036) and TLG (p = 0.033). Conclusions: Our study demonstrates that basal bioumoral values and 18F FDG PET/CT parameters could have an important role in predicting the response to ICIs, mainly because they seem to reflect the immune status of patients, thus helping in stratification and personalization of therapy. Prospective studies are needed to better establish their effective role. Circulating mirnas as prognostic biomarkers in advanced gastroentero-pancreatic neuroendocrine tumors. correlation with peptide receptor radionuclide therapy efficacy, 18FDG and 68GA-Dotatoc pet uptake M. Bocchini 1 , I. Grassi 2 , S. Nicolini 2 , M. Tazzari 1 , S. Ravaioli 3 Background-Aim: Peptide receptor radionuclide therapy (PRRT), targeting SSTR2, have shown cytoreductive potential and prolonged disease-progression free survival (PFS) in patients with unresectable metastatic Gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs). Although PRRT extends PFS, about 15-30% of patients with advanced well-differentiated GEP-NETs progress during treatment between 6 months and 1 year. 18 F-FDG PET uptake is used as a prognostic indicator of aggressiveness in GEP-NETs but further prognostic biomarkers for stratification and management of GEP-NET patients are needed. Circulating miRNAs as well, are considered promising biomarkers for disease detection and monitoring. This study aims to identify circulating and measurable prognostic miRNAs in pancreatic (p-NETs) and ileal NETs (SINETs). Methods: From October 2016 to September 2019, patients with advanced G1, G2 and G3 GEP-NET, were enrolled in the non-randomized LUX (NCT02736500) and LUNET (NCT02489604) clinical trials. Whole miRNOme NGS profiling was conducted in plasma of well-differentiated GEP-NETs, prior to PRRT (screening set, n = 24). Differential expression analysis was performed between 18 F-FDG positive and negative patients, and candidate miRNAs were also evaluated for their correlation with 68 Ga PET uptake and therapeutic efficacy. Validation was conducted by Real Time q-PCR in two distinct well-differentiated GEP-NET cohorts, considering the primary site of origin (p-NETs n = 38 and SINETs n = 30). The Cox regression was applied to assess miRNAs signature value as independent biomarker for clinical parameters, imaging, and survival p-NETs. Results: While any miRNAs emerged to be deregulated in SINETs, three miRNAs were found to correlate with 18 F-FDG-PET positivity in p-NETs (p-value: \ 0.005). In addition, statistical analysis revealed miR-B (cut-of 70) as independent predictor of shorter mPFS (p-value: \ 0.001) and mOverall Survival (p-value: \ 0.05) upon PRRT (6 and 12 months, respectively). Of clinical relevance, increased miR-B level in plasma allows to identify 18 F-FDG-PET positive p-NET patients with worse prognosis after PRRT (pvalue: \ 0.005). In addition, Cox regression model showed anticorrelation of miR-B with 68 Gallium-PET uptake (p-value:.05) and with SSTR2 expression in tumor tissue, at single cell level. Conclusions: Three miRNAs were identified with high prognostic power for 18 F-FDG-PET status. In addition, miR-B well performs as an independent biomarker of worse prognosis especially in 18 F-FDG-PET positive patients. Importantly, miR-B seems to downregulate SSTR2 expression, affecting PRRT efficacy. Role of 68GA-dotatoc PET in pre-operative prediction of DAXX/ ATRX loss of expression in pancreatic neuroendocrine tumours P. Mapelli 1 , C. Bezzi 2 , S. Ghezzo 2 , C. Canevari 3 Background-Aim: DAXX/ATRX loss of expression is a well-known genetic marker and a feature of aggressiveness in patients affected by pancreatic neuroendocrine tumours (PanNETs). The aim of the present study is to evaluate the role of 68Ga-DOTATOC PET parameters in predicting the DAXX/ATRX loss of expression in patients with PanNETs candidate to surgery. Methods: This retrospective study included 40 patients (15 females, 25 males, median age: 60 years, range: 40-80) with histologically proven PanNET who underwent to 68Ga-DOTATOC PET (19 PET/ MRI, 21 PET/CT) at IRCCS San Raffaele Scientific Institute (June 2018-June 2021) for staging purpose. The following PET parameters were extracted form primary PanNET: SUV max , SUV mean, somatostatin receptor density (SRD) and total lesion somatostatin receptor density (TLSRD). Nonparametric Mann-Whitney U test was used to investigate the potential of PET parameters in differentiating patients according to immunohistochemical staining for DAXX/ ATRX. Benjamini-Hochberg correction for multiple testing was performed, and parameters coupled with adjusted p-value \ 0.05 were selected for subsequent analyses. The population was split into a train (80%) and a test (20%) set, and univariate and multivariate Logistic Regression analyses were performed on the train set and validated on the test set, collecting accuracies and log losses. All statistical analyses were performed using Python 3.7. Results: Eleven/40 PanNET patients presented DAXX/ATRX loss of expression and 29/40 showed wild-type genotype. A statistically significant difference in SRD40 parameter (p-value = 0.005; adjusted p-value = 0.020) was observed between wild-type and loss of expression categories. After correction for multiple testing, statistical significance in distribution of TLSRD40 values was lost (p-value = 0.049; adjusted p-value = 0.098), and SUV parameters (SUV max ; SUV mean 40) did not discriminate the two groups. On the test set, univariate Logistic Regression analyses provided an accuracy of 0.88 (log loss: 0.47) and 0.63 (log loss: 0.52) for SRD40 and TLSRD40, respectively. Multivariate logistic regression model combining SRD40 and TLSRD40 showed no further increase in accuracy (0.88) and small reduction of the log loss (0.41). These results, together with the high correlation measured between SRD40 and TLSRD40 parameters (r = 0.89, p-value \ 0.001), suggest that SRD40 alone seems sufficient in the pre-operative evaluation and prediction of DAXX/ATRX mutation. Conclusions: The association between 68Ga-DOTATOC parameters and DAXX/ATRX expression has been reported. SRD40 showed a significant difference between patients with and without mutation, demonstrating its role in predicting the presence of DAXX/ATRX loss of expression. Relevance of volumetric parameters applied to 68GA-DOTATOC PET/CT in net patients treated with PRRT Background-Aim: the aim of this work was to assess the relevance of volumetric parameters applied to 68Ga-DOTATOC PET/CT, in relation to clinical outcomes of NET patients treated with peptide receptor radionuclide therapy (PRRT). Methods: We retrospectively evaluated 39 patients (21 males, 18 females, mean age 60.7 years) with NET of various origin who were treated with PRRT within FENET2016 trial (CTiD:NCT04790708). PRRT was proposed with 177Lu-DOTATOC alone or combined with 90Y-DOTATOC. 68Ga-DOTATOC PET/CT was performed 3 months before and after PRRT. For each PET/CT, we calculated SUV max , SUV mean , somatostatin receptor expressing tumour volume (SRETV) and total lesion somatostatin receptor expression (TLSRE), as well as their percentage of changes (D) for liver tumor burden and for total tumor burden, referred to the five most relevant lesions according to RECIST 1.1 criteria. SRETV was estimated by a semiautomatic tumor-contouring software with a predefined threshold of 40% of SUV max , while TLSRE was obtained multiplying SRETV and SUV mean . Early clinical response was evaluated according to RECIST 1.1 criteria and institutional NET board, while progression free survival (PFS) was compared using the Kaplan-Meier method and the log-rank test. Results: We treated NET from pancreas (n = 19), midgut (n = 7), bronchial (n = 6), cerebral (n = 1), paraganglioma (n = 1) and unknown origin (n = 5). Grading was G1, G2, and G3 for 4, 31, and 3 patients respectively. Grading was unknown in 1 patient. Median Ki67 was 8%. Early clinical response documented 9 partial response (PR), 25 stable disease (SD), and 5 progressive disease (PD). Median follow-up was 31 months. Post-treatment SRETV and DSRETV for total tumor burden were progressively increased among response groups (median post-SRETV was 11.3 for PR, 37.4 for SD and 139.2 for PD, p = 0.02; median DSRETV was -37.4% for PR, ? 14.5% for SD and ? 24.8% for PD, p = 0.03). Likewise, median post-SRETV for liver burden was significantly higher in PD patients (10.1 for PR, 63.8 for SD and 468.4 for PD, p = 0.03). Contrarily, SUV max and TLSRE did not correlate with early clinical response, both for total and liver tumor burden. Furthermore, no correlation was found between volumetric parameters and Ki67. Patients with post-treatment SRETV for total tumor burden lower than the median value (34.8) showed a trend for longer PFS (31 vs 27 months; p = 0.06). Likewise, patients with DSRETV for total tumor burden lower than the median value (-4.17%) had a statistically significant longer PFS (36 vs 25 months; p = 0.006). Conclusions: volumetric parameters, expressed by liver and total tumor burden SRETV, correctly assessed early treatment response to PRRT. Moreover, total tumor burden DSRETV was able to discriminate patients with longer PFS. However, further prospective investigations are necessary to confirm our preliminary results. Long-term follow-up of patients thyroidectomized for thyroid papillary carcinoma (PC) with associated Graves's disease (GD): a 131I-SPECT/CT diagnostic study A. Marongiu 1 , S. Nuvoli 1 , A. Spanu 1 , G. Madeddu 1 1 Background-Aim: The relationship of thyroid differentiated carcinomas (DTC) with GD is still unclear and it is a matter of controversy whether cancer behavior is more aggressive in this condition. The present study aimed to evaluate DTC patients with associated GD in a long-term follow-up after total thyroidectomy and radioiodine ablation. Methods: We retrospectively enrolled 30 consecutive patients with GD and PC, 16 with microcarcinoma. We also evaluated 312 euthyroid control PC patients matched for sex, age, and tumor size who underwent total thyroidectomy and radioiodine ablation during the same period as GD patients. All control cases, at surgery, did not show risk factors, such as extra-thyroid tumor extension (ETE), multifocality, and neck and distant metastases. Both GD and control patients were followed up postoperatively by 131I whole-body scan (WBS) and SPECT/CT after 185 MBq radioiodine dose using a hybrid dual-head gamma camera, and by thyroglobulin (Tg) assay; the mean follow-up period was 10 years. Results: Fourteen/30 GD patients underwent metastases during follow-up (Group 1), while 16 did not develop metastases (Group 2). Of the 14 Group 1 patients, 10/14 cases did not show risk factors at surgery, 5/10 being microcarcinomas. SPECT/CT detected 13 neck lymph node metastases, 2 of which were unclear, 1 wrongly classified, and 10 occult at WBS; Tg was undetectable or very low. Of the remaining 4/14 cases, 2 patients, 1 with microcarcinoma, had minimal ETE at surgery and SPECT/CT detected 2 neck metastases at followup occult at WBS, 1 patient with neck metastases at surgery developed further metastases only visualized at SPECT/CT, and in 1 patient with 5 lung metastases at surgery, both SPECT/CT and WBS confirmed these at follow-up; Tg was undetectable only in 1 case. Of the 16 Group 2 cases, 10 patients, 5 with microcarcinomas, had no risk factors at surgery and were negative for metastases at SPECT/CT and WBS at follow-up with Tg undetectable; of the other 6/16 patients, one had minimal ETE at surgery and the remaining 5 cases with microcarcinomas were multifocal and negative at SPECT/CT and WBS at follow-up with undetectable Tg. Of 312 PC control cases, 21 patients, 8 with microcarcinoma, developed metastases during follow-up, with SPECT/CT identifying 27 lesions, 18 of which occult at WBS; Tg was undetectable or very low in 17/21 cases. Comparing GD patient Groups with the control Group, the percentage of patients who developed metastases, among those without risk factors at surgery, was 33.3% for GD cases while it was 6.7% for control cases (p \ 0.001). Conclusions: In the present study, PC and GD patients had aggressive behavior in 46.7% of cases with neck and distant metastasis appearance at follow-up also when carcinoma characteristics were favorable and some cases also were microcarcinomas. PC patient comparison between GD and non-GD cases seems to suggest that there is an increased risk to develop metastases in GD during follow-up. Routine 131I-SPECT/CT proved useful to identify metastases also when Tg was undetectable or very low with significantly higher performance than WBS. FDG-PET/CT versus genomic analysis in symptomatic multiple myeloma: is there a correlation? Background-Aim: Multiple myeloma (MM) is a pathological condition characterized by impressive differences in clinical presentations and prognosis due to different genomic profiles observed since the earliest stages of disease. A spatial heterogeneity can be also demonstrated at FDG PET/CT images, where focal bone lesions (FL) and paramedullary (PM) involvement may be associated to diffuse medullary infiltration (BM) and extramedullary localizations (EM). The aim of this study was to explore a possible correlation between FDG PET/CT characteristics and genomic profiles in symptomatic MM at diagnosis. Methods: We retrospectively enrolled patients affected by symptomatic MM at diagnosis who underwent the evaluation of the tumor fraction of bone marrow genomic DNA (gDNA), obtained by conventional bone biopsy, and tumor fraction of cell free DNA (cfDNA), obtained by liquid biopsy. Consequently, patients with a different genomic profile between cfDNA and gDNA were identified and their FDG-PET/CT distribution patterns compared. FDG PET/CT, performed within 1 month from the genomic analysis, were read and reported through IMPETUS criteria. These include a visual image interpretation that quantifies FDG uptake of the hottest lesion, using SUV max and the Deauville score (DS), in association to BM diffuse uptake, FL uptake and number, PM or EM lesions. To compare different PET characteristics and genomic profiles we used the Wilcoxon rank test. Continuous variables were correlated through the Spearman rank correlation. Results: Between 2016 and 2021, FDG-PET/CT scans of 90 patients meeting the inclusion criteria were retrospectively retrieved. Overall mean ctDNA was 10%, while mean gDNA was 58%. Regarding gDNA we found a statistically significant difference between pts with a negative PET and those with a positive PET on the BM only (according to IMPETUS, BM DS [ = 4) (p = 0.045, median 54.4% vs 68.7%). Regarding the ctDNA obtained by the periferal blood, we found: 1. a remarkable although not statistically significant difference between pts with a negative PET and those with a positive PET regardless the site of disease (p = 0.195, median 2.5% vs 5.2%) 2. a remarkable although not statistically significant difference between pts with a negative PET and those with PM and/or EM disease (p = 0.20, median 2.5% vs 8.7%) 3. a statistically significant difference between patients with a negative PET and those with PM and/or EM disease and at least one FL (p = 0.047, median 2.5% vs 14.8%) 4. a significant but weak correlation between SUV max of FL and cfDNA (p = 0.0058, rho = 0.36). 8 pts presented different genomic profiles between cfDNA and gDNA, 6/8 had at least one FL at PET and a gDNA significantly higher than the mean value.3/6 had also PM disease. Conclusions: According to our preliminary results, BM PET positivity reflects a higher tumor fraction of bone marrow. Furthermore, patients presenting with focal disease in terms of concomitant FL and PM and/or EM disease reflect a higher circulating DNA fraction. Further studies are needed to deepen the value of all these parameters in order to refine the patients prognostic curves. does not provide insight on tumour biology and prognosis consistently. We hypothesized that microscopic tracer distribution patterns within and in the proximity of the tumour could disclose relevant prognostic information. To test this hypothesis, we performed a texture analysis of 18 F-FDG PET imaging and we compared the output of this analysis with the pathology characteristics and the patients' outcome after the complete resection of the tumour. Methods: All patients preoperatively imaged with 18F-FDG PET-CT who underwent hepatectomy for IHC in the period 2010-2019 were retrospectively evaluated. On PET images, manual slice-by-slice segmentation of IHC was performed (tumour-VOI). A 5-mm margin region was semi-automatically generated around the tumour (Margin-VOI). Textural analysis was performed using the LifeX Ò software. Analysed outcomes included: tumour grading (G3 vs. G1-2), microvascular invasion (MVI), overall survival (OS), and progression-free survival (PFS Moreover, models including radiomics had a non-inferior performance than those that included the complete the pathology and postoperative data (C-index = 0.81 for OS; 0.79 for PFS). Of note, none of the models retained the standard SUV measures. Conclusions: The PET-based radiomics of IHC can predict pathology data and allow a reliable preoperative evaluation of prognosis. Radiomics of both the tumoral and peritumoral areas had clinical relevance. The combined clinical-radiomic models outperformed the pure preoperative clinical ones and achieved performances non-inferior to the postoperative models. Overall, radiomics analysis of the pre-operative 18F-FDG PET allows achieving the same level of prognostic confidence that is granted by the post-operative data. Radiomics in locally advanced cervical cancer using 18F-FDG-PET/CT images Background-Aim: In the era of precision medicine, in order to tailor a more targeted treatment strategy, imaging techniques and novel technologies could be the key for predicting the tumor response before therapy. Recently, there has been a growing interest towards the extraction and analysis of quantitative features from medical images, denoted as radiomics. This study aims to assess whether radiomic features extracted from pretreatment PET/CT in locally advanced cervical cancer (LACC) patients, treated with neoadjuvant chemoradiotherapy (nCRT) followed by surgery, could be used to identify responding and non-responding patients as well as to predict tumor aggressiveness with the aim of personalizing treatment. The medical records of all LACC patients, which were referred to the Division of Gynecologic Oncology of our Institution between July 2010 and July 2016, were reviewed. PET/CT was performed for each patient before nCRT. Primary tumor volumes were delineated semiautomatically on all PET images using an isocontour method with a threshold of 50% of SUV peak corrected for local background activity. Radiomic features were extracted and correlated with pathological response using Mann-Whitney or independent t test as appropriate. Univariable logistic regression analysis was used to identify predictors of pathological tumor response among the parameters. Results: A total of 195 patients fulfilled the inclusion criteria. At histopathological evaluation after surgery, 131 patients (67.2%) had pathological response (pR0-pR1) while 64 patients (32.8%) had pathological non-response (pR2). SUV mean and contrast were significantly higher in patients achieving pathological response than in those with pR2 (p = 0.039 and p = 0.0007, respectively). Center of mass shift, inverse difference moment normalized and zone distance non uniformity normalized were significantly higher in patients with pR2 than in those with pathological response (p = 0.035, p = 0.013, p = 0.040, respectively). Univariable logistic regression analysis revealed that higher values of SUV mean and contrast were significantly predictive of pR0-pR1, whereas higher values of MTV, morphological volume and zone distance non uniformity normalized were significantly predictive of pR2. Conclusions: In LACC patients treated by nCRT followed by surgery, radiomic features are useful to predict histopathological response to treatment. The identification of high-risk patients at diagnosis allows to plan a personalized treatment. However, these radiomic features should be validated in larger, prospective multicentric studies before considering their integration into clinical decision algorithms. Background-Aim: Amyloid PET imaging is used as a non-invasive method to assess cortical amyloid burden in patients with Alzheimer's disease (AD). The standard approach for the interpretation of amyloid PET is the visual reading performed by experts, which involves inherent limitations associated with the inter-reader variability. In this work, we propose a novel amyloid PET visual interpretation support system that aims to improve the confidence of visual reading through the use of a convolutional neural network (CNN). Methods: For training and validation data, we used a database of 18 F-Florbetaben PET/CT collected between 2017 and 2021 in the Nuclear Medicine Unit and composed of 95 patients, 57 of which were amyloid positive. According to the visually assessed criteria of 18 F-Florbetaben, two nuclear medicine specialists labeled these PET scans either negative or positive. As for the tests, our 18 F-Florbetaben PET/ CT dataset included 31 amyloid negative and 40 amyloid positive subjects. All patients underwent a 20 min dynamic positron emission scan at 90 min after the intravenous injection of 300 MBq of 18 F-Florbetaben; all images were acquired using Siemens Biograph mCT and Vision PET/CT scanners. All dataset groups used the very preprocessing procedure and acquisition protocol. We trained a CNN model to classify positive and negative images. The proposed network is based on the Darknet CNN architecture: Open-Source Neural Networks in C, published on https://github.com/pjreddie/darknet, and consists of 24 convolutional layers, followed by 2 fully interconnected layers. The network uses a linear activation function for the last layer, while for all other layers it uses the following activation function: /(x) = {x if x [ 0 or 0.1 9 otherwise. The network is trained explicitly to adjust the value of the weights w and of the biases b autonomously. For the training phase the neural network uses the cost function, which returns a measure of how much the prediction deviates from the expected result. Results: In order to compare the performance, accuracy, sensitivity, and specificity were calculated: the best results were 84%, 79%, and 90% (respectively) for the training data, vs 82%, 76%, and 90% (respectively) for the dataset tests. The results of our model of evaluation for amyloid positivity classification in 18 F-Florbetaben brain PET scans yielded an average accuracy of approximately 85%, a percentage consistent with other CNN-based neuroimaging classification studies. These results support that this CNN model can help diagnose AD by training a computer-aided detection tool to determine Amyloid positivity, since the above-mentioned model has proven to be able to detect brain Amyloid deposition reasonably well. Conclusions: Our results point out how a deep learning-based onestep amyloid burden estimation system impact on confidence of amyloid PET reading when applied to clinical routine. Radiomics analysis of brain 18F-FDG PET/CT imaging to predict amyloid pet positivity and diagnosis of AD: a preliminary report on the application of SPM cortical segmentation, pyradiomics and machine-learning analysis Background-Aim: Alzheimer's disease (AD) is the most common form of progressive and irreversible dementia. Early in-vivo diagnosis of AD is crucial for an accurate management of patients, in particular to select subjects with mild cognitive impairment (MCI) that may really evolve into AD, and to define other forms of MCI non-AD patients. Brain FDG-PET/CT is a functional neuroimaging evaluating dysfunction, synaptic disconnection and neuronal loss in AD. Amyloid-PET/CT is currently being recognized as a determining role in the diagnosis of AD with high negative predictive value, despite a sub-optimal specificity for possible beta-amyloid deposition in some non-AD conditions. The application of artificial intelligence through the development of radiomics predictive models on functional FDG-PET imaging aiming to increase diagnostic accuracy in the diagnosis of AD is still undetermined. In this field, we propose a radiomics analysis (Pyradiomics) on advanced imaging segmentation method SPM-based completed with a Machine-Learning application to predict the diagnosis of AD, also by comparing the results with following Amyloid-PET and final clinical diagnosis. Methods: From July 2016 to September 2017, 43 patients (mean age 71 years; females = 23; males = 20; Mean MMSE = 20) underwent PET/CT with 18F-FDG and 18F-Florbetaben brain PET/CT and 24 months of clinical/instrumental follow-up and retrospectively evaluated by a multidisciplinary team (MDT = Neurologist, Psychologist, Radiologist, Nuclear Doctor, Laboratory Clinic) at the G. Giglio Institute in Cefalù, Italy. On the basis of the VOI segmentation applied using SPM on the principal cortical macro-areas of each individual patient, Pyradiomics software was used for features extraction, then a machine learning approach with discriminant analysis was tested to select and define the features capable of obtaining the best diagnostic performance in prediction amyloid deposition and the final diagnosis of AD. Results: A total of 11 radiomic features were defined as significantly predictive of cortical beta-amyloid deposition (n = 6) and AD (n = 5). Among these features selected, FDG/PET was found to predict the positivity of Amyloid-PET with maximum values of sensitivity, specificity, precision, and accuracy (respectively of 84.92%, 75.13%, 73.75%, 79.56%) for two features of higher-order (original_glcm_Idmn and original_glcm_Id) extracted from ROI-1 (limbic entorhinal cortical area); while in predicting the final clinicalinstrumental diagnosis of AD we obtained the maximum values of sensitivity, specificity, precision and accuracy (respectively 75.16%, 80.50%, 77.68%, 78.05%) for two other higher-order features (orig-inal_glcm_MCC original_glcm_MaximumProbability) extracted from ROI-2 (frontal cortex) and one higher-order feature (origi-nal_glcm_Idmn 80.88%, 76.85%, 75.63%, 78.76% from ROI-3 (medial Temporale cortex). The results obtained in this preliminary study support the feasibility of the use of artificial intelligence based on advanced segmentation (SPM) of cortical areas and extraction of specific highorder radiomic features (Pyradiomics) in typical cortical areas involved in early AD conditions on 18F-FDG PET/CT brain images, resulted at machine-learning analysis as potentially able to predict Amyloid deposition and final diagnosis of AD. between January 2015-2020. Complete clinical/surgical history, laboratory, imaging, therapy and DUKE/2015 ESC classification criteria were collected. Regions of interests were semiautomatically segmented from PET/CT images (Advantage Workstation, GE) and texture features were extracted with LIFEx software. Descriptive statistics was performed with univariate testing and contingency tables on clinical variables, Manova and logistic regression (LR) on uncorrelated and PCA-reduced radiomic features. Synthetic Minority Over-sampling Technique has been applied to manage imbalanced dataset prior to model building. A Random Forest, cross-validated on training set (80%) and tested on validation set (20%), was implemented for IE prediction from PET/CT. Additionally, patients were clustered in risk classes according to their radiomic signature. Finally a set of LR models was built on different combinations of clinical, imaging, and laboratory information. Results: Through contigency analysis embolisms were most frequently diagnosed in IE sustained by MSSA, E. faecalis and in bloodculture negative IE. Radiomics signature was tested different in IEpositive/IE-negative patients at both inference analysis (p \ 0.05) and classification model (accuracy: 80% in training, 70% in testing). Of interest, the signature of patients with equivocal PET/CT was similar to IE-negative patients' signature. Two classes of patients resulted from clustering analysis: one with milder disease and weak or no [18F]FDG uptake and one with more severe disease and higher [18F]FDG uptake. LR models with incremental complexity showed how the richer the information the higher the performances, up to 90% of AUC. Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 To perform the texture analysis of the PET images, we segmented lesions using three different methods on patients with possible diabetic foot complications, two semiautomatic (with a threshold fixed at 20% and 40% of the relative SUV max on PET, respectively) and one manual (delineating the segmentations on CT). On the control group we segmented the whole foot. Radiomics texture features were extracted using the LIFEx software package both from PET and CT. To avoid redundancy, we remove predictors whose pairwise correlations were over the 0.75 threshold, while in order to compare data extracted from different segmentation methods the ones correlated to volumes were not further selected. Data were correlated with the presence of Osteomyelitis (OM), Soft Tissue Infections (STI) and Inflammation (INF), using the diagnosis based on PET/CT first and then on the final diagnosis as reference. Data were analysed by linear discriminant analysis and validated performing a tenfold cross validation. The diagnostic performance of PET/CT was evaluated in terms of sensitivity and specificity. Results: Texture features analysis allowed to discriminate the presence of OM, STI and INF. The best overall performance was obtained by the manual segmentation, but with almost identical results using the semiautomatic segmentation with a fixed threshold of 40% of SUV max . The latter has also proved to be the most consistent in PET, improving its performance in models based on the final diagnosis. Background-Aim: Hepatocellular carcinoma (HCC) is the fifth most common neoplasm in the world and the second leading cause of cancer-related death. For patients with early-stage HCC the recommended treatment is liver resection or liver transplantation. However, when surgical resection or liver transplantation are not feasible, a loco-regional ablative therapy can be an alternative treatment but with poor results in the case of ''large'' tumors (higher than 5 cm Cumulative OS rates at 1, 2, and 3 years were 58.0%, 47.0%, and 42.0%, respectively. Median TTP after treatment was 18 months (range 0.0-37.4), with 16 cases of progression in untreated liver and 6 cases of extrahepatic progression. In the multivariate analysis the maximum lesion diameter was the stronger independent predictor of poor prognosis: median OS was 42 months in patients with diameter lesion lower than 8 cm and 11 months in patients with diameter lesion higher than 8 cm respectively (p \ 0.05). Furthermore, on multivariate analysis bilirubin levels confirmed a negative relation with TTP that was better in patients with bilirubin levels lower than 1.5 mg/dL (p \ 0.05). Conclusions: Our data showed that TARE is a valid therapeutic option in BCLC stage-A HCC patients with large monofocal lesion, with better results in patients with tumour diameter less than 8 cm and bilirubin level lower than 1.5 mg/dL. Radioembolization with yttrium-90 polymer beads (sir-spheres) in hepatocellular carcinoma: our 5-years' experience Background-Aim: Recently, new radioactive microspheres loaded with Holmium-166 have been made commercially available for locoregional treatment of primary and secondary unresectable liver cancer. 166 Ho shows specific radiological and clinical properties as compared to 90 Y, such as low-energy c-emission for quantitative SPECT imaging to predict microspheres distribution and lung shunting (''ScoutDose'', instead of [ 99m Tc]-MAA), and shorter halflife (26.8 h), yielding deposition of 90% of the radiation in the tumor tissue in 4 vs 11 days. Furthermore, post-treatment distribution imaging using MRI is viable thanks to the paramagnetic properties of 166 Ho. Here, we aim at analyzing early radiological tumor response to 166 Ho-RE in patients with primary or secondary liver tumors. Methods: We retrospectively collected data from all patients treated using 166 Ho-RE between January 2018 and December 2020, following eligibility assessment according to these inclusion criteria: (a) tumor burden \ 50% of the liver volume; (b) liver-only or liverdominant disease; (c) Child-Pugh score within B7; (d) Eastern Cooperative Oncology Group (ECOG) performance status 0-1; (e) no previous radiation therapy; (f) age [ 18 years. The study was approved by the Institutional Review Board and informed consent was waived. Post-treatment dosimetry was assessed by SPECT/CT before patients' discharge. Target and overall tumor responses were assessed on triphasic CT at 6 ± 2 weeks, based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 for all tumor types, and, additionally, modified RECIST (mRECIST) for hepatocellular carcinoma (HCC) and arterially enhancing metastases. In patients with disease control, subsequent response was analyzed on crosssectional images at 12 ± 2 weeks and the best radiological response was collected. Results: Twenty-six patients were included (21 male; mean age 70.6 ± 8.7 years) with intrahepatic cholangiocarcinoma (ICC, n = 5), hepatocellular carcinoma (HCC; n = 12) and metastastic lesions (n = 9). The median administered activity was 3.54 GBq and the median average tumor absorbed dose (TAD) was 107 Gy. Best target and overall OR rates were 50% and 42.3%, respectively, with corresponding DC rates of 76.9% and 57.7%. Early tumor shrinkage as to achieve PR by RECIST 1.1 was observed in 7/26 patients, allowing liver transplantation in one HCC case and resection in an ICC patient. Target response was significantly associated to TAD, with a minimum threshold of 118 Gy to achieve OR (AUC 0.77). Conclusions: Early reduction in tumor size was evident in 25% of patients, making 166 Ho-RE a safe and effective treatment option in primary and secondary liver tumors; further studies are needed to implement personalized dosimetry. Background-Aim: To investigate safety and efficacy of Yttrium-90 transarterial radioembolization (90Y-TARE) in patients with unresectable intrahepatic cholangiocarcinoma (ICC). Methods: We retrospectively evaluated data of 23 consecutive patients with locally advance ICC treated with 90Y glass microspheres as first-line therapy or after chemotherapy failure at a single Institution. Macroaggregated albumin (MAA)-based SPECT/CT dosimetry was used to plan treatment through tumor dose (TD) and non-tumoural whole liver dose (NTWLD). Tumor response was assessed using mRECIST criteria 3-6 months after each TARE. Side effects were assessed using NCI-CTCAE version 5 criteria. Overall Survival (OS) and Progression-Free Survival (PFS) were evaluated from the first TARE (Kaplan-Meier methodology). Results: 90 Y-TARE was administered 30 times (7 repeated administrations), for a total of 35 lesions treated. Eight out of 30 treatments were performed as first line therapy. The mean 90Y-loaded glass microsphere injected activity was 2.5 GBq (95% CI 2.1-2.9). Mean NTWLD was 42.4 Gy (95% CI 34.5-50.3). One grade 3 treatmentrelated liver toxicity was observed. No clinically relevant extra-hepatic toxicity was recorded. We obtained 1 complete response (CR 1/30 = 3%), 1 partial response (PR 1/30 = 3%), 26 stable disease (SD 26/30 = 87%) and 2 progression of disease (PD 2/30 = 7%). Objective response rate (CR ? PR) was 7%; disease control rate (CR ? PR ? SD) was 93%. Two patients underwent post-TARE tumor resection and 1 patients orthotopic liver transplantation. Median OS was 21 months (95% CI 12-34), median PFS was 9 months (95% CI 6-17). Single-lesion dosimetric data were available in 25 out of 35 lesions (single-lesion response: 1 CR, 2 PR, 22 SD). Mean TD of all lesions was 309 (95% CI 235-384) Gy, mean TD to responding lesions (CR ? PR) was 384 (95% CI -129-898) Gy and mean TD to stable lesions was 280 (95% CI 206-354) Gy. Conclusions: Our results show that 90 Y-TARE was safe and effective in controlling the disease. Dosimetric data of NTWLD suggest the possibility to increase 90 Y-glass microsphere administered activity to safely improve efficacy. Background-Aim: 177Lu-PSMA-617 radioligand therapy (177Lu-RLT) is a new promising tool for progressive metastatic castrationresistant prostate cancer (mCRPC) treatment. In this first Italian phase II study whit 177Lu-PSMA-617, mCRPC patients were treated at two different dosages in according to previous received therapies. At present, the primary endpoint is the evaluation of PSA response rate defined by a reduction of at least 50% from baseline value. Secondary objectives are acute and late toxicity, progression free survival and overall survival evaluation. Methods: mCRPC patients who refused or were unfit to be treated with docetaxel received 5.5 GBq/cycle of 177Lu-PSMA-617, while patients already treated with chemotherapy and/or aged more than 75 years old, received lower activities ranging 3.7-4.4 GBq/cycle. Both arms performed 4 cycles, each every 8-12 weeks. Before radiopharmaceutical infusion, patients have been pre-treated with intravenous administration of 500 mL of a 10% mannitol solution, to reduce kidney uptake. In order to reduce salivary gland uptake, cold pad has Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 been positioned onto the parotid glands and polyglutamate folate tablets have been orally administrated during infusion. Results: Between April 2017 and July 2021, 80 patients were evaluated. Full PSA values were available for 76 patients. PSA decreased of C 30% in 43 patients (53.7%) and 33 patients (41.3%) had a decline more than 50%. In the subgroup treated with 5.5 GBq (n = 40 patients), 15 patients had a PSA reduction at least of 50%. The majority of patients, including those treated with the lowest activity, showed a substantial decrease in tumour uptake at whole-body scan after the second or third cycle. RLT was safe and well tolerated, with no G3-4 toxicity. Median PFS is 7.0 months (4.2-9.5) for the low dosage and 7.2 (5.6-8.9) for high. The 12 months OS is 70.0% (57.3-79.6). Conclusions: 177Lu-PSMA-617 Radioligand Therapy confirmed to be a novel and effective treatment for mCRPC patients. In according to these preliminary results, 5.5 GBq per cycle for 4-6 cycles appears to be the most appropriate dosage to achieve a biochemical response. However, in selected patients, low dosages of 177Lu-RLT-617 are safe and can be sufficient to produce a response to therapy. Conclusions: High dose brachytherapy with 188 Re-resin showed to be an effective, non-invasive and safe strategy. It is easy to perform and well tolerated, providing excellent cosmetic results. It seems to be a very promising new treatment strategy for NMSC. Further studies with larger population and longer follow up are needed to find the optimal personalized treatment strategy. Background-Aim: The aim of the work is to study how the attendant students of the 2020-21 and 2021-22 classes of the bachelor degree course in ''Medical Imaging Radiology Techniques and Radiotherapy'' of the University of Turin perceived the teaching mixed modality, adopted in order to protect everyone from the Covid-19 pandemic. Methods: The collected data comes from the Edumeter platform provided by the University. Results: A level of satisfaction between 90% and 95% expressed by the students in both the investigated years. The outcome of the study shows us a good perception of the job done by the University, which has maintained unchanged the number of tutors and teachers and has provided immediate resources such as digital platforms and infrastructures. Head-to-head comparison between WB-MRI and 68 GA-PSMA PET/TC in restaging biochemical recurrent prostate cancer Background-Aim: The prerequisite is to highlight how the correct execution of the ''courtesy call'' can have important impacts on the examination conducting and therefore on the final result of the PET/ CT exam. In fact, contacting the patient by phone the day before does not only significantly improve the perceived quality but also the result of the examination itself, being able to provide useful information and sometimes highlighting the presence of limits, which can affect its performance. Knowing in advance the conditions that may lead in having to apply calibrated strategies for that specific patient or force immediate decisions also have a strong impact on the planning of the exam itself, on patient management and on multiple technical and practical aspects. At the same time, a research was also conducted on patient satisfaction with specific focus on the ''courtesy call''. Methods: Reports were created containing information on the aspects that had an impact on the conduction and the final result of the exam. The parameters were chosen starting from the ''pitfalls'' indicated in the procedural guidelines for oncological imaging with 18F-FDG PET/CT and have been implemented to include all the events that may cause loss of the final quality of the exam. To assess the satisfaction of the ''courtesy call'', a paper questionnaire was submitted to the patients involved, for the impact on the quality of the survey, cases with one or more aspects attributable to this study are still analysed. The data collected was processed through excel. Patients with a performance status of less than 40 according to Karnofsky were excluded from the study; patients who did not give authorized consent; visually impaired patients; patients who had not received the phone call the day before (because results are not available by phone). Results: 104 questionnaires were collected, first examination for 40 patients. Limits: Small sample to analyse; average age of 64, a lower average age would have brought different results; Filling up of the questionnaire before the final result; graphic of the questionnaire is not clear (no cards 29, due to lack of the given age). Conclusions: A significant correlation was observed between the courtesy call and the correct conduction of the examination showing an increased quality perceived by the patient. Nursing management of functioning-NEN patients during PRRT Background-Aim: Fluciclovine labeled with 18F (18F-fluciclovine) is an amino acid analog PET radiotracer approved for imaging of patients with suspected recurrent prostate cancer based on an elevated level of prostate-specific antigen (PSA) after therapy.18F-fluciclovine PET/CT requires special attention to patient preparation, injection technique, and imaging time. Aim of our study is to provide nuclear medicine technologists with the best-practice guidelines for the 18Ffluciclovine PET/CT protocol. Methods: The 18F-fluciclovine is injected intravenously while the patient is lying supine within the PET/CT scanner. Unless prevented by the patient's clinical limitations, the recommended position for imaging is supine with the arms above the head. Because of the rapidity of 18F-fluciclovine kinetics, the highest ratio of tumor to normal background tissue is seen between 4 and 10 min after injection. Therefore, to maximize the early imaging period, it is recommended that the PET acquisition begin at the mid thigh 3-5 min (target, 4 min) after injection and proceed caudocranially, with the bed positions set such that the prostate gland is in the middle of the first bed position. Since the manufacturer's recommended dose is 370 MBq, based on the activity of the radiopharmaceutical sent, no more than 30 min should elapse for the complete examination. In this regard, the illustrative Results: The liver and pancreas demonstrate the most intense 18Ffluciclovine uptake, followed by moderate uptake in the marrow, pituitary, and salivary glands. Mild uptake is seen in the muscle, and variable mild to moderate activity is seen in the small bowel. The lowest 18F-fluciclovine activity is in the brain and lung parenchyma. Emphasis is placed on the localization of lesions with visually increased uptake (with the assistance of quantitation) to improve the specificity of disease detection. For quantitation evaluation, 18F-fluciclovine uptake is measured as SUV max within a region of interest drawn on the target lesion. Although 18F-fluciclovine has a high detection rate for prostate cancer, nonspecific uptake has been reported in inflammatory and benign processes. Moreover, Respecting the times described, we were able to inject all patients with the recommended dose of 370 MBq with a mobile fractionator/injector. Conclusions: 18F-fluciclovine is a new PET radiotracer for restaging in patients with suspected recurrent prostate cancer based on a rise in PSA level after local or systemic therapy. As one of the busiest 18Ffluciclovine PET/CT imaging centers, we provide our best-practice guidelines for the performance of 18F-fluciclovine PET/CT to ensure quality images for disease detection. These guidelines include proper patient preparation and positioning, as well as proper 18F-fluciclovine injection and imaging techniques to prevent artifacts and image misinterpretation. The identification of the correct protocol for 18F-choline PET/ RM in patients with hyperparathyroidism Background-Aim: Obesity is a growing medical problem in western society with a correlated higher cancer risk. PET/CT imaging shows technical limitations in obese individuals due to a poor patient compliance during acquisition time (secondary to breathlessness in supine position) and a low PET image quality (increased image noise because of the increase in photon attenuation and the scatter fraction). Recently, the high diagnostic performance of advanced PET/CT systems and the use of integrated reconstruction algorithm (PSF correction and TOF information) have shown a significant improvement of image quality in patients with high BMI. A technical limitation in obese patients could be the acquisition in supine position, considering the respiratory difficulties and the abdominal size in relation to the gantry diameter. Reviewing the experience of our PET center, we assessed the utility of an adapted acquisition protocol in lateral decubitus in this challenging clinical condition. Methods: PET-CT imaging with 68 Gallium labeled somatostatin analogues (68Ga-DOTA-SSA) was performed in lateral decubitus in an obese (BMI: 32) patient with pancreatic neuroendocrine tumor and respiratory difficulties in supine position. The injected dose was 164.3 MBq. All data were acquired using the digital Biograph Vision PET/CT system (Siemens Healthineers, Germany) which combines a 64-slice CT scanner with a whole-body lutetium oxyorthosilicate PET system. Scanning parameters for CT were as follows: 120 kV, 161 mAs (by applying CARE Dose), 5-mm slice thickness, 0.5 s rotation. The CT data were used for the attenuation correction. Emission data were corrected for randoms, scatter and decay; reconstruction was performed applying Gauss filter, TOF and PSF algorithm. Qualitative image assessment was performed in agreement with diagnostic readers and image quality was also evaluated determining the signal to noise ratio (SNR) in liver tissue. Results: PET imaging in lateral decubitus enabled the diagnostic examination to be completed without time acquisition reduction or motion artefacts. Visual and quantitative (liver SNR: 7.73) assessment of PET imaging was considered adequate for a diagnostic interpretation. Disposition of some intrabdominal organs was modified due to gravity but PET/CT integration led to a sufficient diagnostic evaluation. Conclusions: Management of obese patients in clinical practice could be difficult requiring personalized imaging protocol. The advanced PET/CT setting (digital technology, PSF and TOF reconstruction algorithms, CARE Dose) significantly implemented image quality in a patient with high BMI. In extreme conditions, PET/CT acquisition in lateral decubitus could be the unique strategy to take home the procedure, overcoming patient's limitation (as for respiratory difficulties, claustrophobia, antalgic position) and obtaining all necessary clinical information in the diagnostic work-up of oncologic disease. CT protocol optimisation in PET/CT: presentation of a systematic review Data derived from studies were standardized in order to reduce possible biases, and they were divided into clinically homogeneous subgroups (adult, child or phantom). Subsequently, we divided the CT protocol intents into 3 types (anatomic localization only, attenuation correction only and diagnostic purpose). A narrative approach was used to summarise datasets and to investigate their heterogeneity (due to medical prescription methodology) and their combination in multiseries CT protocols. When weighted computed tomography dose index (CTDIw) was available, we calculated the volumetric computed tomography dose index (CTDIvol) using the pitch value to make the results uniform. Eventually, the correlation between protocol intents and CTDIvol values was obtained using a Kruskal-Wallis one-way ANOVA statistical test. Results: Starting from a total of 1440 retrieved records, twenty-four studies were eligible for inclusion in addition to two large multicentric works that we used to compare the results. We analyzed 87 CT protocols. There was a considerable range of variation in the acquisition parameters: tube current-time product revealed to have the most variable range, which was 10-300 mAs for adults and 10-80 mAs for paediatric patients. Seventy percent of datasets presented scans acquired with tube current modulation, 9% used fixed tube current and in 21% of them, this information was not available. Dependence between mean CTDIvol values and protocol intent was statistically significant (p = 0.002). As expected, in diagnostic protocols, there was a statistically significant difference between CTDIvol values of with and without contrast acquisitions (11.68 mGy vs 7.99 mGy, p = 0.009). In 13 out of 87 studies, the optimisation aim was not reported; in 2 papers, a clinical protocol was used; and in 11 works, a dose optimisation protocol was applied. Conclusions: According to this review, the dose optimisation in PET/ CT exams depends heavily on the correct implementation of the CT protocol. In addition to this, considering the latest technology advances (i.e. iterative algorithms development), we suggest a periodic quality control audit to stay updated on new. clinical utility modalities and to achieve a shared standardisation of clinical protocols. In conclusion, this study pointed out the necessity to better identify the specific CT protocol use within PET/CT scans, taking into account the continuous development of new technologies. Background-Aim: 18F-fluoroethyltyrosine (FET) PET/CT represent the molecular imaging standard technique for the assessment and differential diagnosis of primary brain tumors especially in patients who underwent surgery and/or adjuvant radio-chemotherapy. FET is a lipophilic amino acid that is actively transported into cells by the LAT-1 transporter. The specificity for this transporter, which is highly expressed in neoplastic cells than in inflammatory cells, represents the main advantage of PET/CT with [18F]FET in the diagnosis of recurrence in patients with glioma of various grades. Our work aimed to implement a diagnostic pathway and patient positioning system that is reproducible as between different studies as between early and late detection, thus improving patients' compliance. Methods: Namely, glioma patients often present severely impaired physical-cognitive conditions that do not allow them to easily cooperate. Therefore, in our centre, we implemented a diagnostic pathway useful to optimize the time for the preparation and administration of the radiopharmaceutical, the PET busyness, while always maintaining repeatable and reproducible patients' positioning. The technician provides to place on the temporal-frontal area of the patient, radioopaque markers that cross the Cartesian axes of the laser system; this device allows to reposition the patient according to the same axes in the next detection. We considered an acquisition timing with early static detection (? 10 min from administration) and late detection (? 40 min from administration) as follow: administration (T0); early detection (T0 ? 10 0 ) of about 10 min, during which the second patient is administered; wait for late acquisition (T0 ? 25'), during which the second patient is positioned on the table for the early acquisition; late acquisition (T0 ? 40 0 ). Results: Using this procedure we were able to organize in a single PET session 6 patients, with a stay in the department of about 90 min for each; moreover, the reproducibility of patients' positioning through radio-opaque markers allowed us to obtain a reproducible qualitative and quantitative assessment, also repeatable between different technicians, thus avoiding the need of software adjustments for obtaining a correct alignment. Conclusions: Using this approach we acquired 60 patients in 10 FET-PET sessions, improving the patients' comfort and the diagnostic offer of our department without any diagnostic quality loss. PET-CT GA68-DOTATOC and entero CT with intestinal contrast medium Background-Aim: PET-CT is a diagnostic technique of Nuclear Medicine that, after injection intravenously (about 3 MBq/Kg) the radiopharmaceutical is distributed in the patient's body, allowing to obtain diagnostic images. The PET-CT detects the distribution of Ga68-Dotatoc in the body. CT enteroclysis with mdc is an imaging technique that allows better visualization of the small bowel than standard abdomino-pelvic CT. It is more accurate than CT enterography and provides complementary diagnostic information to digestive endoscopy. Methods: Preparation of the patient provides that the day before the execution of the examination the patient takes laxative farmac. On the day of the examination, the patient must be fasting and presents himself at the Nuclear Medicine Service to carry out the administrative procedures and the compilation of consents for the execution of the PET-CT and CT examination with contrast medium (presentation also of blood tests). The patient is prepared and injected with the radiopharmaceutical Ga68-Dotatoc (3 MBq/kg). Subsequently the patient is given the laxative drug that will be useful for the distension of the intestinal loops, this must be during waiting time. After about 60 min after the somministration of the radiopharmaceutical, the CT examination is performed, the patient is asked to go to the bathroom, he is made to sit in the dressing room, he must wear a disposable gown and placed on the tomographipc bed. CT with contrast medium involves the following scans: basal acquisition abdomen pelvis, arterial acquisition abdomen pelvis, acquisition ''portal'' chest abdomen pelvis. Then we perform a PET-CT wholebody scan: 8 FOV/Bed of acquisition, each bed has a duration of 2 min. Cranio-caudal scanning for both CT and PET-CT scanning. Results: The images obtained CT allow to evaluate very well the distension of the intestinal loops both in the pre and post administration of the contrast medium. The PET-CT Ga68 Dotatoc images allow to evaluate the biodistribution of the radiopharmaceutical in the body districts that metabolize it. The additional difficulty of this examination is due to the double execution of a CT and PET-CT in the same session with the execution times of the overall examination of about 20 min. The second difficulty for the patient is the intake of about 4 L of laxative drug in just over 24 h. This could cause tenderness of the patient or difficulty of the same to be able to lie down too long on the PET-CT bed. The advantages of this method are those of being able to use a single equipment for the execution of the CT examination with contrast medium and Pet-CT. Also have the ability to view in the PET-CT Ga68-Dotatoc images still the vessels opaque by the contrast medium administered previously. The examination consisting of PET-CT and CT with contrast medium provides a complete examination for the diagnosis of neuroendocrine intestinal tumors. The refinement of the CT and PET-CT acquisition protocols should lead to performing a single CT with contrast medium for both methods. What the experience on clinical cases has brought is the execution of a diagnostic CT with contrast medium and the execution of a PET-CT protocol with dedicated acquisition parameters to keep the CT data as low as possible to have a CT ''attenuation map'' and CT ''fusion'' that can provide an iconographic result adequate to the clinical question. Background-Aim: Myocardial 18F-Deoxy-Glucose (FDG) uptake may be a confusing factor in PET/CT evaluation of infective and neoplastic cardiac disorders. In addition to a low carbohydrate diet and prolonged fasting, heparin pre administration is shown to decrease FDG myocardial uptake by increasing free fatty acids levels and reducing glucose-based myocardial metabolism. However, this is considered an off-label use of heparin and may raise some issues for cardiopathic patients often under anticoagulant therapy. Aim: To verify if additional heparin pre administration, associated with an appropriate dietary plan, may help achieve a significant glucose myocardial suppression in patients submitted to FDG-PET/ CT for infective or neoplastic heart disease. Methods: Retrospective evaluation of 54 FDG-PET/CT scans consecutively performed in 44 pts. (31 M and 13 F), 33 for endocarditis, 20 for cardiac or para-cardiac neoplastic disease and 1 for cardiac sarcoidosis. PET/CT were conducted in 21 cases (Group 1) who underwent 4 days of low carbohydrate diet and at least 18 h of prolonged fasting before FDG administration, whilst 33 cases (Group 2) received additional heparin 50 IU/kg in vein administration 15 min before FDG. PET/CT images have been independently evaluated by a nuclear technician and physician, measuring SUV max on the inferiorseptal left ventricular myocardial wall and on the ventricular bloodpool into a 15 mm circular ROI, and SUV max into a 30 mm circular ROI on the liver. SUV max values allowed the application of a semiquantitative visual Scoring System grading from 0 to 4 (5 scores) considering scores 0, 1 and 2 (myocardial uptake equal to blood pool or anyway less than liver uptake) as a good myocardial glucose metabolism suppression, and scores 3 and 4 (myocardial uptake focally or diffusely higher than liver) as a failed suppression. Results: Assessment of ventricular blood pool and liver median SUV max achieved by the technician and nuclear physician were respectively 2.72 and 3.05 for blood pool and 3.63 and 3.58 for liver (p-value 0.17), whereas assessment of myocardial median SUV max was 4 for technician and 3.28 for physician (p 0.008). In 16 out of 21 (76.2%) PET/CT performed in group 1 we obtained a visual myocardial score of 0-2 and in 5 examinations (23.8%) a score of 3-4. In 26 out of 33 (78.8%) PET/CT performed in group 2 we obtained a score of 0-2, and in 7 (21.2%) a score of 3-4 (p-value 0.82). Conclusions: Normal myocardial FDG uptake assessment by a technician may be affected by an incorrect evaluation of neoplastic cardiac involvement and needs a physician confirmation to assess the adequate myocardial glucose uptake suppression. According to our data, prolonged fasting and low carbohydrate diet seem to be the best choice for cardiac glucose metabolism suppression, whereas heparin injection has not proven to add further advantages for this aim. This evidence may be particularly relevant in cardiopathic patients with increased bleeding risk already following an anticoagulant therapy. Transthyretin-related cardiac amyloidosis: 99MTC-HDMP scintigraphy a substitute for biopsy? Myocardial radiotracer uptake was assessed optically based on Perugini Score: (0: absent cardiac uptake and normal bone uptake; 1: mild cardiac uptake, inferior to bon uptake; 2: moderate cardiac uptake with attenuated bone; 3: high cardiac uptake with decreased or absent bone uptake) Diagnosis was confirmed by biopsy and/or laboratory investigation. Results: Diffuse intense myocardial uptake (score 3) verified in 7 patients by 99mTc-HDMP scintigraphy, was consistent with ATTR suspect. In 5 patients whole-body scintigraphy showed a moderate cardiac upatke (Score 2), biopsy was necessary to confirm. In twelve patients cardiac radiotracer uptake was absent (Score 0), so invasive procedure was avoid, like biopsy. Detection of ATTR in our study population by 99mTc-HDMP scintigraphy was accomplished with 100% sensitivity and specificity. Conclusions: Our data indicate that 99mTc-HDMP scintigraphy has a key role in the early diagnosis but even more in the exclusion of patients with the ATTR subtype. 99mTc-HDMP scintigraphy confirms to be a simple, non-invasive, low-cost and widely available modality. It does not require preparation and has no side effect so it can be performed in all types of patients including hemodynamically complicated patients. This examination, optimizing the management of pts who do not require admission to procedures with high costs and more invasive, is useful for earlier diagnosis and screening of CA. Background-Aim: Transthyretin cardiac amyloidosis (ATTR-CA) can be noninvasively diagnosed thanks to high cardiac uptake at Technetium-99m-pyrophosphate or Tc-99m-hydroxymethylene diphosphonate scintigraphy. According to practice guidelines a positive scan suggesting high probability of ATTR-CA requires a heart-to-contralateral lung ratio (H/CL) equal to or greater than 1.5 or a visual score (Perugini's score) of grade 2 or 3 (visual tracer uptake in the myocardium equal to or greater than that in rib respectively). While these gradings based on planar images are adequate for diagnosis, they are insufficient for risk stratification and for assessment of disease progression. The aim of this study is to propose a scoring system based on SPECT imaging, which could have a prognostic value in patients with ATTR-CA. Methods: 58 patients with suspected ATTR-CA underwent 99mTc-HDP planar and tomographic scintigraphy at our Nucleare Medicine unit from january 2016 to december 2021. In patients with a visual score equal to or greater than grade 2, after injection of 740 MBq 99mTc-HDP, we calculated the H/CL ratio and we performed cardiac SPECT at 3 h post-injection. Tomographic images of the heart were processed with the Myometrix software (butterwoth filter with critical frequency 0.3 and power 10) dividing the cardiac area into 17 segments, each of which was assigned a score from 0 to 4 based on tracer uptake (value = 0 for maximum uptake), thus obtaining a summed score (SS) reflecting left ventricular uptake. Further scores were calculated considering the separated SS for single left ventricular walls, specifically the anterior SS (aSS), the posterior SS (pSS), the septal SS (sSS) and the lateral (lSS) and the apex region (arSS). Other clinical data relevant for prognostic assessment were collected: age, sex, ejection fraction (EF), ECG abnormalities, presence of cardiac risk factors and cardiovascular drugs. Results: Among 58 patients (40 men and 18 women), we selected the 27 patients with visual score equal to or greater than grade 2 (12 patients with visual score 2 and 15 with visual score 3). The EF was lower than 55% in 18 patients (66%). The majority of them (25 patients) had cardiuvascular risk factors while ECG abnormalities were detected in only 12 patients. The mean H/CL ratio in patients with visual score 2 and 3 were 1.56 and 1.91 respectively. Analyzing SPECT imaging, we obtained a mean SS of 37.2 in patients with visual score 2 and 20.8 in patients with visual score 3. The separate SS were calculated to assess whether it could be a correlation between higher uptake in a specific cardiac wall and patients' prognosis; our preliminar data seem to suggest that higher sSS is associated with lower EF. Conclusions: We proposed a SPECT-imaging score evaluating 99mTc-HDP cardiac uptake in patients with ATTR-CA. If these preliminar data of tomographic tracer biodistribution in the cardiac area might have a role in prognostic assessment, is going to be demonstrated in a larger population and after clinical follow-up. The study is ongoing. Comparison of QGS, myometrix and corridor 4DM using cardiac magnetic resonance as reference, in the evaluation of left ventricular volumes and ejection fraction, from gated myocardial perfusion spect processed with ''myovation evolution'' algorithms has made it possible to preserve a good quality of cardiac images in spite of reduced number of counts during study acquisition. Aim of this study was to evaluate the performance of three software packages in the quantification of EDV, ESV and LVEF applying a RR algorithm (GE Myovation Evolution) against to cardiac MRI (cMRI), considered as gold standard. Methods: We have retrospectively analyzed 21 patients (16 men, 5 women; age range: 42-81, mean 63), with suspected (15) or known (6) coronary artery disease. All patients were underwent a dual-day protocol gated-SPECT and cMRI, with a maximum interval of 6 months between the two methods. Images at rest were reconstructed by filtered back projection (FBP) and by an iterative protocol with the RR algorithm. EDV, ESV and LVEF were automatically computed employing Quantitative gated SPECT (QGS), Myometrix (MX) and Corridor 4DM (4DM). Any difference in EDV, ESV and LVEF estimation between cMRI and the three software (with FBP and iterative reconstruction with RR) was tested using Wilcoxon or paired t-test, with assumption of normality assessed using Shapiro-Wilk test. Agreement between imaging reconstruction algorithms and between gated-SPECT software packages and cMRI was studied with Pearson's (r) or Spearman's (R) correlation coefficients and Lin's concordance correlation coefficient (LCC). Results: Intra-software evaluation revealed very strong correlation coefficients (R, r C 0.8) and excellent LCC coefficients (LCC [ 0.95). Only LCC coefficient between MX-FBP and MX-RR in EDV evaluation was considered very good (LCC = 0.94). EDV and ESV were significantly lower when calculated with the RR algorithm with respect to FBP reconstruction in QGS and MX. LVEF estimation did not show significant differences for QGS-FBP, QGS-RR, MX and 4DM-RR in comparison to cMRI. Conclusions: All reconstruction methods systematically underestimate EDV and ESV, with higher underestimation applying the RR protocol. However, no significant differences were observed between 4DM-RR and 4DM-FBP, for each parameter, when 4DM package was used. Background-Aim: Complete revascularization by coronary artery bypass grafting (CABG) is the gold standard treatment in multivessel coronary artery disease (MVCAD). In selected patients an ''incomplete anatomical revascularization'' could be the preferred therapeutic approach. So far, the effects of an incomplete revascularization on myocardial blood flow (MBF) and coronary flow reserve (CFR) in non-revascularized segments are unknown. We prospectively evaluated regional and global changes of MBF and CFR in patients undergoing incomplete versus complete anatomical revascularization by CABG. Methods: This was a single centre, prospective, observational, casecontrol study. Inclusion criteria were age C 18 years and MVCAD (stenosis diameter C 70% in at least 2 epicardial coronary arteries). 16-bin ECG-gated myocardial perfusion-PET with 13 N-ammonia was performed at rest and during adenosine stress before and 4-6 months after CABG. CFR was calculated as the ratio of stress MBF (mL/min/g) to corrected for RPP resting MBF (mL/min/g). Quantitative data were calculated for the whole LV and for each of 17 myocardial segments according to the individual coronary anatomy and CABG surgery data. Results: Seven male patients were enrolled (mean age 61 years, range 51-77). Three patients underwent complete anatomical revascularization and 4 patients incomplete anatomical revascularization. A total of 101/119 (85%) myocardial segments were completely revascularized, of which 50 from patients non completely revascularized. Eighteen (15%) myocardial segments were not revascularized. CFR significantly increased after CABG in revascularized and not revascularized segments, with a greater increase in revascularized segments: from 1.21 ± 0.45 to 1.82 ± 0.53 in revascularized segments and from 1.25 ± 0.49 to 1.44 ± 0.33 in not revascularized segments (p \ 0.001 within each group, p = 0.013 between groups). Stress MBF increased from 1.23 ± 0.44 to 1.64 ± 0.42 in revascularized segments vs. 1.20 ± 0.53 to 1.41 ± 0.44 in not revascularized segments (p \ 0.005 within each group, p = 0.037 between groups). On a per patient analysis, CFR and stress MBF significantly increased after CABG in both groups, with a greater increase in the completely revascularized group. Delta left ventricular ejection fraction improved after CABG in both groups. Conclusions: The ''incomplete anatomical revascularization'' strategy could have beneficial effects even in myocardial segments not directly revascularized through the improvement of flow by collateral vessels and coronary microvascular function. This could led to the systematic adoption of this approach in high risk profile patients. The diagnostic and prognostic value of semiquantitative evaluation in 99TC-DPD and 99TC-HMDP bone scintigraphy with SPECT/CT for TTR-related cardiac amyloidosis Background-Aim: 99m Tc-DPD (3,3-diphosphono-1,2-propanodicarboxylic acid) and 99m Tc-HMDP (hydroxymethylene diphosphonate) scintigraphy is indicated for the diagnosis of Transthyretin amyloidosis (aTTR). Severity of cardiac involvement is routinely assessed on planar images by qualitative Perugini Score (PS). The aim of our study was to investigate the diagnostic value of semiquantitative approach (SUV max and SUV mean ) on SPECT/CT images and find a reliable cut-off value to improve diagnostic accuracy and a valuable therapy monitoring tool to the recently introduced TTR amyloidosisspecific drugs. Methods: 75 patients (52 men, 23 women), median age 67.5 (43-92) who underwent 99 Tc-DPD (68 patients) and 99 Tc-HMDP (7 patients) bone scan and myocardial SPECT/CT between June 2019 and November 2021 for suspected TTR amyloidosis were retrospectively evaluated. Qualitative analysis of total-body scan was performed according to Perugini Score (0-3): 0-no cardiac uptake; 1-cardiac uptake \ than bone; 2-cardiac uptake C than bone; 3-cardiac uptake [ than mild/absent bone signal. Semiquantitative analysis was performed on SPECT/CT images using Q-metrix software: SUV max and mean (body weight, body surface area, lean body mass) of interventricular septum (IVS), left ventricular lateral wall (LW), sternum and one thoracic vertebra as background reference, were calculated. Statistical analysis was performed by Mann Whitney and Kruskal-Wallis tests to determine whether differences between datasets scored by Perugini grade were statistically significant. ROC curve was used to define a cut-off value of both IVS and LW SUVs improving PS accuracy. Results: According to Perugini score, 30 scans were classified as nondiagnostic (PS 0, n = 23; PS 1, n = 7) and 45 cases as diagnostic (PS 2, n = 9; PS 3, n = 36) for aTTR. Statistical analysis found significant differences (p \ 0.001) both between all median values of IVS and LW SUV max/mean in non-diagnostic vs diagnostic scans and also within the four different PS groups, with a linear trend of increase of median values within each PS group. In particular, median IVS and LW SUV max bw were 1.87 (0.98-7.27) and 2.10 (0.63-4.03) in PS 0, 6.73 (3.66-12.86) and 4.10 (3.04-10.87) in PS 1, 7.36 (0.67-19.42) and 6.72 (0.55-19.38) in PS 2, 16.18 (1.25-29.97) and 12.18 (1.07-21.88) in PS 3, respectively. No significant differences were found for background semiquantitative values in the bone between different groups. ROC curves showed, for each semiquantitative parameter, promising cut off accuracy values to discriminate between aTTR diagnostic and non-diagnostic cases: 5.4 IVS SUV max (96% sensitivity and 83% specificity), 2.0 IVS SUV mean , 4.4 LW SUV max , 2.0 LW SUV mean (96% sensitivity and 90% specificity). Conclusions: Our data suggest the promising diagnostic value of SPECT/CT semiquantitative analysis in 99 Tc-DPD and HMDP scan for TTR amyloidosis stratification. A larger sample size of patients and prospective studies are required to confirm these data, to find a reliable cut-off value to differentiate among different PS classes and to evaluate the prognostic impact of these parameters. Background-Aim: Recent studies show that prevalence of ATTR-CM is higher than initially thought. 99mTc-DPD scintigraphy (99mTc-DPD S) is a low cost test, but it must be used only within diagnostic processes without radioexposure and precise clinical scenarios. Methods: From June 2020 to January 2022 we enrolled 37 patients (PTS) visited by cardiologists in our Department. All PTS were submitted to ecocardiography (EC), elettrocardiography (EL), serum free light chain ratio (SFLCR), serum and urine elettrophoresis with immunofixation (SUEI), serum troponin and Pro-B-type natriuretic peptide (STPBNP-l) evaluation. In 23 PTS SFLCR and SUEI were abnormal; this result was suggestive for light chain amyloidosis (AL A), so they weren't submitted to 99mTc-DPD S, but they were sent to other Department for extracardiac biopsy such as of abdominal fat pad. Unfortunately at the moment we haven't results of these biopsies. 14 PTS (with normal SFLCR and SUEI) were submitted to 99mTc-DPD S, but not to abdominal fat pad biopsy, because diagnostic accuracy of extracardiac biopsy is slow in ATTR-CM, due to high false negative rate. These PTS underwent planar chest static image at 1 h from injection of tracer and whole body scan and SPECT/CT at 3 h from radiotracer injection. We used SPECT/CT Discovery MN/CT 870 DR GE gamma camera with 256 9 256 matrix, preset 750 Kcounts and 1.46 zoom for planar acquisitions, while in SPECT/CT image we planned 90°angle, 128 9 128 matrix, rest and ungated, time for view 20 s and zoom 1. In this group of PTS we measured volume of heart (ml), greatest, lowest and total counts in heart ROI, percent of injection dose fixed in heart wall, standard deviation of counts and heart/chest bone ratio (H/CB). We considered H/CB greater than 1.5 suggestive for ATTR-CM. In SPECT/CT chest image we assessed Perugini score with visual and qualitative comparison between uptake of radiotracer in heart wall and chest bones uptake: score 0: no heart uptake and normal bone uptake; score 1: heart uptake \ bone uptake; score 2: heart uptake = bone uptake; score 3: heart uptake [ bone uptake. Results: We obtained H/CB greater than 4 in 2 PTS; from 4 to 2 in 4 PTS; from 2 to 1.5 in only 1 PT. In 7 PTS we had H/CB less than 1.5. All PTS with H/CB [ = 1.5 had specific pattern in EC and EL: global hypertrophic left ventricular with left ventricular wall thickness [ = 14 mm, reduction in longitudinal strain with apical sparing, diastolic disfunction with normal ejection fraction and discrepancy between increased left ventricular thickness and low QRS voltage in EC and EL respectively. 7 PTS without this EL and EC pattern had H/CB less than 1.5. Conclusions: PTS with suspected ATTR-CM must be submitted to 99mTc-DPD S only when they present EC and EL specific pattern. Counseling pre-myocardial perfusion gspect imaging: a good practice to improve quality of the nuclear medicine service Background-Aim: In 2018 the nuclear medicine unit of Centro Diagnostico Italiano (CDI) conducted a failure mode and effect analysis (FMEA) as a proactive risk assessment method applied to the gated myocardial perfusion SPECT (GSPECT), which allowed to implement additional safety measures to mitigate risks associated to the procedure, mainly due to the stress test. These included the introduction of a counseling activity performed before the GSPECT. The counseling activity allows the nuclear medicine physician to thoroughly investigate the medical status of the patients, in order to ensure that they can undergo the GSPECT safely. Methods: The counseling project started at the beginning of 2018, introducing an additional appointment with the patient 2 weeks before the GSPECT. During the meeting the nuclear medicine physician fills out a specific form reporting various information about the patient's health condition. Through the analysis of this information, the physician, in cooperation with the cardiologist, establishes if the patient is eligible to undergo the examination and which are the best conditions (physical or pharmacological stress test). If additional medical examinations (e.g. recent echocardiogram, supra-aortic trunks ultrasound) are necessary to evaluate the patient's health status, they will be scheduled in our health center within the GSPECT. Results: Being CDI an ambulatory care center, the nuclear medicine physician used to meet the patient and evaluate his health conditions the same morning of the GSPECT. If the patient turned out to be unsuitable for the examination, he was dismissed, resulting in a sense of frustration for the patient and a negative impact on the department productivity. This situation caused a drop-out rate of 45%. With the introduction of the counseling meeting, on a total of 1128 patients: • 17.73% resulted unsuitable for the myocardial scintigraphy. • 82.27% resulted suitable for the examination. • Among the suitable patients, about 50% required additional medical examinations. The second advantage, besides reducing the drop-out percentage, is that the physician may clearly explain the necessary preparation for the examination, significantly decreasing the number of patients who do not follow the correct preparation protocol for the exam. The counseling project has proven to be an efficient system to increase the safety of the patients and the nuclear medicine unit. Although it requires additional commitment for the physician, it minimizes risks associated to the procedure and increases the patient's satisfaction. Indeed, the counseling also aims to make the patient feel safe and contented about the care received. In addition, it allowed us to decline the drop-out rate significantly. All these factors contributed to improve the quality of our ambulatory care. For the above reasons, it is recommendable to adopt this practice in other nuclear medicine departments to promote the quality of the provided services. Can exaggerated systolic hypertensive response to exercise help to predict MPI parameters? Background-Aim: The pathophysiology of exercise hypertension, defined as an abnormal blood pressure response to exercise, is still mainly unknown, with conflicting data on its role in predicting cardiovascular (CV) events. An excessive increase in systolic blood pressure during physical effort seems to be associated with false positive findings on stress electrocardiography and echocardiography, while its impact on myocardial perfusion imaging (MPI) is not fully understood. The aim of the present study was to investigate the association between excessive hypertensive response to exercise and myocardial perfusion abnormalities, assessed by single-photon emission computed tomography (SPECT). Methods: A cohort of 246 diagnostic patients was retrospectively analysed from consecutive patients with suspected coronary artery disease, undergoing exercise testing for 99mTc-tetrofosmine SPECT MPI (02/2019-12/2021). Stress test was performed using bicycle ergometer starting with 25 W and increasing of 25 W/2 min until maximal heart rate was reached. SPECT imaging was performed using a dedicated cardiac CZT SPECT system (Spectrum Dynamics Medical). Patients were classified in two groups, according to the presence (GROUP-1) or absence (GROUP-2) of exercise induced hypertension, considering a cut off of peak systolic blood pressure during exercise C 220 mmHg. MPI scores summed stress score (SSS%), summed rest score (SRS%), summed difference score (SDS%) and total perfusion deficit index (TPDi) were compared between the two groups. P values were estimated by the Monte Carlo technique and those \ 0.05 were considered significant. Background-Aim: One of the main unmet needs of patients with ATTR amyloidosis is the diagnostic delay, generally due to a lack of awareness of the disease (both for its rarity and for its genotypic and phenotypic heterogeneity) and to initial incorrect diagnoses that can also lead to choice of inappropriate therapeutics. Therefore the diagnostic process is now multidisciplinary and involves different clinicians, that collaborate to reach diagnosis in the right time. Although nowaday the gold standard is still endomyocardial biopsy, studies have shown that nuclear medicine can play a role in the diagnostic process. Infact highly sensitive and specific imaging techniques as scintigraphy with osteophilic tracers or florbetaben PET, allow early detection of myocardial infiltration of amyloid, even before the appearance of echocardiographic abnormalities. Methods: 99m Tc-HDMP was employed in our institution. Wholebody scan (WB) was performer two hours after radiopharmaceutical somministration and thoracic tomography was performed in presence of myocardial uptake at WB to better define ventricular walls involvement. The semiquantitative Perugini visual scoring system has been used to define the degree of cardiac uptake with Score 0 representative of absent cardiac uptake, Score 1 of mild cardiac uptake inferior to bone uptake; Score 2 of moderate cardiac uptake with attenuated bone uptake and Score 3 of strong cardiac uptake with mild or absent bone uptake. Results: 8 pts underwent bone scan because of clinical suspicion of cardiac amyloidosis on the basis of echocardiographic and magnetic resonance results. Bone scan was positive in 4 pts. In the others we can suppose a different amyloidosis type (AL) or different illness ethiology. 5 pts underwent bone scan for oncological staging and unexpected cardiac uptake was detected. In all pts an high Perugini score was detected and omogeneus ventricular wall radiofarmaceutical distribution was observed according to diffuse amyloidotic infiltration. Conclusions: Nuclear imaging is useful when echocardiography and RM results are inconclusive for diagnosis and moreover provide histological type diagnosis (AttR) without biopsy confirmation. Often the disease is underdiagnosed due to the lack of correct evaluation of some symptoms and instrumental investigations as represented in our series where the amyloidosis incidence as an incidentaloma was 38%. Spleen uptake of 99MTC-SESTAMIBI reflects the sympathetic nervous system response to physical exercise: a proof-of-concept study Background-Aim: Clinical assessment of sympathetic nervous system (SNS) function usually focuses on heart rate and arterial pressure. However, the variegate SNS contribution to the hemodynamic response to exercise also involves its capability to divert blood flow from splanchnic district to the skeletal muscles and central nervous system. A main contributor to this task is the contraction of vascular smooth muscle cells in the spleen. The present study thus aimed to evaluate whether exercise modulates blood flow and thus 99mTc-Sestamibi uptake in the spleen that is almost always included in the field of view of myocardial perfusion imaging (MPI). Methods: Rest and stress MPI images of 286 consecutive patients (age 67.3 ± 11.9) performed at our Institute in the course of 2019 were retrospectively analyzed. Among them, 228 patients were submitted to physical exercise, and 58 underwent pharmacological vasodilation with dipyridamole. Both stress and rest scans were acquired 30 min after tracer injection. Spleen counting rate (counts per second, NCPS) was calculated and corrected for the administered dose. Left ventricular (LV) end-diastolic volume (EDV) and ejection fraction (EF) were measured by the conventional QPS/QGS approach. Summed stress, rest, and difference scores (SRS, SSS and SDS, respectively) were determined, and ischemia was defined as SDSC3. Results: Patients submitted to exercise were younger than patients receiving pharmacological stress (66.3 ± 11.3 vs 71.3 ± 13.3; p \ 0.01), while gender distribution was similar. Patients submitted to exercise showed higher rate pressure products when compared to the dipyridamole group (21,600 ± 5200 vs 11,400 ± 2600 bpm x mmHg, respectively, p \ 0.01) and a higher prevalence of ST segment depression at stress peak (74/228 vs 0/58; p \ 0.0001). By contrast, the occurrence of symptoms was similar between the two groups (16/228 vs 7/58; p = ns). LV EDV, EF, SSS, SRS and SDS were similar in the two groups. Spleen NCPS was higher after exercise than at rest (3.4 ± 1.7 vs 2.6 ± 1.7; p \ 0.0001). By contrast, patients submitted to dipyridamole MPI showed superimposable spleen uptake values in stress and rest scans (3.1 ± 1.1 vs 3.0 ± 1.4; p = ns). Similarly, % increase of spleen NCPS from rest to stress was significantly higher in patients submitted to physical exercise than in the dipyridamole group (169% ± 101% vs 126% ± 66%; p \ 0.01). Conclusions: Spleen uptake of a perfusion tracer as 99mTc-Sestamibi is significantly and selectively enhanced by physical exercise and not by pharmacological vasodilation, indicating an increased blood flow rate of this organ in response to exercise. This finding agrees with the acknowledged SNS effect on splenic blood vessels, configuring this spleen uptake as a possible index of splanchnic SNS activation during effort. A. Cimino 1 , A. Mita 1 1 Background-Aim: Alzheimer's disease (AD) is the most common cause of dementia; its definitive diagnosis is a complex process requiring instrumental and clinical examinations, often non-specific. Common feature of definitive AD diagnosis is presence of extracellular plaques of insoluble beta-amyloid. Amyloide PET, able to identify of amyloid plaques, is powerful tool in AD management, especially at the earliest stage. Aim of our study is to assess process and pathway of Amyloid PET/CT, based on our experience, despite of location. Methods: During 18 months, we performed 22 Amyloid PET/CT in patients with suspected AD (10/22 female, 12/22 male; 13/22 age B 65 years; 9/22 age [ 65 years). In 10/22 patients we used as tracer 18F-Flutemetamol (group 1), in the remaining 12 PET/CT was performed with 18F-Florbetaben (group 2). The calculated dosage were: • 185 MBq ± 10% in maximum volume of 10 ml for 18F-Flutemetamol. • 300 MBq ± 20% in same volume for 18F-Florbetaben Both tracers were injected as a single slow bolus (in max of 60 s); flushing with at least 5-15 cc of normal saline followed. In all patients, emission acquisition started at 90 ± 1 min after injection, using PET/CT scanner PHILIPS GEMINI TF 642014 (3.5.2.2). CT scan was acquired prior to emission scan; dynamic 3D scan consisted of 4 acquisitions of 5 min each and as typical reconstruction parameters for Brain PET was used OSEM3D. To avoid motion between transmission/emission, comfort position was guaranteed (head and neck in relaxed position) and forehead velcro restraints recommended. Results: In group 1, 7/10 amyloid PET/CT scans resulted positive for amyloid deposition and 3/10 pts resulted negative. In group 2, 7/12 pts had positive PET scan, the remaining 5 were negative for amyloid deposition. Despite of hospital location, there were no days cancellation for tracers lack supplying. After injection, no patient reported side effects. Based on our protocol, all PET/CT were performed with success. Our standardized range of dosage and acquisition time allowed to obtain no poor quality imaging. Use of comfort position (if patient cannot comfortable maintain right position, a slight tilt was acceptable) limited movement artifacts; rescan never were necessary. Conclusions: Our data confirm that it's important for nuclear staff to develop dedicated training and protocol for Amyloid PET/CT to improve patient experience and consequently lead to a more efficient department. Our experience, related to a south hospital, suggests that good organization, from production to scan, allow high level and specialistic examinations, despite of location. Background-Aim: Semi-quantification with automatic tools can reliably assist visual reading of DaT SPECT, especially in borderline cases. Several tools include the computation of z-scores (ZS) of specific binding ratio (SBR) with respect to normal subjects' database (CTR). A cut-off of -2 ZS in the striatal or putaminal SBR with respect to CTR has been previously proposed to discriminate normal from abnormal scans. This cut-off has not been experimentally validated yet in PD or DLB patients. We aimed to explore accuracy of different cut-offs for ZS of SBR in striatal, substriatal regions and putamen/caudatus ratio (PCR) to discriminate de novo PD and DLB patients on one side, with respect to their 'natural' comparators: patients with ET and AD respectively. Methods: We retrospectively recruited 204 patients: seventy-six de novo PD (age 71.9 ± 8.0), seventy-nine ET (70.7 ± 8.8), thirty-five DLB (77.3 ± 6.1) and fourteen AD patients (79.1 ± 4.1) who underwent DaT SPECT from 2019 to 2021 in our center. Patients' final clinical diagnosis served as gold-standard. Images of PD patients were flipped to have the most affected hemisphere (MAH) on the same side for all patients and then analysed with Datquant Ò . SBR ZS of striatum, caudatus, anterior and posterior putamen and PCR were computed for both MAH and LAH (less affected hemisphere) with respect to the provided age-matched CTR dataset. Receiving Operating Curves analysis were used to optimize cut-offs for ZS for the identification of de novo PD and DLB patients with respect to ET and AD, respectively. Most accurate cut-offs for each variable were computed by using the Youden index (YI). Results: Posterior putamen was the most accurate parameter to separate PD versus ET in the MAH with a cut-off of -1.5 ZS (YI 0.897) and in the LAH with a cut-off of -0.9 (YI 0.871) while the whole bilateral putamen was most accurate for DLB versus AD with a cutoff of -1 ZS (YI 0.757). The second most accurate parameter for DLB versus AD was the entire striatum in the LAH (cut-off -0.7 ZS; YI 0.729). Of note PCR was accurate to differentiate between PD and ET (ZS -1.5 in the MAH and -1.8 in the LAH) but not AD versus DLB. Most accurate cut-offs for all parameters provided by the software were lower with respect to -2 ZS without losing specificity. Conclusions: Semiquantification of DaT SPECT images confirmed to discriminate patients with PD and DLB with respected to ET and AD with high accuracy. Different cut-offs should be considered to identify PD or DLB patients as well as when looking to MAH or LAH in PD patients. Using less conservative ZS cut-offs with respect to the originally proposed -2 ZS provide higher sensitivity and is not associated with a lower specificity. Given the less severe, but widespread, dopaminergic degeneration in DLB, ZS close to -1 might still support disease diagnosis. Background-Aim: Patients with idiopathic normal pressure hydrocephalus (iNPH) can show a global reduction of glucose metabolism in brain [ 18 F]FDG PET, without a specific cortical pattern and an hypometabolism in basal ganglia. [ 18 F]FDG PET may identify a coexisting neurodegenerative disease, thus improving selection of patients for shunt surgery. Exploring the full potential of this method can be important in determining the optimal timing for therapeutic intervention and developing new treatments. The presence of caudate hypometabolism has been identified as a potential biomarker in iNPH, yet no data in literature reported hypermetabolic PET findings in patients with iNPH so far. Methods: Seven iNPH patients (mean age 74 ± 6 years) were evaluated before surgery by means of [ 18 F]FDG PET and compared to a control group, matched for age and sex, by SPM analysis. Results: SPM group analysis revealed clusters of significant hypometabolism (p = 0.001) in iNPH in the dorsal striatum, involving caudate and putamen bilaterally, as expected. Unexpectedly, clusters of significant hypermetabolism (p = 0.001) was revealed in the bilateral superior and precentral frontal gyrus (BA 4, 6). Conclusions: In this cohort, in line with previous literature, patients with iNPH showed subcortical hypometabolism, including bilateral dorsal striatum. To the best of our knowledge, this is the first report demonstrating a hypermetabolic pattern in the primary motor and premotor areas in patients with iNPH. This finding might explain, at least in part, presence of gait disturbances in these patients. Further studies are needed to establish whether these hypo and hypermetabolism findings taken together could be considered typical for iNPH and to understand whether the reported metabolic alterations may be transient or they may change with the severity of the disease. Furthermore, it remains to be defined if these findings may change after the successful outcome of the surgical treatment and correlate with the possibility of patient recovery. Background-Aim: The value of quantitation of VIZAMYL amyloid PET scans was assessed by surveying routine users in Italy as part of an overall EU survey. The aim was to better understand the extent and value of the clinical use of quantitation as an adjunct to visual interpretation of the PET image. The use of quantitation has increased over the last few years but there is still a significant proportion of physicians that rely on visual inspection. Education, accessibility and sharing the value that quantitation brings were identified as the solutions to increase its usability in order to achieve more accurate and reliable image interpretation. Methods: An online questionnaire of 27 questions was created using a survey tool (surveymonkey.com, San Mateo, CA, USA). After answering a pivot question on using or not using quantitation for VIZAMYL amyloid PET scan interpretation, responders followed two different branches of questions. In case of the affirmative answer, the other questions were on why and how they use quantitation and what would improve their experience using it. In case of a negative answer, questions were on reasons why they don't use quantitation and on possible future quantitation usage. Results: A total of 43 (out of 62) non-duplicate responses came from Italian nuclear medicine specialists (69% response rate). Survey participants who performed fewer scans (0-50 scans/year) were less likely to use quantitation for image interpretation versus those who performed [ 50 scans/year. In this current survey 50% of physicians use quantitation for the majority of processed images while the other 50% who don't use quantitation, cite the lack of software tools in their clinic as the major reasons for not performing this step. Respondents using quantitation gave a variety of reasons for the added value. The primary reasons were validation of visual read, increased diagnostic confidence and increased accuracy of diagnosis. Secondary reasons included decreases time to interpret the scan and the quantitative metric is of interest to the referring physician. Reporting to the referring physician was mostly by a written reporting including images, or by providing the quantitation value, amyloid status or regional distribution. Specific features which might require additional quantitative assessment, were mainly equivocal visual read, or significant atrophy and complex pathology. 64% of clinicians experienced some discordance between visual and quantitative result but this was only in a minority of scans assessed (3-5%). The quantitative software tools used by respondents were prevalently CE Marked software (95%) and the most common quantitative metrics used in clinical routine were Z-scores, SUVR, or the Centiloid metrics. Conclusions: Approximately 50% of Italian nuclear medicine physicians are using quantitation to supplement their visual reads whilst the other 50% interpret VIZAMYL amiloyd PET scan using the visual read methodology alone. All respondents that are not using quantitation currently said they are considering using it in the future and factors that would convince them to use quantitation included to confirm qualitative assessment, improve reporting time and accuracy. Background-Aim: In patients with autoimmune encephalitis (AE), the pathological process frequently affects the limbic system, with typical bilateral involvement of the medial temporal lobes on T2weighted MRI as a key diagnostic feature of limbic AE. On the other hand conventional MRI has poor sensitivity in some subtypes of AE (e.g. anti-NMDA receptor AE) or can fail to detect abnormalities in clinically relevant anatomical areas. In this scenario, [18] FDG-PET can add diagnostic information by detecting metabolic abnormalities which are invisible at structural MRI, both in limbic or extra-limbic structures. Arterial spin labeling (ASL) provides information on cerebral blood flow. There is a well-known coupling between neuronal function and brain metabolism and perfusion. However, there are scarce data on the use of ASL in AE and on the comparison between ASL and FDG-PET findings in these type of patients. We aimed to compare [18F]FDG PET and ALS images in patients with AE. Methods: Patients with a confirmed diagnosis of AE submitted to [18F]FDG PET at baseline or during therapy monitoring in our center from 2015 to 2021 were initially considered. Both patients with positive autoantibodies and seronegative patients have been included. Results of standard MRI (either normal of abnormal) were recorded. Pattern of abnormal brain metabolism highlighted at [18F]FDG PET were compared with ASL perfusion changes. Results: 19 patients with confirmed diagnosis of AE were submitted to [18F]FDG PET in our center (mean age 54.3 ± 22.3; range 17-86 years; 4 anti-NMDR; 4 anti-LG1; 2 anti-Ma; 1 anti-caspr2, 1 anti-hu, 1 anti-Tr and 1 anti-yo and 8 seronegative). Standard MRI was normal in 8 patients. FDG was normal in 2 patients while hypermetabolism and hypometabolism were evident in 7 and 10 patients respectively. ALS was performed in 4 patients with negative MRI. In these patients areas of hypermetabolism or hypometabolism at [18F]FGD PET had corresponding hyperperfusion or hypoperfusion on ASL with the exception of one patients in which bilateral hypometabolism was evident at [18F]FDG PET while hyperperfusion was unilaterally evident on ASL. The concordance between [18F]FDG-PET and ASL was evident also in cases with follow-up imaging (with a progressive resolution of both metabolic and perfusion abnormalities). Conclusions: We report similar patterns when comparing ASL and [18F]FDG PET in patients with AE with normal standard MRI thus suggesting a potential role of ASL when [18F]FDG PET is not promptly available. The partial mismatch highlighted in one case between metabolism and perfusion in limbic structures supports the multifaceted nature of hypermetabolism in AE, possibly due to different underlying mechanisms (neuroinflammation or seizure activity). . We investigated brain 18F-FDG PET/CT usefulness in patients with uncertain PPA diagnosis and in those with already ascertained diagnosis to evaluate a possible early development into AD or FTD. Methods: We retrospectively enrolled 49 consecutive patients: 15 cases with uncertain symptoms attributable to PPA variants of recent appearance (Group A) and 34 with PPA already ascertained with suspicious clinical signs for early development into AD or FTD (Group B). All patients underwent PET/CT after i.v. injection of 370 MBq dose of 18F-FDG using a Discovery tomograph (GE). Images were analyzed both qualitatively (QL) and quantitatively (QN), the latter by an automated software (Cortex ID, GE Healthcare, USA) that produces brain metabolic map compared with normal age matched controls. Results: QL and QN analyses of PET/CT showed different patterns of cortical hypometabolism in the two Groups of patients. In particular, in Group A, 8/15 patients showed a selective hypometabolism in fronto-temporal and fronto-parietal regions (6 bilateral and 2 in left hemisphere) and were classified as PNFA and SV variants, respectively. In 5/15 cases hypometabolic areas were detected in temporoparietal regions (3 bilaterally and 2 in left hemisphere), in 1/15 cases in right temporo-parietal regions with the patients classified as affected by LPA variant, while hypometabolism was diffuse in the remaining 1/15 cases. QN analysis could better discriminate the areas of bilateral hypometabolism including the apparent diffuse hypometabolism evidenced at QL in one case; thus, 9/15 patients were classified as at higher risk of early progressing into AD (6 cases) or FTD (3 cases), confirming the initial suspect clinical symptoms of disease. In 18/34 Group B cases, PET/CT evidenced areas of hypometabolism in fronto-temporal and fronto-parietal regions (14 bilateral and 4 in left hemisphere) and the classification in PNFA and SV patients was confirmed, while the 13/34 cases with reduced FDG uptake in temporo-parietal regions (8 bilateral, 3 in left and 2 in right hemispheres) were classified as LPA variant. Considering the data of QN analysis, 22/31 (71%) cases showed a considerable hypometabolism in bilateral brain areas and were classified as high risk of progressing into AD ( 8 cases) or FTD (14 cases). Moreover, in the 2/34 cases with diffuse hypometabolism the diagnosis was uncertain also at QN analysis as well as in the remaining case in whom FDG uptake was apparently normal despite suspect symptoms of disease. Conclusions: 18F-FDG PET/CT proved a valuable diagnostic tool to give a useful support for PPA variant diagnosis and for establishing the development of PPA into FTD or AD in both recent and advanced stage of diseases with QN analysis representing the best methods to reach the diagnosis. However, the finding of diffuse hypometabolism in two cases and normal cortical FDG uptake in one case despite the symptoms of PPA remains to clarify with a close follow up. A larger number of cases and a longer follow up is necessary to confirm the present data. Background-Aim: Alzheimer's Disease (AD) and Lewy Body Dementia (DLB) are characterized by a symptomatic overlap in the initial stages; thus, it is required the use of diagnostic methods other than clinical evaluation alone to differentiate them. 18 F-FDG PET/CT can differentiate spatial pattern of hypometabolism of the brain structures allowing to support the process of differential diagnosis in doubtful forms and early stages of the disease. The scientific progress allowed to develop new and more accurate methods of evaluation of PET images; among these, the role of the semi-quantitative evaluation has been proved to be more prominent, due to its contribution in supporting the standard process of visual qualitative rating. The aim of this study consists in comparing the sensitivity and sensibility of both qualitative and semi-quantitative evaluation in differential diagnosis between DLB and AD. Methods: This observational retrospective study evaluated brain 18 F-FDG PET/CT scans of 46 patients selected and followed in the Neurology Department of San Gerardo Hospital (Monza, Italy). These patients were divided in two groups: one of AD patients and the other of DLB patients. The 18 F-FDG PET/CT scan images were retrospectively analyzed using two different methods of evaluation: qualitative analysis (Visual Rating) and semi-quantitative analysis with Cortex ID software (GE Healthcare, Milwaukee, Wls). The statistical analysis of the results was carried out using the SPSS 25 program (IBM Corp. Released 2017, IBM SPSS Statistics for Windows, Version 25.0). The comparison of the frequency of the areas of hypometabolism found in the two groups was carried out by statistical analysis with v 2 (chi-square), while the diagnostic performance of the two evaluation methods in discriminating the two types of dementias was verified by calculating sensitivity, specificity and diagnostic accuracy. Results: A comparison of the prevalence of areas of metabolism in the two forms of dementia was carried out for both 18 F-FDG PET/CT evaluation methods the qualitative analysis showed a statistically significant difference in the prevalence of the alteration of the 18 F-FDG uptake in the right occipital area (AD 0.0% vs DLB 42.1%, p-value = 0.003); on the other hand the use of the Cortex ID showed a significant trend for two areas: right lateral prefrontal area (AD 17.60% vs DLB 47.40%; p-value = 0.083) and right occipital area (AD 29.4% vs DLB 63.2%; p-value = 0.054), whose hypometabolism was detected more frequently in DLB than in AD. These results demonstrated that Cortex ID is better than Visual Rating in making a differential diagnosis between AD and DLB in terms of sensitivity (79%), specificity (100%) and diagnostic accuracy (89%). Conclusions: Our study confirms the importance of 18 F-FDG PET/ CT in the challenging task of making a differential diagnosis between AD and DLB, especially in the early stages of dementia and in the doubtful cases. In order to improve the accuracy, a valuable help can come from the concomitant use of Visual Rating and a semi-automatic software, which has been proved to add specificity and sensitivity to the evaluation. Background-Aim: Despite 123 I-Ioflupane SPECT (DaTscan) in young patients has high diagnostic accuracy as in elderly ones, no clinical impact of images results have been demonstrated. Indeed we believe that in young people is crucial differential diagnosis from Parkinson/Parkinsonism and other neurological disorders to avoid side effects of incorrect therapy and to estabilish the appropriate therapy for young people PD affected, who don't benefit from standard treatment with levodopa. Our objective is to examine the clinical utility in confirming or ruling out clinical diagnosis of PD/Parkinsonism in a subgroup of patients less than 60 years old. Methods: Between 2019 and 2021, 447 patients (pts) suspected with PD underwent 123 I-Ioflupane scintigraphy (DaTscan). 43 pts were younger than 60 years old.17 pts were less than 50 years old and 6 less than 40 years old. A range of 111-185 MBq were injected and tomographic images of brain wereacquired 3-4 h after tracer injection with double head gamma-camera. Semiquantitative analysis by DaTQUANT and Basal-Ganglia was performed. Results: 28 pts had pathological images (9 pts less than 50 years old, 2 less than 40 years old), 10 pts with prevalent putamen impairement, 18 with severe nigro-striatal compromise and one of these pts with ''burststriatum''. One pt had image reppresentative of normal striatum but discordant semiquantitative analysis because of reduced radiofarmaceutical uptake values. In only seven pts familiarity for disease was evidenced. More frequent symthoms were rest tremor, often one side (32pts), bradykinesia (19 pts), rigidity (15 pts), depression (13 pts). Conclusions: Clinical suspicion of Parkison or parkinsonism in pts under 60 years old need diagnostic confirmation by datscan to correct therapeutic management. Our experience shows the fair incidence of the disease even in younger subjects. Infact 65% of pts studied in our institution have positive scan and a large part (9 pts) was less than 50 years old. An early and accurate diagnosis provide the better therapeutic management of this group of pts. A. Cistaro 1 , A. Limberti 2 , C. Casalone 3 , F. Govone 4 , S. Margotti 5 , P. Fania 6 , I. G. Schiera 7 , C. Atzori 8 , D. Imperiale 9 , A. Di Sapio 4 , N. Quartuccio 10 1 Nuclear Medicine Unit, Salus Alliance Medical, Genoa, Italy. 2 Psychology Dept, Liverpool Heart and Chest Hospital NHS Foundation trust-Liverpool, UK. 3 She had a flu-like form with associated asthenia and drowsiness and no lack of sense of smell. It has been resolved in 25 days. Later, she developed progressive immediate memory loss, word-finding issues, motor and thinking slowing down. Methods: CT brain scan appeared as within the norm as well as liver enzymes, TSH, Vitamin B12, Folate and Rapid Plasma Reagine. Anti-ENA DNA ANA HIV TPO TG were negative too. In October, the patient had a further neuropsychological assessment that showed an overall picture characterized by partial orientation to space, working memory disorders, writing and comprehension (of complex tasks) issues, and immediate memory loss (possible sign both of attention span and concentration reduction). The auto-antibodies were assessed in November and they resulted negative. Moreover, the brain MRI scan and EEG (dated at the end of November) were both within the range. CSF neurodegenerative biomarkers and anti-neuronal antibodies appeared in the norm too. Results: Ultimately, in December 2021 she underwent an 18F-FDG PET brain scan and the SPM analysis showed an extensive hypometabolism in the bilateral frontal cortex and bilateral straight gyrus. Spared the cingulate cortex. Conclusions: The patient contracted Covid in March 2021. She developed neurological deterioration identified by FDG-PET. Negative autoantibodies and CSF biomarkers. PET scan was the only exam to define the brain damage in the patient above. Symmetrical bilateral frontal cortex and bilateral straight gyrus hypo-metabolism have been observed, the last one at the direct level of the olfactory bulb. In this area, in patients who died from Covid-19 it has been histologically demonstrated (data to be published) the presence of cellular inclusions named Corpore Amylacea. They would be a small hyaline mass that functions as a waste container that accumulates in the human brain in aging and in neurodegenerative and infectious processes. It is hypothesized to be that it can be involved in a sort of brain cleaning process1. Recently it has been described that they contain some neoepitopes that are recognized by natural IgMs, revealing a possible link between them and the natural immune system2. However, to now in our patient, the only diagnostic tool to evaluate the brain condition has been the 18F-FDG PET. Background-Aim: To evaluate the additional value of CT data to the prognosis of patients with DLBCL who underwent FDG-PET/CT before and after chemotherapy. Methods: A retrospective single-center observational study. Patients affected by DLBCL with a baseline and post chemotherapy FDG-PET/CT images and a follow-up of at least 1-year post-therapy were included. All basal and post-therapy FDG-PET/CT images were independently evaluated by 2 experienced nuclear medicine physicians to determine the type of metabolic response according to the Lugano criteria and the Deauville score. Baseline and post-therapy CT were independently evaluated by 2 experienced radiologists to determine changes in lesion size found on CT according to the Cheson's criteria. The event-free survival (EFS) was measured from the beginning of treatment until evidence of an event. Results: Ninety-one patients were selected in according to the inclusion criteria. Out of them, 84 (92%) showed a complete or partial metabolic response to therapy (R-CHOP in 49 pts, R-COMP in 22 pts and others in 20 pts) (n = 66, 78.6% and n = 18, 21.4% pts, respectively). At CT images, 77 (88.5%) and 10 (11.5%) pts had a complete and partial response, based on the Cheson criteria. Sixty-two pts had a complete metabolic response (CMR) and complete morphologic response (CR), while 3 had partial metabolic response (PMR) and partial morphologic response (PR). Moreover, 14 patients had a CR and PMR, while 4 pts had a PR and CMR. After a median follow-up of 25.5 (0-143) months, 27 (32.1%) patients had a recurrence of disease. The median EFS were 31 (6-143), 30 (5-143), 20.5 (5-122) and 11 (5-14) months, respectively in pts with CMR, CR, PMR plus CR and PMR plus PR. Conclusions: The addiction of a morphological data by CT to metabolic parameters of response to therapy in pts with DLBCL can help in evaluating the prognosis, mainly in patients with a PMR. Background-Aim: PEComa has been shown to be a rare tumor, especially the malignant type originating from the lung. For this reason, diagnostic criteria and treatment strategies of such tumor have not been fully established. We describe the potential of bio-molecular imaging in a case of patient a!ected by a malignant pulmonary PEComa undergoing a fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for post-therapy purposes. Methods: A woman (73 y old) was admitted at Nuovo Ospedale Santo Stefano of Prato Italy due to right subclavicular swelling incidentally detected. A subsequent CT scan showed large mass in right superior pulmonary lobe slightly attached to mediastinal pleura. Several nodules were also detected in the medium and lower right pulmonary lobes. A mild enlargement of mediastinal lymph nodes was an additional morphological finding. CT-guided biopsy of the lung mass showed features favored a diagnosis of PEComa of the lung. At beginning patient underwent at therapy with sirolimus (5 mg) but due to pulmonary toxicity after 3 months the therapy was modified with sirolimus therapy (4 mg) and exemestane. A further CT scan after treatment revealed lesion in right superior pulmonary lobe to present with significant increase of dimensions (49 mm vs 39 mm). Besides, number of secondary nodules in the medium and lower right pulmonary lobes was found to be significantly increased. Several lesions suggestive of metastasis were also found in mediastinal and latero-cervical lymph nodes, hepatic parenchyma and left adrenal glands. No lesions were detected in bones. Results: Along with CT scan, the patient underwent a 18F-FDG PET scan showing the solid mass on the right superior lung to present with a high radioligand concentration (SUV max 19.06). A significant hypermetabolism was observed on mediastinal and latero-cervical as well as on supraclavicular axillary, celiac, para aorto-caval and hepatic hilar lymph nodes. Increased concentration of radioligand was also present on six hepatic lesions (SUV max:15) and on left adrenal nodule. The PET scan also detected multiple hypermetabolic metastatic lesions in almost all bone segments (SUV max 14.87 vertebral bodies and SUV max 10.93 pelvis), with the only exclusion of the skull case. Importantly, none of the bones showing a pathological increase of glucose metabolism presented with morphological abnormalities on diagnostic CT scan. Conclusions: In this contest, results of this case and previous studies suggest that 18F-FDG PET could have a key-role in the diagnostic and therapeutic management of patients affected by this mesenchymal neoplasm. Background-Aim: To assess the role of FDG PET/CT in the evaluation of response to immunotherapy in patients (pts) with solid tumors. Methods: Data from a multicenter (n = 17), retrospective datasheet collected between March and November 2021 were analyzed. Pts with a confirmed diagnosis of neoplasm, who underwent serial FDG PET/CT (before and after one or more cycles of immunotherapy), age [ 18 years and with at least a follow-up of 12 months from the first PET/CT scan were included. Pts who were enrolled in other clinical trials or without any confirmed diagnosis of cancer were excluded. The authors defined the complete, partial, stable or progressive metabolic response to immunotherapy based on the visual and semiquantitative analysis, in accordance with the EORTC criteria. Clinical response to immunotherapy, assessed close to PET images, was compared to the PET response. Results: Totally 357 pts (median age: 42; range: 24-84 years) were included. Lung cancer was the most frequent neoplasm (n = 189, 52.9%), followed by melanoma (n = 113, 31.7%). Nivolumab and pembrolizumab were used in 171 (47.9%) and in 138 (38.7%) pts, respectively. In total, 357 pts had a baseline PET and a first PET (PET1) after immunotherapy, 228 (63.9%) a second PET (PET2), 120 (33.6%) a third PET (PET3), 55 (15.4%) a fourth PET (PET4) and 31 (8.7%) a fifth PET (PET5) scan. Median time between the start of immunotherapy and PET1, PET2, PET3, PET4 and PET5 were 1, 3, 7, 13 and 15 months, respectively. Clinical responses to therapy were available in 295, 194, 96, 48 and 27 pts, respectively. The agreements between PET response and clinical response were 36% for the first, 53% for the second, 29% for the third, 37% for the fourth and 19% for the fifth control. After a median period of 19 (1-31) months, 213 (62.3%) pts died. At Kaplan-Meier analysis, metabolic responders had a better prognosis than the non-metabolic responders, in at least three PET controls after the start of immunotherapy (all p \ 0.001). Conversely, clinical response was prognostically informative mainly for the first two controls, after the start of immunotherapy. Conclusions: FDG PET/CT should have a role in the evaluation of response to immunotherapy in pts with cancer. It can provide both diagnostic and prognostic information in this setting of pts, complementary to the clinical response, thus prompting to a correct therapeutic management. Background-Aim: To assess the prognostic role of baseline FDG PET/CT scan in patients (pts) with oncological disease candidates to immunotherapy. Methods: Data from a multicenter (n = 17), retrospective datasheet collected between March and November 2021 were analyzed. Pts with a confirmed diagnosis of neoplasm, who underwent serial FDG PET/CT (before and after one or more cycles of immunotherapy), age [ 18 years and with at least a follow-up of 12 months from the first PET/CT scan were included. Pts who were enrolled in other clinical trials or without any confirmed diagnosis of cancer were excluded. PET was visually and semiquantitatively interpreted by the experts. A PET region-based analysis was used, in term of T, N and M (alone or in combination). Overall survival (OS) was calculated as the time between PET date and death or last follow-up. Results: Data from 365 pts (median age: 43 years, range: 24-84) were analyzed. Pts were affected by lung cancer (n = 190, 52%), melanoma (n = 114, 31%), genitourinary tract (n = 12, 3%), lymphoma (n = 17, 5%) and others (n = 32, 9%). Nivolumab and Pembrolizumab were the most common prescribed immunotherapy (47% and 39.5%, respectively). Baseline FDG PET/CT was negative in 17 (4.7% pts) and positive in 348 (95.3%) pts. In this latter group, PET/CT showed positive results in a single, double and triple region in 126 (34.5%), 153 (41.9%) and 69 (18.9%), respectively. After a median period of 16 months (1-131), 127 pts died. A significant correlation between the number of positive FDG PET regions and death was found, indeed the rate of death was 33%, 35% and 43% ì, respectively in those with one, two or three positive PET regions. Moreover, the median OS in these three subsets of pts was 21 (1-131) mo., 15 (1-92) mo., and 11 (0-78) mo., respectively for one, two and three positive PET regions (chi-square: 8.467, p \ 0.015). Conclusions: Baseline FDG PET/CT in oncological pts candidates to immunotherapy can help to stratify the prognostic mortality risk. Background-Aim: To evaluate the ability of FDG PET/CT to detect the presence of suspected sites of adverse events correlated with the administration of immunotherapy in patients (pts) with known cancer. Methods: Data from a multicenter (n = 17), retrospective datasheet collected between March and November 2021 were analyzed. Pts with a confirmed diagnosis of neoplasm, who underwent serial FDG PET/CT (before and after one or more cycles of immunotherapy), age [ 18 years and with at least a follow-up of 12 months from the first PET/CT scan were included. Pts who were enrolled in other clinical trials or without any confirmed diagnosis of cancer were excluded. Serial PET scans were performed after the administration of immunotherapy, and the images were visually and semiquantitatively interpreted by the experts. Overall survival (OS) was calculated as the time between PET date and death or last follow-up. Results: Data from 364 pts (median age: 43 years, range: 24-84) were analyzed. Pts were affected by lung cancer (n = 190, 52%), melanoma (n = 114, 31%), genitourinary tract (n = 12, 3%), lymphoma (n = 17, 5%) and others (n = 32, 9%). Nivolumab and Pembrolizumab were the most common prescribed immunotherapy (47% and 39.5%, respectively). Pts were submitted to five serial PET scans after the start of immunotherapy, with an interval between therapy and PET scan ranging between 1 and 15 months. PET findings potentially referred to an inflammation were described in 61/364 (16%), 36/230 (16%), 19/120 (15%), 7/55 (12%) and 4/32 (11%) pts respectively at PET1, PET2, PET3, PET4 and PET5. FDG uptake suspected for inflammation was located in the lung parenchyma, thyroid gland, gastrointestinal tract, lymph nodes and in more than one site in a range of 25-47%, 5-20%, 16-50%, 14-16% and 5-24% pts, respectively for all PET controls. After a median follow-up time of 16 (1-131) months, a slight better OS was reported in pts without any evidence of inflammation at the first FDG PET/CT after immunotherapy than the counterpart (median OS: 15 and 20 mo., respectively). In the same PET control, Deauville Score of the bone marrow was significantly higher in dead as compared survived pts (2.4 ± 1.0 vs. 1.97 ± 0.9, respectively; t-Student test p \ 0.001). Conclusions: Inflamed sites of FDG uptake at PET/CT in pts undergoing immunotherapy are variables, being more frequent in the lung and in the gastro-intestinal tract. The identification of these sites would have an impact on the long-term OS. The role of FDG PET/CT in guiding to radiation treatment planning in head and neck cancer and rectum-anal cancer Background-Aim: The role of PET/CT with FDG is already confirmed in the staging and restaging phase of various solid tumors, and to guide to radiation therapy planning (RTP). In the RTP it is essential to correctly identify the volume to be treated to ensure an adequate dose to cancer tissues and to minimize the dose to healthy tissues. The aim of the study was to evaluate the usefulness of FDG PET/CT in delineating the gross tumor volume (GTV) during RTP in patients with head and neck cancer and rectum/anal cancer. Methods: We retrospectively analyzed thirteen patients with head and neck cancer (n = 7, 54%) and rectum/anal cancer (n = 6, 46%) candidates to RT. FDG PET/CT was performed with patients in the same position of the CT for RTP, utilizing specific devices to improve the reproducibility. After image acquisition and co-registration (software co-registration for PET/CT and CT systems), the GTVs for primary tumor and metastatic lymph nodes detected by PET/CT (GTV-PET) and from CT (GTV-CT) were assessed, and later compared one with the other. Volumes based on CT and FDG PET\CT were compared with a paired Student's t-test. Results: GTVs for the primary tumor were significantly larger on CT (mean 51.5 cc) than PET (mean 37.4 cc) with an average of 27.4% volume reduction (p = 0.01). No volume change was observed for lymph nodes (mean of 1.48 cc on FDG PET/CT vs 1.50 cc on CT; p = 0.1). In 3 patients (23%), additional areas of disease were seen only in PET/CT; in 2 patients (15%) PET/CT led to change of the stage from M0 to M1, leading to change in RTP. Conclusions: FDG PET/CT has an important role in staging and for the definition of the target volume, thus improving the irradiation planning, in patients with head and neck cancer and anal/rectal cancer. Background-Aim: The most frequently tumor that metastasized to adrenal glands is rappresented by lung cancer. However thare are other tumors that can also involve adrenal glands. The purpose of this study was to evaluate the diagnostic performance of 18F-FDG PET/ CT in the evaluation of primary and metastatic adrenal tumors that originate from lung and non lung cancer primary tumors. Methods: We investigated 15 patients with abnormal adrenal 18F-FDG uptake (9 male and 6 female; age 62.8 ± 11 The diagnosis of malignancy was well known in 12 patients that were referred to our Istitution for initial staging, treatment response evaluation-follow-up and unknown in 3 patients with mass-like lesion on surrenalic gland suggesting primary tumor or metastasis. PET/CT scan was performed with standard procedure, with acquisition started after 60 min after intravenously injection of radiotracer. Imaging was performed by the PET/CT tomograph, with low dose CT scan for attenuation correction, in craniocaudal direction for 2 min per bed position. Images analysis was carried out visually and by semiquantitative determination calculating the maximum standardized uptake value (SUV Max) of lesion. The PET/CT imaging results were compared with histopathology, follow-up or MRI results as the gold standard. Results: Among the 3 patients who were referred for primary tumor evaluation, the primary site was the adrenal gland in 2 patients and the other one had diagnosis of lymphoma The primary tumor of the remaining 12 patients, with well known malignancy, were the following: 1 stomach, 3 colon, 2 rectum, and 6 lung. The adrenal gland lesions of the patients were at left side (n = 6), right side (n = 8) and bilateral (n = 1). All the lesions showed significant FDG uptake (SUV max level was mean:11.8 ± 7.04). The 18F-FDG PET/CT revealed also other metastatic lesion at the following sites: lung (1 patient), lymph nodes (9 patients), spleen (1 patient), bone (3 patients) and periton (1 patient). The histopathology, follow-up and MRI results demonstrated metastatic lesions in 13 patients and primary tumor in 2 patient. Conclusions: According to the results of our cases, 18F-FDG PET/ CT clearly demostrates the metastatic and primary adrenal lesions in the patients with lung and not lung cancer, in consideration of significant 18F-FDG uptake. Moreover PET/CT imaging provides additional informations that can change the patients management and staging. ITA-IMMUNO-PET: comparison between CT and FDG PET/CT in the evaluation of response to immunotherapy and their impact on the prognosis Methods: Data from a multicenter (n = 17), retrospective datasheet collected between March and November 2021 were analyzed. Pts with a confirmed diagnosis of neoplasm, who underwent serial FDG PET/CT (before and after one or more cycles of immunotherapy), diagnostic or non-diagnostic CT, age [ 18 years and with at least a follow-up of 12 months from the first PET/CT scan were included. Pts who were enrolled in other clinical trials or without any confirmed diagnosis of cancer were excluded. The authors defined metabolic responder/non-responder to immunotherapy based on the visual and semiquantitative analysis, in accordance with the EORTC criteria. While the iRECIST criteria was used for the identification of responders/no-responders at CT images. Results: Totally 357 pts (median age: 42; range: 24-84 years) were included. Lung cancer was the most frequent neoplasm (n = 189, 52.9%), followed by melanoma (n = 113, 31.7%). Nivolumab and pembrolizumab were used in 171 (47.9%) and in 138 (38.7%) pts, respectively. Serial CT and PET/CT images were available respectively in 321 and 357 after the 1st cycle, 205 and 228 after the 2nd cycle, 101 and 120 after the 3rd cycle, 47 and 55 after the 4th cycle, 26 and 31 after the 5th cycle of immunotherapy. Diagnostic CT was performed in 57 (18%), 33 (16%), 22 (22%), 11 (23%) and 9 (25%) pts, respectively for each cycle of immunotherapy. The agreements between PET/CT and CT response were 70% for the 1st, 79% for the 2nd, 73% for the 3rd, 61% for the 4th and 640% for the 5th control. After a median period of 19 (1-31) months, 213 (62.3%) pts died. The median OS in metabolic responders were significantly higher than non-responders for the first 3 cycles of immunotherapy, and similarly also in morphological responders than non-responders (all p \ 0.01). Conclusions: Morphological and metabolic response to immunotherapy assessed respectively by CT and FDG PET/CT seems to be complementary, being the agreement between the imaging techniques moderate, but both able to stratify the prognosis. Background-Aim: Regorafenib (REG) has been recently approved for the treatment of relapsed glioblastoma multiforme (GBM). Contrast-enhanced (CE) magnetic resonance (MR) imaging represents the gold standard for diagnosis and surveillance of brain tumors. We evaluated the potential role of 18F-DOPA PET/CT in determining the response to REG in a case series of patients with recurrence of highgrade gliomas. Methods: Three patients with recurrence of high-grade gliomas underwent CE-MR and 18F-DOPA PET/CT within 1 week before and at 8 week intervals after REG therapy. 18F-DOPA PET was analyzed using qualitative and quantitative approaches. For the quantitative analysis, maximum (SUV max ), mean standardized uptake values (SUV mean ) and metabolic tumor volume (MTV) were obtained. Results: In two patients, an early metabolic response to REG treatment, both visually and in terms of reduction of SUV max , SUV mean and MTV was observed. In one subject no metabolic response was detected. Metabolic PET data were in agreement with morphological and perfusion MRI data in two patients. In one patient, while 18F-DOPA was able to correctly diagnose a metabolic response to REG, MRI had misdiagnosed a pseudo-progression of the disease. Conclusions: These preliminary findings suggest that 18F-DOPA PET/CT allows an early and reliable assessment of metabolic response to the REG treatment. A major advantage of PET seems to be obtained in patients in whom MR is unable to differentiate nonresponse vs tumor pseudo-progression. Background-Aim: Novel parameters in PET imaging, such as volumetric parameters, are gaining interest in the scientific literature, but the role of dopaminergic tumor volume (DTV) and total lesion 18F-FDOPA activity (TLDA) and the correlation between PFS (progression free survival) and OS (overall survival) is not defined yet. Methods: 133 patients (61 females, 72 males) with primary brain tumors (grade II-IV gliomas) underwent 18F-FDOPA PET imaging and were retrospectively analyzed. The volumetric parameters and SUV max ratio (the occipital region was chosen to generate ratios of tumor SUV) were calculated and compared with PFS and OS. Results: The prognostic parameters data were normalized, and regression models were applied in univariate analysis. The PFS resulted significant correlated with SUV max ratio (p:0.01, R square: 0.05) and not significantly correlated with DTV and TLDA. The OS resulted not significantly correlated with DTV, TLDA and SUV max ratio. Conclusions: Further papers in larger samples are needed but, according to our results, TLDA and DTV are not correlates with PFS and OS, whereas PFS is correlated with SUV max ratio. 11C-Methionine brain PET imaging for differential diagnosis between tumor progression and radiation-induced changes in patients with brain metastasis Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 MET-PET appears to differentially stratify disease stability on MRI by identifying a substantial amount of complete remissions or even progressions, suggesting its potential role to better characterize morphological residuals or anticipate biological disease changes. Moreover, MET-PET appears to be critical in clinical stratification of the MRI suspected progression by identifying a considerable amount of stability of disease. Therefore, the integration of MET-PET into the clinical work-up for patients with CNS malignancies appears to be crucial and cost-effective. A single center 18F-DOPA PET/CT experience in patients with primary brain tumors after treatment: preliminary results Background-Aim: Positron emission tomography/computed tomography (PET/CT) with 18 F-l-dihydroxyphenylalanine ( 18 F-DOPA) has emerged as a promising diagnostic tool in the evaluation of primary brain tumor. The primary objective of our study was to evaluate the diagnostic and prognostic value of PET with 18 F-DOPA in patients with clinical suspicion of primary brain tumor progression and inconclusive MRI. Methods: 28 patients (15 M and 13 F), median age 54 years (33-79) with brain tumor that underwent 18 F-DOPA PET/CT at Nuclear Medicine Division of our Institution between 11/2020-11/2021 were retrospectively included. All patients performed brain 18 F-DOPA PET scan for disease restaging after a suspicious or not conclusive MRI for disease progression (PD). For each patient clinical data, histological information and molecular biomarkers were collected. All patients underwent previous neurosurgical resection followed by one or more lines of therapy. 18 F-DOPA PET/CT study was performed ± 20 min after the injection of about 185 MBq of 18 F-DOPA. PET images were categorized by two expert physicians in positive in case of abnormal uptake higher than background or negative if not. For background the contralateral striatum (S) and the normal contralateral parenchyma (N) were considered as reference regions. SUV max , SUV mean , SUVpeak for target lesion (T) and SUV max T/N and SUV max T/S, corrected for body weight (BW), were collected by drawing a VOI on a dedicated workstation. Inferential analyses were performed by Mann Whitney and Kruskal-Wallis tests. Results: Patients presented with astrocytoma in 3 (11%), oligodendroglioma in 16 (57%) and glioblastoma in 9 (32%) cases respectively. PET was considered as positive in 13 cases (46%, 6 with T/S [ 1) and negative in 15 cases (54%). 5 of 28 patients lack MRI data: of these 3 had negative PET and 2 positive PET due to PD. PET ruled out PD in 8/13 patients with dubious MRI and confirmed PD in 5 cases. In 10 patients with suspected PD at MRI, PET was negative in 4 and positive in 6. Therefore, PET had an added value in 17/28 (61%) patients. Median follow up was 12 months. 9/13 patients who had a positive PET for PD started a new treatment. The median Ki67 in patients with negative PET was 7% vs 35% in patients with positive PET (p = 0.01). Furthermore, at Ki67 increasing by one point, the probability of PET positivity increased by 9%. Target lesion median SUV max was 3.1 (2.3 in oligodendrogliomas, 2.7 in astrocytomas and 5.4 in glioblastomas) but not statistically differences were found among the different histologies. Conclusions: Our preliminary data confirm the added value of PET in the setting of brain tumor restaging with a complementary role to MRI, in particular to confirm or not the progression of the disease, with an impact on therapeutic choice. Interestingly PET positivity was found to be correlated with tumor Ki67. Further prospective studies on a larger sample of patients with greater homogeneity are needed to confirm these results. 18F-FDG brain and whole body (WB) PET/CT in intracranial leptomeningeal carcinomatosis and in paraneoplastic neurologic syndromes F-FET were determined, using cut-off values of 2.15 and 2.5, respectively. Pts were divided into two groups according to their WHO classification (WHO grade II-III vs WHO grade IV) and according to MRI results based on the qualitative intensity of gadolinium uptake (absent/low enhancement being considered negative for recurrence, while high enhancement being considered suspected for tumor relapse). We applied Student t-Test to estimate statistical differences between these groups in terms of SUV max and TBRmax. Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 presence of nodal metastasis (p = 0.002), SUV max (p = 0.024), SUV mean (p = 0.036), MTV (p = 0.002) and TLG (p = 0.002) were significantly correlated with PFS. However, at multivariate analysis these parameters did not confirm these evidences. Furthermore, at univariate analysis presence of nodal metastasis (p = 0.008), SUV max (p = 0.002), SUV mean (p = 0.017), SUVlbm (p = 0.022), MTV (p = 0.039) and TLG (p = 0.032) were significantly correlated with OS. Subsequent multivariate analysis confirmed only the presence of nodal localization of disease (p = 0.042), SUV max (p = \ 0.001) and SUV mean (p = 0.003) as independent prognostic factors for OS. Conclusions: In conclusion, our work underlines the prognostic role of baseline 18 F-FDG PET/CT semiquantitative parameters in paranasal sinuses SCC. In particular, presence of nodal metastasis, SUV max and SUV mean reveaked to be independent prognostic factors for OS. The use of the receptor-targeted radiotracer 99MTC-tilmanocept in sentinel lymph node biopsy in patients with early oral squamous cell carcinoma Background-Aim: The concomitant presence of neuroendocrine carcinoma (NEC) and squamous cell carcinoma (SCC) represents a rare event, especially in the neck region. Methods: We report the case of a 71-yrd-old man smoker with a large (6 cm) left laterocervical mass suggestive at biopsy for poorly differentiated carcinoma of neuroendocrine origin and a concomitant oropharynx primary SCC. The patient came to our attention to perform a whole body 18F-FDG PET/CT study that was acquired according to standard protocol. Images were analysed both qualitatively and semiquantitatively, measuring SUV max at the level of hypermetabolic lesions. The patient had previously undergone contrast-enhanced CT of neck and chest regions and contrast-enhanced magnetic resonance imaging (MRI) of the head and neck. These procedures evidenced the two neck lesions mentioned above and multiple metastatic lymph nodes in the left laterocervical region. Results: 18F-FDG PET/CT scan showed a large area of marked uptake (SUV max : 17.40) in the known left laterocervical mass and a smaller focal area of increased uptake (SUV max : 6.75) at the level of the primary oropharynx cancer. Multiple small focal areas of increase uptake were also evident in left laterocervical lymph nodes (SUV max: 12.78). PET/CT examination showed 2 further areas of marked increased uptake in the tenth right rib (SUV max : 9.34) and in the right side of sacrum (SUV max : 21.55), respectively, suggesting occult skeletal metastases. The sacral lesion was biopsied and showed the same neuroendocrine histopathological characteristics of the left laterocervical mass. Because the coexistence of NEC and SCC and distant bone metastases, the patient was treated with immunochemotherapy and left neck radiotherapy and died 5 months after the PET scan. Conclusions: In this rare case with concomitant NEC and SCC in the region of neck, 18F-FDG-PET/CT confirmed all the lesions evidenced at conventional radiological imaging procedures and evidenced occult distant bone metastases, contributing to complete disease staging. Moreover, PET images showed a SUV max markedly higher in NEC than in SCC lesions, suggesting a higher aggressiveness for the former component and a worse prognosis. Role of 18F-FDG PET-CT in evaluating lymph node status in patients with head and neck squamous cell carcinoma Background-Aim: Metastatic cuteanous squamous cell carcinoma (cSCC) is a very rare condition. The lack of definition of an oligometastatic subgroup means that there is no consensus for its treatment, unlike the mucosal head and neck counterpart. As the latter, the cutaneous form is able to develop bulky tumor masses. When this appens, the classic care approach is just for palliative intent due to a likely unfavourable benefit-risk balance typical of aggressive treatments. On the basis of FDG-PET/CT imaging it was possible to precisely define not only the disease burden (detecting an unknown metastasis) but above all the inhomogeneity of the metabolic activity of the bulky mass. This has allowed health physicists and radiotherapists to propose a new radiotherapy technique to treat the bulky mass and to obtain an excellent patient outcame. Methods: We treated a case of facial cSCC with three metastases: two of them by classic stereotactic RT, the other by lattice RT supported by metabolic imaging (18F-FDG PET) due to its excessively large dimensions. For the latter lesion, we compared four treatment plans with different RT techniques in order to define the best approach in terms of normal tissue complication probability (NTCP) and tumor control probability (TCP). Moreover, we developed an ad-hoc mathematical radiobiological model that could fit better with the characteristics of heterogeneity of this bulky metastasis for which, indeed, a segmentation of normoxic, hypoxic and necrotic subvolumes might have been assumed. We followed the efficacy of the RT performed by checking it with FDG-PET/CT interim and after treatment. Results: We observed a clinical complete response in all three disease sites; the bulky metastasis actually regressed more rapidly than the other two treated by stereotactic RT. For the large lesion, NTCP predictions were good for all four different plans, but even significantly better for the lattice RT plan. Neither the classic TCP nor the ad-hoc developed radiobiological models could be totally adequate to explain the reported outcome. This finding might support a key role of the host immune system. Conclusions: PET-guided lattice RT might be safe and effective for treatment of bulky lesion from cSCC. FDG-PET/CT was better than CE-CT in defining the total disease burden and response to radiotherapy just a few days after its onset. Recently the Hopkins criteria were introduced with promising results. We proposed a 3-point score, similar to Deauville score and compared its diagnostic accuracy with Hopkins criteria for the evaluation of treatment response in LC. Our aim was to validate our qualitative and simpler interpretation system to assess therapy response and survival outcome in patients with advanced stage of LC. Methods: We retrospectively included 93 patients with advanced stage (III-IV) LC who underwent 18F-FDG-PET/CT after completion of first-line treatment. PET/CT scans were interpreted according to a 3-point scale like Deauville score criteria (score 1 = uptake lower than blood-pool activity; score 2 = uptake higher than blood-pool but lower than liver activity; score 3 = uptake higher than liver). Patients were followed up for a median of 18 Background-Aim: Texture analysis is an emerging tool for assessing intratumoral heterogeneity allowing the extraction of texture features from different imaging modalities, such as 18F-FDG PET/CT. Among these features, coefficient of variation (CoV, SD divided by SUV mean ) is a simple and easy to calculate first order parameter that reflects the heterogeneity of glycolytic phenotype. The aim of our study was to test the ability of CoV derived from 18F-FDG PET/CT scans in the evaluation and quantification of the heterogeneity of glycolytic phenotype in primary and metastatic lesions of non-small cell lung cancer (NSCLC) patients with advanced stages and to test its ability to predict overall survival (OS) in the same patients. Methods: Eighty-four patients (59 men, 25 women) with advanced NSCLC who had undergone whole-body 18F-FDG PET/CT scan before any therapy were included in the study. Imaging parameters including SUV max , SUV mean , CoV, total MTV (MTVTOT) and whole-body TLG (TLGWB) were determined. Student's t-test was used to compare means of unpaired data. Univariate and multivariate analyses of clinical and imaging variables were performed using Cox proportional hazards regression. Survival analysis was performed using Kaplan-Meier method and log-rank tests. Results: A total of 194 lesions were analyzed including 84 primary lung tumors, 48 regional lymph nodes, 17 non-regional lymph nodes, 9 liver metastases, 23 bone lesions and 13 metastases in other sites. Average CoV values of primary lesions, regional lymph nodes, nonregional lymph nodes, liver metastases, bone lesions and other distant metastases were 0.36 ± 0.13, 0.36 ± 0.14, 0.42 ± 0.18, 0.30 ± 0.14, 0.37 ± 0.17, 0.34 ± 0.13, respectively. No statistically significant differences were found between CoV values of primary tumors, regional lymph nodes, non-regional lymph nodes, liver lesions, bone metastases and other distant lesions. Survival analysis was performed including age, gender, histology, stage, MTVTOT, TLGWB and imaging parameters derived from 84 primary lung tumors. At univariate analysis OS was predicted by CoV Background-Aim: Clear cell renal carcinoma (RCC) is a disease generally represented by low-FDG avidity. Accordingly, FDG-PET is not recommended to stage the primary tumor. However, its role to assess metastatic disease locations, namely for lung metastases, is still unclear. Therefore, the aim of this study was to evaluate the diagnostic accuracy of FDG-PET to correctly identify RCC lung metastases using histology as standard of reference. Methods: Records of 205 patients affected by RCC and with radiological (ceCT) evidence of lung nodules detected during clinical follow-up, were retrospectively analyzed. Inclusion criteria were: a) histologically proven RCC; b) at least one lung nodule observed in ceCT suspected for malignancy; c) FDG-PET performed prior to surgery; d) lung surgery performed, with histological analysis of surgical specimens; e) complete follow-up available. A per-lesion analysis was performed, and diagnostic accuracy was reported as sensitivity and specificity, using histology as standard of truth. FDG-PET semiquantitative parameters (SUV max , MTV and TLG) were collected for each lesion. Results: Sixty-nine (n = 69) patients were included (49 females, 20 males, median age 65 years old), and a total of 111 lesions were evaluated. Lung metastases from RCC were detected in 57/111 of cases, 50/111 lesions were related to primary lung malignancy, while 4/111 were non-malignant nodules. Solitary lung nodule was detected in 44/69 of patients. Applying an arbitrary cut-off of SUV max C2, the sensitivity/specificity of FDG-PET for correctly detect RCC lung metastases were 33.3% (95% CI 21.1-45.6%) and 29.6% (95% CI 17.5-41.8%), respectively. Applying the same SUV max cut-off for detecting malignant (RCC and non-RCC) vs non-malignant nodules, the sensitivity/specificity were 52.3% (95% CI 42.9-61.8%) and 75.0% (95% CI 32.6-100.0%), respectively. The median values of SUV max , MTV and TLG among patients with RCC lung metastasis were 1.58, 0.12 cm3 and 0.05 respectively, whereas the median values among patients with other lung malignancy were 4.63, 1.49 cm3 and 5.41, respectively (all p \ 0.001). Conclusions: This analysis demonstrated sub-optimal diagnostic accuracy of FDG-PET to discriminate between RCC versus other lung malignancies, and its use to correctly identify RCC lung metastases should be discouraged. However, since FDG-PET is still routinely used in the screening of cancer patients, also affected by RCC, the extraction of semiquantitative volumetric PET parameters might help in the correct identification of malignant vs. non-malignant lesions. Further studies enrolling larger population will clarify if the application of different SUV max cut-off values will improve the diagnostic accuracy. Background-Aim: 18F-FDG PET/CT has an essential role in the correct staging of NSCLC and in particular is of great importance for a correct mediastinal lymph node staging in early stages, where surgery with curative intent is the treatment of choice. The aim of this study is to evaluate the diagnostic performance of 18F-FDG PET/CT validated by histopathology surgical findings. Methods: This retrospective study included 57 NSCLC patients (38 males and 19 females, aged 50-81 years, mean age: 67.9 years) who preoperatively underwent 18F-FDG PET/CT. All patients had undergone diagnostic chest or whole-body CT. With regard to histological subtypes 38 were adenocarcinomas, 15 squamous cell carcinomas, 1 adenosquamous carcinoma, 1 neuroendocrine carcinoma, 1 atypical carcinoid and 1 unspecified NSCLC. Regarding the lymph node involvement, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated for both CT and 18F-FDG PET/CT using the final histopathological N-staging (pN0 to pN3) as reference standard. Results: Mediastinal lymph nodes were B 1 cm in their larger diameter at diagnostic CT in 29/57 28/57 patients, while mediastinal lymph nodes measured [ 1 cm in the remaining 28/57 cases. The mediastinal lymph node uptake at the 18F-FDG PET/CT was not significant in 42/57 cases and of high degree in 15/57 cases. The histopathological evaluation showed no lymph node metastasis in 52/57 patients, 28 of them correctly assessed by CT and 41 of them correctly assessed by 18F-FDG PET/CT. Metastatic lymph node involvement was seen by histopathological evaluation in 5/57 patients, 4 of them correctly assessed either by CT and 18F-FDG PET/CT. Therefore in this study CT yielded 80% sensitivity, 54% specificity, 14% PPV, 96% NPV and 56% accuracy. 18F-FDG PET/ CT yielded 80% sensitivity, 79% specificity, 27% PPV, 98% NPV and 79% accuracy. SUV max was calculated in both true positive and false positive cases and it was equal to 7.12 ± 4.87 and 4.32 ± 0.95, respectively. The only 18F-FDG PET/CT false negative result referred to a case of atypical carcinoid where the peri-bronchial lymph nodes were indistinguishable from the primary lesion that was attached to the mediastinum. Among the 11 PET/CT false positive cases, 8/11 had mediastinal lymph nodes [ 1 cm, with a pattern of anthracosis in 4/8 patients. Moreover, a medical history of chronic bronchitis, emphysema or occupational exposure to asbestos was reported in 6/11 cases. Conclusions: In the present study, 18F-FDG PET/CT showed high sensitivity and specificity values and an excellent negative predictive value in the pre-operative NSLC mediastinal lymph node staging. Moreover, in our series, 18F-FDG-PET/CT demonstrated a lower rate of false positive findings than CT. Therefore, in agreement with previous studies, pre-operative invasive mediastinal staging may be omitted in cases with negative 18F-FDG PET/CT. Background-Aim: Gastro-entero-pancreatic Neuroendocrine Tumors (GEP-NET) are a heterogeneous group of tumors having a common feature, the membrane expression of somatostin receptors (SSTR). They then represent a good target for radionuclide molecular imaging; the first radiopharmaceutical (RF) available on market was 111Inpentetreotide in late 1980s. After demonstration of its reliability and the diffusion of PET/CT systems, imaging of SSTR-expressing tumors shifted to SSTR-binding 68Ga-labelled PET RF. Their clinical performance is terrific, but their widespread availability is still limited because of their high cost for centres with a small patient throughput (\ 50 pts/year). More recently, a technetiated SSTR-binding RF, EDDA-HYNIC-TOC, (TCSSR) was approved for diagnostic use. Without expecting a sensitivity comparable to 68Ga-labelled RF, nevertheless its reliability on a patients-based clinical evaluation has never been fully tested, having been available only in recent years. We then reviewed accordingly our experience. Methods: Between the 103 scans performed in years 2018-2021, we enrolled 66 patients with suspected or ascertained GEP-NET. Clinical evaluation of the results (post-scan evaluation, PSE) were made according to surgical, histo-pathological, radiological and clinical follow-up data, whatever available. PSE data were unavailable in 8, leaving 58 cases for analysis. Due to the time span considered, there is no follow-up longer than 3 years. Results: We had 20 scans without demonstration of SSTR ? pathologic findings and 38 patients with SSTR ? lesions. Between the negative cases, PSE revealed 5 false negative results, all in highly aggressive GEP-NET (4 out of 5 had also FDG avid lesions). Between the positive cases, PSE demonstrates in all that TCSSR gave a disease staging adequate for the following surgical treatment or medical management. The sensitivity of TCSSR was 88% and accuracy 91% Conclusions: All SSR-binding RF had greater affinity for, in decreasing order, SSTR2, SSTR5 and SSTR3 receptors. Difference in imaging accuracy depends, apart from the density of SSR on the cell surface, from the acquisition system performance. This is a clearly, well-known superiority of PET vs SPECT, often enhanced by the lower quality of the CT system available on SPET/CT machines. But GEP-NET lesions present, often, with a size and a spreading that makes the clinical yield unaffected by the lower resolution of SPET/ CT system. It must also be underlined that our SPET/CT systems are not as ''state-of-the-art''. More, it is known that GEP-NET may have different degree of dedifferentiation also into the same patient, and that one component may be FDG avid, as in 4 out of 5 our FN patients. In conclusion TCSSR seems a reliable clinical tool for centres with no availability of SSTR-binding PET RF and a small patients throughput, being also, in this setting, cheaper and equally flexible in using. Of course, its use cannot be suggested for characterizing small lesion (diameter below 10 mm), also if in our experience we visualized lesions as small as 8 mm. At end, in case of larger lesion TCSSR negative, FDG-PET can be a reasonable and more prognosis-impacting alternative to SSTR PET. Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 Results: The exam showed increased uptake of receptorial radiopharmaceutical on the sternum (Krenning score 3) and right sacroiliac junction (Krenning score 3-4). Therefore the patient started lanreotide acetato e.v. (Ipstyl 90 mg) every 28 days and 3 months after, bone pain reduction expecially at sacro-ilac junction was obtained. Conclusions: According to initial promising results of treatment of advanced HCC by somatostatin analogues we obtained benefit from treatment with somatostatin analogues in our patient. Theexpression of somatostatin receptors in the tumor might select patients who could benefit from therapy. We suggest an early use of octreoscan in patients with advanced but not terminal stage HCC. Background-Aim: 131I-SPECT/CT, obtaining functional and anatomic fusion images, has proved capable of improving the performance of planar whole-body scan (WBS), for many years considered the reference diagnostic tool in patients thyroidectomized for DTC in association with serum Tg assay and radiological procedures. We further investigated whether routine SPECT/CT use may have an incremental value than WBS increasing sensitivity and accuracy and allowing precise anatomic localization and characterization of the lesions. All patients had undergone a [68Ga]-DOTATOC PET/CT scan prior to the treatment to assess SSTR overexpression and had liver metastases associated with lymph node disease in 13 cases, skeletal in 5 cases and peritoneal in 1 case. Most patients had undergone primary surgery, followed by adjuvant therapy with Capecitabine or Sunitinib in 5 patients. During the treatment, patients were clinically and laboratoristically monitored (blood count, creatinine, albumin, bilirubin) and by scintigraphic (planar and SPECT/CT) post-therapeutic imaging. Efficacy was evaluated by RECIST criteria starting from 3 months after the fourth treatment cycle. As response criteria, changes in lesions' [ 68 Ga]-DOTATOC PET/CT uptake and Chromogranine-A (CgA) values had been evaluated. Results: Sixteen patients completed the treatment consisting in 4 administrations of Lutathera Ò (740 MBq) every 8 weeks, 1 patient died from an unrelated cardiovascular event and 1 patient dropped out because of a severe thrombocytopenia due to a pre-existing disease. The treatment was well tolerated and no changes contraindicating subsequent treatment were found, but a significant mean decrease in erythrocyte (p \ 0.01) and leukocyte (p \ 0.05) count and hemoglobin concentration (p \ 0.05) was observed. Conversely, there was no significant reduction in other haematological parameters. At 3 months after treatment, 9 patients presented a stable disease (SD), 5 patients a partial response (PR), 1 patient a complete response (CR) and 1 patient a disease progression (DP). Compared to baseline, CgA values during and after treatment had not significantly modified while a significant reduction of scintigraphic indices of Lutathera Ò uptake Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 was observed comparing the fourth acquisition versus the first one. Pearson's linear regression did not show any statistically significant relationship between % changes in CgA and scintigraphic uptake indices. In the group of patients who had CR and PR, decrease in uptake indices was significantly greater than in those with SD and PD (p \ 0.05). Conclusions: PRRT with Lutathera Ò represents an effective and tolerable option for no longer operable patients with progression disease. Imaging is valuable for patient selection, monitoring and disease response evaluation while less clear is the role of CgA. Background-Aim: Purpose of this study was to correlate somatostatin receptor and proliferative activity profile at immunohistochemistry (IHC) with SSTR-PET/CT imaging features in a retrospective series of lung neuroendocrine neoplasms (NEN). Proliferative activity by Ki-67 was also correlated to 18F-FDG-PET/ CT parameters, when available. Methods: Consecutive patients with a confirmed diagnosis of lung NEN who underwent SSTR-PET/CT with 68Ga-DOTA-somatostatin analogs (SSA) between 2011 and 2020 were included. PET/CT images were reviewed by qualitative and semi-quantitative analyses. IHC for SSTR2, SSTR5 was scored as negative or positive, and Ki-67 was assessed. An inferential analysis was performed including kappa statistic and Spearman's rank correlation test. Results: Of 35 included patients, definitive diagnosis consisted of 32 low-intermediate-grade NEN (26 typical carcinoids-G1 and 6 atypical carcinoids-G2) and 3 high-grade NEN. SSTR2-IHC positivity was found in 63% of samples, while SSTR5-IHC positivity was only 17.6%. A correlation between SSTR2-IHC and SSTR-PET/CT was found in 26/35 cases (74.3%, p = 0.003): 22 were concordantly positive, 4 concordantly negative. In detail, positive and negative IHC had 100% and 30.8% concordance with SSTR-PET/CT, respectively. In 9 cases, IHC was negative while SSTR-PET/CT was positive, even though with low uptake in 8/9 cases. Another significant correlation was found between low SUV max values corresponding to negative IHC, and higher SUV max values to positive IHC (p = 0.0007). When correlating SUV max from 68Ga-DOTA-SSA or 18F-FDG (available for 16 patients) with Ki-67, a significant result was found for 18F-FDG only (p = 0.015). Conclusions: This retrospective study showed an overall good agreement between SSTR2-IHC and tumor uptake at SSTR-PET/CT in lung NENs. SSTR-PET/CT SUV max values can be used as a parameter of SSTR2 density. SSTR2-IHC may be proposed as surrogate of SSTR-PET/CT in selected lung NEN patients for clinical decision making when SSTR-PET/CT isn't available. Background-Aim: Primary hyperparathyroidism (pHPT) is one of the most common endocrine disorders, generally discovered incidentally during routine blood tests which show hypercalcemia. Diagnosis is established biochemically: inappropriate levels of PTH in a patient with hypercalcemia are consistent with the diagnosis of pHPT, although sometimes pHPT may be normocalcemic. A cure can only be achieved by removing all unhealthy glands. The correct preoperative localization of the hyperfunctioning gland(s) represents a crucial step, mostly if a minimally invasive procedure is contemplated. This retrospective study aims to establish 18F-fluorocholine (FCH) PET/CT performance in finding hyperfunctioning parathyroid glands, to analyze a potential role for semi-quantitative PET parameters and to assess factors which may influence PET/CT outcome. Methods: Forty patients with suspect pHPT and negative/equivocal conventional imaging underwent FCH-PET/CT in our institution. Values of PTH and serum calcium were measured within a week before FCH-PET/CT exam in all patients. All PET/CT scans were executed 60 min after FCH administration (110 ± 8 MBq). Visual and semi-quantitative analyses were performed on PET/CT images for every single lesion. In qualitative analysis a lesion was considered positive if a clear focus of uptake, significantly higher than regular thyroid tissue, was identifiable. Ectopic focal uptake was also considered as positive PET result. Lesion SUV max was measured by assigning a spheric VOI to the suspect area of uptake. Thyroid SUV mean was assessed by placing a spheric VOI inside the contralateral thyroid lobe and SUV ratio (SUVr) was calculated using this background region. All patients were subsequently submitted to surgery and histopathologic workup (longest diameter and ki67 values were collected). Sensitivity, positive predictive value (PPV) and accuracy were calculated basing on histopathologic reports for every single lesion. Receiver operating-characteristic (ROC) analysis was used to determine the optimal cutoff for SUVr in predicting true hyperfunctioning parathyroids. Pearson's test was used to assess a correlation between laboratory and histopathologic features with SUVr. Results: Four out of the 40 patients who underwent surgery for pHPT had more than one histologic proven unhealthy parathyroid and three had additional papillary thyroid cancer (PTC). A total of 48 lesions were analyzed. We found 42/48 lesions (87.5%) to have true-positive uptake whereas 3 lesions (6.7%) had false-positive uptake (PTC). Three histologic proven parathyroid adenomas showed no uptake (6.7%); the sensitivity/PPV were 93.3% and accuracy was 87.8%. Mean SUV max and SUVr were 3.6 and 1.9, respectively. ROC curve analysis did not show an appropriate cut-off for SUVr to semiquantitatively identify hyperfunctioning parathyroid glands. Pearson's test showed a significant correlation between PTH values and parathyroid size with SUVr values (r = 0.56 and 0.55, respectively; p \ 0.01 for both features). Conclusions: As stated in recent literature, we observed excellent diagnostic sensitivity of FCH-PET/CT in patients with pHPT, providing surgeons a fine tool to optimize treatment. More studies are needed to enhance the evaluability of semi-quantitative parameters towards a further improvement of diagnostic accuracy. Background-Aim: Evidence based studies about neuroendocrine tumors' (NETs) follow-up are largerly missing. Long-term follow-up allows the later recurrence discovery and earlier relapse diagnosis. Aim of the study is to confirm the benefit of medium-long term follow-up by 111 In-pentetreotide (SRI) in resecated patients (pts) with pancreatic, small bowel and lung NET and to evaluate the benefit of follow-up also in NETs from other sites in the digestive tract or from gynocological system and when metacronus/sincronus tumor are associated. Methods: Between 2014 and 2021, 72 pts affected with NET (GEP, pulmonary and other origin sites NETs) have been on follow-up with octreoscan on the basis of multidisciplinary oncological group decision. The resecated pts follow-up was performed routinely twice or one a year according to national and International guidelines in pancreatic, ileal and pulmonary NETs and in other NETs' types when morfological imaging were doubtful or the tumor was particularly aggressive or in presence of clinical or laboratory progression without progression on conventional imaging or conversely when a new indeterminate lesion appared on conventional imaging with unclear progression. Pts with syncronus or metacronus tumor were on followup too. 111 In-pentetreotide (185 MBq) were administered e.v. and images have been acquired at 4 and 24 h after injection by a dual head equiped gamma-camera. Planar images have been acquired using a large-field-of-view gamma camera fitted with a medium-energy collimator. Planar localized images of the head, chest, abdomen, pelvis have been acquired for 10-15 min/image. Whole-body images were acquired with a speed of up to 3 cm/min in a single pass as ENETS guidelines suggest. Early and delayed SPECT imaging of chest and abdomen at 4 h and 24 h have been performer too. Results: 20 pts with pancreatic NETs (5 G1, 11 G2, 3 G3, 1 n.c.) had metastatis at onset but in 3 pts metastatic spread was detected in the subsequent imaging follow-up. 8 pts on medical therapy with analogues in combination with everolimus or chemiotherapic regimens remained stable or were on progression regardless of G1-G2 grade. The G3 pts treated with analogues were on progression and requested chemio-immuno therapeutic regimens. 7 pts with ileus NET underwent to surgery. 3 pts were metastatic at onset and one patient was in progression at follow up. All pts were treated with analogues and in six pts stable disease was observed but in one patient metastatic spread was observed and treated. pts with lung NET were on followup, 19 were tipic carcinoid stable over time, 1 patient was metastatic at onset and 2 pts were in progression on follow-up. were affected with NET from other sides (stomach, colon, uterus, appendix, etc.). 7/72 pts had a synchronous or metachronous tumors; 5 pts treated by analogues were stable and 2 had disease progression. Checks frequency was different ranging from 6 to 12 months. Some pts with well differentiated NETs are on follow-up from more than 4 years. Conclusions: Octreoscan allows early recognition of recurrence and distant metastases and is able to highlight changes in tumor and metastases histology over the time. Hence the need for routine and long lasting control for NETs. Conclusions: SPECT is superior to planar imaging in the detection of parathyroid adenoma. Bases on available literature, it conceivable to obtain an higher DR using SPECT/CT. In the case of a low raise of the PTH above the upper normal limit, the probability of both negative planar imaging and SPECT is significant. Inconclusive scintigraphic exams, despite an elevated PTH, should be followed by a Choline Positron Emission Tomography/Computed Tomography (PET/CT) scan. Background-Aim: 68Ga-DOTATOC PET/CT is increasingly used for the imaging of neuroendocrine tumors (NET). Recently, a new formulation of 68Ga-DOTATOC has been developed which is based on the use of a cold kit (SomaKIT TOC, 40 lg edotreoide/vial) for manual radiopharmaceutical preparation. The aim of the present study was to assess the preparation feasibility of this formulation, including labelling and quality control, and the clinical utility of the procedure in NET patients. Methods: From January to December 2021, 45 consecutive patients (25 females and 20 males, aged 34-81 years) with suspicion or biopsy proven NET underwent 68Ga-DOTATOC PET/CT. After elution of 68Ge/68Ga generator, the radiotracer was prepared manually according to manufacturing instructions. The radiolabelled solution was submitted in all cases to quality control tests (appearance, pH, labelling efficiency colloidal gallium-68 species and labelling efficiency % Free gallium-68) and then i.v. injected to patients. A learning curve on 4 SomaKIT TOC vials was necessary before using the radiotracer in clinical practice. PET/CT images were acquired 45-60 min after injection of 129-150 MBq of radiotracer. The clinical utility of 68Ga-DOTATOC PET/CT has been evaluated. Results: The radiotracer was prepared and checked in approximately 20 min. No vials of SomaKIT-TOC were rejected. Solutions were clear and free of visible particles at visual inspection and showed pH values within acceptance criteria (3.2-3.8) in all cases. Moreover, radiolabelling efficiency tested via thin layer chromatography (ITLC) was equal to 100% in all cases. No adverse reactions after administration of 68Ga-DOTATOC were found in any of the 45 patients. All cases demonstrated normal radiotracer physiological distribution respectively in pituitary gland, adrenals, spleen, liver and uncinated process of the pancreas. 68Ga-DOTATOC PET/CT resulted positive in 30/45 patients and negative in the remaining 15/45 cases. Among the 30 positive patients, the procedure was determinant for the initial diagnosis in 11 patients with suspicious NET, evidencing the primary tumor (pancreatic in 9 cases, gastric in 1 and pulmonary in 1) subsequently confirmed at biopsy; PET/CT also detected metastases in liver and/or lymph nodes in 3/11 cases. 68Ga-DOTATOC PET/CT evidenced the primary tumor in 4 further patients with biopsy proven NET (pancreatic in 3 cases and ileum in 1 case) at initial staging; additional local lymph nodes metastases were detected in 2/4 cases and multiple local and distant metastases in bone and lungs in 1/4 cases. Finally, in the remaining 15 positive NET patients (6 pancreatic, 6 ileum, 1 gastric, 1 prostatic, 1 pulmonary) enrolled for restaging purposes, PET/CT evidenced persistent disease at the primary site and metastases in 6/15 cases, while only local and/or distant metastases were detected in the remaining 9/15 cases. Conclusions: Our 1-year experience in employing 68Ga-DOTATOC PET/CT proved that the new radiotracer is easy to prepare, safe and well tolerated by patients. Moreover, the procedure has been confirmed of great clinical usefulness in patients with NET. Background-Aim: Radiotherapy with concurrent 5-fluorouracil/mitomycin-C based chemotherapy has been established as definitive standard therapy approach for anal cancer. Intensity modulated radiotherapy (IMRT) leads to a precise treatment of the tumor, allowing dose escalation on GROSS TUMOR VOLUME (GTV), with a surrounding healthy tissues sparing. Our study assessed the impact of 18-Fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT) on the radiotherapy contouring process and its contribution to lymphatic spread detection, resulting to a personalization of clinical target volume (CTV) and dose prescription. Methods: Thirty-seven patients (28 females and 9 males; mean age 55 years), with histologically proven squamous cell carcinoma of the anal canal (SCCAC) were analyzed. All patients were evaluated with history and physical examination, trans-anal endoscopic ultrasound, pelvis magnetic resonance imaging (MRI), computed tomography (CT) scans of the chest, abdomen and pelvis and planning 18F-FDG PET/CT. The GTV and CTV were drawn on CT, MRI and 18F-FDG PET/CT images. Results: Thirty-four (91%) out of 37 patients presented lymph nodes involvement, in one or more areas, detected on 18F-FDG PET/CT and/or MRI. The PET/CT showed positive lymph nodes not detected on MRI imaging (PET? , MRI-) in 14/37 patients (38%). The 18FDG-PET/CT planning led to change the stage in five (14%) cases when compared to MRI, particularly in four (11%) cases the stage changed from N0 to N1 for positive inguinal LN and in one (2.5%) case from M0 to M1 for common iliac LN involvement. In 10/20 (50%) patients with positive mesorectal LN, MRI outperformed 18FDG-PET/CT in detecting LN in this area. The 18FDG-PET/CT helped us to target volume delineation: in one case with PET-positive common iliac LN, the CTV was extended cranially to include this area. In 14/37 (38%) patients 18FDG-PET/CT led to a dose escalation on PET-positive LN reaching 50-54 Gy. Conclusions: PET-CT and MRI are both useful to define the Clinical Target Volume (CTV). An accurate definition of lymph nodes involvement allows dose escalation and CTV personalization. However, PET/CT seems to have a higher potentially relevant impact in staging and target volume delineation/definition in patients affected by anal cancer. In fact, in our experience the clinical stage variation occurred in 14% of cases, in accordance with other series reported in literature showing the usefulness of PET/CT in the initial staging of patients. The potential role of dynamic pet with 13N-ammonia for evaluating response to sorafenib in advanced HCC patients with sorafenib has adopted as the standard of care. In order to reduce treatment toxicity and high costs, it is important to early identify responder-patients who can benefit from this target agent, and resistant-patients who can be candidate to alternative treatments. Since HCC is characterized by high vascularisation and sorafenib acts on angiogenesis, our preliminary prospective study aims to assess the potential role of PET with 13 N-ammonia, a perfusion tracer, for evaluating early response to sorafenib in advanced HCC patients, correlating changes in 13 Nammonia uptake of liver lesions with mRECIST response. Methods: Eleven male patients (age: 63.7±6.9 years) with advanced HCC were evaluated. All patients underwent contrast-enhanced CT and dynamic PET with 13 N-ammonia (acquisition lasting 20 min; 370 MBq) before (baseline) and 8-10 weeks after (post-therapy) the start of sorafenib treatment. For each patient, quantitative analysis was performed: VOIs were drawn on the descending aorta (input function), on up to five HCC lesions and on two normal liver areas using baseline and post-therapy CT, and transferred on baseline and post-therapy PET, respectively. K1 (ml/min/gr) and k2 (min -1 ) parameters were estimated using 1-tissue compartment model. For each patient, percentage changes of K1 and k2 in HCC lesions (DK1 and Dk2) between baseline and post-therapy PET were correlated to mRECIST response criteria, used as standard reference. Results: HCC lesions (n = 37) showed higher median K1 and k2 values than normal liver both at baseline (2.17 vs 0.47, p \ 0.0001 and 0.31 vs 0.12, p = 0.0022, respectively) and at post-therapy PET (2.23 vs 0.56, p = 0.0001 and 0.42 vs 0.13, p = 0.0001, respectively). According to mRECIST criteria, 8/11 patients were classified as ''disease control'' (1 complete response, 1 partial response, 6 stable disease) and 3/11 patients as ''progression''. At post-therapy PET, HCC lesions in all 8 patients in ''disease control'' showed a reduction in K1 and k2 values, whereas an increase was observed in the 3 ''progression'' patients (median DK1 = -7.41% vs 45.84%, p = 0.0388; median Dk2 = -22.49% vs 217.46%, p = 0.0058). Conclusions: From our preliminary results, dynamic PET with 13 Nammonia seems a promising and feasible tool for early evaluating response to sorafenib in patients with advanced HCC. After treatment, changes in K1 and k2 values reflect the sorafenib mechanism of action, since a reduction of perfusion parameters in ''disease control'' patients and an increase in ''progression'' patients were observed, according to mRECIST criteria classification. The role of 13 N-ammonia PET for predicting time-to-progression and prognosis in our HCC population is matter of ongoing analyses. Background-Aim: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. The most common locations are stomach and gut. GISTs present with a wide spectrum of benign to malignant findings, but all have potential malignant evolution. Therapy with imatinib, a TKI inhibitor, is the standard treatment option for metastatic, recurrent or unresectable GISTs. Metabolic behaviour and the prognostic value of 18FDG PET/CT in gastrointestinal stromal tumors has to be better investigated. The aim of our study was to analyze metabolic behaviour of GISTs and the prognostic role of 18FDG PET/CT. Methods: In this study we retrospectively evaluated 18 patients (mean age 65 y) with histological diagnosis of GIST who underwent 18FDG PET/CT scan pre and post imatinib treatment. PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value corrected for body weight (SUVbw), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). For each parameter, we estimated variation between baseline and post-imatinib values (DSUVbw%, DMTV%, DTLG%). According to PERCIST criteria, patients were classified in complete metabolic responders (CMR), partial metabolic responders (PMR), stable metabolic disease (SMD) and progressive metabolic disease (PMD); CMR and PMR were further classified as metabolic responders (MR) while SMD and PMD as metabolic non responders (MNR). An unpaired student t-test was applied to investigate differences in semi-quantitative parameters between the two groups. Kaplan-Meier method was used to achieve time to progression (TTP) curves for each group and results between MR and MNR were compared using Long-rank test. Results: 3/18 patients were CMR (16.7%), 3/18 patients (16.7%) were PMR, 4/18 (22.2%) patients were SMD and 8/18 patients (44.4%) were PMD. Among the 4 groups CMR had mean DSUVbw% = -29.6, mean DMTV% = -52.7 and mean DTLG% = -58.7. PMR had mean DSUVbw% = -59.6, mean DMTV% = -60.5 and mean DTLG% = -86.3. SMD had mean DSUVbw% = -34.9, mean DMTV% = 56.6 and mean DTLG% = 64.3. PMD had mean DSUVbw% = 54.7, mean DMTV% = 146.5 and mean DTLG% = 273.8. In MR mean DSUVbw% was -44.6, while in MNR was 24.8; t-test resulted not statistically significant. Mean DMTV% was -56.6 in MR and 116.6 in MNR with difference statistically significant (p = 0.008). Mean DTLG% in MR was -72.5 while in MNR was 204.1 resulting statistically significant (p = 0.03). TTP was 27.7 months for the whole cohort. MR showed a significantly longer TTP (mean 24.6 ± 2.1) months than MNR (mean 14.7 ± 6.3 months) (p = 0.006). Conclusions: Metabolic semi-quantitative tumor features (DMTV% and DTLG%) show significant differences in metabolic responder and non-responder patients. Therefore, our data suggest a possible significant value of 18FDG PET/CT in assessing treatment response to imatinib and as a predictor of clinical outcome in aggressive GISTs. The clinical value of 18F-FDG PET/CT in predicting treatment response and prognosis of patients with metastatic breast cancer treated with cyclin-dependent inhibitors Background-Aim: The use of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in combination with endocrine therapy currently plays an important role in hormone receptor-positive metastatic breast cancer, being able to significantly improved progression-free survival (PFS). Despite their great efficacy, not all patients respond to treatment and many of them eventually develop acquired resistance. Aim of the study was to assess the potential role of 18F-FDG PET/CT in assessing treatment response and in predicting PFS, in patients with metastatic breast cancer treated with CDK4/6i ? endocrine therapy. Methods: 114 women with metastatic breast cancer who performed an 18FDG-PET/CT scan before starting treatment (PET1) with CDK4/6i (palbociclib n = 57; ribociclib n = 45, abemaciclib n = 12) and 2-6 months after (PET2) were retrospectively enrolled. Metabolic response was evaluated according to European Organization for Research and Treatment of Cancer (EORTC) criteria and PET Response Criteria in solid Tumours (PERCIST), classifying the patients into 4 response groups: complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD). Classes of metabolic response, absolute value of SUV max of the hottest lesion at PET2 (SUV2) and its percentage change between PET2 and PET1 (DSUV) were related to PFS using the Kaplan-Meier method and Log-rank test. Results: A high agreement between EORTC and PERCIST criteria was observed (k = 0.92). According to EORTC criteria, 20 patients had CMR, 60 PMR, 10 SMD and 24 PMD. With PERCIST, 20 patients had CMR, 52 PMR, 18 SMD and 24 PMD. Disease progression occurred in 55 patients (48.2%) after a median follow up time of 21.8 months. In patients who did not progress at PET2 (n = 90), PFS rates were not significantly different between SMD, PMR and CMR groups, according to both EORTC and PERCIST criteria. Differently, patients showing a SUV2 \ 3.8 had a significantly longer PFS (median = 42.8 vs 21 months; 2-year PFS rate 74.6% vs 49.1%, p = 0.025). Conclusions: EORTC and PERCIST criteria correctly classified patients responders and no responders to treatment with CDK4/6i. PFS is prolonged in patients showing a SUV max \ 3.8 at PET2, while it did not differ significantly among metabolic response groups (SMD, PMR, CMR), regardless the criteria applied. Background-Aim: In patients with locally advanced breast cancer (LABC), neoadjuvant chemotherapy (NAC) followed by surgical resection is the main treatment option. Pathological complete response (pCR) after NAC assessed at surgery is associated with improved prognosis. A non-negligible patients' rate shows residual disease (no-pCR). Early prediction of NAC response is clinically relevant: to identify poor-responders might allow to change or refine the planned treatment, also impacting on outcome. Aim: to investigate if baseline 18F-FDG PET/CT parameters could be early predictors of NAC response in LABC patients. Methods: 108 LABC patients (mean age: 50.4 ± 10.8 years), undergone a baseline 18F-FDG PET/CT for staging and treated with NAC ? surgical resection, were retrospectively analysed. Data on tumor histology and final pathological NAC response (pCR vs no-pCR) were collected. The following PET parameters were calculated and compared between pCR and no-pCR patients (statistical significance: p-value \ 0.05): (1) primary tumor activity (SUV max , SUV mean , SUV peak , MTV, TLG), tumor-to-liver ratio (TLR SUV max , TRL SUV mean ); (2) lymphoid organs activity as spleen and bone marrow SUV max , spleen-to-liver ratio (SLR SUV max , SLR SUV mean ), bone marrow-to-liver ratio (BLR SUV max , BLR SUV mean ); (3) activity of the most metabolically active lymph node (SUV max , SUV mean , SUV peak ) and tumor-to-node ratio (TNR SUV max ) in those patients presenting with regional nodal involvement (cN?). Results: At histology: [ 80% were invasive ductal carcinoma, [ 70% Luminal-subtype; 31/108 pts (29%) were classified as pCR after NAC, 77/108 (71%) as no-pCR. In pCR patients, BLR SUV max , BLR SUV mean , TLR SUV max and TRL SUV mean were significantly higher than in no-pCR (p = 0.03). Although a trend in higher tumor SUV max in pCR than no-pCR patients was observed (median: 8.6 vs 6.8), no differences in other PET parameters were found between the 2 groups, not even in PET nodal parameters in cN ? patients (82/108). Moreover, significant differences were found in Ki-67% with higher values in pCR-group (p = 0.003), but not in tumor grade distribution. Conclusions: In LABC patients, bone marrow activity at baseline 18F-FDG PET seems able to predict individual NAC response, supporting a role of lymphoid organs metabolism as expression of immune system activation/systemic inflammatory response against the tumor. Moreover, higher baseline tumor activity suggests a favorable pathological response to NAC. Predictive value and reproducibility of BC metabolism is likely affected by histology characteristics of each BC population, being different tumor histotypes responsible for different metabolic patterns. More advanced PET image analyses, able to better intercept the BC tumors heterogeneity, are needed to further evaluate the role of PET for predicting NAC response. The following baseline clinical and radiological variables were considered for each patient: age, FIGO stage and HPV-status, MRI finding in terms of extension of primary lesion (T), lymph nodes (N) number and site, and invasion of parametrium and/or vagina; FDG PET-derived maximum and mean SUV, MTV and TLG for both T and N were recorded. All variables were entered in the univariate and multivariate analysis. Results: Univariate analysis showed FIGO stage, T TLG and MTV, N SUV max , TLG and MTV, and the number of MRI-detected lymph node as significant predictors of the OS. Only MRI-based number and PET-based MTV of lymph nodes were identified as independent predictors of the OS at multivariate analyses (p = 0.035 and p = 0.042, respectively). A post-hoc analysis was thus performed after binarizing PET and MRI metrics of the N (cut-offs N-MRI [ 10 and N-MTVC3.55) and patients were subgrouped based of both cutoffs to further disclose the prognostic relevance of these variables by means of a Kaplan-Meier analysis. Three groups identified based on the two cut-offs showed a significantly different OS (median duration expressed in months; p = 0.004). In fact, when both predictors were below both cut-off OS was 53 months (n = 36), when both predictors were above the cut-off OS was 22 months (n = 7); when, at least one predictor (either PET or MRI) was above cut-off OS was 42 months (n = 17). Conclusions: The combination of baseline lymph-node number at MRI and PET-derived N-MTV distinguishes three classes of patients affected by LACC characterized by significantly different OS. Present findings confirm the role of FDG-PET in combination with MRI imaging in staging squamous LACC. Integration of multi-modal imaging techniques may also allow to develop more targeted treatment strategies in cervical cancer. Background-Aim: To explore the predictive value of 18F-FDG PET/ CT for pathological prognostic factors, including tumour type and FIGO score, in gestational trophoblastic disease (GTD). Methods: In this retrospective monocentric study, 24 consecutive patients who underwent to 18F-FDG PET/CT from May 2005 to March 2021 for GTD staging purpose have been enrolled. From the primary tumour, the following semiquantitative PET parameters have been extracted and used for the analysis: maximum and mean standardized uptake values (SUV max , SUV mean ), metabolic tumour volume (MTV) and total lesion glycolysis (TLG). Statistical analysis included Spearman's correlation coefficient to evaluate the correlations between imaging parameters and tumour type (non-molar trophoblastic vs. postmolar trophoblastic tumours) and risk groups (high vs. low, defined according to the FIGO score). Area under the curve (AUC) of the receiver operating characteristic (ROC) curve has been used to assess the predictive value of PET parameters and Mann-Whitney U test has been applied to further describe the potentiality of PET parameters in differentiating the populations. Results: SUV max resulted a fair predictors of tumour type (AUC = 0.783, 95% CI 0.56-0.95) with a low (rho = 0.489, adjusted-P = 0.030) correlation; SUV mean resulted as a good predictor (AUC = 0.811, 95% CI 0.59-0.97), showing moderate (rho = 0.538, adjusted-P = 0.027) correlation. According to FIGO score, TLG was a fair predictor (AUC = 0.770, 95% CI 0.50-0.99) for patient risk stratification. Conclusions: SUV max and SUV mean are predictive for tumour type and TLG for risk stratification in GTD, therefore suggesting the potential role of 18F-FDG PET parameters in predicting GTD pathological prognostic factors. Background-Aim: Sentinel lymph node (SLN) biopsy is a widely accepted procedure in the surgical staging of early vulvar cancer, but the most accurate method for the identification of the SLN is not yet defined. This meta-analysis aimed to determine the method with the highest pooled detection rate (DR) for the identification of SLN and compare the average number of SLNs detected by planar lymphoscintigraphy (PL), blue dye injection, and indocyanine green (ICG) fluorescence. Methods: The meta-analysis was conducted according to the PRISMA guidelines. PubMed/MEDLINE and SCOPUS databases were interrogated by three investigators seeking independently for studies investigating the use of lymphoscintigraphy, blue dye, and ICG for the detection of SLN in patients with vulvar cancer. The search string for the literature search was: ''sentinel'' and ''vulv*''. The time period for the literature search was from Jan 1st, 2010 to Dec 31st, 2020. After excluding non-original articles, the full text of the articles was retrieved to verify the following inclusion criteria: (1) a study cohort or a subset of a minimum of 10 patients with vulvar cancer undergoing either PL or blue dye or ICG fluorescence for the identification of SLN; (2) possibility to extrapolate the DR or the average number of SLNs detected by a single technique (3) no evidence of other malignancies in the patient history. Results: A total of 30 studies were selected. In a per-patient and a per-groin analysis, the DR for SLN of PL was respectively 96.13% and 92.57%; for the blue-dye was 90.44% and 66.21%; whereas for the ICG the DR was 91.90% and 94.80%. At a patient-based analysis, no significant difference was documented among the three methods (p = 0.28). Conversely, PL and ICG demonstrated a significantly higher DR compared to blue dye on a per-groin analysis (p \ 0.05). The average number of SLNs on a per-patient analysis was available only for PL and ICG with a median number of 2.61 and 1.78 lymph nodes detected, respectively, with no statistical difference between the two techniques (p = 0.17). Conclusions: This meta-analysis favors the use of ICG and PL alone and in combination for the identification of the SLN in early vulvar cancer. Nevertheless, it is important to underline that the guidelines of the European Society of Gynaecological Oncology (ESGO) do not mention ICG yet and state that ''the use of a radioactive tracer is mandatory; the use of the blue vital dye is optional''. As demonstrated for other oncotypes (breast, head and neck cancer, and melanoma), we suppose that the use of single-photon emission computed tomography (SPECT) may further increase the accuracy of lymphoscintigraphy in this setting. Opportunistic skeletal muscle metrics as prognostic tools in metastatic castration-resistant prostate cancer patients candidates to receive radium-223 anthropometric composition and metabolism are associated with unfavourable overall survival (OS) in a retrospective cohort of metastatic castration-resistant prostate cancer (mCRPC) patients submitted to 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging before receiving Radium-223. Methods: Low-dose CT were opportunistically analysed using a cross-sectional approach to calculate SM and adipose tissue areas at the third lumbar vertebra level. Moreover, a 3D computational method was used to extract psoas muscles to evaluate their volume, Hounsfield Units (HU) and FDG retention estimated by the standardized uptake value (SUV). Baseline established clinical, lab and imaging prognosticators were also recorded. Results: SM area predicted OS at univariate analysis. However, this capability was not additive to the power of mean HU and maximum SUV of psoas muscles volume. These factors were thus combined in the Attenuation Metabolic Index (AMI) whose power was tested in a novel uni-and multivariable model. While prostate-specific antigen (PSA), alkaline phosphatase (ALP), lactate dehydrogenase, hemoglobin, metabolic tumor volume, total lesion glycolysis and AMI were associated with long-term OS at the univariate analyses, only PSA, ALP and AMI resulted in independent prognosticator at the multivariate analysis. Conclusions: The present data suggest that assessing individual patient's SM metrics through an opportunistic operator-independent computational analysis of FDG PET/CT imaging provides prognostic insights in mCRPC patients candidates to receive Radium-223. Background-Aim: Digital positron emission computed tomography (dPET/CT) represents a recently introduced technology, characterized by superior sensitivity and increased diagnostic certainty with respect to its traditional counterpart, the so-called analogue PET/CT (aPET/ CT). The aim of our paper was to compare the diagnostic performance of 18 F-choline and 18 F-FACBC (anti-1-amino-3-18Ffluorocyclobutane-1-carboxylic acid) in 2 matched cohorts submitted to dPET/CT due to prostate cancer (PC) biochemical recurrence (BC). Methods: Two cohorts, each one encompassing 36 subjects, previously submitted to radical treatment (surgery or radiotherapy) for PC and presenting BCR according to Phoenix criteria, were enrolled, as closely matched as possible for stage (TNM), PSA values before scanning, age and Gleason Score. The first cohort was submitted between December 2019 and October 2021 to dPET/CT with 18 Fcholine (CHO-group) while the second underwent, in the same period and with the same device, dPET/CT with 18 F-FACBC (FAC-group). Detection rate (DR) was measured in both cohorts, also by stratifying patients according to PSA value. Two-tailed Student test and Fisher exact test were applied to analyze differences among groups, with significance at p \ 0.05. Results: Mean age resulted in 74.3 ± 7.2 and 75.2 ? 5.4 years while mean PSA value was 1.6 ± 0.8 and 1.58 ± 0.8 ng/mL for FACgroup and CHO-group, respectively, without significant differences among group (p = 0.7). In both groups median Gleason score was 7 and the number of subjects with PSA value\1 ng/ml was 11 (30.5%) for each group. 18 F-FACBC resulted positive in 28 subjects, with a DR of 77.7%, while 18 F-Choline PET/CT was positive in 24 patients with a DR of 66.6%. The most prevalent sites of disease localization were prostate bed and pelvic nodes both for FAC-group and CHOgroup (i.e. 82.1% and 75.2%, respectively). No significant difference in overall DR was found between groups (p = 0.67). When stratifying patients by PSA values, at PSA level\1 ng/mL 18 F-FACBC PET/CT resulted positive in 8/11 cases (i.e. DR 72.7%) while 18 F-choline PET/CT in 2/11 subjects (i.e. DR 18.1%), with a significant difference between groups (p = 0.03). Conclusions: dPET/CT, used in combination with recently introduced tracer 18 F-FACBC, resulted in a meaningful DR in patients presenting PC BCR, also at low PSA levels, and outperformed dPET/ CT with 18 F-choline. Results: In Group A (mean PSA: 0.8 ng/mL, range: 0.3-1.3; median GS: 7) 3/15 (Subgroup A1) had positive PET pelvic nodal findings, 12/15 (Subgroup A2) showed no pelvic nodal findings (7/12 with a PET positive local relapse, 5/12 without PET evidence of local relapse). In Subgroup A1 a change of therapy management was carried out on PSMA-PET basis, from SRT to Metastasis-Directed RT (MDRT) on pelvic nodal findings, while in Subgroup A2 previously scheduled SRT was confirmed even without a PET-proven local relapse. In Group B (mean PSA: 1.5 ng/mL, range: 0.4-1.8; median GS: 8) 9/15 (Subgroup B1) had positive PET pelvic nodal findings, 2/15 (Subgroup B2) showed pelvic nodal involvement or low-volume metastatic bone disease, 4/15 (Subgroup B3) had high-volume bone spreading disease. Therapy management was carried out on a PSMA-PET basis, scheduling a MDRT on pelvic nodal findings in Subgroup B1, MDRT on pelvic nodal findings in addition to androgen deprivation therapy (ADT) in Subgroup B2 and early start of ADT in Subgroup B3 (mean PSA: 1.2 ng/mL). PSMA-PET results directly changed initially planned treatment (SRT) in 20% of Group A patients and guided therapy management in 100% of Group B patients. PSA levels after PSMA-PET imaging guided therapy were available in 10/30 patients (A2:6; A1:1; B1:3): an average 50% reduction of PSA levels was registered after a minimum 3 months follow-up. Conclusions: Our preliminary retrospective experience is in agreement with literature data and confirms that [ 18 F]PSMA-1007 PET/CT plays a crucial role in clinical decision-making for PCa patients with low level PSA increase after primary surgical treatment. Decreased PSA levels after PET-guided therapeutic procedures represent a proof-of-concept of PSMA-PET diagnostic accuracy. In reference to PSA before PET/CT, patients were stratified in group 1 \ 1 ng/ml (19 patients), group 2 = 1-2.5 ng/ml (8 patients), group3 [ 2.5 ng/ml (4 patients). Scans were scored for sites of disease and multi-disciplinary meeting (MDM) records were reviewed to access management decisions following PSMA-PET/CT. All PSMA-positive lesions were confirmed by means of morphological imaging. Results: 18F-PSMA-1007-PET/CT was positive in 19 (57.1%) and negative in 12 (42.9%) cases. The overall positivity rate of increased with higher PSA levels (ng/mL): 79% (group 1), 75% (group 2) and 100% (group 3). Management decision differed significantly for PETpositive versus PET-negative patients. Specifically, among PETpositive patients, ablative cyberknife radiotherapy was administered to prostate lodge and pelvic lymph nodes in 8 patients (6 of group 1, 1 of group 2, 1 of group 3) and to bone metastases, especially to spinal column and pelvic bones in 5 patients (2 of group 1, 2 of group 2, 1 of group 3). In 8 (42%) PET positive patients (3 of group 1, 2 of group 2 and 3 of group 3) hormonal treatment was proposed. Among group 1, 2 of 19 (10.5%) of the PET-positive patients was submitted to active surveillance, compared with 6/12 (50%) PET-negative patients. Salvage radiotherapy (sXRT) was performed in 6/12 (50%) PETnegative patients versus 1/19 (5.2%) PET-positive patients with PSA pre-treatment \ 1 ng/ml. Conclusions: Even if in a small cohort, our first experience confirmed that 18F-PSMA-1007-PET/C is a highly promising diagnostic tool in the work-up of BCR, because it allows metastasis-directed treatment. In particular, the preliminary results showed major impact on patient management, with 100% influence in group3, 88% in group 2 and 47.4% in group 1. Among the considered risk factors, preRT PSA [ 0.5 ng/ml appears to be linked with a shorter PFS in the total cohort. Of those who had a negative PET and received no treatment, 100% (50/50) had a PSA relapse at follow up, with a median progression free survival (PFS) of 8 months at the Mantel-Haenszel curve. In both PET positive (10/59) and PET negative (19/101) groups treated with sRT that presented PSA relapse at follow up (29/160), we observed no meaningful differences in PFS and no statistically significant correlation on logistic regression analysis was found amongst the considered risk factors and PSA relapse. In case of negative PSMA PET, with the exception of PSA persistence, no other clinical feature holds a statistically based correlation with PFS. Conclusions: Patients with negative PSMA PET/CT who underwent sRT had comparable outcome to radiotrated men with positive PET findings. In case of negative PSMA PET, with the exception of PSA persistence, no other clinical feature holds a statistically based correlation with PFS. According to our results, executing sRT in patients with a negative PSMA PET/CT after early BCR correlates with a longer PFS, and there's no reasonable evidence that supports an ''active surveillance'' approach. Cohen's Kappa analyses were used to measure agreements. Results: According to the reference standard, PET scans were positive in 23/40 patients (T = 11, N = 13, M = 7). The general agreement among the readers was fair in both time points (K = 0.45 and 0.42 for standard and late imaging, respectively). The forced diuresis late scan improved the general diagnostic accuracy from 65% (K = 0.43) to 69% (K = 0.47). This effect was mainly driven by the favourable impact of late imaging on N-accuracy, which increased from 77.5% (K = 0.50) to 80.5% (K = 0.54), and, to a lesser extent, on T-accuracy, which increased from 72.5% (K = 0.44) to 74.5% (K = 0.46). Of note, the added value of forced diuresis late imaging was independent from prior reader's experience. Conclusions: Forced diuresis late acquisition increases the diagnostic accuracy of 68Ga-PSMA-11 PET/CT in BR of PCa, regardless the PET reader's level of expertise. The maximum standardized uptake value (SUV MAX ) in patients with recurrent or persistent prostatecancer after radical prostatectomy (RP) and psma-pet-guided salvage radiotherapy. a multicenter retrospective analysis Background-Aim: Recurrence rate after salvage radiotherapy (sRT) is heterogeneous and additional prognostic markers are needed to improve risk-stratification and guide personalized treatment. We evaluated the association of the SUV max in PSMA PET prior to sRT on freedom from progression (FFP) in a large multicenter cohort. Methods: Patients who underwent 68Ga-PSMA-PET after RP due to biochemical recurrence or PSA persistence were enrolled in four high-volume centers in this retrospective multicenter study. Only patients with PET-positive local recurrence (LR) and/or nodal recurrence (NR) within the pelvis were included. Patients were treated with intensity-modulated-sRT to the prostatic fossa and elective lymphatics in case of nodal disease. Dose escalation was delivered to PET-positive LR and NR. Androgen deprivation therapy was administered at the discretion of the treating physician and in accordance with EAU guidelines. LR and NR were manually delineated using a windowing of SUVmin-max: 0-5. SUV max was extracted from LR and NR. Cox-regression was performed to analyze the impact of clinical parameters and the SUV max -derived values on FFP, defined as serum prostate specific antigen [ 0.2 ng/ml above the post-sRT nadir without initiation of additional salvage therapies. Results: 235 patients were included in the final cohort. The presence of LR was associated with favorable FFP (p = 0.016). Presence of NR was associated with unfavorable FFP (p = 0.007). While there was a trend for SUV max median (p = 0.071), SUV max values C 75%quartile in LR were significantly associated with unfavorable FFP (p = 0.022, HR: 2.1, 95% CI 1.1-4.6). SUV max value in NR was not significantly associated with FFP. SUV max in LR stayed significant in multivariate analysis (p = 0.030). Sensitivity analysis with patients for who had a follow up of [ 12 months (n = 197) confirmed these results. Conclusions: In patients with biochemical recurrence/persistence after RP, presence of PSMA-avid pelvic lymph nodes on PET is associated with reduced freedom from progression after salvage-radiotherapy. Most importantly, the non-invasive biomarker SUV max predict outcome in patients undergoing sRT and recurrence confined to the prostatic fossa in PSMA-PET. Its addition might contribute to improve risk-stratification of patients with recurrent PCa and to guide personalized treatment decisions. Background-Aim: PET/MRI is an innovative approach for prostate cancer (PCa) staging, and its performance may be further improved by the combined use of different radiotracers. The aim of this study is to assess the performance of 68Ga-PSMA PET, 68Ga-DOTA-RM2 PET and MRI in high-risk PCa staging by using a fully integrated hybrid PET/MR system. Methods: Thirteen patients (mean age 66.74, sd 8.77) with biopsyproven high-risk PCa candidate to radical prostatectomy underwent both 68Ga-PSMA and 68Ga-DOTA-RM2 PET/MRI for staging purpose as part of an ongoing clinical trial (EudraCT: 2018-001034-18). Qualitative evaluation of PET and MR images was performed by an expert Nuclear Medicine Physician and an expert Radiologist. Imaging findings relative to the primitive tumour, local extension of the disease and pelvic lymph nodal (LN) involvement were validated by histological specimens gathered after surgery. Results: The primary intraprostatic lesion was identified by all the investigated imaging modalities, with only one discordant finding concerning the intraprostatic site of disease in 1 patient where both 68Ga-DOTA-RM2 PET and MRI were concordant with histology in identifying the primary lesion in the right lobe of the prostate, while 68Ga-PSMA PET detected the primary tumour in the opposite lobe. Seminal vesicle invasion, as reported by histological analysis, occurred in 2 patients but it was not detected by imaging investigation. Since 68Ga-PSMA and 68Ga-DOTA-RM2 PET have limited spatial resolution for extracapsular extension (ECE) assessment, histological validation of ECE has been performed only by MRI. In 5 patients histology and MRI agreed (3/13 negative and 2/13 positive for ECE), with 8/13 patients being discordant (3/13 positive on MRI but not confirmed at histology and 5/13 with ECE at histology but not on MR). 79 LN regions were investigated at histological examination, and among these, only two were positive. 1/2 was detected by both 68Ga-PSMA PET and MRI and 1/2 was missed by all imaging modalities (lesion diameter: 1 mm). 68Ga-PSMA reported LN involvement in 5 more patients, that were not confirmed as true positive by histology. MRI identified LN involvement in two regions that were negative at histology; 68Ga-DOTA-RM2 PET did not detect any LN uptake. Conclusions: These first findings suggest the potential complementary role of 68Ga-PSMA PET, 68Ga-DOTA-RM2 PET and MRI in the staging of high-risk PCa patients. A dual-tracer approach might improve primary tumour characterization by highlighting different metabolic aspects of the disease, thus improving patients' management and allowing a tailored treatment. Background-Aim: 18F-Fluorocholine PET/CT has a well-established role in the evaluation of prostate cancer (PCa) recurrence in patients with biochemical relapse (BCR), even if its detection rate (DR) is suboptimal for low PSA values. 18F-Fluciclovine was approved for restaging PCa patients in BCR following primary treatment and its performance showed promising results also in case of low PSA levels (PSA \ 1 ng/ml). Nowadays, there is still no consensus on the most accurate imaging modality in this setting of patients. Our study aimed to compare the diagnostic performance of 18F-Fluorocholine and 18F-Fluciclovine PET/CT in PCa patients with BCR, according to clinical and biochemical features. Methods: Between September 2019 and September 2021, a total of 68 PCa patients with BCR (mean age 71 years, range 51-84 years) was restaged with PET/CT and assigned to 18F-Fluciclovine or 18F-Fluorocholine group, randomly. The two groups were homogeneous for PSA value (mean PSA 1.4 ng/mL, range 0.2-5.67). Our sample was stratified according to Gleason Score (GS \ 7 or C7), EAU risk group (low risk/intermediate-high risk) and biochemical parameters (PSA value\1 or C1 ng/mL; PSA doubling time\ 6 or C 6 months). 18F-Fluciclovine and 18F-fluorocholine PET/CT DR was statistically compared in per-patient analysis, per-lesion analysis and according to clinical and biochemical features, using Chi-Square test and McNemar's test. A p \ 0.05 was considered statistically significant. Results: In the per-patient analysis, the overall DR was 21/34 (62%) in 18F-Fluciclovine group and 9/34 (26%) in 18F-Fluorocholine one, with a statistically significant difference (x 2 = 8.589, p = 0.003). The per-lesion analysis showed a total of 27 positive findings in 18F-Fluciclovine group and 9 in 18F-Fluorocholine group. DR in prostate bed, lymph node and bone was 16/27 (59%), 9/27 (33%) and 2/27 (7%) in the first group and 3/9 (33%), 5/9 (56%) and 1/9 (11%) in the second group, respectively; no statistically significant difference was demonstrated. 18F-Fluciclovine and 18F-Fluorocholine positive scans were significantly correlated with GS (p \ 0.001), EAU risk group (p = 0.002), PSA doubling time (p \ 0.001) and PSA value (p = 0.013). Particularly, for PSA \ 1 and C1, DR was 44% and 78% in 18F-Fluciclovine group, and of 18% and 35% in 18F-Fluorocholine group, respectively. This result was further investigated using the following PSA stratification: PSA \ 1, 1-2 and [ 2 ng/mL. Regarding this analysis, DR resulted 44%, 70% and 88% in 18F-Fluciclovine group and 18%, 10% and 71% in 18F-Fluorocholine group, without a statistically significant difference. Conclusions: Our data confirmed the better diagnostic performance of 18F-Fluciclovine PET/CT in terms of DR compared to 18F-Fluorocholine PET/CT for restaging PCa patients in BCR, particularly in detection of local recurrence, also due to a negligible urinary excretion. The significantly higher 18F-Fluciclovine DR for low PSA values supports its use in clinical practice in this setting of patients (PSA \ 1 ng/ml), instead of 18F-fluorocholine. has not yet been extensively studied. MFS is a surrogate parameter for PCa specific survival. The purpose of this analysis was to assess (i) MFS in the era of PSMA-PET guided sRT and (ii) the metastatic patterns on PSMA-PET images after sRT. Methods: This retrospective, multicenter (9 centers from 5 countries) study included patients referred for PSMA PET due to biochemically recurrent or persistent disease after radical prostatectomy. Patients with distant metastases (DM: lymph nodes above iliac bifurcation, bone/visceral metastases) on PSMA PET prior to sRT were excluded. MFS was the primary study endpoint. Cox-regression analysis was performed to assess the impact of clinical parameters on MFS. Finally, the distribution of PET-positive DM following sRT and their respective risk factors were analysed. Results: The study included 815 patients. All patients received intensity-modulated RT to the prostatic fossa. In case of PET-positive pelvic lymph nodes (PLN-PET1, n = 275, 34%), elective pelvic lymphatics had been irradiated. Androgen deprivation therapy had been given in 251 (31%) patients. The median follow-up after sRT was 36 months (IQR: 24-48) and 259 (32%) and 137 (17%) patients had biochemical recurrent disease and DM, respectively. The 2-and 4-year MFS rates following sRT were 93% and 81%, respectively. In multivariate analysis the presence of PLN-PET1 was the strongest predictor for MFS (HR = 2.42, 95% CI 1.6-3.6, p \ 0.001). Following sRT DM were detected by PSMA PET in 128/XX (YY%) patients and two metastatic patterns were observed: 43% had DM in sub diaphragmatic paraaortic LNs (pattern 1: regional-lymphatic) whereas 28% in non-pelvic bones, 27% in pelvic bones, 9% in supra diaphragmatic LNs and 6% in visceral organs (pattern 2: distant). Two distinct signatures with risk factors for each pattern were identified, respectively. Conclusions: sRT, most obviously due to the higher detection rate of DM in PSMA PET after sRT. The presence of PLN-PET1 may be proposed as a new surrogate parameter predictive of MFS. Analysis of recurrence patterns in PET after sRT revealed risk factor signatures for two distinct metastatic patterns (regional-lymphatic and distant), which may allow individualized PSMA-PET-guided sRT concepts in the future. Results: Overall DR resulted 66%, while DR was 53%, 28%, and 7% in prostate/bed, lymph nodes, and bone, respectively. Out of all PETpositive patients, 55% showed a disease confined in prostate/bed, while 45% had an extraprostatic disease. Overall DR significantly increased with higher PSA values (p = 0.009) and 0.45 ng/mL was identified as the optimal cut-off value for predicting a positive scan (AUC 0.68, 95% CI 0.51-0.84). Similarly, a shorter TTR was significantly associated with positive findings. Regarding semiquantitative analysis, SUV max (p = 0.006) and SUV mean (p = 0.003) showed a significant linear correlation with PSA and resulted significant parameters in interpreting malignant from benign lesions. [18F]Fluciclovine PET/CT reached a sensitivity, specificity, PPV, NPV and accuracy of 87.10%, 80.00%, 87.10%, 80.00% and 84.31%, respectively. The therapeutic strategy was changed in 51% of patients. The most frequent changes were from clinical surveillance to hormonal systemic therapy (38%)/radiotherapy (31%). Conclusions: Our results support [18F]Fluciclovine PET/CT as a reliable tool for early restaging PCa patients, with an optimal PSA cut-off value of 0.45 ng/mL that together with TTR could be considered for patients' selection. The high DR of recurrence in prostate/ bed, due to its irrelevant urinary interference, led to a significant impact on clinical management. Semiquantitative analysis with SUV max and SUV mean revealed useful for supporting the interpretation of visual assessment. Methods: We enrolled 122 pts in this study, 89 in the [68Ga]PSMA-11 arm (arm A, mean age 72 years ± 34 years) and 33 in the arm B (mean age 73 years ± 7 years). All PET/CT were performed with Discovery710 (GE Healthcare). For radiomics analysis images were semiautomatically segmented using 40% SUV max threshold (Advantage Workstation, GE) and texture features extracted by LIFEx software. Lesions were grouped based on lesion burden using oligo/plurimetastatic categorization (with 3 or 5 lesions cut-off) and Gleason Score (GS, class-0 = GS 6, 7; class-1 = GS 8, 9). LR was used as a classifier after applying Lasso algorithm for data-dimensionality reduction (80% training and validation, 20% for test-set and cross-validation using 5, 7, 10 K-folds), using AUC to validate the model accuracy. Results: Oligo/plurimetastatic disease was diagnosed in 53/36 pts and 74/48 using 3 or 5 lesions cut-off, respectively. A different distribution in PSA and SUV max values was found in oligo/plurimetastatic using the 3 lesions cut-off. No differences were found in lesions features based on the size/organ, despite bone disease showed higher PSA levels. ML was able to classify pts with less aggressive phenotype, GS 6 vs more aggressive disease having GS 7-8-9 (AUC of 0.87), however, subgroups of GS 7, 8 and 9 presented a very similar signature. Intention to treat was significantly changed after [68Ga]PSMA-11 PET/CT in higher number of pts candidate to EBRT (n = 60) or ADT (all 19 plurimetastatic), being the watch and wait strategy reserved to 10 cases. A higher number of lesions for single study was found with [18F]FMCH with a higher detection rate for [68Ga]PSMA-11, able to identify disease in all the 33 patients including low-risk pts with a clear impact on treatment decision making (21 pts treated with EBRT, 9 with ADT, 0 watch and wait). Conclusions: ML revealed a radiomic signature of [68Ga] PSMA-11 in pts with GS 6 PCa as compared to pts with more aggressive disease. The systematic use of [68Ga]PSMA-11 PET/CT change the intention to treat to EBRT or ADT in all cases of oligo/plurimetastatic disease, significantly reducing the proportion of pts suitable for a watch and wait strategy. Results: For the whole cohort, there was almost perfect interobserver agreement for pathological (E-PSMA 4-5) findings in pelvic district (Fleiss'j = 0.86) with substantial agreement also regarding the number and the site of findings (Fleiss' j = 0.78, 0.73), no significant variation was found in subgroups A and B (Fleiss' j always [ 0.60). Interobserver agreement was almost perfect also for pathological findings and number of findings in abdominal district (both Fleiss' j always [ 0.90 for the entire cohort, group A and B). Interobserver agreement was moderate for pathological findings in bone district, also regarding the number and the site of findings for the whole cohort (Fleiss' j = 0.53, 0.43, 0.45), fair in group A (Fleiss' j = 0.31, 0.22, 0.22) and moderate in group B (Fleiss' j = 0.63, 0.56, 0.55). Interobserver agreement was moderate for pathological findings and number of findings in prostate bed in the whole cohort (Fleiss' j = 0.60, 0.50), slightly lower in group A (both Fleiss' j = 0.49) and higher in group B (Fleiss' j = 0.73, 0.57). Finally, interobserver agreement for undetermined (E-PSMA 3) and benign (E-PSMA 2-1) findings (also considering number and site of findings) was always from slight to fair (Fleiss' j always \ 0.30), regardless of the study group. Conclusions: According to this preliminary experience, E-PSMA criteria represent a highly reproducible reporting format, with a moderate-high level of agreement among readers for pathological findings (E-PSMA 4-5). Even though a slight inter-observer agreement was found for indeterminate results (E-PSMA 3), highlighting the need to better clarify the definition of this subcategory. E-PSMA metrics appear to be feasible in clinical practice and represent the premise for effective and unambiguous communication with the clinicians. Background-Aim: In Europe, prostate cancer (PC) is the most commonly cancer in men. Patients with PC treated with hormones gradually become castration-resistant PC (CRPC) and ultimately experience metastasis (mCRPC). Median overall survival (OS) for mCRPC patients is * 2.5 years. Having imaging method to assess response to therapy (i.e. novel hormone therapies, taxanes, and novel radioligand treatments) allows clinicians to optimize decision making on appropriate treatment options. In PC, there is growing evidence to support the superiority of PET/CT with 68Ga-PSMA-11 (PSMA PET) over biochemical and conventional imaging for early response to therapy. Consequently, PSMA PET is emerging as a potential standard of care for PC imaging and could help avoid the administration of ineffective therapies that are toxic and costly. There are currently very limited data on PSMA expression in mCRPC patients and it is unclear how PSMA expression can be affected during the course of treatment. The present study aims to characterize PSMA expression in mCRPC patients and will examine the impact of treatment on PSMA expression, thus informing the usefulness of PSMA to guide clinical decision making in this difficult-to-treat population. Methods: A single-centre, retrospective observational cohort study was conducted at the MD of Nuclear Medicine of the IRCCS AOU Bologna, Italy, between 1 March 2016 and 31 October 2020. Inclusion criteria were: diagnosis of PC and CRPC by the EAU guidelines (serum testosterone \ 50 ng/dL or 1.7 nmol/L) ? either rising serum PSA levels or radiological progression. All patients performed a PSMA PET (PET1) and if clinically needed underwent a second PSMA PET (PET2). Results: Increased PSMA expression at PET1 was confirmed in 152/160 participants (96%) and were classed as mCRPC, despite prior systemic treatment: among 79 participants who underwent systemic treatment, 78 participants (99%) had an increased PSMA expression. There was 79% agreement between PET and PSA response (k = 0.553, p \ 0.001). However, 5/70 (7%) participants were PETresponders but PSA non-responders, and 10/70 (14%) were PET nonresponders and PSA responders. 63 participants with follow-up were included in the analyses of PFS and OS, that showed non-responders had an increased risk of progression/relapse compared with responders (HR 2.53 [95% CI 1.24-5.15]; p = 0.011). Adjusted Cox regression (with adjustment for PSA at baseline, age and number of therapy lines) showed that PSA non-responders had an increased risk of progression/relapse compared with PSA responders (HR 2.63 [95% CI 1.23-5.62]; p = 0.013). PSA and PET response are both significant risk factors for PFS, so we analyzed the two variables in combination. PET non-responders and PSA non-responders had a significantly higher risk of disease progression/relapse (HR 3.08 [95% CI 1.40-6.79]; p = 0.005) compared with responders. There was no significant difference in OS between either PET responders and nonresponders (p = 0.223), or between PSA responders and non-responders (p = 0.992). Conclusions: PSMA expression is increased in 95% CRPC patients, regardless of prior systemic therapies/ongoing treatments. PET and PSA response were both significant risk factors for PFS, nevertheless PET response may be a more significant prognostic factor than PSA response. Background-Aim: [68Ga]PSMA11 PET in prostate cancer patients is even more important and diffuse in clinical setting. An increasing number of data on the positive correlation between prostate specific antigen (PSA) and standardize uptake value (SUV max ) are accumulating on high risk prostate cancer patients at staging. Conversely, less data is available on upper intermediate risk prostate cancer patients. The aim of the present pilot study was to investigate the association between PSA and SUV max even in the low and intermediate risk patients. Methods: A cohort of patients with a diagnosis of high and intermediate risk prostate cancer prior of any specific therapy (n = 49; mean age = 70 years; all patients with Gleason score C 6) was used to evaluate the association between PSA at PET levels and SUV max . Correlation between PSA and SUV max was assessed by Kendall correlation, more appropriate for small sample. Because of skewed distribution, values of PSA levels and SUV max were log-transformed and then standardized. In order to assess the association between exposure and outcome unadjusted and adjusted regression models were performed. Age at recruitment, primary Gleason and number of prior biopsies were considered as possible confounders in fully-adjusted model. Association values were reported as beta (SE) per 1-SD increase in standardized log SUV max levels. Results: Kendall correlation between PSA levels and SUV max was positive (i.e. 0.26, p-value = 0.006). In a linear regression model, the association between PSA levels and SUV max was significant (beta = 0.30; SE = 0.10; p-value = 0.006). After adjustment for age the association became stronger (beta = 0.29; SE = 0.10; p-value = 0.005). A bigger significant association was observed when primary Gleason and number of prior biopsies were considered (beta = 0.36; SE = 3.6; p-value = 0.021). Conclusions: PSA levels and SUV max values were strongly and positively associated in patients with prostate cancer. Further analyses in larger sample are needed to investigate the association of PSA and other PET metrics also in other cohorts. Background-Aim: The aim of this retrospective study was to investigate the impact of PSMA PET/CT findings on improving sRT planning in early BCR and the subsequent influence of PSMA informed sRT on patients outcome. Methods: We retrospectively analyzed men with PCa who underwent PSMA PET/CT from 2016 to 2019 for BCR (two consecutives serum PSA values [ 0.2 ng/ml) after RP and who received PSMA guided sRT or no treatment. Exclusion criteria were M1 (lymph nodes above the iliac bifurcation, bone or visceral metastases), any systemic treatment, including ADT, prior or after PET. We recorded tumor stage, iPSA, ISUP score, risk classification, PSA persistence after surgery (PSA C 0.1 ng/ml), PSA doubling time, PSA before PET (stratified in \ 0.5 ng/ml-[ 0.5 ng/ml), PET scan results, following management (sRT ? /). Treatment response was defined as PSA \ 0.1 ng/ml. PFS was defined by PSA relapse (two consecutives serum PSA values [ 0.2 ng/ml with undetectable PSA after sRT or persistence). Kaplan-Meier estimator and log-rank test was performed to determinate difference in patients subgroups. Background-Aim: Subcutaneous tissue as a manifestation of generalized disease is commonly involved in lymphomas. However, only skin involvement without other sites of extracutaneous disease was rarely presented, especially in diffuse large B-cell lymphoma (DLBCL). We reported an unusual case of primary cutaneous DLBCL, presenting with widespread extranodal involvement and with multiple diffuse high-FDG uptake nodules on PET/CT images. PET/CT is very helpful for diagnosing primary cutaneous DLBCL. Methods: An 57-year-old man was admitted to our department due to a 2-month history of inappetence, repeated fever and presenting with swelling of the right orbital and laterocervical region bilaterally. There was no history or sign of infection or any chronic comorbidity. The levels of C-reactive protein (75.2 mg/L reference range, \5 mg/ L) and procalcitonin (0.25 ng/L; reference range, .046 ng/L) were significantly elevated. Other routine laboratory tests, including renal and hepatic functions was within normal limits. LDH was 156 U/L. On physical examination noted a widespread skin thickening, especially evidence in right temporal region, and multiple firm subcutaneous nodules, of which one, measuring 5.0 cm in diameter, was palpated in his upper left arm. Soft tissues ultrasound study showed several cutaneous and subcutaneous nodules also in the abdomen, back upper limbs and gluteal region. The hyperechogenicity of the nodules suggested a probable diagnosis of lipogenic tumors. 18F-FDG PET/CT scan was performed for metabolic characterization of lesions. Results: Eleveted FDG uptake (SUV max right orbital region 12.0) in cutaneous and subcutaneous nodules, ubiquitously located on MIP images, was demonstrated. There were, also, enlarged and hypermetabolic cervical, axillary, and intra-abdominal lymph nodes intense and pathological FDG accumulation was evidence in nasopharynxoropharynx and in right submandibular gland. These findings were suggestive of lymphoproliferative disease. An excisional biopsy of left arm nodule was performed and histological examination demonstrated the diffuse infiltration of large, atypical cell in subcutaneous tissue, positive for CD20, CD10 and CD5. The final diagnosis of DLBCL with high activity of proliferation and widespread extranodal involvement was made. Conclusions: Our case underlines the PET/CT role in the differential diagnosis of subcutaneous nodules. In addition of lymphomas, soft tissue sarcoma, sarcoidosis, granulomas or cancer metastases may present onset with the appearance of metabolically active subcutaneous nodules. In particular, our study, show how salient PET imaging coupled with characteristic clinical manifestations, medical history, patient age may allow accurate differential diagnosis. Furthermore, the important role of PET in defining staging and correct treatment in lymphoma is highlighted. Background-Aim: Metabolic response (MR) after induction immunochemotherapy (ICT) assessed with FDG PET/CT has been confirmed as a strong prognostic factor in patients with follicular lymphoma (FL). So far, there is a lack of data supporting the use of early MR (iPET) for the evaluation of first-line therapy in follicular lymphoma. The aim of this study was to investigate the prognostic value of iPET and to define interactions with other available prognostic factors in patients with FL treated with first-line ICT. Methods: FOLL12 trial is a multicenter, randomized, phase III trial comparing standard vs response adapted maintenance in treatment naïve adult patients with grade 1-3a, stage II-IV and with a high tumor burden FL. MR was centrally assessed at the end of induction (fPET) using 5-point Deauville scale (DS). In this study we included only the patients for whom iPET during ICT between cycle 4 and 5 was available and centrally reviewed. PET scans were considered positive for DS4-5. Semiquantitative evaluation of iPET was also performed using the following parameters: qPET (the ratio of SUVpeak of most active lesion to liver SUV mean ) and rPET (ratio of SUV max of the most active lesion to liver SUV max ). The primary endpoint was 3-year Progression Free Survival (PFS). Results: iPET was performed in 211/807 patients enrolled in the FOLL12 trial and central report was available in 113 cases. Fortyeight percent of patients were older than 60 years, 32% had a highrisk FLIPI2 and 44% received R-Bendamustine (RB) as induction ICT. Eighteen patients/113 (16%) had a positive iPET and fPET. iPET and fPET showed a concordance rate of 91%: 90 out of 95 iPET-was confirmed negative at fPET. Regarding the 18 cases with iPET?, a fPET-was achieved in 5 patients. In univariate analysis iPET ? patients had a lower PFS comparing to iPET-group (70% vs 32%: HR of 2.69, 95% CI 1.29-5.61). In multivariate analysis iPET? confirmed the prognostic role on PFS (HR 2.65, 95% CI 1.26-5.54) and was independent from FLIPI 3-5 (HR 2.24, 95% CI 1.11-4.50) and from RB vs R-CHOP treatment (HR 0.98 95% CI 0.49-1.97). qPET [ 1 and rPET [ 1.5 was also associated with a shorter PFS with a HR, respectively of 3.68 (95% CI 1.83-7.40) and 2.27 (95% CI 1.13-4.57). Conclusions: Stage FL treated with standard ICT. Considering the high concordance rate with fPET, iPET may be considered to define a novel generation of early response adapted trials in FL. The prognostic role of baseline metabolic tumour burden in patients with follicular lymphoma on watchful waiting Background-Aim: Patients with follicular lymphoma (FL) and low tumor burden are often managed with an initial watchful waiting (WW) strategy. Approximately 25-40% of patients managed with WW will develop disease progression within 24 months. Clinical prognostic models incompletely identify patients at risk for early progression. In the era of precision medicine, 18 F-FDG PET/CT could play a crucial role for patient risk stratification at diagnosis. The aim of the study was to investigate the prognostic value of baseline total metabolic tumor volume (TMTV) and whole-body total lesion glycolysis (WB-TLG) in low tumor burden FL patients on WW and their added value to existing clinical prognostic indices. Methods: We retrospectively included 54 patients on initial WW (grade 1-3a) from 2010 and 2019 with a staging 18 F-FDG PET/CT and a follow-up C 24 months. TMTV and WB-TLG were calculated using an automatic whole-body segmentation (LesionID, MIM Software Inc.). Time to treatment (TTT) was calculated from the date of diagnosis until the date of start of systemic therapy. ROC analysis was used to define the optimal cut-off for prediction of TTT within 24 months by PET parameters. Survival functions were calculated by Kaplan-Meier estimates. Cox regression model was applied to evaluate PET prognostic power and Wilcoxon-Mann Whitney test for the multivariable analysis. A p value \ 0.05 was considered statistically significant. Results: Thirty-one (57%) patients had advanced stage of disease (III-IV), 28 (52%) an intermediate-high (C 2) Follicular Lymphoma International Prognostic Index (FLIPI) score. After a median followup of 59 months, 22 (41%) patients started immuno-chemotherapy due to progression, the remaining 32 (59%) continued WW at a median follow-up of 43 months. Median TTT was 22 months (range 7-79). Median overall survival was 52 months (range 21-122). Median TMTV and WB-TLG were 7.1 cm 3 and 43.3, respectively. The optimal cut-points identified for TTT within 24 months were 14 cm 3 for TMTV and 64 for WB-TLG (p \ 0.005). The expected probability of not starting treatment at 24 months after diagnosis was 87% in patients with TMTV \ 14 cm 3 and 53% for TMTV C14 cm 3 (p \ 0.005). A significant association was found between TMTV or WB-TLG and the stage of disease (p \ 0.05) and FLIPI C 2 (p \ 0.05). When restricting the analysis to 31 (57%) patients with advanced stage, the prognostic impact of TMTV and WB-TLG was confirmed. By multivariable analysis, patients with both TMTV C14 cm 3 and FLIPI C2 had only 18% probability of not starting treatment at 36 months, while patients with TMTV \ 14 cm 3 and FLIPI C2 had a 75% probability. Similar results were obtained for WB-TLG. Conclusions: Baseline TMTV and WB-TLG in low tumour burden FL can identify patients at high risk for early progression. In combination with FLIPI score, quantitative PET parameters may contribute to develop a risk-adapted individualized care in FL patients. The prognostic role of interim 18F-FDG PET/CT in non HODGKIN lymphoma: focus on Deauville score and semiquantitative parameters Medicine centre. Clinical prognostic features (gender, age, histology and initial stage) and follow-up data (progression/death) were considered for the analysis. All PET/CT examinations were qualitatively evaluated and DS were visually assigned both at iPET and ePET. The final response based on Lugano classification was considered as the gold standard. The following semi-quantitative parameters of the reference lesion were collected in both bPET and iPET: SUV max , SUV mean , TLG, MTV, SUV max tumour/SUV max liver ratio (TLR); D SUV max was also calculated. DS and semi-quantitative parameters were correlated with final therapy response and follow-up data. Continuous and categorical variables were analysed by Student's T and Fisher's exact tests. Multivariate Cox's regression was performed for the survival analysis (PFS and OS), using the median values of each semi-quantitative parameter to stratify the population. A p value \ 0.05 was considered statistically significant. Conclusions: Our preliminary results showed the possible prognostic significance of iPET evaluation with DS in NHL patients, demonstrating its good relation with final therapy response. Semiquantitative PET/CT parameters, particularly SUV max of the reference lesion collected both at bPET and iPET, could help not only to predict end of treatment response but also to better distinguish between patients with good/poor prognosis in the long term evaluation. Methods: Thirty-two patients affected by MM (n = 17) or NMSK (locally advanced squamous cell carcinoma = 14; mixed basocellular/ squamous carcinoma = 1), submitted to ICI (i.e. pembrolizumab or nivolumab for MM, cemiplimab for NMSK), were retrospectively evaluated. All patients underwent baseline 18 F-FDG PET/CT before starting therapy and the following PET-derived parameters were carried out: maximum standardized uptake value (SUV max ) of the hottest lesion, summary of the SUV max of all the active lesions (sum-SUV max ), whole body metabolic tumor volume (wb-MTV) and total lesion glycolysis (wb-TLG). The following laboratory data were calculated at baseline, as surrogate biomarkers of systemic inflammation: neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-tomonocyte ratio (LMR). Patients were followed-up through clinical examination and serial imaging at regular intervals of time: best clinical response (BCR) was established by multidisciplinary consensus meeting at 6 months and dichotomized as clinical benefit (CB) or no-clinical benefit (no-CB). Receiver Operating Characteristic (ROC) analysis was used to identify PET-parameters and blood biomarkers predictive of response to ICI, significance was established at P \ 0.05. Results: All enrolled subjects showed 18 F-FDG-avid lesions at baseline PET/CT. In MM patients, the sites of metastatic disease were lymph nodes (76.2%), skin (47%), lung (23.5%), adrenal glands (12%) and pancreas (6%). Subjects affected by NMSK presented unifocal or multifocal cutaneous lesions associated with lymph node metastases in 10 cases (71.4%). Baseline mean values were: SUV max 11.4 ± 6.4, sum-SUV max 23 ± 16.1, wb-MTV 12.9 ± 24.1 cubic centimeters (cc), wb-TLG 62.5 ± 115 g (g), NLR 2.8 ± 1.2, LMR 2.4 ± 0.9. At BCR assessment, 18 subjects (56.2%) were classified having CB and 14 (43.8%) as no-CB. Among baseline parameters, only wb-TLG and sum-SUV max efficiently predicted response to ICI with an area under the curve of 0.83 (cutoff 15.2, sensitivity 81.8%, specificity 100%, P = 0.003) and 0.89 (cutoff 17.6, sensitivity 72.7%, specificity 100%, P \ 0.0001), respectively. Conclusions: Among baseline PET-derived parameters and blood biomarkers, overall burden of metabolically active tumor, measured through wb-TLG and sum-SUV max , presented high predictive value on MM and NMSK patients' response to ICI. Background-Aim: Gold standard therapy for patients with advanced melanoma consists of immunotherapy. At least three PET-based criteria are available for the early assessment of response to this kind of therapy: PECRIT, PERCIMT and EORTC. These criteria differentiate response to therapy in progressive metabolic disease (PMD), stable metabolic disease (SMD), partial metabolic response (PMR) and complete metabolic response (CMR), according to the variations of different parameters. The aim of this study was to assess their capability of properly stratifying patients in terms of Overall Survival (OS) and Progression-Free Survival (PFS). Methods: Patients were retrospectively enrolled. Inclusion criteria were: diagnosis of advanced melanoma treated with immunotherapy and monitored with of two [ 18 F]F-FDG PET/CT scans, respectively pre-treatment and ad interim (approximately 4 months after therapy onset). [ 18 F]F-FDG PET/CT scans were analysed according to the three different criteria of response to immunotherapy (PECRIT, PERCIMT and EORTC). Prognosis curves of different PET responses according to different criteria were evaluated in terms of PFS and OS by Kaplan-Meier estimates and were compared by log-rank test. Results: 20 patients were enrolled: 12/20 were treated with nivolumab, 6/20 with pembrolizumab and 2/20 with ipilimumab. By PECRIT criteria, 10 patients were classified as PMD, 5 as SMD, 2 as PMR and 3 as CMR. For the PERCIMT criteria, there were 6 PMD, 7 SMD, 4 PMR, and 3 CMR. Finally, for the EORTC criteria, 9 patients were categorised as PMD, 2 as SMD, 6 as PMR and 3 as CMR. In 7 cases out of 20, at least one criterion differed from the other two. Furthermore, for one patient, each criterion differed from the others. While all three criteria were successful in stratifying patients, PER-CIMT criteria demonstrated the strongest prognostic stratification, identifying patients with PMD as those with a significantly worst prognosis both in terms of OS (with a median survival of 229 days for PMD and 830 days for SMD, respectively; p = 0. 07) and PFS (median 89 days for PMD and 477 days for SMD, respectively; p = 0.07). Conclusions: The PECRIT criteria showed a statistically significant difference only on median OS between PMD and SMD (555 and 1528, respectively; p = 0.1), but not on PFS (p = 0.2). PERCIMT criteria, although more complicated to apply, showed higher accuracy in early stratifying prognosis, as compared to PECRIT and EORTC criteria. Background-Aim: Undifferentiated sarcomas are the second most common histotype of soft-tissue sarcoma (STS) in the adults after leiomyosarcoma. The standard of care is surgical excision, while the use of neoadjuvant and adjuvant treatment is still controversial. Aim of the present study was to investigate the value of pre-treatment 18 F-FDG PET/CT textural features in predicting disease-free survival (DFS) and overall survival (OS) in patients with localized resectable soft-tissue undifferentiated sarcomas. Methods: Fifty-one consecutive patients with non-metastatic undifferentiated soft-tissue sarcoma (STS) who underwent 18 F-FDG PET/ CT prior to treatment were retrospectively enrolled. Conventional PET parameters (SUV max , Subpeak, MTV and TLG) were measured and textural features were extracted from PET images derived from first-order and higher order matrices: grey level co-occurrence matrix (GLCM), neighbourhood grey-level different matrix (NGLDM), greylevel run length matrix (GLRLM), and grey-level zone length matrix (GLZLM). Independent PET and clinical predictive factors for DFS and OS were determined using Cox proportional hazards regression models. Results: The study population included 31 males and 20 females, median age 62.4 years. Sites of primary tumors were limbs (n = 44) or trunk (n = 7). 15 patients received a neoadjuvant chemotherapy, 31 patients an adjuvant treatment after surgery (radiotherapy ± chemotherapy). During a median follow up of 50.7 months, 23 (45.1%) and 29 (56.9%) patients had death or disease progression, respectively. Univariate analysis revealed a significant association for (1) adjuvant treatment, stage (IIIb vs II/IIIa), MTV, TLG and the texture parameter GLCM-correlation (GLCM_cor) with OS and for (2) adjuvant treatment, MTV, TLG and GLCM_cor with DFS. In multivariate analysis adjuvant treatment and GLCM_cor ([ 0.514) were the only relevant prognostic features for OS (hazard ratios [HR]: 0.31, p = 0.005 and HR: 7.07, p = 0.002, respectively) and DFS (HR: 0.41, p = 0.019 and HR: 4.6, p = 0.002, respectively). By combining both the above parameters patients can be stratified in four different prognostic classes (median OS not reached for those with a lower GLCM_cor and/no adjuvant therapy, 51.5 months for high GLCM_cor/adjuvant treatment and 15.2 months for high GLCM_cor/ no adjuvant treatment). Conclusions: GLCM_cor could have a prognostic role in DFS and OS in patients with undifferentiated STS and its use could be proposed to select those patients who could more benefit for an adjuvant treatment approach. Prospective confirmatory studies in larger population of patients are warrented. Background-Aim: Congenital hyperinsulinism (CHI) is a rare but complex disorder caused by unregulated secretion from the beta-cells of the pancreas. Maintenance of euglycemia is necessary to minimize neurologic damages like cerebral palsy, epilepsy, neurodevelopemental deficits and even death. CHI occurs due to mutations in key genes and now is classified into three groups: diffuse, focal and atypical forms. The diffuse form is medically unresponsive and will require a near total ([ 95%) pancreatectomy; the focal form, requires a limited pancreatectomy. Thus, the pre-operative differentiation of these two subgroups is necessary. Because US, CT and/or MRI are unable in distinguishing the diffuse and focal forms of CHI, the imaging modality of choice to diagnose CHI is 18FDOPA PET/CT scan. Methods: An infant boy, body weight 4446 g, length 52 cm, head circumference 35 cm, showed normal APGAR scores. Due to the early detection of hypoglycemia the infant was transferred to the neonatal intensive care unit, was on full enteral feeding, and received intravenous glucose treatment at 1.2 gr/kg/day dose to maintain normal blood glucose values. Therefore, genetic analysis and 18F-DOPA PET/CT scan were organized. The patient received 4 MBq/kg of 18F-DOPA intravenously. After 60 min, a whole-body scan was obtained in 3 bed positions. Iterative reconstruction was performed and the images were evaluated in a 3D display using axial, coronal, and sagittal views to define pancreas. Results: Laboratory tests showed persistent high insulin levels (over 30 mcg/ml), negative ketonemia, low free fatty acid (213 mcmol/l), normal IGF-1, cortisol, and ammonia levels in the setting of hypoglycemia, suggesting diagnosis of CHI. Diazoxide treatment produced limited response while subcutaneous octreotide allowed a significant decrease of intravenous glucose infusion. The diazoxide unresponsiveness suggested a potassium channel gene mutation. Next generation sequencing method allowed the identification of a mutation variant in ABCC (p.Leu 40 Arg). 18F-DOPA PET/CT images showed intense 18F-FDOPA uptake in the head of the pancreas, confirmed by a semi-quantitative evaluation (SUV max = 6.67). Conclusions: We confirm that 18F-DOPA-PET/CT is a safe, noninvasive and the investigation of choice in distinguishing between the focal and diffuse forms of CHI; the prompt and accurate localization permits the correct enucleation of the focal lesion preventing the risk of developing iatrogenic diabetes mellitus and pancreatic insufficiency. We confirm that advances in molecular genetics, imaging methods (18F-DOPA PET-CT), medical therapy and surgical approach have completely changed the management and improved the outcome of these children. Background-Aim: SPECT/CT is less famous than PET/CT but hybrid imaging has the potential to advance conventional nuclear medicine studies as well. As for adults, also in pediatric field a more detailed imaging allows a more accurate assessment improving diagnostic-therapeutic decision-making process. Management of pediatric patients (and their parents), assessment of peculiar clinical indications and interpretation of functional and anatomical pediatric pattern could be technically difficult requiring a well-trained team with specific expertise. Reviewing the experience of our pediatric center, we assessed the role of SPECT/CT imaging in pediatric clinical practice. Methods: Planar imaging was integrated by SPECT/CT in 459 examinations (296 children) performed in our nuclear medicine unit from October 2020 to December 2021 (with optimized low dose CT and advanced xSPECT TM technology since April 2020). Hybrid imaging was routinely applied in case of mIBG scan for neuroblastoma, 123 I WBS in thyroid carcinoma, post radionuclide therapy imaging ( 131 I mIBG, 131 I NaI and 177 Lu-peptide, integrated by dosimetry) and WBC scan. In the rest of conventional nuclear medicine studies, SPECT/CT procedure was performed in cases of choice. Results: Conventional hybrid imaging practice is the standard of care in mIBG scintigraphy for neuroblastoma (31%), 123 I post-surgical imaging of children with thyroid carcinoma (8%) and post radionuclide therapy imaging (13%). Bone scintigraphy represented the 34% of cases: in malignant (38%) and benign (12%) oncologic conditions as for non-oncologic indications (50%-orthopedic, rheumatological and condylar disease). Hybrid imaging added useful information in lung imaging (1%, considering the current lack of ventilation kit system), infection/inflammation (2%) and intestinal transit studies (3%-in chronic intestinal pseudo-obstruction and Hirschsprung disease). Functional imaging was also improved by anatomical information in a series of nuclear medicine procedures for preoperative planning (in Meckel diverticula, intestinal bleeding, proteinlosing enteropathy, hyper functional parathyroid, spleen function assessment, lymphatic malformation and sentinel lymphonode imaging). Also the old renal scintigraphy was improved by SPECT/ CT even if in very selected cases (ectopic kidney location in DMSA study or abnormal ureteral stasis due to retrocaval ureter by MAG scan). Conclusions: In our experience, hybrid imaging improved localization, characterization, detection and diagnostic confidence of functional findings reducing indeterminate results and additional imaging. The utility to perform absolute quantification in SPECT/CT is a matter of fact. The gain (in terms of diagnosis and management change) in this selected but clinically relevant field makes up for all the daily efforts. In hybrid imaging era is dutiful ensuring the best clinical practice based on a multidisciplinary approach, especially in pediatric field. Background-Aim: Brain tumors are the most common cause of death among all childhood, with a wide range of histological classification and survival times. Building on advances in medical imaging and on a heavy clinical need, new applications of 18 F-di-idrossi-fenil-alanina ( 18 F-DOPA) PET are under development for the evaluation and management of pediatric brain tumors without defined practice guidelines. Describing our experience, the aim of the present study is to provide a comprehensive assessment of the clinical applications of 18 F-DOPA PET in pediatric population affected by brain tumors, considering clinical benefits and radiation safety profile. Methods: We retrospective assessed 55 18 F-DOPA PET scans in 50 pediatric patients referred to our institution for the presence of primary, residual or recurrent brain tumors (28 boys, 22 girls; mean age 8.6 years: 1 month-21 years; mean weight 39 Kg: 3-102 kg). 18 F-DOPA PET/CT and brain MRI were co-registered to obtain a more accurate PET image evaluation. 18 F-DOPA uptake parameters (lesion-to-normal background-T/N-and lesion-to-striatum ratios-T/ S) were compared with histology and correlated to WHO tumor grade. Dosimetric impact of 18 F-DOPA PET/CT was assessed considering PET tracer (administered activity: from 30 to 340 MBq) and X-ray radiation dose contribution. Results: Histological data were obtained for all patients: 31/50 (62%) high-grade glioma, 9/50 (18%) low-grade glioma, 10/50 (20%) others. Considering WHO tumor grade we had 39 (78%) and 11 (22%) patient with high and low-risk tumor, respectively. 21 18 F-DOPA-PET were performed for diagnostic purpose, 4 for suspected relapse, 25 for post-treatment evaluation and 5 for follow-up. We observed heterogeneous patterns of 18 Conclusions: 18 F-DOPA PET imaging provides useful information about tumor metabolism in different steps of oncologic disease (diagnosis, residual, relapse and progression), resulting fully justified in terms of radiation exposure. It remains crucial to define 18 F-DOPA PET guideline, specifically standardized for pediatric patients. Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 Background-Aim: PET with [ 18 F]-DOPA can be used to evaluate grading and aggressiveness of paediatric cerebral gliomas. However, standard uptake parameters may underperform in circumscribed lesions and in diffuse pontine gliomas. In this study, we tested whether dynamic [ 18 F]-DOPA PET could overcome these limitations. Methods: Patients with available dynamic [ 18 F]-DOPA PET were included retrospectively. Static parameters (tumour/striatum ratio and tumour/cortex ratio; T/S and T/N, respectively) and dynamic ones, calculated on the tumour time-activity curve (TAC), including timeto-peak (TTP), slope steepness, the ratio between tumour and striatum TAC steepness (dynamic slope ratio, DSR), and TAC shape (accumulation vs plateau) were evaluated as predictors of high/low grading (HG and LG) and of progression-free and overall survival (PFS and OS, respectively). Results: Fifteen patients were included; T/S, T/N, TTP, TAC slope steepness and DSR were not significantly different between HG and LG. The accumulation TAC shape was more prevalent in the LG than in the HG group (75% vs 27%). On PFS univariate analysis, TAC accumulation shape predicted longer survival (p \ 0.001, while T/N and DSR showed borderline significance; on multivariate analyses, only TAC shape was retained (p \ 0.01, Harrel's C index 0.93-0.95). On OS univariate analysis, T/N (p \ 0.05), DSR (p \ 0.05) and TAC ''accumulating'' shape (p \ 0.001) predicted survival; once more, only this last parameter was retained in the multivariate models (p \ 0.05, Harrel's C index 0.86-0.89). Conclusions: Dynamic [ 18 F]-DOPA PET analysis outperforms the static parameter evaluation in grading assessment and survival prediction. Evaluation of the curve shape is a simple-to-use parameter with strong predictive power. The lack of tracer accumulation in lesions with poor prognosis could be hypothetically explained by the reported higher prevalence of blood-brain barrier damage in highgrade forms. Background-Aim: Congenital hyperinsulinism (HI) is a heterogeneous condition due to mutations in genes involved in the regulation of glucose metabolism. The management of HI is challenging, as each form of HI (focal, diffuse and atypical) requires its own therapeutic strategy. 18 F-DOPA PET/CT scan is currently the first-line imaging technique allowing to differentiate between diffuse and focal form and, in the latter case, to localize the focus within the pancreas with high precision. By assessing all clinical, instrumental and genetic data, we reviewed our experience to investigate PET/CT value in the HI diagnostic-therapeutic decision-making process. Methods: From 2008 to 2021, 41 children (21 males and 20 females; age range 1 month-18 years; median age, 38 months) with diagnosis of HI were referred to a 18 F-DOPA PET/CT scan to distinguish between focal and diffuse form. 4 MBq/kg of 18 F-DOPA were intravenously administered 45 min before PET/CT acquisition (performed under general anesthesia in younger children, with the continuous assistance of pediatric metabolic physician). The images were first visually analysed; when a focal area of intense uptake in the pancreas was detected, a sequentially co-registered contrast-enhanced CT was performed to localize the focal. Quantitative analysis using the DOPA uptake ratio (focal area of uptake vs normal pancreas) [ 1.2 was considered indicative of a focal lesion. In case of focal PET pattern, a multidisciplinary team conference was planned before surgery. Results: The presence of the pediatric metabolic physician and the pediatric anesthetist allowed to perform all PET/CT scan safely. In 11 of 41 (27%) pts, PET/CT scan showed a focal uptake in the pancreas (6 in the head, 4 in the body and 1 in the tail); one of them (1/11 pts) had negative genetic result for Sur or Kir gene mutation, suggesting an atypical form. Abdominal contrast CT scan showed increased contrast enhancement in the arterial phase corresponding to pancreatic focal lesion in 6/11 (55%) pts, revealing a small area of reduced enhancement in 1/11 (1%). All preoperative assessment (genetic analysis and PET/CT scan) were pathologically confirmed after surgery, resulting in complete remission of hypoglycemia, until the last follow-up. Conclusions: PET/CT provides a bright light on HI disease but there is a more complex world beyond PET imaging pattern. An accurate analysis of hybrid imaging data helps to obtain a correct localization of focal lesion guiding surgical resection. Looking further ahead, a careful assessment of all hybrid imaging data could lead to discover uncommon findings increasing diagnostic confidence (especially for small/large HI focal lesion) and improving the knowledge of a challenging disease with heterogeneous features. In specialized centers with specific expertise, a multidisciplinary approach based on clinical, instrumental and genetic investigations solves the puzzle for a successful diagnostic-therapeutic decision-making process. Background-Aim: 123I-MIBG scintigraphy is indispensable in the evaluation of disease extent in neuroblastoma staging and in the evaluation of response to treatment. Aim of our study is to evaluate the additional diagnostic value of hybrid imaging (SPECT-CT) in 123I-MIBG studies over planar images. We retrospectively evaluated 730 123I-MIBG scintigraphies (planar and SPECT images) of 252 children (age at diagnosis ranged from 1 month to 17 year old) which referred to our Institution for neuroblastoma from 2003 to 2021. Since 2009 all SPECT studies were processed by manual fusion with CT by a dedicated software (544 SPECT-CT) and since October 2020 SPECT-CT (111 studies) were acquired with an hybrid gamma camera (Symbia Intevo Bold TM , Siemens Healthineers). SPECT-CT findings and areas of increased 123I-MIBG uptake on planar images were compared. Results: In 478/655 (73%) studies, SPECT-CT was concordant with planar images, showing no areas of pathological uptake in 196/478 studies (41%), one or more area of pathological uptake in 282/478 studies (59%). In 177/655 (27%) studies SPECT-CT provided more information than planar images: in particular, in 106/177 (60%), it allowed to identify areas of pathological uptake close to sites of physiological uptake; in 50/177 (28%), SPECT-CT excluded uptake in known pathological tissue located near sites of physiological uptake; in 21/177 (12%), it enabled the accurate identification of the anatomic site of pathological uptake (bone/bone-marrow versus soft tissue) when the pathological tissue was present in ambiguous locations (mandibular region in 6/21, orbital region in 6/21, vertebral intraforaminal and vertebral endocanalar in 9/21). Conclusions: In our experience, SPECT-CT was useful in the precise evaluation of disease extent, both when it confirmed the findings of planar images and when it provided additional information. Background-Aim: 123I-MIBG scintigraphy is indispensable in the evaluation of disease extent in neuroblastoma staging and in the evaluation of response to treatment. Unfortunately, qualitative evaluation of images is not sufficient in order to determine accurately treatment response. Aim of our study is to evaluate the usefulness of semi-quantitatively assessment of tracer uptake in 123I-MIBG scintigraphies in the estimation of response to treatments and in follow-up in pediatric patients affected by neuroblastoma. Methods: We retrospectively evaluated 30 scintigraphies performed in 11 patients affected by neuroblastoma (age ranged from 7 months to 17 year old). All scintigraphies (planar images and xSPECT/TC acquisitions) were performed with an hybrid acquired with an hybrid gamma camera (Symbia Intevo BoldTM, Siemens Healthineer). Each patient underwent at least 2 scintigraphies (5 patients underwent 2 studies, 4 patients underwent 3 studies, 2 patients underwent 4 studies). 7 studies were an evaluation to chemotherapy, 5 studies were an evaluation to 131I-MIBG, 4 studies were an evaluation to CAR-T therapy, one study was an evaluation to radiotherapy and 4 studies were an off-therapy follow up evaluation. Treatment response after every treatment was classified as progressive disease or stable disease (PD and SD), partial and complete response (PR and CR) based on a comprehensive evaluation (CT data, qualitative evaluation of 123I-MIBG scan, trephines data) and correlated to the variation of the ratio of SUV max lesion (SUV max LE)/SUVaverage liver (SUVavgLI). Results: We found in 17/19 cases (89.5%) a concordance between the classification of the response and the variation of the SUV max Le/ SUVavgLI ratio and only in two cases we found a mismatch; in particular, these two studies, despite the classification of the response in stable disease, showed an increase of the SUV max LE/SUVavgLI ratio (respectively ?33% and ?42%). Conclusions: In our experience, semi-quantitatively determination of 123I-MIBG uptake is a useful tool in the evaluation of response to treatment in Patients affected by neuroblastoma. When a discordance between semi-quantitative analysis and clinical assessment is observed, further evaluation is needed in order to determine the biological cause of such phenomenon and its influence on clinical management. Background-Aim: Intestinal transit scintigraphy (ITS) is a noninvasive method for the quantitative evaluation of overall and regional intestinal transit to localize any sites of obstruction in pediatric patients with gastrointestinal motility disorders both in relatively benign conditions (functional constipation, FC) and in more serious disorders (Hirschsprung disease, HD, chronic intestinal pseudoobstruction, POIC). In FC, in fact, ITS provide information to distinguish normal transit from rectosigmoid outlet obstruction and slow-transit constipation; in HD and POIC, it can help to identify the correct level of decompressive stoma or segmentary resection necessary to relief obstruction and to improve enteral tolerance. Despite its incontrovertible utility, ITS is far from routine and remains limited to few specialized centers. Our purpose is to evaluate the role of ITS as complementary tool to standard radiology and surgery, to improve the bowel function outcomes in motility intestinal disorders. Methods: We retrospectively reviewed clinical and scintigraphic data of children who performed ITS at Bambino Gesù Children's Hospital between January 2015 and December 2021. 67 Ga citrate radiolabeled semiliquid meal was administered. After a standard gastric emptying study, abdominal static images were acquired at 1-3-6-24-48-72 until 144 h. Since January 2021, SPECT/CT was performed by a hybrid gamma camera in cases of choice, in order to better define the sites of stasis of radiolabeled meal. Because of the variability of bowel anatomy in our population, the interpretation of small-bowel and colon transit studies consisted in visual analysis and calculation of total transit time. Clinical and surgical data were collected and descriptive analysis was used to describe patient outcomes. Results: 139 patients with intestinal motility disorders were investigated: 90 constipated children (47 males; median age 11.5 years, range 1-18) and 49 patients with severe intestinal motility disorders (SIMD) (37 males, median 3.1 years, range 0.05-21); among them, 20/49 (41%) were affected by POIC and 29/49 (59%) by HD (20/29 total colonic, 9/29 extended). Administered activity ranged from 1.34 to 19 MBq (median 7.29). In 14/139 (10%) patients, SPECT/CT was performed. In FC group, ITS showed a complete rectal emptying in 72 h in 32/90 patients (36%), retention into the rectosigmoid colon at 72 h in 20/90 (22%), and retention throughout the colon at 72 h in 38/90 (42%). In SIMD group, 29/49 (59%) had abnormal transit and in 23/29 (80%) there was a change in surgical management (8 Bo-Tox injection, 7 stoma revision, 4 ileal resection, 4 jejunostomy closure) with clinical improvement in all. Conclusions: In our experience, ITS, in association with other diagnostic tools, plays a crucial role in pediatric gastrointestinal motility disorders' management, providing useful information for therapeutic decision-making. The utility of renal static scintigraphy in detecting scars in patients with normal kidney and renal dysplasia Background-Aim: Kidney scarring can be detected in 6-15% of cases after a febrile urinary tract infection. The aim of this study was to present our single-center experience and determine the diagnostic performance of 99m Tc-renal scan in depicting renal scars in a large collection of patients with normal kidney and renal dysplasia. Methods: In this retrospective study, patients with and suspected infection (based at least on clinical symptoms and signs as fever and elevated infectious markers), who underwent a 99mTc-DMSA scan, were searched in our internal hospital database. The patient underwent a planar scan after 3 h from the injection of 99m Tc-DMSA, eventually followed by SPECT. Follow-up imaging and clinical data (minumum:6 months) were used as standard of reference to calculate sensitivity (SS), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy (AC). Results: A total of 198 patients were retrieved and divided into a group of 129 patients with normal kidneys and a group of 69 patients with renal dysplasia. In the group of patients with normal kidneys, SS, SP, PPV, NPV, and AC were 82.86%, 92.55%, 80.56%, 93.55%, and 89.92%, respectively. In patients with renal dysplasia, SS, SP, PPV, NPV and AC were 78.95%, 97.26%, 88.24%, 94.67% and 93.48%. Conclusions: In our single-center experience, the renal scan showed satisfactory accuracy in the detection of scars either in patients with normal kidneys or renal dysplasia, possibly influencing patient management. Università degli studi di Perugia. 2 Background-Aim: Pediatric nuclear medicine exams represent approximately 10% of all nuclear medicine exams. Pediatric nuclear medicine deals with the morpho-functional study of almost all body organs and with radiopharmaceutical therapy. Even though the nuclear-medical evaluation is minimally invasive and exposes the little patient to low doses of radiation, it is a procedure that requires well-trained personnel capable of establishing a good interpersonal relation not only with children, especially those of tender age but also with parents. When children are required to undergo radiological investigations, specific processes are needed to calm their fear of being exposed to gowns and uniforms, but also of massive equipment, which may appear to them almost ''monstrous''. Indeed, the little ones are unable to dominate reality and overcome the state of fear that this unknown environment causes, if not through a fantastic elaboration of the experience. Nevertheless, they must be helped and encouraged in this process. This is what inspired the creation of Sunny & Tim, two cartoon characters who help children to understand the different stages of medical exams through simple and joyful adventures. Methods: Aiming to alleviate children's fear and enhancing the diagnosis accuracy, through a more fruitful collaboration between healthcare professionals and young patients, Dr. Ronald Van Rheenen, Nuclear Medicine Doctor at the University Hospital of Groningen (Netherlands), started a non-profit project called ''Involved''. The characters he brought to life are Sunny the Isotope and Tim the Tracer, cartoon characters who appear in three different stories where they respectively represent the radioactive substance and the tracer, which together make up the radiopharmaceutical administered by injection to the patient. Sunny & Tim's videos on diagnostic methods and nuclear medicine therapy are currently only available in Dutch, English, and German. Results: Inspired by Dr. Van Rheenen project, I decided to import this project to Italy, hoping to help the little patients of our country. I translated and dubbed one of the Sunny & Tim episodes in Italian. The episode is called ''Lights in your body'', which in the Italian version became ''Una luce speciale dentro di te''. Sunny represents the radiating light in the patient's body, while Tim is the tracer which helps his friend to find the correct way. Together they need to find the ill spot in the patient's body, namely Rob. Helping the photo doctor to identify the ill spot and take a photo. Conclusions: Technology does not alone qualify the work of the radiology technician and the entire radiological team. Empathy and humanity, have equal or greater importance when performing a nuclear medicine exam or any other radiological investigation. Especially in Italy, pediatric nuclear medicine needs new initiatives in order to change e renew how the exams for young patients are. With ''Una luce speciale dentro di te'' I hope to be able to contribute to the initiation of this change in the nuclear medicine field in Italy. The FDG pattern of autonomously functioning thyroid nodules correlates with TSH and histopathology Background-Aim: While the 18 F-FDG PET/CT pattern of malignant thyroid neoplasia is quite known, the glucose uptake of benign lesions, firstly the autonomously functioning thyroid nodule (AFTN), has not been fully investigated. In this study, we aimed to analyze the FDG pattern of AFTNs and its correlation with clinical, laboratory, ultrasonography and histological features. Methods: This was a retrospective, bi-centric study. Patients diagnosed with AFTN on a thyroid scan and who underwent a 18 F-FDG PET/CT for various indications during the period 2009-2018 were reviewed. The PET pattern (presence of uptake) was compared with the thyroid hormone asset and with the histopathology. Results: Forty-five patients (35 females, median age 65 years) were included. Suppressed TSH, high Free-T3, and high Free-T4 were observed in 40%, 11%, and 20% patients, respectively. Over a 36-month follow-up, 20 patients underwent surgery and 4 cancers, 10 follicular adenomas (FA), and 6 follicular hyperplasia (FH) were found. Twenty-two (48.9%) AFTNs was FDG-positive (median SUV ratio 2.53) while the remaining 23 (51.1%) were not. TSH was significantly lower in FDG-positive AFTNs than in negative ones (0.055 [0.02-0.42] vs. 0.65 [0.2-0.96] mIU/l, p = 0.0018). At multivariate analysis including several parameters, only TSH was independently associated to FDG pattern (p = 0.008). At ROC curve analysis, TSH \ 0.08 mIU/l detected FDG-positive AFTNs with 64% sensitivity, 87% specificity, 4.88 LR ? , and 0.42 LR-. Among histologically proven benign lesions, TSH was significantly lower in FAs than in FHs (p \ 0.001). Patients with cancer had TSH in the lownormal range. Conclusions: AFTNs show heterogenous uptake FDG pattern. Furthermore, follicular adenomas tend to display increased glucose uptake and suppressed TSH. Background-Aim: Thyroid nodules suspicious at ultrasounds necessitate fine-needle aspiration cytology (FNAC) as confirmative test, which suffers from high indeterminate reports, up to 25%. Indeed, these lesions are addressed to surgery, resulting as benign in of cases. In this population whole body FDG-PET/CT (wb-PET/ CT) has a high negative predictive value for malignancy, ranging between 81 and 100%. However, this imaging modality is not recommended in the diagnostic workup, mainly because of high radiation exposure and costs. The aim of the study is to preliminary estimate tracer dose, dosimetric and scan-time impacts of low dose FDG-thyroid-PET/CT (t-PET/CT) either versus wb-PET/CT, in patients undergoing FDG PET/CT for an oncologic query, and 99m-TcO4 -thyroid scintigraphy (t-S). Methods: Wb-PET/CT of 50 patients (64.7 ? 12 years; 50% male) were retrospectively compared with t-PET/CT, defined as the cervical part (1 bed) of wb-PET/CT. The ratio between scan-length of t-PET/ CT and wb-PET/CT was the basis to estimate temporal, tracer dose and radiation exposure relationship between the two modalities. Data obtained in a population matched by age and gender undergoing t-S were also evaluated. Tracers dose (FDG or 99m-TcO4-, expressed in MBq), radiation exposure (ED, in mSv), scan-time and additional cancer risk (ACR) were assessed. Results: In wb-PET/CT, the radiation exposure is determined by CT (60.4%) and 18F-FDG (39.6%). The ratio between scan-length of t-PET/CT vs wb-PET/CT was 0.20. Mean scan-time and dose of wb-PET/CT were 17.9 ? 1.9 min and 276.1 ? 51 MBq, respectively. Based on the time-dose equation, t-PET/CT would need a mean dose of 55.2 MBq, which is 20% of wb-PET/CT, to obtain the same counting rate. Considering a cervical scan instead of a WB, ED decreases from 4.4 to 0.88 (p \ 0.0001), from 6.7 to 1.34 (p \ 0.0001), and from 11.1 to 2.22 mSv (p \ 0.0001) for PET, CT and PET/CT, respectively. For t-S, using a 99m-Tc dose of 158.6 ? 29 MBq, mean scan-time and ED were 5.4 ? 1.7 min and 2.1 ? 0.4 mSv, respectively. Considering prices in our Institution, tracer's cost was 9.4 euro for t-PET/CT and 5-10 euro for t-S. ACR was calculated 0.106% for wb-PET/CT vs 0.008% for t-PET/CT (p \ 0.0001); 0.003% for t-PET vs 0.006% for t-S (p \ 0.0001). Alternatively, using the same FDG dose of wb-PET/CT, the scan time of t-PET was 4.1 vs 5.4 min of t-S (p \ 0.0001). Conclusions: These preliminary data support the hypothesis that lowdose t-PET/CT is a conceivable diagnostic strategy in patients with indeterminate high risk nodules. This imaging approach would be cost/effective in clinical setting, having a potential role in limiting the rate of futile thyroid surgery. The diagnostic performance of 99MTC-MIBI SPECT/CT in primary hyperparathyroidism assessment and correlation with pre-scan data Background-Aim: Primary hyperparathyroidism is a common endocrine disorder usually associated with hypercalcemia and high level of parathyroid hormone (PTH) and Dual phase 99mTc-MIBI SPECT/CT is commonly used in pre-operative parathyroid glands localization. The aim of the study is to evaluate the relationship between dual phase 99mTc-MIBI SPECT/CT result and pre-scan radiological or biochemical data (including parathyroid diameter, PTH and serum calcium levels). Methods: We retrospectively evaluated 177 patients who performed 99mTc-MIBI SPECT/CT since May 2018 to June 2019. Patients with glomerular filtration rate \ 45 mL/min/1.73 m 2 or kidney transplant and patients without subsequent histological or radiological diagnosis of parathyroid adenoma or hyperplasia were excluded. Finally, 66 patients were included. We collected clinical (presence of osteoporosis, vitamin D treatment), biochemical (PTH, calcemia, phosphatemia and 25(OH)-vitamin D levels) and morphological (parathyroid diameter measured by ultrasound) data and we compared them with SPECT/CT findings by assessing t test and chi test. Optimal cut-off value of PTH and parathyroid diameter were assessed by applying receiver operating characteristic (ROC) analysis. Results: Among 66 patients with a final diagnosis of parathyroid adenoma or hyperplasia, 42 (64%) had a true positive 99mTc-MIBI SPECT/CT, while the remaining 24 (36%) had a false negative study. Of 42 patients with enlarged parathyroid at pre scan neck ultrasound, 29 (69%) had a positive SPECT/CT; instead only 11/24 (46%) patients with negative SPECT had enlarger parathyroid gland. Mean PTH and calcemia values were significantly higher in patients with a true positive 99mTc-MIBI SPECT/CT compared to negative scan (187.29 pg/mL vs 119.35 pg/mL, p = 0.0157; 10.35 mg/dL vs 10.97 mg/dL, p = 0.0037). ROC analysis showed a cutoff value of 98.0 pg/mL for PTH with a sensitivity of 90.5% and specificity of 42% in predicting scan results. Considering patients with positive ultrasound, mean parathyroid diameter value was significantly higher in patients with a true positive result at 99mTc-MIBI SPECT/CT (13.92 mm vs 8.5 mm; p = 0.0360) and ROC analysis shows a cutoff value of 8 mm with a sensitivity of 79% and specificity of 73%. No significant differences were found considering phosphatemia, 25(OH)-vitamin D levels, presence of osteoporosis and vitamin D treatments between the two groups. Conclusions: In the diagnosis of primary hyperparathyroidism PTH, calcemia and parathyroid diameter measured by ultrasound are significantly correlated with 99mTc-MIBI SPECT/CT findings. ROC analysis suggest PTH and parathyroid diameter cut-off value of 98 pg/mL and 8 mm as best predictors of SPECT/CT results. Studies with larger number of patients help to clarify better this relationship and help to define when further examinations with higher sensitivity, such as 18F-fluorocholine PET/CT, could be early performed. Background-Aim: To evaluate the role of PET/MR with 18F-Choline in identifying hyperfunctioning parathyroids in patients with clinical hyperparathyroidism and negative or doubtful conventional imaging (i.e. neck ultrasonography and/or 99mTc-sestamibi scintigraphy). Methods: Between January 2020 and December 2021, 30 patients underwent PET/RM investigation with 18F-Choline for the localization of hyperplastic parathyroids. All images were reviewed by at least 2 nuclear physicians and 1 radiologist. For the interpretation of images, both visual and semiquantitative assessment were used for PET, while MR images were only visually analyzed. For the semiquantitative PET analysis, the maximum standardized uptake value (SUV max ) and the ratio between the SUV max in the hyperplastic parathyroid (A) and the SUV mean in the thyroid gland (usually the contralateral in respect to the hyperplastic parathyroid) (T) was obtained. Results: The detection rates of PET and MR for the localization of hyperplastic parathyroids were 83% and 66%, respectively (concordance index 0.571; p \ 0.005). In particular, PET/MR was able to identify 100% of hyperplastic parathyroids in patients with previous parathyroidectomy surgery. The median value of SUV max at the level of the hyperfunctioning parathyroid was 3.16 (range 2.1-13.4) and the median value of the A/T ratio was 2.0 (range 1.2-6.1). PET/MR was positive mainly in patients with high serum calcium (higher serum calcium value in patients with positive PET vs. those with negative PET), while a poor correlation with serum parathormone (PTH) was observed. Conclusions: The present study demonstrates that 18F-Choline PET/ MR shows greater identification of hyperfunctioning parathyroids than MR alone. In addition, the value of serum calcium seems to play an important role in guiding patient selection, whereas serum PTH seems to play a limited role. Background-Aim: Image-guided thermal ablation (LTA; RFA)are well established therapy option in selected BTN, especially non functioning ones. PMWT is a new mini-invasive technique recently applied in thyroid disease; aim of this work is to investigate its effectiveness inside therapeutic management of BTN. Methods: From May 2021, 35 patients (22 F 13 M, aged 37-85 years, mean 60.5) with BTN symptomatic/in growing refusing/ non eligible to surgery were enrolled. Inclusion criteria: maximum nodule diameter C 2 cm, mainly solid C 20%, 2 FNA cytology pathologically confirmed as benign (TIR2 sec ITCCS 2014). At baseline were performed an anesthesiology and ENT consults, ECG, laboratory assessment (serum levels of fT3, fT4, TSH, TPOAb, TgAb, calcitonin, blood count and clotting indexes). Additionally 21/35 pts done Thyroid Scintiscan with 99mTc-Pertecnetate (3 hot nodule; 15 cold nodule; 3 non focal findings). Ultrasound-guided PMWTA was carry out at interventional radiology of our Hospital under local anesthesia through TATO antenna (18G 9 8 cm or 17G 9 10 cm-Terumo) delivering 10-15 W in 10-15 min, depends on the volume of BTN. Nuclear medicine physician effects a clinical-anamnestic evaluation, thyroid physical examination assigned an Aesthetic Score (AS from 1-no palpable/visible nodule to 4 palpable visible nodule in all positions), rating the compressive symptoms with a Compressive Score (CS on a 10 cm visual analog scale) and US thyroid scan determining Volume of BTN target (VnT) before procedure and repeated during follow-up scheduled at 1, 3, 6 months after procedure. Additionally a volume reduction rate %(VRR)was calculated and the success rate fixed in a volume reduction C 50%. Results: No peri-procedural major complications were observed. 1/35 has developed in 10 days after PMWT transient thyrotoxicosis and atrial fibrillation pharmacologically reverted. Clinically was registered during follow-up a mean reduction of CS score from 4.7 to 1.6 and regards AS from 4 to 2. The mean VnT pre-procedure was 19.45 mL (range from 77 to 1.6) and mean VnT post-procedure was 7.97 mL (range from 32.9 to 0.31). The estimated mean VRR at 1, 3 6 months was 57% (range 12-82%), 69% (range 45-91%) and 79% (range 49-94%), respectively. If consider as a therapeutic goal a volume reduction of C 50% the success rate was approximately of 97.1% in 6 months. Neither a re-growth occurred in this short-term evaluation. Conclusions: From our preliminary results PMWT is a powerful procedure inside the therapeutic management of BTN as described above with high successful rate in terms of effective nodule shrinking, safety with a low complication rate, good cosmetics/sympomatics results and well tolerated. Our data needed a validation in more large series and long term follow-up. Role of 18F-FDG PET/CT in patients treated for differentiated thyroid cancer with negative 131I-wholebody scan and elevated serum thyroglobulin Background-Aim: 18F-FDG PET/CT is increasingly performed in patients in follow up for thyroid cancer The purpose of our study was to assess the impact of 18F-FDG PET/CT on clinical-therapeutic management of patients with elevated serum thyroglobulin (TG) and negative 131I whole body scan (WBS) which often represent a dilemma for clinicians. Methods: A total of 16 patients (5 males and 11 females; age range 26-82 years), with history of thyroid cancer (9 papillary thyroid cancer, 5 follicular thyroid cancer, 1 hurthle cell carcinoma and 1 insular carcinoma), treated by total thyroidectomy and 131I ablation, underwent to 18F-FDG PET/CT scan All patients had a negative 131I-WBS and TG serum level increase after stimulation (4 patients TG [ 10 ng/ml, 12 patients \ 10 ng/ml). 131I-WBS was performed with a Dual head Gamma-Camera, with high energy parallel hole collimator. Anterior and posterior WB images were acquired with an additional 5 min planar image on the neck-upper mediastinum. SPECT was not routinely performed. 18F-FDG PET/CT scan was performed within 2-3 weeks after 131I-WBS, with standard modality, 60 min after tracer injection. PET/CT scans were acquired from the skull vertex to the feet., with low dose CT. All areas with increased FDG uptake corresponding to a CT abnormality (lymph nodes or tissue mass) were interpreted as positive. The 18F-FDG PET/CT findings were considered: true positive (TP) if were confirmed by histologic biopsy, FNAC with TG eluate assay or TG decreasing after active therapy; false positive (FP) if biopsy samples were negative or TG decreasing without active therapy; true negative (TN) if elevated TG had normalized without any treatment or if recurrence was not evident during follow-up; false negative (FN) in case of persistent high TG levels. Predictive values negative (VPN) and positive (VPP), sensitivity and specificity were calculated. Results: 9/16 were PET positive and WBS negative, whereas 7/16 were negative for both investigations. Among the 9 patients PET positive, 7 underwent surgery with subsequent histological examination, 1 had pulmonary metastases and 1 vertebral metastasis and referred respectively to oncology and radiotherapy. 5/7 were TP with proven differentiated thyroid carcinoma, whereas the other 2 patients were FP (1 sarcoidosis and 1 inflammatory). TG levels were [ 10 ng/ ml in 4/7 TP patients and \ 10 ng/ml in the remaining patients. Among the 7 patients negative, 6 were TN confirmed by decreasing TG levels during follow-up, 1 FN due to progressive rising TG levels that subsequently showed cervical nodal metastases 1 year later on neck ultrasound. TG levels were [ 10 ng/ml in 1/6 TN patients and \ 5 ng/ml in 5 patients. VPP, VPN, sensibility and specificity were respectively: 78%, 86%, 88% and 75%. Conclusions: 18F FDG PET/CT is useful to improve diagnostic accuracy and impacts on the clinical-therapeutic management of patients with differentiated thyroid cancer who exhibit rising TG levels and negative 131I-WBS. Background-Aim: Bowel dysfunction is one of the most widespread clinical comorbidities associated with spinal cord injury (SCI), significantly impacting patients' quality of life. Transanal irrigation (TAI) system is a valid treatment that allows intestinal empting, when conservative treatment fail. Colorectal scintigraphy (CRS) during TAI with 99mTc-DiethylAminoPentaceticAcid Saline Solution (99mTc-DTPA-SS) allows to visualize the progression of the solution along entire colon. This prospective study aims to detect the different pattern of peristalsis activation with CRS and abdominal ultrasound (US). Methods: We enrolled 7 patients with SCI (6 traumatic, 1 non traumatic) who underwent a TAI (Peristeen Ò ) session with dynamic CRS (1 frame/0.5 s) to detect the 99mTc-DTPA-SS progression throughout the bowel; simultaneously whirlpools created from the solution transit were visualized on US, providing a qualitative score (normovalid-hypovalid), considering splenic flexure as anatomic landmark. 99mTc-DTPA-SS pumping system was stopped at T = 30 s (T0). Qualitative evaluation of post-evacuation images were done at CRS. Colon was divided into six segments corresponding to a Region of Interest (ROI) at dynamic CRS: cecum, ascending, transverse, splenic flexure, descending, rectosigmoid. Time activity curves (TAC) were obtained for each ROI and counts at 30 s time intervals were evaluated. Results: In 5/7 patients TAC suggested the presence of preserved peristalsis: decreasing counts in ROI drawn on distal colon segment, followed by increasing counts on proximal one, corresponded to a spike on the TAC, suggesting retrograde peristalsis activation. An opposite trend was suggestive of anterograde peristalsis. In these patients, at T0, both splenic flexure and ileocecal valve were detected with CRS and US showed normovalid whirlpools. In 2/7 patients, TAC showed a plateau in each ROI, suggesting a passive retrograde progression of 99mTc-DTPA-SS due to its pushing within the pump system and a single peak at the end of the dynamic exam corresponded to an anterograde peristalsis, coinciding with the evacuative stimulus. In this group, at T0, only splenic flexure was detected with CRS, while ileocecal valve was displayed later; US showed hypovalid whirlpools. Qualitative evaluation of post-evacuation images showed complete intestinal emptying in the first group, incomplete in the second one. Conclusions: Our preliminary results suggest that CRS is an imaging method able to evaluate progression of 99mTC-DTPA-SS along the entire colon during TAI. CRS could examine the peristalsis activation in SCI patients and could predict the treatment response. Background-Aim: The ethiology of chronic diarrhea in adults is often difficult to ascertain, so that patients (pts) may carry out many tests before reaching the correct diagnosis. Malabsorption of bile acids is one of the causes of chronic diarrhea and is due to the reduced ability to reabsorb bile acids, essential elements for fats and sterols digestion in the intestine, in the distal ileum. Normally, more than 90% acids are reabsorbed. Accurate diagnosis with effective treatment can lead to improvement in patients' quality of life. Bile acid sequestrants, therapy of choise for bile acid malabsorption (BAM), may be poorly tolerated by pts with a possible 25% failure to respond to treatment due to reduced compliance to treatment. 75-Seleniumhomocholic acid taurine (SeHCAT) is a licensed radiopharmaceutical for use in BAM investigation Tauroselcolic acid is an analogue of bile acid which exhibits a physiological behavior identical to the natural one of conjugated bile acids. Methods: In the last 6 months we began to study by SeHCAT pts affected with chronic diarrhea. One capsule containing 370 KBq SeHCAT was orally administred. The patient should have fasted from midnight and should refrain from eating until after the first measurement. To ensures mooth passage of the capsule into the stomach, it is recommended that 15 ml drinks of water are taken by the patient before, during and after swallowing the capsule. An uncollimated camera acquired counts at 3 h after taking the capsule. Further acquisitions toke place at 7 days. A background acquisition is performed each time too. Geometrical mean of anterior e posterior abdominal counts are corrected for background counts and for decay, and the percentage retetion rate at Day 7 was calculated according to a mathematical formula. Results: We have studied 9 pts with inexplicable chronic diarrhea (3 male, 6 female), age ranging from 25 to 60 years. The absorption rate of SeHCAT and therefore of the bile acids has been classified in mild, moderate and severe. A 15% cut-off for nomality has been estabilished. The pathological absorption of SeHCAT were considered as mild \ 15%, moderate \ 10%, severe \ 5% 4 pts had retention rate \ 5% with severe biliary acid absorption impairement. Conclusions: SeHCAT could warrant the current empirical treatment approach with cholestyramine. A significant percentage of patients with BAM reported poor tolerance or side effects for cholestyramine. Aderence to this drug without valid diagnostic confidence could be uneffective. Instead a positive SeHCAT test found in 45% of our pts could improve compliance with cholestyramine and allow dose adjustment. SeHCAT is well tolerated and non-invasive and has a clear inverse relationship between its retention at 7 days and the response to bile acid sequestrants giving a prognosic value too. Background-Aim: Peritoneal dialysis (PD) is a treatment alternative in patients with advanced chronic kidney disease, although it is not exempt of complications. The infusion of liquid into the peritoneal cavity leads to an increase in intra-abdominal pressure, which can sometimes produce leaks to the chest, giving rise to pleuroperitoneal communication. However, this is not a common complication, but it brings about high drop-out rates among patients using the technique. Hydrothorax is a PD-associated complication that is mainly secondary to pleuroperitoneal communication. Pleuroperitoneal communication occurred in approximately 1.6%-10% of patients on PD; it was more frequent in women than men and was located more on the right side than on the left. Diagnosis must be suspected in patients with sudden dyspnoea with low ultrafiltration and pleural effusion in the chest X-ray. Peritoneal rest and a temporary transfer to haemodialysis, and pleurodesis can be effective treatment strategies. Our objective is to evaluate the safety and efficacy of diagnosis of pleuroperitoneal communication in patients on peritoneal dialysis by scintigraphy with technetium-99m-labeled macroaggregated albumin. Methods: In the last year, three of our patients presented the sudden appearance of a right ipsilateral pleural effusion. In the suspicion of peritoneo-pleural communication, the patients underwent a scintigraphic study the following day. The examination was performed by introducing 2000 ml of dialysis solution marked with about 185 MBq of Technetium-99m-labeled macroaggregated albumin (99mTc-MAA) into the abdomen, evaluating in the following hours, up to 24, if the onset of dose activity in the pleural cavity could be recorded. Results: In all patients, the tracer is homogeneously distributed at the level of the peritoneal cavity. The sequential images obtained on the thorax and abdomen in the anterior and posterior projections at 10', 30' and 60' do not document the presence of activity at the level of the pleural cavity in two patients. The image acquired at 3 h confirms the lack of activity in the chest, excluding pleuroperitoneal communication. On the other hand, a progressive uptake in the right lung field was visualized in one patient from the first images, allowing the diagnosis of pleuroperitoneal fistula. Conclusions: In our experience, the scintigraphic study, through the introduction of a ''labeled'' dialysis solution into the abdomen, made it possible to confirm the clinical doubt of hydrothorax in patients on peritoneal dialysis within 24 h, thus allowing a certain diagnosis with subsequent motivated passage of the patients undergoing hemodialysis treatment. If the patient does not exhibit pleuroperironeal communication, he can continue to perform peritoneal dialysis, which is more easily performed and appreciated than hemodialysis. Although not very common and ''dated'', this scintigraphic examination is easy, non-invasive, inexpensive and is of its importance in the management of patients on dialysis with hydrothorax. Angio-CT scan identified an AVF in 12 cases (75%), and a PA in the remaining 4 (25%). Most of the patients were treated with a single embolization procedure. Renal scintigram was performed at a median follow-up of 31.5 months (16-57) following surgery. All patients showed at least an area of a slight or absent 99mTc-DMSA uptake. In 13/16 (81%) patients, the area of a slight or absent 99mTc-DMSA uptake corresponded with the initial tumor location. At quantitative analysis, the residual renal function at scintigram suggested that the operated kidney had numerically lower relative renal function (45% and 37% in the right and left operated kidney vs. 63% and 55% in right and left non-operated, respectively; p = 0.035 both). In detail, the renal segments who harbored the renal tumor showed a residual function ranged from 24 to 36%. Conclusions: Acute postoperative bleeding following PN is a rare but life-threatening complications. Notably, we found that, after PN and selective embolization of the bleeders, the residual renal units (and even the renal segments initially harboring the renal mass) had good renal function at 99mTc-DMSA renal scintigram. Background-Aim: We showed in a preliminary study the utility of the novel semiquantitative parameter, perfusion-to-blood pool ratio (P/BP ratio), in the prediction of septic loosening. The P/BP ratio was obtained by dividing the count ratios in the perfusion (Pr) and bloodpool (BPS) phase images of three-phase bone scan (3PBS) between the prosthetic knee and the ''healthy'' knee. The goal of this study was to predict through the extraction of 3PBS-derived parameters the results of 99mTc-hexamethylpropyleneamine oxime (HMPAO)-labeled autologous leukocytes scintigraphy, a more complex and expensive, as well as less available examination, in patients with unilateral knee arthroplasty. Methods: Patients with unilateral knee arthroplasty and available 3PBS and 99m Tc-HMPAO-labeled autologous leukocytes scintigraphic images were searched in two hospitals (A and B). In center A, the perfusion phase was not considered. Regions of interest (ROI) were delineated in the perfusion (P) and blood-pool (BP) phase images, incorporating the prosthetic region and applying an isocontour (40% of the maximum pixel activity); corresponding mirror ROIs were placed on the ''healthy'' knee. The P/BP ratio was calculated as {[(Pr/BPr) 9 100] -100}. Receiver operator curves (ROCs) were generated for each semiquantitative parameter to identify the optimal cutoff for predicting the results of the autologous leukocytes scintigraphy. Results: In the whole group (104 patients), BPr demonstrated an area under the curve (AUC) of 0.72 (optimal cutoff = 1.43). In center A (52 patients), BPr demonstrated an AUC of 0.737 (cutoff = 1.43), whereas, in center B (27 patients), AUC for BPr was 0.708 (cutoff = 1.55). A better diagnostic performance was obtained selecting Pr (AUC = 0.908; cutoff = 2.24) and P/BP ratio (AUC = 0.927; cutoff = 25%) for the differential diagnosis between septic and aseptic loosening. Conclusions: The novel P/BP ratio confirms its ability to predict septic loosening in this larger patient sample. It is conceivable that high arthropathy in the ''healthy knee'' may influence the accuracy of this parameter. These findings warrant confirmation in a multicentre study. Background-Aim: 18 F-FDG PET/CT is a useful tool to aid in the diagnosis and therapy of large vessel vasculitis (LVV). The visual assessment method is more commonly used than semi-quantitative assessment scores, although it is described that the performance of the former is generally lower than that of the latter. The purpose of our study is to review and reanalyze our LVV cases to verify the correlation between FDG uptake, assessed by visual and semi-quantitative methods, in comparison with inflammatory markers and Angio-CT findings. Methods: The 18 F-FDG-PET/CT of LVV affected patients (GCA, TAKA, Aortitis/periaortitis) searched in the internal database of patients with vasculitis were evaluated. PET/CT scans, inflammatory markers, and Angio-CT were performed in an interval of 7 days for blood tests or 30 days for Angio-CT, either out of therapy or without a change in therapy in the meantime. Ten control subjects underwent PET for oncological pathology, but found normal, were selected. Meller's visual score and hepatic SUV max /SUV ratio were calculated. A Pearson correlation analysis between SUV max , hepatic SUV max / SUV ratio and CRP (mg/dL) was performed and two different CRP cut-offs for disease activity were compared. Finally, visual class 3 ratio and hepatic SUV max /SUV [ 1.2 were selected and compared with Angio-CT to find agreement with vessel wall thickness, contrast enhancement and extension. Results: Eighteen PET/CT scans of 11 patients (7 F and 4 M; mean age 54.27 years) were available for analysis, all with inflammatory markers and with at least one Angio-CT scan to compare. LVV SUV max was statistically superior to controls (student t = 2.97, p = 0.006). The linear correlation between SUV max and CRP was highly significant (Pearson: r = 0.7621, p = 0.000237) but the correlation for the SUX max /hepatic SUV ratio was also significant (Pearson: r = 0.6578, p = 0.003005). By applying a cut-off for SUV max /hepatic SUV only when [ 1.2, statistically significant agreement with CRP is found. When PET/CT was compared with angio-CT scans, PET/CT was considered positive for visual score 3 or SUV max /hepatic SUV [ 1.2, which correlated with increased contrast but not with thickening of the vessel wall. Conclusions: Although further studies are foreseen to confirm our data, semiquantitative classification methods related to disease activity should be applied to offer a reliable and repeatable tool to assist clinicians in the management of LVV, especially for the efficacy of therapies. Methods: A series of 22 consecutive patients with suspected IE were evaluated with a (99m)Tc-HMPAO-WBC SPECT scintigraphy from January 2020 until December 2021. Patients with pacemakers were included in the analysis. All patients had inconclusive CT findings, and underwent a series of exams: radiography, trans esophageal echocardiography, blood cultures. The administered activity was 370 MBq. Round ROIs of 32 pixels were drown on the heart and liver on both planar and SPECT images acquired 3 h after radiopharmaceutical injection and the heart to liver ratios of the total counts were assessed. All data were analyzed using descriptive statistics. Receiver Operating Characteristics (ROC) curve analysis (AUC) was used for statistical evaluation in order to define the cut-off maximizing specificity and sensitivity of both planar and tomographic heart to liver ratios (pH/L and tH/L). Results: Mean age was 70 ± 19.5. Radiographic imaging showed an increased heart volume in 13 patients, 7 had positive blood cultures. CT imaging showed alterations in 10 patients, 6 had intraventricular liquid and 4 had increased heart volume. (99m) TC-HMPAO Scintigraphy was true positive in 10 of the 22 patients. pH/L were above 1 in 5 patients, 4 of whom were (99m) TC-HMPAO scintigraphy scan positive for IE and 1 was negative. tH/L were above 1 in 13 patients, 9 of whom were (99m) TC-HMPAO scintigraphy scan positive for IE and 4 were negative. The odds ratio (OR) obtained from planar imaging analysis was 14.67 (1.42-454.86), p = 0.017. A cut-off of 1.33 pH/L showed a sensitivity of 70% and a specificity of 81.8% in diagnosing IE with AUC of 79.09%. As concerning SPECT acquisitions, the OR was 7.39 (1.56-77.71), (p = 0.008). The optimal cut-off of 0.75 tH/L demonstrated a sensitivity of 81.8% and a specificity of 90.9% in diagnosing IE with AUC 79.75%. Conclusions: This study revealed a significant association between positive scans and IE in patients with doubtful IE diagnosis. In particular (99m)TC-HMPAO-WBC radiolabeled leucocyte tomographic scans yields significantly higher sensitivity and specificity in predicting IE, as well as reduction of possible IE misdiagnosis. Early segmental PET/CT after whole-body PET/CT in short-term monitoring of inflammation, suspected neoplasm and response to therapy. A preliminary study Background-Aim: In the definition of a diagnostic algorithm, the cost/effective ratio affects appropriateness and justification. Although the clinical role of FDG positron emission tomography (PET)/computed tomography (CT) has been well established, the considerable amount of exposure radiation limits its wider use. International PET/ CT procedure guidelines consider limited-area imaging scan, but this modality is generally not performed. On the other hand, studies limited on a specific region of interest, as for CT and magnetic resonance (MR) imaging, and for cardiac and cerebral PET/CT, could decrease PET/CT effective doses (ED) and associated cancer risk. To evaluate the usefulness of an early segmental-PET/CT, after wholebody (wb) PET/CT, in short-term monitoring of inflammation or suspected neoplasm and in the evaluation of the response to therapy. Methods: This preliminary study involved five patients who underwent, segmental-PET/CT within 3 months of the wb-PET/CT, to obtain a diagnostic definition not achieved by previous diagnostic techniques. Imaging was done by a Siemens Biograph mCT, PET/CT system using a standard protocol with integrated 3-D mode PET/CT systems, scanning from the base or top of the skull to the mid-thigh (wb-PET/CT), starting 60 min after tracer administration. The acquisition mode was a continuous-motion PET/CT by flow modality. The sliding speed of the bed was 0.7 mm/sec. The dose of FDG administered was 3.5 MBq/kg. Segmental-PET/CT was defined as the bed covering the region of interest, highlighted in the previous wb-PET/CT as area of abnormal tracer uptake. For segmental-PET/CT, the dose of FDG administered was 0.8 MBq/kg, with a scan-time of a single bed of 10 min. The ED (mSv) for both wb-PET/CT and segmental-PET/CT was calculated. Results: Segmental-PET/CT within 3 months of the wb-PET/CT, allowed diagnostic definition in all five patients. In one patient, CT, MR, wb-PET/CT, and biopsy did not allow a differential diagnosis between inflammation and neoplasia of a space-occupying lesion of the hepatic hilum well clarified by the segmental-PET/CT that showed the complete regression of the pathological tracer uptake. Similarly, in two patients with solitary pulmonary nodule, associated with a moderate increase of FDG uptake, segmental-PET/CT showed the regression of hypermetabolism. In one patient with history of operated colon cancer, a single liver metastasis was treated with chemotherapy and thermal ablation. Segmental-PET/CT at 3 months highlighted the regression of the treated lesion, with the appearance, however, of a new liver lesion. Finally, in a patient with abdominal aortic graft infection, treated with antibiotic therapy, control segmental-PET/CT showed a lack of response to therapy. The mean ED of segmental-PET/CT was about 1/5 of that of wb-PET/CT. Conclusions: An early segmental-PET/CT after wb-PET/CT, in short-term monitoring of different clinical subsets, may contribute to diagnostic definition. This strategy, consistent with the increasing demands for individually targeted protocols, dramatically reduces radiation exposure of PET/CT, improving its cost/effective ratio and thus promoting its wider use. Results: The mean time between cardiac surgery and symptoms onset was 32 months (range 10 months to 7.7 years). Echocardiography (TTE ? TOE) detected endocarditis (IE) signs in 3/9 patients (sensibility 33%, 6/9 pts having mechanical aortic valve); blood culture was positive in 5/9 patients (sens. 56%). At diagnosis 7/9 PET/CT scans were positive for IE and/or aortic root prosthesis infection (sens. 78%). All diagnostic PET/CT scans were suggestive for systemic infection with hypermetabolism in one or more extracardiac sites (e.g.: lymph nodes, lung, muscle, liver spleen, kidney, CNS, axial skeleton). Conclusions: 18F-FDG PET/CT proved to be a useful tool in diagnosis of disseminated M. chimaera infection in order to assess the extent and to identify potential sites of biopsy when routine microbiological work-up does not isolate M. chimaera. Seriated scans define the activity of disease over time and may contribute to clinical work-up as prolongation or modulation of antimicrobial therapy, prognosis formulation and referral to revision surgery. Background-Aim: PET Vascular Activity Score (PETVAS), by adding together PET qualitative visual scores in nine selected arterial regions, is a new composite score with the purpose of quantifying overall vascular inflammatory burden in LVV that showed to be effective in discriminating patients with clinically active disease from inactive ones. Aim of our work was to assess the role of PET/CT and PETVAS in differentiating LVV clinically active from inactive ones in a cohort of patients. Methods: Between June 2007 and September 2020 one-hundred patients with LVV were enrolled by our Rheumatology Unit and underwent full clinical, laboratory and imaging evaluation at baseline, annually and when a relapse was suspected. Medical records of patients were retrospectively reviewed from baseline visit until 30 September 2020, last follow-up or death. Interpretation of 18F-FDG PET/CT and PETVAS score were calculated for each scan and their performance in discriminating between LVV active patients from inactive ones were compared to clinical judgement (reference standard) based on comprehensive signs/symptoms assessment, laboratory and imaging data (excluding PET/CT). Results: 100 LVV patients [51 giant cell arteritis (GCA), 49 Takayasu arteritis (TAK)] underwent a total of 474 PET scans. PET/ CT discriminated patients in clinically active LVV (n121) from inactive ones (n352) with a sensitivity of 60% and a specificity of 80%. The following sensitivity and specificity values were found in LVV subgroups: 73% and 77% for TAK, 51% and 82% for GCA, respectively. Patients with higher PETVAS scores were more frequently classified as having active disease: age and sex adjusted OR 1.15 (95% CI, 1.11 to 1.19), p \ 0.0001. Similar results were found in LVV subgroups. The area under receiver operating characteristics (ROC) curve (AUC) of PETVAS in differentiating between clinically active LVV from inactive ones was 0.73. Similar results were found in LVV subgroups. A PETVAS C 10 provided 61% sensitivity and 80% specificity in differentiating between clinically active LVV from inactive ones (52% sensitivity and 82% specificity in GCA subgroup, 73% sensitivity and 78% specificity in TAK subgroup). Retrospective nature of the study, patients enrolled at different times during disease, glucocorticoids adiministration, differences in disease duration and application of NIH criteria might have interfered with PET/CT sensitivity. Conclusions: PET/CT is a well-established tool for evaluation of disease extent and disease activity in LVV, for monitoring therapy efficacy and for excluding other causes of systemic symptoms. PETVAS is an interesting complementary tool for the assessment of vascular inflammatory load that still needs further studies to confirm its potential role. Methods: A total of 317 patients (200 men; mean age 61 years) with FUO who underwent 18F-FDG PET/CT at 8 hospitals were retrospectively recruited from 2014 to 2021. Local expert physicians revised PET: it was considered true positive in case of abnormal FDG uptake that contributed to diagnosing the cause of FUO; true negative in case of a normal FDG uptake without a definitive diagnosis after investigation or follow-up; false positive in case of abnormal FDG uptake that didn't help to make the diagnosis; false negative in case of normal FDG uptake with a subsequent cause of FUO detected by other ways. The final diagnosis for each patient was established based on the laboratory, imaging and histopathologic examinations, and clinical follow-up for at least 6 months. It was classified into four categories: infectious diseases, inflammatory diseases, malignancies/ pre-malignancies causes and unknown cause. The Mann-Whitney U test and chi-square test were used to compare continuous and categorical variables. Background-Aim: Cardiac implantable electronic devices infection (CIEDI) is a frequent sequela in clinical experience and generally requires surgical CIED removal. Early diagnosis is of primary importance in order to promptly define the most accurate and specific therapeutic plan for each patient. Whole-body 18F-FDG-PET/CT plays an important role in the management of patients with suspected CIEDI, allowing to detect even eventual septic dissemination. Several semi-quantitative parameters have been proposed in disease assessment, but a unique value has not been defined yet. This study aims to assess the 18F-FDG-PET/CT reliability in the early diagnosis of CIEDI by considering the consistency of different semi-quantitative parameters. Methods: We retrospectively evaluated 35 patients with clinical suspicion of CIEDI who referred to our Nuclear Medicine Unit to perform 18F-FDG-PET/CT. Microbiological results after CIED removal and/or clinical follow-up, considered as reference gold-standard, identified two groups (CIEDI ? /CIEDI-). Both qualitative and quantitative analysis were performed on PET images. The following semi-quantitative PET/CT parameters were collected: SUV max , semi-quantitative ratio (SQR) and target-to-background ratio (TBR). 18F-FDG-PET/CT sensibility, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy (DA) were calculated. T-student's test was performed to establish if a statistically significant difference existed between each semi-quantitative parameter into two groups. ROC curves were employed in order to estimate the best semi-quantitative parameters cut-off values able to predict CIEDI. Background-Aim: European Society of Cardiology (ESC) guidelines have recently been modified by the addition of 18F-FDG PET/CT as a major criterion in the diagnosis of infective endocarditis (IE). A systematic comparison between updated ESC criteria and traditional modified Duke's Criteria (mDC) has not been evaluated yet, to assess the additional value of 18F-FDG PET/CT, in particular in prosthetic valve endocarditis (PVE). Validated semi-quantitative parameters with standardized methodology have not been defined yet. In addition, diffuse splenic uptake has been investigated, but its relevance has to be ascertained. The aims of this study were the evaluation of 18F-FDG PET/CT additional role in patients with suspected PVE, the assessment of semi-quantitative parameters and the description of the diffuse splenic uptake finding. Methods: We retrospectively included 30 patients with clinical suspicion of PVE who referred to our Nuclear Medicine Unit in the last 3 years to perform 18F-FDG PET/CT. All patients were classified as possible PVE at admission, according to mDC. After 18F-FDG PET/ CT qualitative analysis, patients were reclassified as definite PVE or rejected PVE. The final diagnosis, considered as gold-standard, was based on the Endocarditis Team's evaluation, established 3 months after hospitalization. The following semi-quantitative PET parameters were collected: maximum standardized uptake value (SUV max ), semiquantitative ratio (SQR) and target-to-background ratio (TBR). Mean values of splenic uptake were also collected. Sensibility (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy (DA) of 18F-FDG PET/CT were calculated. t-student's test was performed to establish if a statistically significant difference between values, in patients confirmed for PVE and not, existed. Results: 18F-FDG PET/CT resulted positive in 20/30 (66.7%) patients and negative in 10/30 (33.3%). After Endocarditis Team's evaluation during follow-up, 18/30 (60%) patients were confirmed for PVE (all true positive at PET examination), while the remnants 12/30 (40%) were rejected for PVE (10/12 True Negative, 2/12 False Positive at PET examination). Se, Sp, PPV, NPV and DA of 18F-FDG PET/CT resulted 100%, 83.3%, 90%, 100% and 93.3% respectively. Differences of mean values of SUV max , SQR, TBR and splenic uptake between the two groups (confirmed PVE and rejected PVE) resulted statistically significant (p \ 0.05). Conclusions: Our preliminary results confirm the additional role of 18F-FDG PET/CT in patients with suspected PVE and evaluate the usefulness of semi-quantitative parameters, collected with a reproducible methodology, as well as the possible relevance of a diffuse splenic uptake. Further studies are mandatory in larger populations. Background-Aim: The cumulative incidence of infection of the left ventricular assist device (LVAD) is over 50% within the first 3 months after implantation. The infection of VAD represents a serious adverse event for the patient, requiring rehospitalization and determining an increased direct cost for the health system. Any component of VAD can be subject to infection, including the pocket site, surgical site, driveline, preperitoneal device pocket site, and the pump. Since the use of CT or MRI is of debatable value, due to the presence of metallic artifacts and MRI contraindication, there is an unmet need for a non-invasive imaging tool to allow the identification of site, severity, and extent of infection in patients with VAD. Leukocyte scan has proved useful in the identification of infections in patients with cardiovascular implantable devices, although specific data on the assessment of infection in VAD is extremely limited. Methods: In this retrospective study, 19 patients with suspected infection of VAD (based at least on clinical signs or symptoms as fever, positive blood culture, or elevated infectious markers) underwent a total of 11 99m Tc-exametazime-leukocyte planar and SPECT scans at 4 h and 24 h post-injection of autologous labeled leukocytes to evaluate suspected device-related infections (n = 17) or to assess the efficiency of current antibiotic therapy (n = 2). The scans were visually assessed and considered positive in case of detection of regions of increased radiotracer uptake compared with adjacent background over time. Foci of non-physiologic abnormal uptake that did not increase or decreased in intensity at 24 h post-injection were considered inflammatory. Microbiological analysis, clinical and follow-up (minimum 6 months) imaging were used as the reference standard. Results: In this restricted cohort, the leukocyte scan resulted positive in 14 cases, providing the extent, severity, and site of the infection in all patients. In 4 cases leukocyte scan correctly ruled out any VADrelated infection. The sensitivity of 99m Tc-exametazime-leukocyte scan was 94.74% and the specificity was 100%. These findings contributed to changing the clinical management in 7/19 cases. Conclusions: In our single-center experience, the leukocyte scan showed satisfactory accuracy in the detection of VAD-related infections and influenced patient management. Background-Aim: Anxiety is a state of agitation of strong apprehension due to fear, uncertainty, waiting for something. In the taxonomy NANDA is defined as a vague sense of unease or fear accompanied by autonomous responses whose source is often unspecified or unknown to the person. It is a sense of apprehension caused by the forecast of danger. It has been observed that women who have to undergo pre-operative breast cancer lymphoscintigraphy, manifest a heightened state of anxiety related to poor information. A comparative descriptive study to evaluate the effectiveness of nursing interventions aimed at reducing anxiety began in June 2020 and ended in March 2021. Methods: 100 women (aged 30-70 years) without cognitive impairment were divided into 2 study groups: 50 without information about the diagnostic examination and the other with an empathic communication approach, active listening and a calming technique. In all patients were performed:• Detection of vital signs (VS): blood pressure, heart rate, respiratory rate and PO2 value • Administration of the reduced Hamilton Scale (sweating, agitation, dry mouth, crying, change in tone of voice) with clinical evaluation for the severity of anxiety symptoms, with a score from 0 (not present) to 4 (severe). Total score ranges 0-24, where \ 8 indicates mild, 9-16 mild to moderate, and 17-24 from moderate to severe. The first group had no informative approach but only detection of the VS of the Hamilton scale before and after the procedure. The second group detected the VSs and administered the reduced Hamilton scale with the nursing intervention of empathic communication, active listening and calming technique. Results: The data collected show that 90% of patients have an increase in HR in the pre-treatment phase, with a 70% reduction in the post-treatment phase in both groups. In the first group, the Hamilton scale found that 33% experienced mild to moderate anxiety before the procedure, with 52% persisting after the scintigraphic examination. In the second group, the Hamilton scale finds that 20% experience mild to moderate anxiety before the procedure, with a reduction to 8% after the diagnostic procedure. Conclusions: An empathic approach through effective communication, active listening, with calming and distraction techniques allow a reduction of anxiety objectively confirmed by the detection of VS and data obtained with the Hamilton scale. This allows for greater compliance of patients, with better acceptance of the exam and the ability to maintain immobility during acquisition. Background-Aim: Lung cancer is a leading cause of death among men and women, non-small cell lung cancer (NSCLS) being the major responsible. Clinical assessment as well disease staging are crucial for treatment decisions and imaging plays a key role leading into invasive biopsy as confirmation of the histopathological diagnosis. Multi-disciplinary approach helps facilitating patient's workout for treatment settings. CT and PET aid in non-invasive tumour size (T), lymph nodal (N) and metastatic (M) assessment in cancer patient, still considering their relative sensitivity and specificity but nonetheless important in avoiding futile surgery whenever PET studies are performed and in leading up to biopsies. Surgery main limitation is microscopic involvement of resection tumour margins (R1) with significantly poor prognosis compared to negative microscopic margins (R0) and local recurrences up to half of cases. Different medical devices can aid in tumour detection and margin removal. Intraoperative radiation detectors were first introduced in 1949 and have been improved ever since. Methods: The GonioProbe is a prototype of probe for radio-guided surgery made up by two integrated systems: the Navigator system and the lock-on-target system. Four independent scintillation crystals replace the collimation system of traditional gamma cameras and provide the Navigation function while a central crystal confirms the source location and directs the operator to the target (lock-on). Probe characteristics were tested on three BALB/c mice after implantation of human lung cancer cell lines in the form of solid tumour and injection of 18F-FDG intraperitoneally followed by microPET scan. Spatial resolution, instrument response time, effectiveness, time to identify the tumour lesion and accuracy in localization were taken into account. Detection system analysis was done with the implementation of new algorithms for the goniometric characteristics of the probe. Results: Mice testing showed very high statistical counts for GonioProbe, with expected error less than 1 mm, proving to be far superior to other available devices. The navigation system can increase counts considerably per crystal when near the radioactive source leading to an error measurement of less than 1°when the central crystal is engaged. Tumour localization time was kept to a minimum thanks to the aforementioned system, being able to guide the operator hand to the source in the direction of the crystal with the higher count-rate. Conclusions: As per old devices where high efficiency was at the expense of high resolution and vice-versa due to the need for a passive collimation system, GonioProbe overcomes this issue by making the collimators sensitive to radiation, thus lowering the amount of radioactivity injected as well as exposure time to patients and personnel. Tumour margins resection is also improved thanks to hight lesion to background contrast allowing to removed tissue residues by the operating surgeon. Background-Aim: The aim of our study is to assess the feasibility and the usefulness of integrating PET-CT images to reconstruct 3D anatomical models for preoperative planning in gynecologic oncology surgery complex cases. Methods: Image segmentation was made with a dedicated software (Mimics Medical, Materialise, Leuven, Belgium) and it was fused with other anatomic structures adjacent to the lesion, that were segmented from previously acquired contrast enhanced-CT (ce-CT) scan. Finally, we reviewed the reconstructed 3D anatomical model with the surgeons before and after the surgery discussing the results. Results: The integration of PET images with ce-CT data for 3D anatomical model reconstruction provided detailed 3D images useful for tumor localization. Up to now, we segmented a metabolically active lesion from a 18F-FDG PET/CT scan of a patient referred to our Center with the diagnosis of uterine sarcoma relapsed after the primary treatment and elected for secondary surgery. This allowed the surgeons to predict some procedural issues during the pre-operative analysis of the images and to carefully plan complex surgical maneuvers. The reconstructed 3D digital models proved to be beneficial also during surgery. The usefulness of digital 3D models was then confirmed in a post-surgery meeting when we compared video fragments of the operation with the 3D rendered images. Conclusions: Integration of PET images in a 3D digital model was feasible. By our experience, surgeons obtained valuable information from our images in terms of surgery planning and reported a good correspondence between the reconstructed 3D digital model and the intraoperative anatomy. Therefore, we promote this technique for future development and routine use in selected cases. Background-Aim: Axillary reverse mapping (ARM) is the identification and preservation of arm draining lymph node during an axillary dissection rather than its removal. The aim of the study was to ascertain whether axillary reverse mapping and selective axillary dissection (ARM-SAD) is effective in reducing the risk of Breastcancer-related lymphedema (BCRL). Methods: Patients in the control arm were assigned to ALND, and those in the study arm to ARM-SAD. Six to 24 h before surgery, patients received 3 intradermal injections of 99mTc-Nanocolloid to the back of the hand ipsilateral to the breast involved, and lymphoscintigraphy was performed to identify perivascular axillary lymph nodes draining the upper limb that were (ARM-SAD arm) or were not (ALND arm) to be preserved during axillary dissection. Twelve months after surgery, patients underwent a physiatric assessment for BCRL, the excess volume in the operated limb was calculated, and the drainage impairment was assessed using lymphoscintigraphy. Results: 130 patients were enrolled (52 had nodal involvement ascertained by fine needle biopsy; 38 had a previous positive sentinel lymph node biopsy; 40 had confirmed nodal involvement and received neoadjuvant chemotherapy) and randomly assigned to have surgical treatment: 65 underwent ALND while 65 had ARM-SAD. In four of the latter patients, nodes were not identified on ARM or not preserved, indicating an overall 94% feasibility of SAD. Twelve months after surgery, 123 patients underwent at least one follow-up procedure to examine any BCRL. Comparing the physiatric findings, excess volume, and lymphoscintigraphic results between the two treatment approaches indicated a significantly lower rate of BCRL in the SAD arm than in the ALND arm (p 0.0105, 0.0006, and \ 0.0001, respectively). Cases of BCRL were also more severe in the AD arm. Conclusions: ARM-SAD can significantly reduce the likelihood of BCRL after axillary surgery. Effectiveness of sentinel-node biopsy in detecting nodal metastatic involvement in non-small cell lung carcinoma: a prospective study Background-Aim: Localized non-small cell lung cancer (NSCLC) can be treated with curative intent through surgical excision. Intraoperative identification of nodal disease can be challenging, leading to incomplete excisions with a higher rate of relapse. The intraoperative identification of tumour-draining lymph nodes (SLN) via radiopharmaceuticals has been used in several tumour types successfully, most commonly in breast cancer and melanoma. In this study, we tested the effectiveness of the SLN approach in the nodal disease identification in NSCLC. Methods: Selected patients referring to our centre for surgery in early-stage NSCLC were prospectively recruited between May and December 2021. During surgery, immediately after the identification of the tumour site, a peri-tumoral injection of 99m Tc-nanocolloids (Nanotop) was performed. Starting from 10 min after the injection, the surgical removal of the primary tumour and the locoregional lymph nodes was performed according to best clinical practice. All the excised lymph nodes were examined with a gamma probe ex vivo and considered as SLN if they showed any activity; the remaining ones were considered non-SLN. Thereafter, the surgical field was scanned with the gamma probe, and any further radioactive lymph node was removed; these were labelled as ''extra'' SLN (eSLN). All non-SLN, SLN and eSLN were sent to histology and the presence or absence of metastases was recorded. Results: Thirty patients were enrolled. A median activity of 32 MBq (range 26-37) was injected. During surgery, a total of 169 lymph nodes were dissected; these included 95 SLN, 19 eSLN, and 55 non-SLN. A total of twenty lymph node metastases were identified in twelve patients (40%); all but one of the nodal localizations (19/20, 95%) were located within a SLN. On the other hand, no tumour metastases were found in eSLNs. There was no correlation between count intensity and presence of tumour cells within a SLN. Conclusions: The SLN technique is easy to perform and safe, showing a high positive predictive power for intraoperative nodal metastases identification: this information could be used to implement radio-guided surgical protocols in NSCLC. The extra sentinel lymph nodes removed after the standard excision procedures do not seem to bear relevance in a more precise definition of metastatic spread in early-stage NSCLC; however, a higher number of cases is needed to confirm these preliminary data. Background-Aim: In breast cancer melanoma, the prognostic significance of multiple drainage basins is still unclear. We aimed to detect the prognostic significance of lymphoscintigraphic detection of parasentinel lymph nodes in patients with breast cancer. Methods: In this retrospective study, patients with parasentinel lymph nodes, who were evaluated by a 99m Tc-nanocolloid lymphoscintigraphy according to the national guidelines, were searched in our internal hospital database. The patients underwent a dynamic scan, followed by planar and SPECT images. Follow-up imaging (range: 6-36 months) was used as standard of reference to calculate the proportion of patients developing recurrence within 3 years. A control group of consecutive patients with breast cancer without scintigraphic evidence of parasentinel lymph nodes was used for comparison purposes (follow-up range: 36-72 months). Results: A total of 17 patients with evidence of parasentinel lymph nodes were retrieved. 6 out of 17 (35.29%) developed breast cancer recurrence within 3 years. In the control group (n = 50 patients), a significantly lower number of patients experienced disease recurrence (p = 0.02), with only 5 cases (10%) of recurrences recorded within the first 3 years after surgery. Conclusions: According to our study, despite this small and heterogeneous patient sample, detection of parasentinel lymph nodes may be correlated to a trend towards a higher risk of disease recurrence in patients with breast cancer within 3 years from initial surgery. Larger study samples are warranted. 99MTC-Sulfur colloid reticuloendothelial system scintigraphy confirming ectopic thoracic splenosis. A case report Background-Aim: Thoracic splenosis (TS) is a rare benign condition defined as autoimplantation of ectopic splenic tissue in the thoracic cavity that occurs following splenic injury. TS is less common than abdominal splenosis and most cases of TS are asymptomatic and usually incidentally found. Multiple, asymptomatic, pleura-based lesions associated with a history of thoracoabdominal injury and splenectomy represent key points for suspecting TS. However, when typical TS features are missing, especially when a long interval between the initial trauma and lesions discovery occured, TS diagnosis could be particularly challenging leading to an extensive workup and unnecessary invasive diagnostic procedures including thoracotomy. The purpose of this case report is to highlight the role of 99mTc-sulfur colloid scintigraphy in supporting the identification of TS during the differential diagnosis work-up of left-sided, pleuralbased pulmonary nodules or masses. Methods: A 51 years old man underwent to a chest X-ray for precordialgia with subsequent occasional finding of a left pleural mass. A chest CT was subsequently performed for further characterization. The CT scan showed multiple left thoracic pleural nodules measuring up to 2.7 cm: one mass was found in the postero-medial epidiaphragmatic area in the left lung base and one in the posterior paravertebral area. Detailed medical history revealed previous myocardial infarction, surgery for bowel obstruction and a car accident (18 years earlier) with multiple injuries and splenic rupture. Due to the clinical suspicion of TS related to the previous thoracic-abdominal trauma, the patient underwent to a 99mTc-sulfur colloid scintigraphy taking advantage of the increased predilection of these particles for reticuloendothelial cells, in order to avoid more invasive investigations (i.e. needle biopsy). Results: Left thoracic masses showed an intense tracer uptake at 99mTc-sulfur colloid scintigraphy related to presence of ectopic splenic tissue. This study was sufficient to confirm the clinical suspicion of TS avoiding further examination. Given the asymptomatic state, conservative treatment and follow-up was performed in this patient. Conclusions: A correct identification of TS on imaging is of pivotal importance in order to avoid unnecessary biopsy or surgical exploration. In this context, CT scan offers an exact anatomic localization but cannot distinguish ectopic splenic tissue from other differentials such as neoplastic lesions. In the presence of clinical diagnostic clues for the presence of TS, 99mTc-sulfur colloid scintigraphy represents a valid tool in order to easily and non-invasively confirm the presence of this condition. Background-Aim: A potential link has been investigated between hyposmia after COVID-19 and an increased risk to develop neurological long-term sequelae also in patients who experienced mild or moderate disease. Hyposmia is a common feature PD and parkinsonism has been reported after COVID-19 suggesting a potential link between SARS-CoV2 infection and PD. [18F]FDG PET may represent a suitable tool to capture potential common metabolic signature of hyposmia after COVID-19 and in PD patients. We aimed to evaluate brain metabolic correlates of isolated persistent hyposmia after mild-to-moderate COVID-19 and to compare them with metabolic signature of hyposmia in drug-naive PD patients. Methods: Forty-four patients who experienced hyposmia after SARS-COV2 infection underwent brain [18F]FDG-PET in the first 6 months after recovery. Olfaction was assessed by means of the 16-item ''Sniffin-Sticks'' test and patients were classified as with or without persistent hyposmia (COVID-hyposmia and COVID-no-hyposmia respectively). Brain [18F]FDG-PET of post-COVID subgroups were compared in SPM12. COVID-hyposmia patients were also compared with eighty-two drug-naïve PD patients with hyposmia. Multiple-regression-analysis was used to identify correlations between olfactory test-scores and brain metabolism in patients' subgroups. Results: COVID-hyposmia patients (n = 21) exhibited significant hypometabolism in bilateral gyrus rectus and orbitofrontal cortex with respect to COVID-non-hyposmia (n = 23) (p \ 0.002) and in middle and superior temporal gyri, medial/middle frontal gyri and right insula with respect to PD-hyposmia (p \ 0.012). With respect to COVIDhyposmia, PD-hyposmia patients showed hypometabolism in inferior/ middle occipital gyri and cuneus bilaterally. Olfactory test-scores were directly correlated with metabolism in bilateral rectus and medial frontal gyri and in right middle temporal and anterior-cingulate gyri in COVID-hyposmia patients (p \ 0.006) and with bilateral cuneus/precuneus and left lateral occipital-cortex in PD-hyposmia patients (p \ 0.004). Conclusions: Metabolic signature of persistent hyposmia after COVID-19 encompasses cortical regions involved in olfactory perception and does not overlap metabolic correlates of hyposmia in PD. An impairment in olfactory judgement seem to underlie hyposmia in PD patients while a more restricted perception deficit seems to explain hyposmia in COVID-19. The potential long term neurological sequelae of COVID-19 are of interest from the clinical and economical point of view. Studies targeting symptoms common to COVID-19 and chronic neurological diseases and aiming to explore potential common pathways are of interest also to avoid unjustified claims about a future high incidence of neurodegenerative diseases secondary to the SARS-CoV-2 pandemic. Management of unilateral axillary lymphadenopathy detected on 18F-FDG PET/CT after COVID-19 vaccination benign reactive node biopsies. The differential diagnosis for unilateral axillary lymphadenopathy is broad and includes benign and malignant etiologies: among the malignant causes, most cases are due to lymphoma or breast cancer. Methods: Shortly after the initiation of vaccination of frail cancer patients, a significant number of cases of unilateral axillary lymphadenopathy were incidentally detected in asymptomatic cancer patients who underwent 18 F-FDG PET/CT for disease diagnosis or follow-up. Results: After deltoid vaccination, significant uptake of 18 F-FDG can be observed in the axillary (level 1, 2 and 3), supraclavicular and cervical lymph nodes. The extent of FDG absorption varies with temporal proximity to vaccination, from intense immediately after administration to barely noticeable after a longer period of time (SUV max range: 2.1-16.2). Also, after vaccination, lymph nodes may show variable morphology on CT, although they are usually normal or show only a slightly thickened cortex with retained fat hilum. In our department, we have added questions regarding the date and laterality of COVID-19 vaccine administration to our intake form prior to all PET/CT exams, to avoid misjudgment in cancer patients. Conclusions: We believe that isolated unilateral axillary lymphadenopathy detected on PET and associated with the ipsilateral vaccine arm is related to the COVID-19 vaccine, if within a few weeks of either dose. As data from clinical trials of the COVID-19 vaccine suggest that the first two FDA-approved vaccines are highly immunogenic, there is a higher percentage of patients who notice both local and systemic reactions than other vaccines. Careful management should avoid unnecessary biopsies of vaccine-related benign reactive lymphadenopathy. Vaccine ipsilateral axillary adenopathy of the arm should be considered as a potential reactive process that nuclear physicians should be familiar with. If a patient has known cancer with laterality, such as breast cancer, most melanomas, sarcoma of the extremities, lung cancer (particularly in the upper lobe), or head and neck cancer, the vaccine should be given in the arm. contralateral to avoid potentially confounding FDG uptake into lymph nodes on the cancer side. However, if active axillary lymph nodes are identified in the ipsilateral vaccinated arm, axillary ultrasound at 4 weeks is recommended. Background-Aim: The importance of timely assistance in oncological patients is undeniable; however it is well known that these patients could have important clinical problems if they were infected by COVID-19, with an increased risk of severe illness and mortality. A recent multicenter Italian study reported a delay both in the beginning of PRRT for new patients (about 45.5% of centers) and in those ones who had already started the treatment (15%), as a direct consequence of COVID-19. The aim of this study was to understand if SARS-CoV2 infection has modified our clinical management, with particular attention to PRRT. Methods: In our ENETS Center of Excellence, the weekly multidisciplinary tumor board never stopped, also during the pandemic period. During these periods, the patients were treated with PRRT in the same way of previous years, remaining one night in Radiometabolic Therapy Unit, according to local laws. During COVID-19 pandemic, the patients received the PCR test the day before the treatment, while the day of PRRT they received a particular triage for avoid admitting patients with Sars-CoV-2 infection. We made a comparison between the number of PRRT cycles (either in clinical practice or in clinical trials) performed at European Institute of Oncology (IEO) from February 2020 to July 2021, with those performed in the previous year (February 2019-January 2020). Results: From February 2019 to January 2020, we performed 10 PRRT cycles, instead in the following months, during and despite of COVID-19 pandemic, from February 2020 to July 2021, we increased the number of patients treated. In fact 126 PRRT cycles were performed without any delay (either in clinical practice or in clinical trials). Only one Italian patient was unable to receive the treatment at IEO because he couldn't travel during lockdown period, so he performed PRRT near home. On the contrary, another patient coming from a different Nation, received PRRT on time. During this period, only two patients were affected by COVID-19 at the end of the treatment even if they were not yet vaccinated and, fortunately, the disease was mild, without consequences. These patients didn't stopped the therapy with SSA during COVID-19 disease. Moreover we performed a dosimetric study in almost all the patients during the first cycle of PRRT. Conclusions: These results focusing on PRRT treatments and COVID-19 pandemic, show that centers with more experience are able to adapt to the new global situation and to the new rules imposed by governments, providing continuity in care without any delay and even to increase the number of treatments. Background-Aim: While a frontal dysfunction is reported in post-SARS-CoV-2 with neurological symptoms (neuro-SARS-CoV-2), it is unclear whether this brain vulnerability is long lasting or reversible. The present study evaluated brain dysfunctions-as measured by FDG-PET-in neuro-SARS-CoV-2 over time to provide a better understanding of physiopathology underlying central nervous system involvement. Methods: 26 patients with neuro-SARS-CoV-2 were included. Seven patients were in the acute, the others in the sub-acute and chronic phase, namely, four at 1-month, four at 2-months, four at 3-months, four at 5 months and four at 7-9-months after onset. Patients underwent FDG-PET exams, clinical and cognitive evaluations. One patient was evaluated longitudinally, during the acute phase, and at a 5-months follow-up. Brain metabolism was analysed at the singlesubject and group levels by a comparisons with healthy controls. Correlations between severity/extent of hypometabolism and clinical variables of interest (global cognitive cognition, blood oxygen level saturation, and inflammatory status -C-reactive protein measurements) were also assessed. Results: Patients with acute neuro-SARS-CoV-2 showed the most severe and diffuse cortical hypometabolism, affecting almost all cortical areas. 2-months after the acute infection, a significant decrease in hypometabolism extension emerged, affecting mainly the frontal and temporal cortex. At 5-months after the acute phase, a recovery of cortical hypometabolism was evident, with limited residual clusters in frontal regions. At 7-9-months, no regions with brain hypometabolism were present. The only patient evaluated longitudinally showed a significant brain metabolic improvement from the acute phase (with diffuse cortical hypometabolism) to a 5-months follow-up (brain hypometabolism limited to frontal areas). Of note, the extent and severity of hypometabolism were associated with severe global cognitive dysfunctions, low blood oxygen level saturation, and high inflammatory status in all patients. Background-Aim: The SARS-CoV-2 infection was declared a global pandemic in March 2020 and initially had a wide diffusion in Northern Italy, especially in area of Bergamo. From December 2019 to May 2020 (peak of pandemic period), an increase of interstitial pneumonia cases was observed at [ 18 F]FDG PET/CT in oncological patients in Bergamo area. Further, a significant increase of PETpositive interstitial lung alterations was found with higher incidence compared to the pre-pandemic period. These observations suggested the use of [ 18 Background-Aim: Post-mortem studies showed that in patients with COVID-19 the poor prognosis is due not only to the worsening of the ventilation function but it can be related to the perfusion impairment due to massive pulmonary thrombosis or micro-thromboembolism. We aimed to investigate the clinical impact of lung perfusion (Q) scintigraphy in patients discharged after COVID-19 disease but still symptomatic for dyspnea. Methods: 33 patients (pts), discharged at least 1 month after COVID-19, underwent Q scan at T0 (1-3 months after acute disease) and at T1 (after 6 months if lung perfusion defects were evident at T0). Inclusion criteria were (1) residual dyspnea: mild (12/33pts), at minimal motor activity (9/33) and after prolonged effort (12/33), (2) No thromboembolism at CT pulmonary angiography during hospitalization. Exclusion criteria were: previous history of lung disease (e.g. Cancer, COPD, emphysema) or abnormal pulmonary CT findings (e.g. lung bullae). Planar and Q-SPECT/CT images were obtained for evaluation of lobar or segmental or subsegmental peripheral perfusion defects for each bronchopulmonary segment. Perfusion images were qualitatively and semiquantitatively analysed. Q-lung software by GE Healthcare was used for SPECT/CT images for obtaining percent evaluation of pulmonary lobar perfusion (counts/volume % for each lobe), considering as normal a value of defect within: -5%/each lobe, if represented in C 1 lobe. Q-scan was then compared with high resolution CT (HRCT) obtained during hospitalization in the acute phase (T-acute) and repeated after 1-3 months (T0). Significant pulmonary perfusion defects at Q scan were considered for addressing targeted therapy. Results: At T0: preserved lung perfusion was observed in 17/33 pts, thus excluding the vascular cause for the symptoms. Lung perfusion defects were detected in 16/33 patients who underwent T0 and T1 control. Defects were scored as following: severe (7 pts with dyspnea at minimal motor activity), at least one wedge-shaped peripheral defect estimated as C 50% of a pulmonary segment without corresponding HRCT abnormalities, suggesting a new CTPA within 3 months and an appropriate therapeutic strategy; moderate (6 pts with dyspnea after prolonged effort): consisting in multiple ([ 3) subsegmental defects;-mild: (3 pts with mild dyspnea B 3 sub-segmental defects). At T1 lung perfusion improvement (C 10% vs pathological lobe in T0), was observed in a total of 8/16 pts. Conclusions: In the age of precision medicine, Q scan-SPECT/CT in pts with recent COVID-19 can address clinical knowledge and management of SARS-CoV-2-induced lung abnormalities, suggesting the differential diagnosis with respiratory disease of different etiology and the appropriate patient-centered therapeutic strategies. Background-Aim: Cognitive impairment may represent a long lasting symptom after COVID-19 resolution and FDG brain PET is useful to evaluate if brain metabolic changes are transient or long lasting. Hypometabolism was shown in many brain areas, i.e. cingulate cortex, bilateral gyrus rectus, prefrontal and orbitofrontal cortex and cerebellar vermis. Methods: We report the case of a 62 years old man with type 2 diabetes, affected by COVID-19 infection in October 2020. After resolution, the patient had short-term memory loss and speech deficit affecting daily living and working activities and referred to the Gerontology and Geriatrics Institute (Univ. of Perugia). Neurological examination and neuropsychological tests were carried out and no alterations were found. In October 2021, the neurological examination was still normal, as well as neuropsychological tests. Brain MRI showed only two small chronic ischemic foci without bi-hemispheric white matter clinically significant abnormalities. In November 2021, the patient underwent FDG brain PET/CT (discovery ST, G.E.) according to standard protocols and images were evaluated both qualitatively and semiquantitatively. Results: An area of moderate significant hypometabolism was identified in the precuneus (predominant on the right side) and others multiple small and mild hypometabolic regions were localized in bilateral pre-frontal cortex, sensorimotor and parietal cortex both on left hemisphere. PET and MRI fusion images (Syngo.via VB10B image processing software, Siemens) showed that hypometabolic areas corresponded to structurally intact parenchyma at MRI. In January 2022 clinical and neuropsychological follow up did not evidence cognitive impairment, although the patient still felt depressed and impaired in memory, attention and daily living activities. Conclusions: In this case, FDG brain PET/CT was the only diagnostic procedure showing findings consistent with patient symptoms. In particular, precuneus hypometabolism may represent in this patient an early hallmark of dementia (i.e. Alzheimer's disease-AD), although other characteristic brain areas are not significantly impaired (i.e. cingulate cortex). In this case, FDG brain PET use, during follow up, could be crucial to evaluate if the metabolic changes may evolve into a chronic state, thus supporting mild cognitive impairment clinical suspect due to AD or confirming a stable COVID related neuronal damage. Furthermore, a second normal FDG brain PET/CT scan may suggest a post-acute infection transient phase, preluding to normal functional status. In conclusion, FDG brain PET/CT may represent an important diagnostic tool in modifying subsequent diagnostic assessment suggesting or routinely clinical follow up or other investigations for dementia (i.e. amyloid PET, amyloid and Tau protein liquor measurement). In our study, fused PET and MRI images were used, although hybrid PET/MRI system could be the choice option if available. Background-Aim: 18F-FDG PET/CT currently represents the nuclear medicine imaging procedure of choice for staging and posttreatment response assessment in patients with Hodgkin lymphoma (HL). It is well known that 18F-FDG also accumulates in sites of inflammation and infection. Here we report a case of a patient affected by lung HL and concomitant incidental COVID-19 interstitial pneumonia. Methods: The case refers to a 67 years old female patient affected by nodular sclerosing classical HL involving left axillary lymph nodes and both lungs. The patient came to our attention to perform wholebody 18F-FDG PET/CT at initial staging (scan 1), after two cycles of ABVD (scan 2) and at the end of treatment (scan 3). All 18F-FDG PET/CT examinations were performed according to standard acquisition protocols, starting approximately 60 min after i.v. injection of 3.7 MBq/kg of 18F-FDG. Results: At scan 1, 18F-FDG-PET/CT showed hypermetabolic left axillary lymph nodes and multiple disseminated avid lesions in both lungs. Scan 2 demonstrated complete metabolic response associated to almost complete resolution of axillary lymphadenopathy and lung lesions at CT scan. At the end of treatment, scan 3 showed hypermetabolic mediastinal lymph nodes and multiple areas of increased 18F-FDG uptake in both lungs, mostly in pulmonary regions other than those of the basal scan, and in correspondence of multiple ground-glass opacities and consolidations at CT. These findings were more suggestive for interstitial pneumonia than for HL residual disease; in addition, contrast-enhancement CT performed 1 week before scan 3, resulted completely negative. Given the ongoing SARS-CoV-2 pandemic, the patient, although asymptomatic, was scheduled to perform nasopharyngeal molecular swab test for COVID-19; the test resulted positive, corroborating the hypothesis of early interstitial pneumonia. The patient was clinically monitored and 3 months later underwent a further 18F-FDG PET/CT scan which was negative, definitively confirming the absence of lymphomatous disease. Conclusions: In this patient affected by lung HL, an incidental early COVID-19 pneumonia was detected by 18F-FDG PET/CT. The comparison of basal and post-treatment PET/CT scans in combination with lung CT patterns have led to a correct assessment of chemotherapy response. Methods: We retrospectively reviewed 80 cHL, who underwent PET/ CT at staging. Lesions were delineated using an automated preselection of FDG-avid structures (SUV C 2.5). Volumetric and radiomic parameters were measured using LIFEX software both for bulky mass and for nodal and extranodal lesions. Evaluating PET/CT after2cycles of chemotherapy (interim)and at the end of therapy (EoT), patients were ranked according to the Lugano-scale as complete (CMR)or not CMR. All patients had the clinical follow-up of at least 1 year, in order to determine overall survival (OS). The prognostic significance of the clinical characteristics and texture features was assessed in relation to presence of recurrence/relapsed (R/ R)disease. The stepwise discriminant analysis was carried out to select variables for evaluate of CMR vs noCMR. All parameters were compared between survivors vs. non-survivors and R/R vs. no-R/R and their prognostic capability was assessed using ROC analysis and Kaplan-Meier method (KM). Results: At discriminant-stepwise analysis SUV mean and GLRLM_LRHGE were able to correctly identify CMR and noCMR, respectively the first in evaluation of PET interim with accuracy (acc.)of 86.7%and the other in PET EoT with acc. of 88.7%. R/R disease was observed in13/61patients. The majority of GLRLM and GLZLM features, SUV mean , NGLDM_contrast and GLCM (correlation, entropy and dissimilarity)are shown to be significant in relation to R/R (p \ 0.005). SUV mean , GLRLM (HGRE and LGRE)display the highest ROC analysis accuracy (acc. = 0.7)and the best discriminant value on KM analysis (p \ 0.005). At clinical follow-up, 52patients survived, the remaining7 were found non-survivors. Kurtosis, skeweness, SHAPE_Sphericity, NGLDM_coarness (coarness)were significantly higher in non-survivors than in survivors On the contrary, GLRLM_GLNU was significantly higher in survivors than in non-survivors (P \ 0.05). ROC curve resulted statistically significant for coarness, SHAPE_Sphericity and GLRLM_GLNU with acc [ 0.7. The cut-off value of coarness was0.0021. At KM patients with high coarness showed significantly shorter OS compared to those with low coarness (p \ 0.05). The combination of this feature with the stage identified4groups:-group1 = initial stage-coarness \ 0.00215, group2 = initial stagecoarness [ 0.00215, group3 = advanced stage-coarness \ 0.00215, group4 = advanced stage-coarness [ 0.00215. Those groups demonstrated significantly different OS (p = 0.01). Conclusions: Based on our results, conventional and textural PET parameters provide a reference for prognosis evaluation of patients with mediastinal bulky cHL. In particular the best prognostic value was reached by SUV mean , GLRLM (HGRE and LGRE)in the prediction of R/R and by the combination coarness/stage, in the identification of OS. Background-Aim: Medical imaging represents a fundamental part in the management of patients with cancer, providing a variety of information on tumour structure, metabolism and functions in the diagnosis and in staging and restaging phases. The recent developments of technological tools based on artificial intelligence (AI) and machine learning (ML), provide new opportunities for better detection and classification of cancer, optimization of imaging, improvement of clinical picture and workflow. INCISIVE is a 42-month research project, funded by the European Union's Horizon 2020 research and innovation programme, that will develop and validate an AI-based toolbox that improves the accuracy, specificity, sensitivity, interpretability and cost-effectiveness of existing cancer imaging methods. INCISIVE aims to support the diagnosis, prediction and follow-up of cancer management improving sensitivity and specificity of diagnostic methods such as X-rays, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), predicting tumour spread, and improving the interpretability of results. For this aim, 4 types of cancer will be analysed: breast cancer, colorectal cancer, lung cancer and prostate cancer. In this project, 26 participants from across Europe are involved: The University of Rome Tor Vergata will participate to INCISIVE coordinating and conducting the trial at Policlinico Tor Vergata, addressing the complexities in managing the data of cancer patients. Methods: The University of Rome Tor Vergata and other clinical partners involved in INCISIVE are currently providing existing imaging data (X-rays, ultrasound, CT, MRI, and PET), clinical-laboratory and histopathological data that will be analysed retrospectively and will be used for the implementation of the system. Sensitive patient data are collected directly from medical equipment or manually entered by researchers; they are stored in an archive service, which is responsible for sharing between internal medical units and exporting to external care services. Data provided are related to different time points of cancer disease that include the baseline, phases after surgery and after therapy (such as chemotherapy, radiotherapy, immunotherapy, target therapy). This is a retrospective study that will pave the way for a validation of the performance of the INCISIVE platform in the 4 tumor groups (prospective study). Results: The results from the ongoing retrospective study will be obtained this year. Conclusions: INCISIVE is an ongoing research project that will develop and validate an AI-based toolbox that enhances the accuracy, specificity, sensitivity, and interpretability of existing cancer imaging methods. Automatic classification (classification tree, k-nearest neigbourhood, support vector machine) of Parkinson's disease vs. essential tremor: comparison among different semi-quantitative methods (BASGANV2 and DATQUANT) . One hundred thirty-three patients were classified as Parkinson's disease (PD) and 36 as essential tremor (ET). All the patients were previously evaluated with neurologic examination, neuropsychological tests and magnetic resonance imaging. A clinical follow up of at least 6 months confirmed the diagnosis. Semi-quantitative image analysis was performed using two different semi-quantification tools: DaTQUANT (GE Healthcare, Chicago, Illinois, US) and BasGanV2 ( http://www.aimn.it/struttura/gruppi/gs_neuro.php) to extract radiopharmaceutical uptake values from 4 regions-i.e., left and right caudate and putamen. The uptake values were fed into 3 classification models (classification tree-ClT, k-Nearest neigbourhood-K-NN and support vector machine-SVM) to automatically discriminate between PD and ET. The ability of the classifiers to predict the correct diagnostic label was assessed via split-sample validation with stratified sampling using 70% of the population for training the classifier and the remaining 30% for estimating the accuracy. The results were averaged over 250 splits into train and test set. Results: Classification accuracy based on DaTQUANT data and ClT, k-NN and SVM respectively was 91.7%, 92.7% and 93.1%; accuracy based on BasGanV2 data was 88.9%, 91.5% and 91.9%. For each classifier the predictions based on DaTQUANT were more accurate than those based on BasGanV2 and the difference was statistically significant (p \ 0.001). Limitations of the study are the retrospective nature and the smaller number of ET versus PD patients, although it does not influence the automatic classification performance. Conclusions: The 3 automatic classification techniques were all useful to discriminate PD and ET patients based on the data generated by the 2 software tools used, being both able to accurately discriminate PD and ET, although DaTQUANT achieved slightly better performance than BasGanV2. The results should be further validated in future works, ideally on a more balanced study population. Artificial intelligence applications on restaging [18F]FDG PET/ CT images of metastatic colorectal cancer Background-Aim: Artificial intelligence and radiomic analysis have gained increasing interest in oncology, especially for the analysis of biomedical images. In a cohort of intermediate-high risk prostate cancer patients (pts) at staging, we applied radiomics analysis to their FCH-PET/CT images to select the radiomic features most predictive of biochemical recurrence (BR). Methods: We selected 58 pts (median age: 68 year, range 58-84 year) who underwent FCH-PET/CT for staging purposes. The whole prostate gland was delineated by two expert physicians from co-registered PET/CT data. Subsequently, two alternative conventional thresholds (THs) were applied to the whole prostate to obtain two additional segmentations of the metabolically active tumour: TH1 = 41% of the maximum SUV (SUV max ) value inside the gland, and TH2 = 2.5 SUV. All three segmentation methods were separately considered in the radiomic analysis. Clinical parameters, including PSA, pre-and post-surgery Gleason score (GS), lymph node involvement, clinical stage were also available for the patients. Radiomic analysis was performed on the three PET segmentations after applying a linear interpolation to create isotropic voxels of 0.2 mm and a SUV resegmentation in the range [0-20]. The in-house, open-source software S-IBEX was used to extract the 169 standardized radiomic features using fixed bin size SUV discretization (FBS) of 0.2, 0.4 and 0.6 and a 3D aggregation approach to derive radiomic textural features. For each FBS value, the possible redundancy among features was addressed by discarding from further analysis highlycorrelated features (Pearson's r [ 0.90). For each discretization approach and each threshold, we trained a logistic regression model in a leave-one-out cross-validation framework to predict BR using both radiomic and clinical features. The least absolute shrinkage and selection operator (LASSO) was adopted to select the most informative parameters to consider in the model with a fivefold crossvalidation on the training set. Results were evaluated in terms of area under the receiver-operator characteristic (AUC) and accuracy (ACC). Results: The final database included 39 pts. Median PSA value was 7.73 ng/ml, the median GS was 8 (GS 6-7 in 13; GS C 8 in 26). The clinical stage was cT1 in 3, cT2 in 31, cT3a in 5. The combination of TH2 and FBS 0.2 achieved the best results for the prediction of BR with AUC = 0.69 and ACC = 0.72, when radiomic features were combined with the patient's clinical information. In general, the dataset corresponding to TH1 achieved the worst prediction performance, independently of the SUV discretization approach used, while the analysis performed on the whole gland did not show any relevant prediction result, and AUC was lower than 0.6. Conclusions: These preliminary results suggest that the use of radiomic analysis in this clinical scenario is a promising tool to select patients who are at risk of BR since the initial evaluation of the disease, thus providing useful information to choose the most appropriate treatment and follow-up strategy. Furthermore, the combination of radiomic with clinical parameters plays a significant role in accurately predicting clinical outcome, but datasets of higher dimension are required to confirm our results. Background-Aim: The inflammatory cascade in patients (pts) with COVID-19 may lead to pulmonary embolism (PE), worsening prognosis. Lung perfusion SPECT/CT (Q-scan) in symptomatic pts discharged after COVID-19 can confirm or rule out pulmonary vascular involvement, helping the differential diagnosis with other respiratory diseases. We aim to investigate an innovative methodology, based on radiomic features and formal methods, as a virtual second look able to detect perfusion abnormalities to better define appropriate patient-centered diagnostic and therapeutic strategies. Methods: A total of 23 pts with a recent history of COVID-19, without any previous pulmonary disease (e.g. lung cancer, emphysema, or pathological findings at CT such as lung bullae) were enrolled for Q-scan for persistent dyspnea 1 month after discharge. They were classified as negative (14 pts) and positive (9 pts) for lung perfusion abnormalities by visual and semiquantitative analysis. Q-Lung Ò software by GE Healthcare was used to obtain percent evaluation of pulmonary lobar perfusion (cts/volume % for each lobe), assuming as a normal value any defect lower than 10% for each lobe. We analysed these data using an innovative methodology based on formal methods techniques centered on mathematical logical reasoning, to build a formal and rigorous representation of a system merging patients clinical conditions and disease-specific characteristics, to confirm or exclude the disease. Results: In a comparative analysis with Q-Scan results, the model showed concordant features in 13/23 pts, identifying perfusion defects in 8/9 pts with a positive Q-Scan, and excluding perfusion defects in 5/14 pts with a negative Q-Scan. Discordant results were observed in the remaining 10/23 pts, in particular in negative pts: however, in this sub-group, the Q-Lung semiquantitative analysis revealed perfusion defects lower than 10% per lobe, which we considered unsignificant but may deserve further evaluation. Conclusions: Although our data are still preliminary and based on a limited population, this methodology based on formal methods showed promising concordance with Q-scan results and needs to be implemented with further analyses including co-registered CT data. When compared to artificial intelligence techniques, this mathematical reasoning may enable (i) to use a reduced dataset of patients and/ or images, without having any impact on the robustness of the model; (ii) to produce an intuitive model easy to understand; (iii) to represent a rigorous and formal tool that may be used by medical specialists in a clinical setting. Nuclear Medicine, Istituto Nazionale Tumori di Milan. 2 Radiology, Istituto Nazionale Tumori di Milan. 3 Oncology, Istituto Nazionale Tumori di Milano Background-Aim: Tumor growth rate (TGR) allows for a dynamic and quantitative assessment of tumor kinetics during SSA treatment and, recently, also during LRT (ligand radio-therapy). The aim of this study is to evaluate the added value of modified TGR as radiological predictor of early response to LRT, in GEPNET patients. Methods: Progressive metastatic G1-G2 GEP-NETs treated with LRT (177Lu-Oxodotreotide, 4 administrations, 7.4 GBq/each) at our centre from 04/2019 to 10/2020 were considered. Inclusion criteria were 3 CT per patient: 1 performed within 3 months before LRT, 1 after 2 LRT cycles and 1 within 4 months after the end of LRT to assess early response, according to RECIST 1.1. TGR was calculated in 2 ways: assuming the volume of the lesions can be calculated applying the volume of a sphere formula (classical formula) or the volume of an elliptical cylinder (modified TGR). In both cases, baseline versus interim evaluations were compared. Patients were subdivided as responders and non-responders (PD), lines of therapies were calculated as possible confounders. Logistic regression was performed to determine predictability of TGR models and clinical features in the evaluation of PD. ROC analysis was applied to assess the performance of the two models and the optimal TGR cut-off values. Results: 27 patients (12 males, 15 females, mean age 63.9) were analysed of which 55.6% were midgut, 44.4% foregut. LRT was applied in second line in 66.6%, in third or further in 33.4%. Considering RECIST, 14.8% were non-responders (PD). Logist regression showed OR of 5.9 with AUC 0.95 (Sensitivity 75%, Specificity 95%) for TGR_cylinder and OR 1.05 with AUC 0.75 (sensitivity 25%, specificity 75%) for TGR_sphere. The optimal cutoff value for PD prediction was 5.5% volume increase/month for TGR_ cylinder (sensitivity 100%, Specificity 86.4%) and 5.3%/month for TGR_sphere (sensitivity 75%, specificity 81.8%). Conclusions: Modified TGR, in particular interim TGR_cylinder, could be an accurate predictor of early progression of GEP-NET disease after the second cycle of LRT. Data validation on a larger cohort study is on course. The Siren Project: development of a real time system to report and collect data for the dose assessment of operators in abnormal events in nuclear medicine therapy Background-Aim: The SIREN Project (2020-2022) aims to develop procedures for reporting abnormal events in the nuclear medicine therapy wards by the implementation of a system based on a Internet of Things (IoT) monitoring system and a mobile application. Methods: This system shall allow the operator to report quickly, easily and as accurately as possible abnormal events. The system will also acquire data for the exposure scenario reconstruction, for the dose assessment and for the proactive monitoring of the medical and paramedical staff for the patient assistance, providing useful data both to reconstruct the event dynamics, and to facilitate the proactive approach to risk management. The prototype of the system will have to meet the following objectives: (i) to simplify entering data of the reporting anomalies and incidents procedure and reduce the time; (ii) to increase the quality of data and information collected, improving the reconstruction of the scenarios and the dose estimation; (iii) to increase the number of reports of accidents, including those not leading to undue doses; (iv) to simplify the subsequent classification of data and information for proactive risk monitoring. Results: The innovative aspects of the proposed methodology compared to existing procedures are: the involvement of operators in the design of the system; an IoT monitoring system for real-time collection of data about the event dynamics and the exposure level; the use of social science methodologies for obtaining reliable descriptions of events. At the moment, the preliminary phase of research has been completed by a cycle of interviews with users, which made it possible to collect the needs and expectations of various actors (radioprotection expert, doctors, physicists, technicians and nuclear medicine nurses). The detection system of the environmental dose and the dose estimation of operator are being designed and the application -by the definition of requirement analysis-and app mockups are being developed. Conclusions: This project try to contribute, with innovative and technologically advanced solutions, to better the operator dose estimation in radiometabolic therapy units when abnormal events happen. The use of a mobile app allows the operator to report the event in a quick, easy and accurate way and in real time. Background-Aim: European guidelines for hyperthyroidism radiometabolic treatment suggest a target dose of 300-400 Gy for unifocal autonomies. Aim of this study was to demonstrate that a lower dose and a personalised pretreatment dosimetric study can be effective in obtaining a stable euthyroid status avoiding both hyperthyroidism persistence and onset of hypothyroidism and in complying with the DLgs 101/2020 optimization principle. Methods: We considered 139 patients with a minimum follow-up of 12 months (92F, mean age 62 ± 13 years, 80 with subclinical hyperthyroidism and 59 with overt hyperthyroidism) with a single nodule of mean weight of 15.9 ± 13.7 g (range: 3.8-110.9 g). They were studied with a pretreatment patient-specific dosimetric study (based on the administration of 48-111 MBq of 123 I, on multiple uptake measurements with a gammacamera and on the MIRD formula corrected for the reduced uptake in therapy with respect to dosimetry) in order to calculate the therapeutic 131 I activity necessary to release to the nodule a dose of 140 Gy. Afterwards, the dose released after the administration of the calculated 131 I therapeutic activity was evaluated by means of 6 uptake measurements at 2, 4, 24, 48, 96 and 168 h and the use of the MIRD formula. Uptake measurements were performed with a gammacamera equipped with a high energy collimator. After the first 12 months each patient clinical outcome was monitored with biochemical analysis (TSH, FT3 and FT4) once a year. Two subgroups of 72 and 43 patients had a follow-up of 5 and 10 years, respectively. Results: All patients were given a single therapeutic 131 I administration with a median activity of 278 MBq [range: 87-625 MBq]. The mean dose released to the nodules was 140 ± 44 Gy. Twelve months after therapy hyperthyroidism was healed in 97% of the patients but 7% were hypothyroid (serum TSH level over 4.2 uU/ml). In the subgroup followed for 5 years, 100% of the patients solved hyperthyroidism but 21% became hypothyroid and in the subgroup followed for 10 years they were 28%. Conclusions: This study demonstrated that a released target dose of about 140 Gy is effective in solving hyperthyroidism due to unifocal autonomy and to maintain a long lasting euthyroid state. This dose is quite lower than the value indicated by the European guidelines for hyperthyroidism treatment. The wide range of administered activity indicates the importance of a personalized pretreatment dosimetric study in order to obtain the clinical goal with the lowest activity. Background-Aim: Radioembolization (RE) with microspheres containing Holmium-166 ( 166 Ho) is a valid option for the loco-regional treatment of liver tumors, with the advantage of performing a. Preprocedural 166 Ho-scout dose. 90 Y-RE was already demonstrated a valuable therapy in terms of tumor extension, radiological response and post-treatment survival. Preliminary experiences reported promising results after 166 Ho-RE, although very small data are available. Particularly, more rapid post-procedure therapeutic effects were supposed in view of 166 Ho physical features. Aim of the study was to evaluate the early radiological response after 166 Ho-RE in patients with liver tumors. Methods: Seven patients (5 males, mean age 65.7 ± 11.2 years) from April to November 2021 who underwent 166 Ho-RE for liver tumors were included. A few weeks before RE, patients had an angiography procedure injecting 166 Ho into the (sub)segmental artery of the tumor-bearing liver segment(s) with diagnostic purposes. Following planar and SPECT/CT scans were performed as a preprocedural planning modality for studying distribution and dosimetry. During RE procedure, the injection position from the planning angiography was mimicked. All the patients had planar and SPECT/ CT scans the following day to verify 166 Ho distribution as well as an early (1 months) post-treatment computer tomography (CT) control. Clinical and procedural data, tumor response according to radiological features and modified Response Evaluation Criteria in Solid Tumours (mRECIST) were analyzed. Results: Three (43%) patients were treated for primitive liver diseases (2 had hepatocellular carcinoma and 1 cholangiocarcinoma). Four (57%) patients had metastatic liver diseases (1 was secondary to neuroendocrine tumor and 3 to gastro-intestinal carcinoma). The mean administered activity was 4.14 GBq (range 2.31-8.82) for a monolobar approach in 6 patients and a bilobar approach in the other one. A high agreement was observed between 166 Ho-scout dose and post-treatment scans. None of the patients reported immediate toxicity or within 1 month. At the early CT evaluation, the treated lesions showed extensive necrosis in 6 (86%) patients and among them one (14%) demonstrated also intralesional calcifications (a possible indirect sign of vascular sclerosis). According to mRECIST, 6 (86%) patients had a partial response to the treatment, the remaining one (14%) a stable disease. Conclusions: 166 Ho-RE is a safe treatment for liver tumors, as well as effective at an early evaluation. This might be particularly attractive in cases with neoadjuvant purposes. Background-Aim: Hepatocellular carcinoma (HCC) is the commonest primary malignant tumor of the liver. It is the fifth most common cancer in men and the eighth most common in women, and it ranks fourth in annual cancer mortality rates. A small percentage of patients with HCC are candidates for curative treatment in form of resection or transplantation. The available treatment options for unresectable HCC like, transarterial chemoembolization, RFA, alcohol injections have variable clinical outcome and had been shown to increase survival. In the last few years, there is a growing interest in TheraSphere radioembolization. It consists of Yttrium90 (Y-90) embedded into nonbiodegradable glass microspheres. It is selectively administered by intraarterial hepatic injection giving high doses of radiation to the tumor and sparing the liver parenchyma. The aim of this study is to evaluate the role of radioembolization for treatment of unresectable HCC. Methods: A retrospective study of patients who underwent RE for unresectable HCC from January 2018 to December 2021 in our hospital was performed. Demographic features, tumor diameter, activity administered, imaging response according to mRECIST, overall survival (OS) and treatment associated complications were analysed. Follow-up was performed with CT after 6 months after RE and then every 6 months. Important factors in determining eligibility for TheraSphere radioembolization include liver function tests and absence of significant lung shunting or collateral flow to the gastrointestinal tract. Arteriography is essential to map the hepatic arterial supply from the celiac and the superior mesenteric artery and is the single most important test to exclude preventable complications. A technetium-99 macroaggregated albumin (The 99Tc-MAA) scan is performed to estimate the dose of radiation that will be delivered to the lungs and/or viscera [9] . Patients with 99mTc-MAA evidence of potential pulmonary shunting resulting in lung doses [ 30 Gy should not be treated. Results: 13 patients (M/F: 12/1, mean age 61 years) underwent RE withs Yttrium-90 glass microspheres in our hospital. Tumor diameter mean was 6.5 cm (range 2.5-13) and mean activity administered was 3.5 GBq (range 2.5-13). The follow-up CT showed a good response in all patients except for one (died after 2 months due to a rapid progression): in three patients there was a complete response; 9/13 patients have presented a significant tumor reduction. During the follow-up, 3 patients died (median OS 6 months). The other 10 patients are still alive: 3 of them were submitted to liver transplantation. Treatment in patients with portal vein thrombosis (PVT) had been successful. Conclusions: Y-90 radioembolization is approved for treatment of unresectable HCC. It has been shown to have good clinical outcome 1 Department of Advanced Biomedical Sciences, University Federico II, Naples, Italy. 2 Background-Aim: After total thyroidectomy with or without lymphnode dissection for differentiated thyroid cancer (DTC), radioactive 131 I (RAI) therapy may be administered for 3 main goals: remnant ablation, adjuvant therapy, or therapy. Although literature offers a huge armamentarium of data on survival benefit of RAI administration in patients with DTC at intermediate-high risk of recurrence, to our knowledge a meta-analysis on successful rate in these patients has not yet been performed. We performed a systematic review and a meta-analysis to investigate the successful ablation rate after RAI administration in patients with DTC at intermediate-high risk of recurrence. Methods: A comprehensive literature search of the PubMed, Scopus and Web of Science databases was conducted according to the PRISMA statement using the following key words: ''differentiated thyroid cancer'' OR ''DTC'', ''thyroid neoplasm'', ''prognosis'', ''outcome'', ''follow-up'', ''radioactive iodine therapy'' OR ''RAI therapy'', '' 131 I ablation'', ''thyroglobulin'' OR ''Tg''. A study was considered eligible if all of the following criteria were met: 1) data were available on age, gender and administered RAI activity, histopathology and extent of surgery; 2) the study presented data of adult subjects with differentiated thyroid cancer at intermediate or high risk of recurrence after RAI therapy according to American Thyroid Association risk classification; 3) the study included at least 100 subjects; 4) follow-up after RAI therapy for at least 1 year; and 5) the study provided data on successful ablation after RAI therapy defined as absence of abnormal findings at neck ultrasonography and undetectable serum Tg in the absence of anti-Tg antibodies. Results: The final analysis included 9 studies accounting for 3103 patients at intermediate-high risk of recurrence. In these patients, the successful ablation rates ranged from 51 to 94% with a 71% pooled successful ablation and was higher in intermediate (72%) than in high (52%) risk patients with a relative ratio of 1.22 (95% confidence interval 1.05-1.42, P \ 0.01). Pooled recurrence rate in intermediate risk patients achieving successful ablation was only 2% during the subsequent 6.4-year follow-up while the pooled recurrence rate was 14% in patients who did not achieve a successful ablation. Conclusions: In a large sample of 3103 patients at intermediate-high risk of persistent/recurrent disease, 71% of them achieved a successful ablation. In these intermediate-risk patients, the probability of subsequent recurrence is low and most recurrence occurred in those with already abnormal findings at the first control. Background-Aim: In pediatric patients with differentiated thyroid cancer (DTC), the risk of recurrence is high and the indication for post-operative 131I administration is still debated. Aim of this study was to assess the risk of structural recurrence in pediatric DTC patients at low-intermediate risk. Methods: We retrospectively evaluated 69 pediatric patients with DTC, treated with surgery and 131I. The patients were classified as low, intermediate, or high risk of recurrence according to the American Thyroid Association (ATA) guidelines. We excluded 8 patients with positive serum anti-thyroglobulin antibody and 7 patients with post-operative ATA high risk, leaving 54 subjects. Follow-up was performed. The need of additional therapy or the observation of structural disease persistence, defined as defined by histology or imaging procedures, were considered as end-point. Annualized event rate (AER) was calculated. Hazard ratios were obtained by Cox regression analyses. Disease free survival analysis was performed by Kaplan-Meier method. Results: Follow-up was available in 45 subjects. During a mean time of 64 ± 53 months, 15 structural events occurred (33% cumulative event rate). The patients with events had higher pre-therapy thyroglobulin values (82 ± 21 vs. 13 ± 18, P \ 0.001), as well as a higher prevalence of age B 14 years (53% vs. 23%, P \ 0.05) and intermediate ATA risk (80% vs. 30%, P \ 0.01), as compared to those without events. A TSH stimulated thyroglobulin value [ 10 ng/ ml before post-operative RAI therapy resulted the best trade-off in predicting the occurrence of events. The occurrence rate of structural events was higher in patients with thyroglobulin [ 10 (AER 15% vs. 0.5%) and those at intermediate risk (AER 11% vs. 1.5%) (both P \ 0.01). At multivariate analysis, a thyroglobulin level [ 10 ng/ml resulted the only independent significant prognostic factor of structural recurrence (P \ 0.001). At Kaplan Meier analysis, the worst prognosis was observed in patients with a serum thyroglobulin level [ 10 ng/mL in both ATA risk and age categories (both P for trend \ 0.001). Conclusions: In this retrospective series of pediatric patients with ATA low or intermediate risk DTC treated with surgery and RAI, post-operative elevated thyroglobulin values ([ 10 ng/mL) have a high independent prognostic impact independently from age and ATA risk. The detection of a high serum thyroglobulin value could improve the post-surgical risk stratification and indicate RAI treatment. Combined bone scintigraphy and 18F-fuorocholine PET/CT predicts response of bone metastases to radium-223 treatment in patients with castration-resistant prostate cancer Background-Aim: Bone metastases burden evaluation is essential before radium-223 therapy. The aim of this study was to assess the value of combined bone scintigraphy and 18 F-fuorocholine PET/CT in predicting the clinical outcome in patients with castration-resistant prostate cancer and bone metastases treated with radium-223. Methods: A retrospective analysis of 48 patients who received radium-223 therapy between 2015 and 2017 was performed. The treatment protocol included six courses of radium-223 and treatment failure was defined as less than six treatment courses. The endpoints were pain relief and overall survival. Bone scintigraphy and 18 Ffuorocholine PET/CT were performed in all patients before radium-223 therapy. Results: The follow-up was 15 ± 10 months (range 2-43 months). Thirty-four patients died during the follow-up and nine patients prematurely discontinued the treatment. After radium-223 therapy, pain relief was observed in 27 (56%) patients P \ 0.001). Among patients without pain relief, 71% had more bone lesions at 18 F-fuorocholine PET/CT than at bone scintigraphy (pre-therapy imaging mismatch) (P \ 0.05). At univariable analysis, variables associated with a poor overall survival were Gleason score (P \ 0.05), treatment failure (P \ 0.001), baseline ALP level (P \ 0.05), post-therapy ALP level (P \ 0.005), persistent or worsened post-therapy pain (P \ 0.05), and pre-therapy imaging mismatch with more lesions seen on PET/CT than on bone scintigraphy (P \ 0.05). At multivariable analysis, only treatment failure and post-therapy ALP level were independent predictors of a poor overall survival (both P \ 0.05). In the sub-group of 39 patients who had completed treatment protocol, post-therapy ALP level and pre-therapy imaging mismatch with more lesions at 18 Fcholine PET/CT than at bone scintigraphy were independent predictors of a poor overall survival (both P \ 0.05). Conclusions: After radium-223 therapy, patients with more lesions at 18 F-fuorocholine PET/CT than at bone scintigraphy had a poor prognosis, suggesting that a combined imaging approach could be useful to predict outcome after radium-223 therapy. Risk of primary breast cancer in patients with differentiated thyroid cancer undergoing radioactive iodine therapy: a systematic review and meta-analysis Background-Aim: Although it has been proven that radioactive iodine (RAI) treatment is an effective and well-tolerated procedure in patients with differentiated thyroid cancer (DTC), there is still some concern regarding the risk of developing a second primary malignancy after RAI administration. We performed a systematic review and meta-analysis to investigate the risk of primary breast cancer in patients with DTC undergoing RAI therapy. Methods: A comprehensive literature search of the PubMed, Scopus, and Web of Science databases was conducted according to the PRISMA statement. Results: The final analysis included 14 studies accounting for a total of 200,247 patients with DTC (98,368 treated with RAI and 101,879 not treated with RAI). The relative risk of primary breast cancer in patients with DTC treated with RAI to those not treated with RAI among studies ranged from 0.45 to 2.55, the pooled relative risk was 0.83 (95% confidence interval, 0.70-0.99), and the heterogeneity was 71.5%. Conclusions: The present meta-analysis indicates that patients with DTC treated with RAI do not have a higher risk of primary breast cancer compared to those not treated with RAI. These findings suggest that RAI therapy does not increase the risk of breast cancer. Background-Aim: Radioiodine (RAI) therapy is a cornerstone in the treatment of differentiated thyroid cancer (DTC). Considering RAI renal clearance, its use in pts on dialysis due to end-stage renal disease (ESRD) may raise concern in terms of safety and operative procedures. We report the results of a single-centre descriptive study on pts with ESRD on dialysis treated with RAI for DTC. Methods: Retrospective systematic search was performed on our clinical database (2007-2021) including pts with ESRD on dialysis treated with RAI for DTC. Therapeutic procedure was the following: on day 1 pts underwent a single rhTSH administration (preparation with 2 rhTSH administrations was discontinued from 1st pt on, having observed a sufficient TSH raise after one rhTSH administration). On day 2 a trace dose of 131I was administered. Blood samples were collected and whole-body activity was measured 2 h after trace dose and on day 3 immediately before and after 1st dialysis, always performed 24 h after trace dose. Red marrow dosimetry assessed maximum RAI activity to be administered with regard to red marrow dose limit, considering the possibility to force post-therapy dialysis rate. On day 3 therapeutic RAI activity was administered taking into account conventional dosimetry and the maximum threshold activity assessed by red marrow dosimetry. On day 4 post-therapy dialysis was performed in the Radiometabolic Therapy Unit room to ensure adequate RAI dismission. On day 5 post-therapy WBS was performed. A diagnostic WBS was performed 6-8 months after therapy and then periodical follow-up included neck ultrasound and serum Tg and anti-Tg Ab measurements. Descriptive statistics were used for clinical and dosimetry data. Results: Final sample included 12 pts (mean age 52 years, range 27-53), all diagnosed with papillary thyroid carcinoma (PTC) (7/12 classical variant, 5/12 follicular variant), after a mean dialysis period of 5 years (range 0.1-18). 11/12 pts were treated for thyroid remnant ablation, 1 pt underwent 2nd treatment due to persistent biochemical disease (mean administered RAI activity 42 mCi, range 27-137). Mean blood RAI dismission percentage after 1st dialysis was 74% (range 61-88%). Mean whole-body RAI dismission percentage after 1st dialysis was 67% (range 49-79%). In all pts, dosimetry allowed to force only the first post-therapy dialysis at 24 h, then personal dialytic schedule was followed. No acute adverse events after RAI therapy were observed. Follow-up data were available in 7/12 pts (mean 24 mts, range 1-104), while 5/12 pts returned to the referral centre. All patients were free from thyroid disease at last follow-up except 1pt with partial response. No delayed RAI secondary effects on target organs were registered. Conclusions: In this single-centre case series, RAI treatment in pts with ESRD on dialysis was feasible thanks to a standardized red marrow dosimetry that estimated the appropriate dialytic scheme to comply with red marrow dose limit. It is worth to notice that, in ESRD patients, the long-term thyroid disease-free outcome provided by RAI treatment is necessary to ensure the inclusion in transplant list. Role of personalized dosimetry in predicting objective tumor response and overall survival in patients with liver metastases treated with 90Y radioembolization Background-Aim: Yttrium-90 (90Y) radioembolization (RE) is an alternative treatment currently used for patients with primary or secondary liver tumors. 90Y microspheres are administrated via a catheter directly into the hepatic artery where they are deposited within the hepatic arterioles surrounding the tumors. Dosimetric and non-dosimetric methods are currently applied to calculate 90Y activity and set up treatment plans; dosimetric methods based on tumor-specific dose estimation seem to be the most reliable. The aim of this study was to evaluate dose-response relationship and overall survival (OS) in patients treated with 90Y glass microsphere RE for liver metastases using a tumor-specific dose estimation based on technetium-99m-labeled macroaggregated albumin (99mTc MAA) single photon emission computed tomography (SPECT/CT). Methods: 25 patients (14 men, mean age 66 years; 11 women, mean age 65 years) with liver metastases treated with 90Y RE on single or both hepatic lobes (32 treatments) were retrospectively evaluated. 17/25 patients presented colorectal metastases; 3/25 breast cancer metastases; 2/25 neuroendocrine tumors (NET) metastases; 1/25 gastric cancer metastases; 1/25 endometrial cancer metastases and 1/25 melanoma metastases. Tumor-specific absorbed dose (TD) and injected healthy liver absorbed dose (HLD) were estimated using a partition model (personalized dosimetry). Treatment response was evaluated at 3 months post 90Y RE on 18F-FDG PET/CT according to Pet Response Evaluation Criteria in Solid Tumors (PERCIST) and tumors with complete (CMR) or partial response (PMR) were considered Objective Responders (OR), while stable (SMD) and progressive metabolic disease (PMD) were considered Non-Responders (NR). NET liver metastases were evaluated according to Krenning score (KS) calculated on 111In-Pentetreotide scan and lesions with KS 0-2 were considered as OR while KS 3-4 as NR. Receiver operating characteristic (ROC) curve was used to evaluate TD in predicting OR. Kaplan-Meier estimation was used for OS analysis from 90Y RE. Results: According to PERCIST 13 of 32 (40.6%) 90Y RE treatments resulted in OR (3/32 were CMR and 10/32 were PMR) and 19 of 32 (59.4%) in NR (13/32 were SMD and 6/12 were PMD). Among OR, OS was 42.4 months ± 4.1 compared to 21.1 ± 2.6 months for NR (p = 0.001). Median HLD was 78 Gy (range 21-120 Gy). Median TD was 209.5 Gy (range 64-455 Gy). Per response category, TD was 277 Gy for OR and 195 Gy for NR. Cut-off value of 228.5 Gy TD predicted a 3-months metabolic response with the greatest accuracy (69% sensitivity and 84% specificity). Lesions treated with a TD [ 228.5 Gy showed an OS of 38.1 months ± 4.1, while lesions treated with a TD \ 228.5 Gy showed an OS of 22.5 months ± 3.1 (p = 0.026). Conclusions: This study demonstrates a significant relationship between tumor dose, estimated with a partition model, and response in liver metastases treated with 90Y radioembolization. A TD of [ 228.5 Gy predicts OR with high sensitivity and specificity and shows a prolonged OS. Background-Aim: The updated restrictions in Radium-223 dichloride therapy (Ra223), as therapeutic option in metastatic castration resistant prostate cancer (mCRPC) patients with more than 6 bone metastases and at least 2 systemic therapies failure, could affect its efficacy. Consequently, the identification of baseline biomarkers reflecting metabolic active tumor burden could be essential for patients' selection. Since the role of baseline 18F-choline PET/CT (bPET) is not well established, we investigated the predictive value of bPET parameters for Ra223 therapy completion and outcome. patients (C 2 previous lines of treatment), who developed instrumental disease progression (p = 0.043). Furthermore, low bHb (p = 0.019) and bPLT (p = 0.044) as well as high bPSA (0.011) and bALP (0.042) values were statistically correlated with a higher incidence of toxicity. Multivariate Cox analysis showed a significant difference in OS among patients stratified by the median values of the bPLT (HR = 0.411, 95% CI 0.188-0.900, p = 0.026) and bPSA (HR = 0.397, 95% CI 0.159-0.995, p = 0.049), as well as number of bone metastases (HR=2.918, 95% CI 1.197-7.114, p = 0.019). Conclusions: Our results suggest that background patient characteristics should be considered before starting Ra223 treatment, having a predictive role on the therapy completion and efficacy. Particularly, high bALP and low bHb were negative predictors for Ra223 completion and, together with low bPLT and high bPSA, were associated with toxicity development. Similarly, high tumor burden was associated with a worse OS and Ra223 early discontinuation. Sapienza University of Rome, 2 University of Bologna, 3 University of Bari, 4 University of Sassari, 5 University of Palermo, 6 University of Tor Vergata, 7 University of Pescara Background-Aim: Radium-223 has proved to be safe and effective in preventing skeletal events in patients with symptomatic metastatic castration-resistant prostate cancer (mCRPC). In oncology, several studies have showed better outcomes, in terms of quality of life (QoL) and overall survival (OS), in patients with diabetes undergoing chemotherapy and treated with insulin and/or oral hypoglycemic drugs, compared to other patients. The aim of this multicentre study is to evaluate whether insulin and/or oral hypoglycemic therapy, in mCRPC and diabetic patients, increases the efficacy of Radium-223 in term of OS. Methods: 430 mCRPC patients of six italian nuclear medicine units were analyzed in this multicenter retrospective study. The whole cohorte was divided into two groups: patients with and without diabetes. Patients with diabetes, were divided into two subgroups based on therapy with insuline and/or oral hypoglycemic drugs. Other relevant variable for OS analysis, such as haemoglobin (Hb), alkaline phosphatase (PA), Prostatic specific antigen (PSA), Eastern Cooperative Oncology Group Performance Status (ECOG PS), have been taken into account. Clinical data have been collected at baseline and at the end of the Radium-223 treatment. Results: Of 430 patients, 55 were with diabetes. 18 patients were in therapy with insuline and 39 with oral hypoglicemic agents. Statistical analysis showed no significant differences between the two groups in term of OS and QoL, instead there is a correlation between the other parameters and the increase of OS. Conclusions: Insulin and/or oral hypoglycemic therapy, in mCRPC patients, does not increase the effectiveness of Radium-223 treatment in term of increase of QoL and OS. However, the results could be affected by the low number of patients studied. Further study should be conducted including a larger sample of patients. Liver function assessment in radioligand therapy using dynamic hepatobiliary scintigraphy Background-Aim: [177Lu]Lu-oxodotreotide radioligand therapy (RLT) is an established treatment for metastatic somatostatin receptor positive GEP-NETs patients, that in rare cases can cause mild side effects, including elevation of liver enzymes. This prospective study aimed to evaluate hepatobiliary scintigraphy (HBS) in assessing liver function in patients treated with RLT. Methods: Dynamic [99mTc]Tc-mebrofenin HBS, in combination with SPECT/CT, was used to quantitatively assess both global and regional liver function, trough mebrofenine uptake rate (MUR). Patients were required to fast for 4 h before scan. HBS was performed by dual head dynamic acquisition of 38 frames (10 s/frame) immediately after intravenous bolus injection of 200 MBq of [99mTc]Tcmebrofenin. Ekmann algorithm was applied to HBSs to assess global liver MUR and divided by individual body surface area. HBS scans were performed before the 1st RLT administration (t1MUR) and it was repeated 3 months after the 4th administration (t2MUR). The percentual relative reduction in MURs for each case (DMUR) was calculated. ALT, AST, GGT, INR, albumin and bilirubin have been collected every 30 days approximately. Adverse event grading has been evaluated according to Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Results: Forty-one GEP-NET patients underwent basal HBS and 14 of them repeated the examination after the completation of RLT. Mean t1MUR value of 5.69%/min/m 2 (range 3.48-8.60, ± 1.42) was significantly different to mean t2MUR value of 4.53%/min/m 2 (range 3.21-6.11, ± 1.49) at paired t-test (p = 0.0058). DMUR resulted in a mean reduction of -10.25% (range -27.84-18.01%, ± 11.41%). Only transient liver enzyme or bilirubin increase have been reported in 9 out of 14 patients during RLT cycles, overall resulting in 10 G1, 5 G2 and 4 G3 toxicity events. Decreasing trend of MUR after therapy can be explained by the radiation-induced liver damage due to RLT, nevertheless t2MUR min value recorded higher than the lower normal value defined in literature (2.7%/min/m 2 ). Conclusions: The preliminary results of this study suggest that dynamic hepatobiliary scintigraphy is a valuable diagnostic tool to assess liver function reduction in patient treated with RLT. This experience supports the use of this technique in hepatotoxic treatments such as systemic therapy, locoregional procedures or liver surgery. Radiation protection prescription after discharge of patients undergoing 131I-MIBG, 131I-NAI and 177LU-dotatate therapies Clin Transl Imaging (2022) 10 (Suppl 1):S1-S111 Background-Aim: This work is aimed to propose a protocol for the discharge patients undergoing treatment with 131I-NaI, 131I-MIBG and 177Lu-DOTATATE based on the patient specific biokinetics. Release criteria and radiation protection safety recommendations have been determined according to the criteria established by European Commission Directive 2013/59/Euratom and their transposition in the Italian law. Methods: In the study have been included administration of 177Lu-DOTATATE (22 treatments), 131I-NaI (61 treatments) and 131I-MIBG (79 treatments) and have been analyzed dose rate at different distances of pediatric patients. Data have been used to evaluate the radiation protection precautions after dismissal of radioactive patients through a calculation model tailored on patients age and needs. Since younger patients need assistance even during hospitalization, caregivers exposure have been estimated through electronic dosimeters and these exposures were taken into account for the evaluation of prescriptions after patients discharge. Results: Effective doses for caregivers of younger patients resulted up to 10 mSv during hospitalization for 131I-MIBG administrations. Radiation protection prescriptions have been evaluated considering the dose constraints for public and caregivers according to the Euratom Directive transposition in the Italian law. For public, obtained results showed that some days of abstention from these activities are necessary especially for patients undergoing 131I-MIBG therapies. Caregivers precautions have been evaluated stratifying patients in different age classes in order to consider that the younger is the patient, the more he need to receive contact assistance. The proposed method has the potential to be a very useful tool to evaluate radiation protection precautions for public and caregivers. It can be achieved and adapted to all patients, radiopharmaceutical and situations since it is based on the patients biokinetics, measured dose rate and social contact information. Background-Aim: 177Lu-Lutathera Ò was recently employed for radiometabolic treatment of neuroendocrine tumours at our hospital. Before treatment, an adjustment of dose calibrator was necessary because 177Lu is not included in control unit. Radioprotection measurements and dose estimate were then carried out in vial and phantom to evaluate dosimetric impact on involved operators considering that patient undergoes a total of four radiopharmaceutical administration of 7400 MBq each. In addition, spectrometry of residual radiopharmaceutical was performed to assess contamination due to Lu-177 m. Methods: A calibrated activity of 177Lu (approximately 7400 MBq) was sent to Nuclear Medicine Department to adjust two Biodex Atomlab100 dose calibrators according to manufacturer instruction. Vial was inserted in the housing and tuning was made to match the exact activity reported in calibration certificate. The same vial was then inserted in a home-made phantom (consisting of two 5 L water bags arranged in sandwich around the vial) and exposition measurements were made at various distances with a Victoreen 450P ionization chamber. Forty days later, the same vial was then used to irradiate for 88 h a set of 10 thermoluminescence dosemeters (TLD LiF100) which were then read in a Harshaw 6600 reader in order to verify the accuracy of previous acquisitions by means of effective dose calculation. Therapeutic dose of Lutathera Ò was injected by infusion pump in approximately 40 min and radiopharmaceutical manipulation, administration and patient assistance timing were accurately measured as well as dose rate and distances between operator and radioactive source (vial, patient) to exactly evaluate absorbed dose. By means of HpGe ORTEC detector and Gammavision analysis software, spectrometry of residual was achieved and contamination activity was calculated taking into account 228 keV emission of Lu-177 m (160 days halflife). Results: A calibration factor of 116 was found for both Atomlab 100 dose calibrators, in total agreement with manufacturer suggested value of 115 for 177Lu (percentage difference activity between measured and expected calibration factor of just 1%). Dose rate measurements were normalized for present activity and reported as a function of distance for vial and phantom to calculate exposition at any distance. As an example, a dose rate of 6.57 lSv/(h*GBq) at 1 m was found for vial source while 3.16 lSv/(h*GBq) is the dose rate from phantom at the same distance. From measured manipulation, administration and assistance timing an effective dose of respectively 0.13 lSv, 6.2 lSv and 14.4 lSv resulted for involved operators per treatment. A very good agreement was found with 10 exposed TLD reading proving that routine dosimetry with LiF100 is reliable even for b emitters such as 177Lu. Contamination from Lu-177 m was radiologically non relevant and even less than 0.02% stated by manufacturer. Conclusions: Dose calibrator adjustment, dose rate measurements together with timing to carry out specific tasks (radiopharmaceutical manipulation and administration, patient assistance) have made it possible a first assessment of radiological impact on operators envolved in treatment with Lutathera Ò . The presence of Lu-177 m is not a problem in solid nor in liquid waste management. This is the starting point for more detailed evaluations when routine personnel TLD dosimetry evidences will be available. Patient-specific dose class in nuclear medicine according to D. LGS 101/20 and 0.0486 ± 0.018, 0.0240 ± 0.016 and 0.0144 ± 0.004 for ALGO-3 (all p \ 0.0001). Compared with REF, ALGO-2 and ALGO-3 led to a percentage reduction in the ACR of 10.0% and 9.2%, respectively, in females, and of 4.1% for both ALGO in males. In these three age brackets, when ALGO was compared to REF, the changes in ACR were respectively -20.1%, -18.7%, ? 8.2% for ALGO-2, and 20.3%, -17.0%, ? 7.4%, for ALGO-3. Conclusions: This study demonstrates the need to consider age and sex, both decisive factors influencing the risk of radiation, when prescribing a dose of PET tracer. Further prospective studies are needed in order to identify the appropriate dose for a given patient a priori, calculating it on the basis of relevant parameters, such as weight, age and sex. Background-Aim: 177Lu-PSMA-617 radioligand therapy (177Lu-PSMA) is a promising treatment for patients with metastatic castration resistant prostate cancer (mCRPC). A standard activity of 7.4 GBq at 6 weeks intervals for a total of four to six cycles is the standard regimen. We present our dosimetric protocol to measure Organs At Risk (OARs) absorbed dose and relevant parameters to define radiation protection and safety necessities. At moment six patient were enrolled for therapy and for only 3 patients dose evaluation of kidneys, salivary glands and red marrow were performed. Methods: The protocol includes the infusion of a 10% mannitol solution as protector agent and an external ice pack cooling strategy was used with the aim of reducing blood flow supply to salivary glands. SPECT-TC images were acquired at different times post injection (2.5 h, 20 h and [ 90 h pi). The activity concentration in kidneys, parotid glands (PGs) and submandibular glands (SMs) was determined by dosimetry toolkit (Q.Volumetrix Ò , a resident software of SPECT/CT Discovery NM/CT 670 system by GE Healthcare) and the absorbed dose was obtained using residence time and personalized organ masses as input data for the OLINDA/EXM Ò software. Moreover, red marrow absorbed dose was assessed by counting blood samples (taken at 0.5, 1.5, 6, 20 and [ 90 h pi) using a NaI (Tl) well counter. Measurements with external gamma probe at different time points (before any excretion, after first voiding bladder and at 1, 1.5, 4, 20 and [ 90 h pi) were carried out to collect the radiation contribution of the entire body of the patient and to estimate the activity within the body of the patient and therefore also that excreted. The retention of 177Lu-PSMA was modelled on a bi-exponential decay process with As and Al the constants of the short and long component and ks and kl the effective decay constants. Dose rates with ionisation chamber at 1 m at discharge (20 h pi) were measured to determine appropriate radiation precautions to be followed in order to comply with national law (D.Lgs.101/2020). respectevely. Mean exposure rate at 1 m at discharge is 12.9 microSv/ h (5.8-20 microSv/h). Conclusions: Our initial experience indicates that dosimetry can be easily realised in routine practice if the patients' compliance allows it. Our dosimetric results are still preliminary but no significant differences were found with recent published data. Comparison between three dosimetry protocols to implement the personalized dosimetry in patients treated with 177LUdotatate Background-Aim: Radio ligand therapy (RLT) is a rapidly developing field, as with any radiotherapeutic treatment is based on measures the Absorbed Dose (AD) to Organ At Risk (OAR) and tumors to implement a patient-specific treatment plan. Dosimetry is time-consuming and requires specialized personnel. On thirty patients with Neuroendocrine Neoplasms (NENs), enrolled in our Institute for PLT with 177 Lu-DOTATATE (four cycles of Lutathera Ò , 3.7 GBq every 8 weeks) dosimetry has been done for any cycles (Standard Method: M0). Based on these data we proposed two simplified protocols for dosimetry: method 1 (M1) uses the dosimetry data calculated after the first administration to predict the cumulated dose from the other cycles; Method 2 (M2) uses the data from the first and last cycles. This strategy allows improving patient comfort and reduced scanner and staff time. Methods: The AD in the OAR (spleen, kidneys, liver, and red marrow) and tumors was evaluated with three sequential abdomen SPECT/CT images at 3, 20, and 70-120 h post-injection, reconstructed using the OSEM method (4 iterations, 10 subjects) and corrected for attenuation, scatter and resolution recovery. The resident software Q.Volumetrix Ò (GE Healthcare) was used to determine activity concentration in OAR and tumors. The AD was obtained using residence time and personalized organ masses as input data for the OLINDA/EXM Ò software. Moreover, the red marrow absorbed dose was assessed by counting blood samples using a NaI (Tl) well counter. These data represent our standard dosimetry protocol (M0). Results: Planar sensitivity factor was 6.5 cps/MBq. Recovery coefficient varied from 0.76 (26.5 ml) to 0.25 (0.55 ml). Thirty patients (13 males, 17 females) had completed all four cycles and the activity administered was 7.3 ± 0.3 GBq/cycle. In OAR, the cumulative AD received after 4 cycles were for kidneys: 16 ± 4 Gy; red marrow: 1 ± 0.5 Gy; spleen: 18 ± 8 Gy; liver: 19 ± 23 Gy. While its range in lesions was for pancreatic tumors 22-267 Gy (mean 114 Gy) and metastatic lesions 40-262 Gy (mean 134 Gy), with a high variability among the patients. Cumulative ADs with M1 or M2 were obtained with the mean difference from the M0 protocol of 14% and 6% for kidneys; 23% and 7% for spleen; 37% and 10% for liver; 20% and 7% for red marrow; 44% and 10% for tumor respectively. Pearson's correlation coefficient for kidneys, red marrow, spleen, liver, and tumour is 0.87, 0.95, 0.84, 0.94, 0.81 between M0 and M1 methods, and 0.95, 0.99, 0.99, 0.99, 0.97 between M0 and M2. Conclusions: Pearson's correlation coefficient values show that among the three methods there are a good agreement. Our experience indicates that a simplified protocol for dosimetry is an acceptable compromise among the outflow of resources and useful patientspecific information. The simplified protocols, M1 or M2, permit to predict the cumulative absorbed dose to OAR. Instead, for tumor doses, M2 is more accurate than M1 because it takes into account the change in the uptake during the RLT cycles. By providing methods to simplify and potentially automate radiation dosimetry, we hope to accelerate the understanding of radiobiology and the development of dose-response models in this unique therapeutic context. Background-Aim: Radioactive 131 I (RAI) therapy is used in patients with differentiated thyroid cancer (DTC) after total thyroidectomy for remnant ablation, adjuvant treatment or treatment of persistent disease. 131 I retention data, which are used to indicate the time at which a 131 I treated DTC patient can be released from the hospital, may bring some insights regarding clinical factors that prolong the length of hospitalization. The aim of this study was to investigate the 131 I whole-body retention in DTC patients during 131 I therapy. Methods: We monitored 166 DTC patients to follow the 131 I wholebody retention during 131 I therapy with a radioactivity detector fixed on the ceiling of each protected room. A linear regression fit permitted us to estimate the whole-body 131 I effective half-life in each patient, and a relationship was sought between patients' clinical characteristics and whole-body effective 131 I half-life. Results: The effective 131 I half-life ranged from 4.08 to 56.4 h. At multivariable analysis, longer effective 131 I half-life was related to older age and extensive extra-thyroid disease. Conclusions: 131 I effective half-life during 131 I treatment in DTC patients is highly variable among patients and is significantly longer in older and in patients with RAI uptake in large thyroid remnants or in extrathyroidal disease that significantly prolongs the whole-body retention of 131 I. Background-Aim: Dosimetry for 177Lu-DOTATOC radioligand theraphy (RLT) is usually performed to ensure dose calculation to tumor and organs-at-risk (OAR). Despite its usefulness, it is considered time and resource consuming as requires multiple post-therapy SPECT/CT scans. Often data collection has to be stopped on the 2nd or 3rd day after therapy for logistic reasons. This study aims to assess the impact on dosimetry by reducing the number of SPECT/CT scans in NET patients undergoing RLT. Methods: In our clinical practice (phase II study FENET 2016-University Hospital S. Anna Ferrara, Italy), dosimetry routinely relies on SPECT/CT scans acquired at 3-time points (3TP), i.e. 1, 24 and 48 h after treatment. Tumors and OARs absorbed doses are calculated following the MIRD scheme, by considering the activity concentration in the primary tumor, kidneys and L2-L4 lumbar vertebrae for bone-marrow (BM). This approach, which is assumed as a reference standard for present analysis, was compared with a shorter 2-time points (2TP) approach. The 2TP protocol includes a 1, 24 h acquisitions and a pseudo-48 h point extrapolated through application of effective half-life derived from the literature. A sample of 50 patients with metastatic neuroendocrine tumors after RLT was analysed. For these patients, the time-integrated activity for both 3TP and 2TP methods was calculated by the uptake curve via OLINDA/EXM. In order to test the consistency of measured dose after 48 h in 3PT vs the extrapolated dose in 2TP, bilateral t-test was applied with a significance level of 0.95. Results: According to our results, 2TP dosimetry estimates were in agreement with 3TP measurements for kidneys [p-value = 0.23 on effective half time; p-value = 0.9 on absorbed dose per administered activity], corresponding to a mean relative difference of less than 8%. The same test was carried out for BM, whereas the 3PT dose measurement appears to be significantly different from the level calculated through the 2PT method [p-value \ 0.01 on both effective half time and absorbed dose per administered activity]. Finally, for tumors a significant difference was observed on effective half time [pvalue \ 0.01], while 2TP absorbed doses per administered activity were in agreement with 3TP measurements [p-value = 0.85]. Conclusions: According to the present study, 2PT dosimetry approach might represent as a feasible tool for faster therapy management and a viable method to improve the patient's comfort. 2TP protocol dosimetry can be considered suitable for monitoring OAR toxicity. For the BM, even though the difference between 3 and 2TP method is statistically significant, the reduction of the number of SPECT/CT scans does not have clinical impact because dose values are well below the threshold value of 2 Gy. However, the applicability of the 2TP protocol will require additional investigations. Background-Aim: In DTC radioiodine therapy, the generally accepted surrogate dose threshold to avoid myelotoxicity, according to Maxon and Benua pioneeristic work, is 2 Gray (Gy). Most of the internal dosimetric measurements, based on MIRD formalism, differ from one another in execution technique, biological features estimation and algorithm calculation. These methods need blood sampling for plasma radioactivity quantification and whole body retention measurements by Geiger-Muller-type counter. In 2009 Hänscheid proposed a new simple method for bone marrow adsorbed dose estimation, based on a single external measurement of body activity retention without any blood sampling. Aim of our study is to develop a new simple method based on two external body activity measurements (with no blood sampling) to estimate bone marrow absorbed dose. We compare this new method (called 2 M) to the conventional AIFM/AIMN method in order to evaluate its accuracy. Methods: The study included 33 DTC patients, aged 24-84 years old (mean 52.5 years old), 22 females and 11 males, admitted to our unit to undergo radioiodine therapy. During hospitalization we perform seven external whole body retention measurements and four blood samples, according to AIFM/AIMN protocol. Body retention measurements were performed with a GM Rotem RAM DA-3 counter, positioned 4 m from the patient. Our 2 M method takes into account only the 2nd and 24th hourmeasurements of body activity retention, already detected during the AIFM/AIMN dosimetric protocol, in order to estimate radiation absorbed dose to the red bone marrow with Hänscheid algorithm. Obtained data first underwent inferential statistical analysis by Student's t-test to verify if the differences between the averages of the values recorded with the two methods could be negligible. After verifying that the hypothesis may not be false (P [ a) , the data were compared with the Bland-Altman method to evaluate the measurement differences between the two methods. Results: Our results show that the whole body retention measurements with the 2 M method provide the same limits of agreement amplitude as those obtained with the AIFM/AIMN reference method. The bone marrow absorbed dose measurements obtained with the 2 M method seem to have the same accuracy when compared to conventional dosimetry with the AIFM/AIMN method. Conclusions: The 2M method is more simple to perform, easier to perform, less invasive and expensive with respect to the conventional method in the estimation of bone marrow absorbed-dose. Radiolabelling, chemical and biological characterization of oncofap derivatives F. Bartoli 1 , P. Elsinga 2 , L. R. Nazario 2 , A. Zana 3 , A. Galbiati 3 , J. Millul 3 , F. Migliorini 3 , S. Cazzamalli 3 , D. Neri 4 , R. Slart 2 , P. A. Erba 1 [ 68 Ga]FAPI-46 activity collected in a sterile multidose vial was enough for multiple patients' administration. Conclusions: The performance of synthesis method for [ 68 Ga]FAPI-46 was evaluated in a clinical trial where 37 patients were studied so far, in the staging of suspected or confirmed cases of lung, ovarian and breast cancer. The labeling conditions provided [ 68 Ga]FAPI-46 with a good and reproducible yield as well as good radiopharmaceutical quality with high radiochemical and radionuclidic purity. The developed synthesis method showed to be a useful and reliable method for [ 68 Ga]FAPI-46 production for clinical trial use. Background-Aim: Photo-thermal therapy (PTT) represents a promising thermo-ablative cancer treatment inducting cell death through the hyperthermia generated when plasmonic nanoparticles are exposed to laser light. Effective PTT with gold nanoparticles (AuNPs) requires both selective AuNPs uptake in tumoral tissues and reliable tracking of AuNPs biodistribution. We provided a 99mTc radiolabeling strategy of keratin-coated AuNPs (Ker-AuNPs) for single photon emission computed tomography (SPECT)-imaging to be applied as a valuable nanoplatform for future functionalization with targeting molecules and subsequent PTT applications. Methods: Both direct and indirect radiolabeling strategies were tested by systematically varying several experimental parameters, such as temperature, time of incubation, pH, use of functional chelators and addition of reducing agents, in order to evaluate their relevance in radiolabeling procedure. The radiochemical purity (RCP) of obtained 99mTc-labeled Ker-AuNPs was evaluated through instant thin layer chromatography-silica-gel (ITLC-SG) and ultraviolet-visible (UV-Vis) spectroscopy to assess colloidal stability and optical quality. Photothermal tests were designed to investigate the ability of 99mTc-Ker-AuNPs to generate the desired temperature increase under resonant laser illumination (# = 532 nm). Results: Optimal conditions for reaching an effective 99mTc labeling of Ker-AuNPs was achieved by incubating the colloidal dispersions at 37°C for 15 min, at physiologic pH (7.35-7.45 ). The indirect approach involving diethylene triamine pentaacetic acid (DTPA) as a metal chelator obtained the best RCP performance. UV-Vis spectrum showed a 26 nm red shift of plasmon peak along with spectral broadening, suggesting surface modification and alteration of colloidal features of Ker-AuNPs. ITLC-SG radiochromatograms depicted a significant modification of radioactivity distribution: in saline solution a radioactivity mark was left at the origin, suggesting the formation of radiocolloid, while with methyl ethyl ketone (MEK) as mobile phase, 99mTc was largely left at the origin, implying the formation of new 99mTc-DTPA-Ker-AuNPs. The obtained ITLC-SG layer was purposely analyzed from a thermoplasmonic perspective showing a significant temperature increase ([ 40°C) in the site where radioactivity had been previously revealed. Conclusions: We showed a reliable 99mTc-radiolabeling procedure of a new generation of biocompatible nanotherapeutics for cancer treatment. The presence of 99mTc easily allows revealing Ker-AuNPs accumulation in tissues through SPECT-imaging, thus enabling precise and accurate spatial localization. The obtained 99mTc-DTPA-Ker-AuNPs could provide a valuable platform to develop a nanocompound suitable for highly selective PTT cancer ablation. Reported results, although preliminary, are extremely promising, deserving further and detailed research. Diagnostic performance of [68GA]GA-PSMA-PET-CT in nonprostatic PSMA-expressing neoplasm: a preliminary prospective single center experience 15 Department of Hematology, IRCCS-Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori General Hospital Ca' Foncello Nuclear Medicine Department Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico MED Foundation, 90133 Palermo, Italy. 3 Institute of Molecular Bioimaging and Physiology, National Research Council (CNR), 90015 Cefalù, Italy. 4 Department of Biomedical and Dental Sciences and of Morpho-Functional Imaging University Hospital ''Paolo Giaccone CT radiomics in Hodgkin's lymphoma: the predictive role of the largest and the hottest target lesions Servizio Integrativo PET/CT -Radiofarmacia Department of Radiology, UCDavis, Sacramento, USA Background-Aim: Aim of the study was to retrospectively investigate the predictive role of baseline 18F-FDG PET/CT (bPET/CT) radiomics from two different target lesions in a large monocentric cohort of patients with Hodgkin's Lymphoma (HL) Wilcoxon test identified the most promising features (p \ 0.05) from both lesions with regards to DS (\ 4 or C4) and PFS (''no event'' or ''event'' at 24 months); all possible radiomic bivariate models were built through Logistic Regression analysis and trained/ tested with a cross-fold validation test. Finally, the best bivariate models were selected depending on ROC curves, mean AUC (mAUC) and Standard Deviation to the normal. Differences among our 2 scanners' performances were also evaluated. Results: 229 patients were included. The best bivariate models for DS prediction had a mAUC of 0.78 ± 0.05, with predominant contribution of Lesion_A features to the combinations. The best bivariate models for 24-months-PFS prediction reached 0.74 ± 0.12 mAUC and mainly depended on Lesion_B radiomic features. A significantly different behavior was observed between scanners' performances. Besides, for DS prediction, 0.95 ± 0.06 mAUC was reached with Lesion_A features, on Scanner_1. For 24-months-PFS prediction, Lesion_B features reached a mAUC of 0.87 ± 0.14, on Scanner_2. Conclusions: In HL patients, bPET/CT radiomic features from the ''largest'' and ''hottest'' lesions may provide relevant information in terms of early-treatment-response and prognosis, respectively, therefore supporting earlier and stronger decision-making in therapeutic strategies Medical Physics Department were considered. Patients were all previously treated with SSA followed by radiological disease progression (PD). Haematopoietic, liver and renal toxicities were collected every 14 days and graded according to CTCAE v5. The population was subdivided as midgut/foregut and G1/G2, according to WHO2019. Patients were categorical grouped according with ECOG-PS, number of metastatic sites, previous treatment lines (1, [ = 2) and therapies received before LRT. To test independence between CTCAE and patient characteristics Pearson/Fisher and Kruskal-Wallis test were assessed. Logistic regression with Firth correction (R Puhr, Stat Med2017) and bootstrap procedure were performed to determine predictability of clinical features and previous therapies for CTCAE onset. Results: 67 patients (31 (46.3%) males, 36 (53.7%) female, mean age 63) were selected. Thirty-eight (56.7%) were classified as midgut, 29 (43.3%) as foregut, 24 (35.8%) G1 and 43 (64.2%) G2. Alkylating chemotherapy and Everolimus were the previous treatments in 13 (19.4%) patients, in both cases. Patients were treated with LRT as third or further lines in 34.3% (23) of cases It is approved as definitive therapy, as bridge to transplantation and as downstaging to surgery. RE is safe in carefully selected patients suffering from HCC, with low although potentially life-threatening complication rates. RE has been proven to be as effective as other currently available treatments. PO152 Five years follow up of ''LU-X'' trial: combined use of 177LU-dotatate and metronomic capecitabine in FDG Nuclear Medicine, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) ''Dino Amadori in IRST ''Dino Amadori''-IRCCs of Meldola (FC), 33 DPD-proficient patients with progressive metastatic or inoperable, FDG positive G1-G3, GEP-NETs (Ki67 \ 55%) were evaluated for response in Lu-X phase I/II trial. They received 5 cycles of 5.5 GBq 177 Lu-DOTATATE each, at all Lu-X patients and by review of IRST in Meldola or physicians' records. Results: After a median follow-up of 63 months (range: 12.6-74.1) a mPFS was 21.2 (range:16.7-36.43) whereas a mOS has not been reached yet. The OS at 60 months from treatment start (95% CI) was 64.8 (range:30.9-85.2) months in patients with Ki67 B 2% and 77.8 (range:51.1-91.0) in those with Ki67 3-20% (p = 0.427). According to the primary tumor site, PFS was 17.7 months (range:14.9-31.4) in pancreatic NETs and 34.3 months (14.2-58.1) in GI-NETs, without statistically significant difference (p = 0.467). The OS at 60 months from treatment start The following PET-based parameters both for the most active lesion (reference lesion, RL), and whole-body (WB) skeletal tumor burden were calculated: SUV max RL, SUV mean RL, metabolic tumor volume (MTVRL) and total lesion activity (TLARL), as well as MTVWB and TLAWB, number of bone metastases (BM), and Bone PET Index (BPI) considered as the percentage of skeletal involvement. These parameters were correlated with Ra223 completion, toxicity and efficacy using Mann-Whitney test and multivariate linear analysis, while they were tested as predictors of OS through Kaplan-Meier and Multivariate Cox analyses (p \ 0.05). Efficacy was assessed as biochemical (ALP and PSA), clinical (pain Multivariate analysis showed a strong correlation between Ra223 completion and TLAWB (p \ 0.001), BPI (p = 0.019) and the number of BM (p = 0.002), with lower values in patients who completed therapy. Similarly, TLAWB (p = 0.015) and MTVWB (p = 0.031) significantly correlated with instrumental response, with lower values in case of partial response or stable disease. Regarding the effect on survival, Ra223 completion significantly correlated with OS (p = 0.007). A significant difference in OS among patients stratified by the median values of the MTVRL (p = 0.036), TLAWB (p = 0.024) and BPI (p = 0.049) was found. Multivariate Cox analysis confirmed TLAWB Efficacy was evaluated in terms of biochemical (ALP and PSA), clinical (pain, established by Brief Pain Inventory Short-Form), and instrumental response (partial response/stable disease vs. progression). Results: Among all patients, 24/53 (45%) completed Ra223 therapy. Median OS was 75 months (range: 1-71). Median bPSA and bALP were 10.4 ng/ml and 198 U/l, respectively. Median value of bHb Almost all the exams performed with 18 F-Cholina (98%) reported a dose class IV. The examinations involving the highest dose class (IV) were WB PET/CT and 18 F-Choline PET/CT because of the CT component. The best patient characteristic discriminating the dose class in PET/TC was the patient weight. A weight cut-off of 73.5 kg (AUC 0.98) and 62.5 kg (AUC 0.95) was found for brain and WB PET/CT (between dose class II to III and from III to IV, respectively). The addition of CT scans of anatomical details increased the percentage of patient in the highest dose class. For WB PET/TC, vasculitis, melanoma and kidney/bladder investigations involved dose class IV in more than 94% of cases. Conclusions: A specific dose class assessment should be performed at each center, particularly for Nuclear Medicine procedure involving the highest exposures. A patient specific class dose assessment should be desirable Milwaukee (WI): a WB scan was performed on one of two scanners; a single FOV PET/CT acquisition on a target lesion was immediately performed on the second scanner. All patients were injected with 3 MBq/kg; time/FOV was 1:30 min for DIQ and 2 min for DMI. Images were reconstructed using 2 different algorithms: standard iterative OSEM with PSF correction (namely Vue Point, aVP) including also TOF for dPET (dVP) and the regularized Bayesian Penalized Likelihood, namely Q. Clear able to modulate the noise (beta factor set at 350 for aPET and 500 for dPET) 0300). For SUV peak values, the only statistically significant difference was obtained comparing aVP vs dVP (2.73-3.46; p = 0.0401). MV calculated on dPET were lower for both reconstructions: aVP vs dVP No other differences were found. Conclusions: Our data didn't show significant improvement of lesion detectability with dPET compared to aPET, but we have a limited population that need to be incremented; conversely, dPET demonstrated significantly improved quantification and reduction in MV values, regardless the reconstruction algorithm Age at the time of exposure and gender are nonetheless two key factors, which can CT. Methods: The study involved 421 consecutive patients (57% male, mean age 63.6 ± 14.3 years, range 18-90 years) who underwent PET for various clinical indications. The radiation exposure for each PET scan was assessed in terms of effective dose (ED in mSv), and additional cancer risk (ACR), both in a reference condition (REF) and after applying an original algorithm (ALGO). The ALGO inversely modified the mean dose of FDG and the PET scan time parameters by 20%: younger patients had a lower dose and a longer scan time, while older patients had a higher dose and a shorter scan time. Patients were divided by age into: two groups for ALGO-2 (with half the patients in each, younger versus older); and three for ALGO-3 (with one third of the patients in each group, younger versus middle-aged versus older). Patients were also classified by age bracket (18-29 years old [17 pts, 4%]; 30-60 years old respectively, in males (REF vs ALGO-2 and ALGO-3 p \ 0.0001). For the three age brackets We consecutively enrolled pts affected by malignancies with possible PSMA overexpression, according to the literature, with the following inclusion criteria: (1) thyroid cancer (TCa) poorly differentiated and/or undifferentiated carcinoma, refractory to radioiodine therapy and/or with increased thyroglobulin after radical surgery, with negative, doubtful or positive imaging that not justify TG level (e.g. US, CT, MRI and [18F]FDG-PET-CT); (2) hepatocellular carcinoma (HCC) suitable for liver resection or orthotopic liver transplant, with hepatic nodules equivocal for HCC detected by contrast-enhanced magnetic resonance imaging (MRI); 3)Symptomatic multiple myeloma (MM) recently diagnosed (according to the updated CRAB criteria of the IMWG-International Myeloma Working Group) and previously staged with [18F]FDG-PET-CT. Exclusion criteria are pregnancy and age \ 18. Images were reviewed independently by two different nuclear medicine physicians. All areas of focal visual PSMA uptake have been compared with standard imaging TCa: 5/7 pts showed significant PSMA overexpression (2 pts with lymph nodal uptake, 2 with bone focal uptake and 1 local relapse). HCC: PSMA uptake was seen in 3/5 pts (2 with focal uptake in the nodule suspected for HCC; 1 with focal uptake within a regenerative nodule detected by MRI, but no uptake in the nodule suspicious for HCC). MM: in comparison with [18F]FDG-PET-CT, 1 pt showed extramedullary lesions with concordant PSMA uptake and similar-to-milder PSMA uptakes at the level of 3 pathological vertebral collapses. The other pt did not show any pathological FDG or PSMA uptake. Conclusions: These very preliminary results confirm a potential clinical interest of PSMA 4 Radiopharmacy, IRCCS Sacro Cuore don Calabria, Negrar, Verona. 5 Hospital Pharmacy IRCCS-IRST ''Dino Amadori National Association of Hospitals Medical Directors (ANMDO) Italian Society of Clinical Risk Management (SIRiC) Background-Aim: Advances in precision oncology results in an increased request for predictive tools able to select and stratify patients for treatments. In this contest machine-learning radiomics is a promising approach to improve the clinical management of non-small cell lung cancer (NSCLC). We aimed to use machine learning to evaluate the prognostic role of radiomic feature-based (18F) fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging in NSCLC patients. Methods: 321 NSCLC patients that underwent PET/CT with FDG before any therapy. Patients were divided in two groups: early stage group (n = 79) and advanced stage (n = 242). A total of 42 radiomics features and standardized uptake values (SUV max ) were extracted from PET studies. Feature selection occurred with a 3-step process consisting of: 1) Spearman's rank correlation versus clinical stage; 2) least absolute shrinkage and selection operator (LASSO) regression model; 3) evaluation of model predictive performance with bootstrap resampling and area under the curve (AUC). Results: The variable combination that best distinguished the two groups of patients included 8 textural features and SUV max . All considered statistical features (specificity, sensitivity, Chi-Square, relative risk and 95% confidence interval, 95% CI) indicate a higher statistical significance of the combined model vs SUV max . This combined 9-parameter model predicted progression-free survival (P = 0.0006 and P = 0.01) and overall survival better than SUV max alone (P = 0.0003 vs P = 0.08). Conclusions: These data indicate that machine learning radiomic analysis can improve subjects stratification in NSCLC patients and can be used to predict survival in NSCLC with greater statistical power than SUV max alone. Machine learning model to predict diagnosis of mild cognitive impairment by using radiomic and amyloid brain PET Background-Aim: The study was aimed to develop a deep learning model for predicting the diagnosis of amnestic mild cognitive impairment (aMCI) using radiomic features and amyloid brain positron emission tomography (PET). Methods: 328 subjects from Alzheimer's Disease Neuroimaging Initiative database and EudraCT 2015-001184-39 trial (159 males, 169 females), mean age 72 ± 7.4 years underwent PET/CT with [18F]-Florbetaben. Study cohort consisted of normal controls (n = 149) and subjects with aMCI (n = 179). For each of the 27 selected brain cortical areas, 13 Gray-Level Run-Length Matrix (GLRLM) radiomic features and standardized uptake values (SUV) were extracted. Least absolute shrinkage and selection operator (LASSO) regression was used to select features with highest predictive value. Feed-forward neural multi-layer network was trained, validated and tested on 70%, 15% and 15% of sample respectively. Accuracy, precision, F1-score and area under the curve (AUC) were used to assess model performance. SUV performance in predicting the diagnosis of MCI was also assessed and compared with that obtained from the machine learning model. Results: Machine learning model achieved an area under the receiver-operating characteristic (ROC) curve of 90% (95% CI 89.4-90.4) on test set with 80%, 78% for accuracy and F1-score respectively). Deep learning model ROC space outperformed SUV performance (AUC 75%, 95% CI 74.5-76.1), with 57%, 50% for accuracy and F1score respectively). By using radiomic and amyloid PET load, machine learning model identifies aMCI subjects with 84% specificity and 81% sensitivity. Conclusions: These findings show that deep learning algorithm based on radiomic data and amyloid load obtained from brain PET images improves the prediction of aMCI diagnosis compared to SUV alone. Background-Aim: High-risk neuroblastoma (HR-NBL), which amount up to 50% of newly diagnosed neuroblastoma cases, is an aggressive malignancy with a high propensity towards metastatization. 18 F-DOPA PET/CT is a sensitive tool to assess the disease spread and the overall tumour burden. However, the prognostic utility of standard 18 F-DOPA PET, such as SUV is limited. In this study, we tested the efficacy of textural PET parameters (defined as ''radiomics'') in predicting the treatment response as well as survival. Methods: The institutional database was retrospectively searched for HR-NBL patients with available 18F-DOPA PET/CT at diagnosis. A texture analysis of the primary tumour was carried out on the PET images using LifeX Ò . Conventional, histogram, GLCM, GLRLM, NGLDM, and GLZLM parameter were extracted; their values were compared with the overall tumour burden (WBMB), the treatment response, and the overall/progression-free survival. Results: Eighteen patients (6 females, median age 27 months, range 4-71 months) were included in the analysis. At bivariate analysis, many parameters, including SUV mean (p = 0.004), entropy (p = 0.026), GLCM_Contrast (p = 0.001) showed a positive correlation with WBMB; homogeneity (p = 0.026) and GLCM_Homogeneity (p = 0.006) showed an inverse correlation with the metabolic burden. At uni-and multivariate analysis, some parameters (GLRLM_run-length_nonuniformity, GLZLM-SZE, and GLZLM_zone-percentage) were associated with response to the induction therapy (p \ 0.05); moreover, a number of parameters GLCM-Contrast, NGLDM_Contrast, and SUV mean were the best predictive parameters of both overall and progression-free survival (p \ 0.01). Conclusions: In this pilot study, many textural parameters linked to the lesions' heterogeneity and the intensity of the 18 F-DOPA were Background-Aim: To investigate the application of [18F]FDG PET/ CT images-based textural features analysis to propose a radiomics models able to early predict disease progression and survival outcome in metastatic colon cancer patients after first-line treatments. Methods: We retrospectively analyzed fifty-two colorectal metastatic patients who underwent restaging [18F]FDG PET/CT during the restaging process of the disease after first-line therapy. Follow-up data were recorded for a minimum of 12 months after PET/CT scan. PET/ TC images were imported in LIFEx toolbox to extract 105 and 66 features from each avid lesion in PET and low-dose CT images, respectively. A statistical system based on correlation matrix and point-biserial-correlation coefficient has been implemented for features reduction and selection, while Discriminant analysis (DA) was used as a predictive model. In order to assess the performance of the features in predicting progression disease we performed: per lesion analysis (standalone PET dataset; PET/CT dataset); per patient analysis (standalone PET dataset; PET/CT dataset); only liver lesions analysis (only PET dataset; PET/CT dataset). All lesions were again considered to assess the diagnostic performance of the features in discriminating only liver lesions. Results: In predicting progression disease in whole group of patients, on standalone PET features radiomics analysis, among per lesion analysis, the feature selected as more accurate for the DA classifier was GLZLM_GLNU, while 3 features (GLZLM_ZLNU and GLRLM_SRHGE among the CT features and GLZLM_GLNU among the PET features) were selected from PET/CT images dataset obtaining a mild empowerment of the accuracy when CT features analysis was merged with PET features performances (AUROC 65.22%). In per patient analysis for standalone PET images, 3 features (GLZLM_ZLNU, GLZLM_HGZ, CONVENTIONAL_RIM_SUVbwstdev2) and 1 feature (CONVENTIONAL_HUKurtosis) considering the PET/CT dataset were selected by DA classifier (AUROC 61%). Performances in prediction of disease outcome by defining at liver per-lesion analysis one PET feature (GLZLM_GLNU AUROC 39.94%) from standalone PET images and three PET/CT features (GLZLM_ZLNU, and GLRLM_SRHGE between the CT features and GLZLM_GLNU between the PET features with AUROC 55.26%) were identified. Similarly, in liver lesions per patient analysis, we found three PET features (GLZLM_ZLNU, GLZLM_HGZ, CONVENTIONAL_RIM_SUVbwstdev2 with AUROC 60.11%), and a PET/CT feature (CONVENTIONAL_HUKurtosis with AUROC 43.48%). In discrimination of liver metastasis from the rest of the other lesions optimal results of standalone PET imaging were found for one feature (DISCRETIZED_SUVbwmin; AUROC 88.91%) and two features for merged PET/CT features analysis (DIS-CRETIZED_HISTO_Energy between the CT features and Background-Aim: Radioiodine (RAI) is one of therapeutic options for a complete thyroid ablation when definitive cure of hyperthyroidism is required. A personalized RAI activity could be performed to reduce radiation exposure and optimize the therapeutic effect. We retrospectively assessed the success rate of RAI therapy in these patients. Methods: We retrospectively enrolled children and adolescents with the diagnosis of hyperthyroidism treated with radioiodine in our Institute during the last 10 years (from 2011 to 2021). We collected patients' baseline characteristics, previous pharmacological treatment data, pre-treatment radioiodine simulation uptake parameters, thyroid scintigraphy parameters and estimated thyroid volume. In order to personalize and to calculate optimal RAI activity, the dosimetry was performed for all the patients using Snyder formula (AIMN guidelines, February 2005). Response to treatment was assessed after at least 6 months from RAI. The onset of hypothyroidism after RAI therapy was considered as therapeutic success, while persistence of hyperthyroidism as failure. Results: We analyzed 12 patients with hyperthyroidism (median age 15 (range 11-18), F:M 9:3). All patients were previously treated with anti-thyroid drugs (methimazole). Median RAI activity was 360 MBq (range 220-600 MBq). Successful treatment rate after a single dose was 66.67%. No significant short-term collateral effects were reported after therapy. Conclusions: Radioiodine is a feasible and safe therapeutic option for hyperthyroidism also in non-adult patients. This small and retrospective experience confirms the success rate of RAI treatment described in literature worldwide regard the young patients. Background-Aim: Nowadays, the use of Radium223 dichloride (Ra223) is restricted to patients with more than 6 bone metastases following at least two systemic therapies failure. The delayed employment of Ra223 in metastatic castration resistant prostate cancer (mCRPC) patients could affect therapy completion and effectiveness. For this reason, it is of utmost importance to select patients who might benefit from Ra223 therapy. We aimed to evaluate whether baseline biochemical, clinical and instrumental parameters can impact on Ra223 therapy completion and efficacy in this setting of patients. Methods: We retrospectively evaluated 53 mCRPC patients (mean age 73 y, range: 54-90), who received Ra223 between February 2016 and September 2021. We analyzed baseline biochemical (bPSA, Background-Aim: Fibroblast activation protein (FAP) is a membrane-bond enzyme overexpressed on the cell surface of cancer associated fibroblasts (CAFs), which highly populate the tumour microenvironment. Expression of FAP is widespread among various cancer types, making FAP an ideal antigen for tumor targeting applications. Over the past few years, several FAP-targeting radiopharmaceuticals have been designed for PET/CT imaging procedures, outperforming [ 18 F]FDG in different clinical indications (such as pancreatic cancer, primary liver tumors, GE tract-cancer and breast cancer). OncoFAP is a small organic ligand with ultra-high affinity for FAP. Methods: OncoFAP-DOTAGA derivatives have been already investigated for their in vivo biodistribution in preclinical models ( 177 Lu) and validated in more than cancer patients ( 68 Ga) for imaging procedures. In an effort to broaden the radionuclide options, we developed two novel OncoFAP-conjugates bearing NODAGA/NOTA as radiometal chelator for the incorporation of Al 18 F. In this ab stract, we present the development of automated radiolabeling procedures with FASTlab 2 module and simple-kit preparation for OncoFAPradio-conjugates and tested the biological proprieties and the biodistribution.Results: OncoFAP derivatives were efficiently radiolabelled using a FASTlab 2 synthesis module with either 68 Ga, 177 Lu or 18 F, affording high chemical purities ([ 99%). Moreover, we developed a novel simple kit (OncoFAP-kit) for radiolabeling OncoFAP-DOTAGA/ NODAGA with 68 Ga (radiochemical purity 95%). The binding properties of OncoFAP-radio conjugates were successfully assayed with co-elution and cell-binding experiments. Radiolabelled derivatives were also tested for their in vitro stability and lipophilicity. In all cases, no radiolysis was observed, hence validating the labelling procedures. While the radiolabeling of OncoFAP-NODAGA with Al 18 F was accompanied with a poor radiochemical yield, OncoFAP-NOTA showed a good conversion with 21% labelling efficiency and high purity. Encouraged by these promising results, we investigated the in vivo biodistribution profile of this novel unexplored derivative in tumour bearing mice. [ 18 F]AlF-OncoFAP-NOTA showed a remarkable selective tumour uptake at 1 h post injection (6.6% ID/g), with a favourable tumour-to-blood and tumour-to-kidney ratio of 6.5 and 4.3, respectively. Conclusions: OncoFAP-based radiotracers are endowed with high selectivity and rapid tumour uptake, therefore representing a breakthrough in tumour imaging. The high portability of OncoFAP enables its radiolabeling with 177 Lu, 68 Ga and 18 F in high yields and purity. These exquisite features pave the way for the safe application of OncoFAP radiopharmaceuticals in the clinical practice. Background-Aim: Fibroblast activation protein (FAP) is a type 2 transmenbrane serine protease, which is selectively overexpressed in cancer-associated fibroblasts (CAFs) in the stroma of many malignant neoplasms. Since FAP is considered a target of great interest for the development of tracers for imaging in oncology, clinical trials are needed to prove the effectiveness of tracers targeting FAP in the clinical diagnostics and reliable and robust methods for internal hospital production are also important for clinical use. The aim of this work was to evaluate the performance of the synthesis. method developed by our radiopharmacy for [ 68 Ga]FAPI-46, a quinoline-structure FAP inhibitor, in a FAPI-based clinical trial. Methods: Before clinical trial use, a synthesis method was developed evaluating different labeling parameters such as reaction time, precursor amount and the type of scavenger added to prevent radiolysis.[ 68 Ga]FAPI-46 production was carried out using an automated synthesis module equipped with sterile disposable cassettes (Modular Lab Pharm Tracer, Eckert & Ziegler) using the eluate obtained by 2 GalliaPharm generators (Eckert & Ziegler, 1850 MBq). The labeling reaction with FAPI-46 precursor (45 nmol, 40 lg, SOFIE) was carried out at 95°for 15 min. The resulting product was purified on SPE C18 column, eluted with ethanol and sterilized using a 0.22 lm filter. Results: Synthesis yield was 89.4 ± 0.8/% (n = 15) corrected for the decay in 25 min, excluding generators elution. Radiochemical purity was 99.7 ± 0.1% (RP-HPLC) and colloids (TLC) \ 3%, pH 5.5, ethanol and 68 Ge content complied with European Pharmacopoeia limits. The product was found to be sterile and apyrogenic. Background-Aim: 18 F-FDG PET/CT is the most accurate imaging method in differentiated thyroid cancer (DTC) patients with either an aggressive histology, an absence of radioiodine uptake in neoplastic foci, or an elevated serum thyroglobulin (Tg) level that progresses with time in the absence of known imaging abnormalities. We evaluated the diagnostic performance of FDG PET/MR in comparison with that of PET/CT. Methods: Following the injection of a single 18 F-FDG activity, simultaneous PET/MR and PET/CT were sequentially performed in 40 consecutive patients with DTC previously treated with total thyroidectomy and radioiodine ablation. At PET/MR imaging, all areas with abnormal FDG uptake corresponding to a MR abnormality (tissue mass or lymph node) were considered as positive. In addition, any focal increased uptake of FDG that did not correspond to normal structures was also recorded as positive. A similar procedure was applied for PET/CT interpretation. Any morphological abnormality identified as lesion on MR or CT was recorded. All patients were followed-up for at least 6 months by serum Tg, Tg-Ab and thyroidstimulating hormone determinations and neck ultrasonography. Other imaging procedures were performed as clinically indicated, wholebody scan was obtained in case of 131 I therapy, and histology was recorded in case of surgery. The date of recurrence or the most recent follow-up examination was recorded, as well as the clinical status at the end of the study. Results: All patients were treated in a range of 6-400 months before study. According to serum Tg levels, abnormal imaging findings were found in 10/22 patients (45%) with a serum Tg C 2 ng/mL (range 20-1050 ng/mL) and in only 1/18 patients (5%) with a serum Tg \ 2 ng/mL. PET/MR was positive in 11 patients and PET/CT in 10 patients. PET/MR detected 33 tumour foci and PET/CT 30 tumour foci. During the follow-up of the 12 patients with negative initial PET studies and with detectable serum Tg, only one patient had a neck recurrence and the administration of an empiric high activity of 131 I in the other 11 patients did not reveal any unknown tumour focus. In the 17 patients with an initial serum Tg level \ 2 ng/mL, no recurrence occurred.Conclusions: This study confirms the high diagnostic accuracy of FDG PET studies in DTC patients with elevated serum Tg levels and shows that PET/MR does not bring significant complementary information over PET/CT imaging. Guidelines on prevention of errors related with radiopharmaceuticals Background-Aim: To lay the groundwork for implementation of guidelines on prevention of errors due to incorrect management of radiopharmaceuticals in hospital care, with the purposes of improve patient safety. Methods: The paper was prepared based on topics covered during the discussion among the Multidisciplinary Expert Panel of authors and considered incidents which can occur during management of radiopharmaceuticals in an hospital setting: order, preparation, administration to patients, potential exposures following a procedure, as well as aspects involved in management of radioactive materials.Results: To minimize the likelihood of unintended and accidental medical exposure due to radiopharmaceuticals, the Panel proposed:(a) The introduction of safety measures at identified critical points in the process, with specific quality control checks at these points. (b) To actively encourage a culture of always working with awareness and alertness. (c) To set up detailed protocols and procedures for each process. (d) To adapt the staff to the needs and provide them with good education and training support to appropriate level and an effective organization, ensuring reasonable patient throughput. (e) To develop continuous professional improvement and practical professional courses, and training in applications for all staff involved in providing NM services. (f) Clear define roles, responsibilities and functions of staff in the NM facility that are understood by whole staff. Preventive measures should include checking the robustness of the safety system of the facility against reported incidents (retrospective risk analysis), as well as applying a prospective risk management strategy.Conclusions: Types of error that can occur are pointed out and recommendations made on safety measures through which the risk of incidents may be minimized then promoting patient safety culture. This guideline could be distributed, discussed and implemented, to evaluate its usefulness in daily clinical practice. Moreover, it may be the basis for an audit tool.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.