key: cord-0952043-7ra3k4sn authors: Schachner, Emma R; Spieler, Bradley title: Three-dimensional (3D) lung segmentation for diagnosis of COVID-19 and the communication of disease impact to the public date: 2020-08-18 journal: BMJ Case Rep DOI: 10.1136/bcr-2020-236943 sha: 1053719ac56586af12f5c811d76871025024963d doc_id: 952043 cord_uid: 7ra3k4sn nan Three individuals were admitted to the hospital (ages 46-56; to men and one woman) with a multiday history of symptoms associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and underwent contrast-enhanced thoracic CT due to worsening symptomatology. Three-dimensional (3D) digital models were created to visualise the extent of the disease within the respiratory system (figures 1 and 2) from the thin section (1 mm) data sets. All patients presented emergently with variable pulmonary symptoms ranging from mild to severe, including shortness of breath and all were febrile. Two of the patients were reverse transcription polymerase chain reaction (RT-PCR) positive for SARS-CoV-2 (figure 1B,D,F; figure 2C,D,G,H). The third patient was RT-PCR negative for SARS-CoV-2, but this was presumed to be a false-negative result given compelling clinical and imaging features indicative of COVID-19 (figures 1C,E and 2E,F). A fourth patient who presented to the emergency department and was suspected of having COVID-19 also underwent CT to assess for the possibility of pulmonary embolus (figures 1A and 2A,B). This individual tested negative for SARS-CoV-2, and the lungs were normal. All CT examinations were obtained using a Philips iCT 256 or iQon Spectral CT systems. Data were acquired using a 128×0.625 mm or 64×0.625 mm detector configuration with dual sampling, rotation time of 0.33 s (120 kVp 72 mAs). The full effect of COVID-19 on the respiratory system remains unknown; 1 however, the use of 3D digital segmented models from CT data provides the opportunity to evaluate the extent and distribution of the disease in one encapsulated view for clinicians, particularly in the case where RT-PCR for SARS-CoV-2 is negative but there is strong clinical suspicion for COVID-19. The 3D digital surface models (figures 1, 2A,C,E,G) were segmented by hand in the scientific visualisation programme Avizo V.7.1 (Thermo Fisher Scientific) following established methods for lungs in non-model organisms. [2] [3] [4] The utility of CT in the diagnosis of COVID-19 pneumonia has been a focus of recent radiologic literature with specific CT patterns of findings being well documented, including patchy and/or confluent, bandlike ground glass opacity or consolidation in a peripheral and mid-to-lower lung zone distribution. [5] [6] [7] [8] [9] [10] [11] [12] Given diagnostic challenges with respect to false-negative results by RT-PCR, the gold standard for COVID-19 diagnostic screening, CT can be helpful in establishing this diagnosis. 13 Importantly, these CT features can range in morphology and appear to correlate temporally with disease progression. 13 14 This allows for 3D segmentation of the data in which lung tissue can be volumetrically quantified, 4 or airflow patterns could be modelled. 15 Moreover, these models provide for a holistic view of the extent of pulmonary disease that can be appreciated by a wide-range medical imaging viewership. 16 17 Unlike simple volume rendered images, these models can be 3D printed, and thus have a much broader functional application that allows for the collaboration between basic and clinical scientists, which is particularly important given the critical nature of COVID-19. 2 18-20 Models demonstrate the relationship, distribution and full extent of the disease in 3D versus the single CT slice which only provides information on the localised position of the infection. ARDS, acute respiratory distress syndrome; C, consolidated infection; GGO, ground-glass opacities; HP, healthy parenchyma. Colour key: blue, healthy tissue; yellow, consolidation and ground glass opacities; green, ARDS. Images not to (relative) scale. Twitter Emma R Schachner @paleofox Understanding of COVID-19 based on current evidence Pulmonary anatomy and a case of unilateral aplasia in a common snapping turtle (Chelydra serpentina): developmental perspectives on cryptodiran lungs Unidirectional pulmonary airflow patterns in the savannah monitor lizard Reproducibility of lobar perfusion and ventilation quantification using SPECT/CT segmentation software in lung cancer patients Xia L: CT features of coronavirus disease 2019 (COVID-19) pneumonia in 62 patients in Wuhan, China Coronavirus disease (COVID-19): spectrum of CT findings and temporal progression of the disease The role of chest imaging in patient management during the COVID-19 pandemic: a multinational consensus statement from the Fleischner Society Chest CT findings in coronavirus Disease-19 (COVID-19): relationship to duration of infection Imaging features of coronavirus disease 2019 (COVID-19): evaluation on Thin-Section CT novel coronavirus (COVID-19) pneumonia: serial computed tomography findings Radiological Society of North America expert consensus statement on reporting chest CT findings related to COVID-19. endorsed by the Society of thoracic radiology, the American College of radiology, and RSNA Coronavirus disease 2019 (COVID-19): a systematic review of imaging findings in 919 patients Use of chest CT in combination with negative RT-PCR assay for the 2019 novel coronavirus but high clinical suspicion Coronavirus disease (COVID-19): spectrum of CT findings and temporal progression of the disease Particle transport and deposition correlation with near-wall flow characteristic under inspiratory airflow in lung airways Modeling real-time 3-D lung deformations for medical visualization Visualization of respiratory flows from 3D reconstructed alveolar airspaces using X-ray tomographic microscopy COVID-19 and the role of 3D printing in medicine Radiological Society of North America (RSNA) 3D printing special interest group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios 3D-printing techniques in a medical setting: a systematic literature review We are grateful to the following individuals and entities ► Three-dimensional segmented digital models provide a dramatically clearer method for visually evaluating the impact of COVID-19 on the lungs than straight radiographs, CT data or reverse transcription polymerase chain reaction alone. ► These printable digital models are additionally very powerful for communicating the impact of COVID-19 on the respiratory system to the general public.Copyright 2020 BMJ Publishing Group. 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