key: cord-0719902-g28ehnmd
authors: Basnet, B.; Pant, S.; Rai, K.; Tulachan, N. B.; Karki, B.; Shahi, R. R.; Basnet, S. B.; Thapa, B. B.
title: A spectrum of HRCT chest findings in RT-PCR positive asymptomatic COVID-19 patients at a COVID designated hospital in Nepal
date: 2021-06-27
journal: nan
DOI: 10.1101/2021.06.25.21259523
sha: 7f2cc2beba5a44cf63761fb14784f379b2cb41ce
doc_id: 719902
cord_uid: g28ehnmd

Introduction: COVID-19 pandemic is grappling the world with the surge of infection time and again. Clinicians are trying to justify the ethics of public health care. Asymptomatic COVID-19 cases are going undocumented and most of them practice self-isolation. Studies have revealed significant radiological changes among RT-PCR positive asymptomatic COVID-19 cases. Objective: The aim of this cross-sectional study is to characterized chest CT findings of asymptomatic RT-PCR-positive patients in one of the COVID designated hospitals in Nepal. Results: Out of 43, 26 (60.5%) participants had positive Chest CT scan findings consistent with COVID pneumonia. 65% had bilateral and 77% had multifocal lesions. The ground-glass opacities (92%), mixed (ground-glass opacities and consolidation) pattern (30.7%), and consolidation only (34.6%) were common chest CT findings. The median CT score was 3.5 (Interquartile range; 2-6). Conclusion: The majority of the RT-PCR positive asymptomatic patient present with CT scan changes of lungs which are important to determine clinical status, prognosis, and long-term sequel in those cohorts.

CT changes of the asymptomatic patients are important not only to evaluate the chest CT as alternative diagnostic modalities for selected COVID-19 cases but also to evaluate the long term outcomes of COVID-19 related respiratory pathophysiology, which is mostly unknown. [9] The objective of our study is to characterize the chest CT scan features and clinical outcomes of RT-PCR confirmed asymptomatic COVID-19 patients in COVID-19 designated hospital (Shree Birendra Hospital), Nepal.

This is a cross sectional study where a cohort of laboratory proven RT-PCR positive COVID-19 asymptomatic adult (age > 18 years) patients were included and were subjected to the HRCT scan of the chest. All the cases included in this study fulfill the WHO criteria of the "close contacts" of the COVID-19 confirmed cases. The study is conducted between October 2020 and December 2020 with ethical approval from institutional review board and consent of the patient and HRCT scan were acquired in the Hitachi Multidetector 128 slice CT scanner .The parameters for used for CT acquisition were helical mode volumetric HRCT with Tube voltage 100kVp-120kVp and tube current 80-500mA, and slice thickness of 1.0mm with reconstruction interval, 0.6mm using a sharp reconstruction algorithm. CT images were obtained with the patient in supine position with full inspiration. Intravenous contrast administration was not used .Acquired images were transferred to a separate workstation for further processing. Image was reconstructed in axial, coronal, and sagittal planes to detect the craniocaudal and axial/peripheral distribution of the lung parenchymal involvement.

All images were viewed on both lung (width, 1500 HU; level, −700 HU) and mediastinal (width, 350 HU; level, 40 HU) settings. The chest CT scan was evaluated by two radiologist characterizing the parenchymal involvement on the basis of the (a) characteristic findings and morphology: ground glass opacities, consolidation, linear bands, bronchial wall thickening, nodules and additional findings like pleural effusion and mediastinal lymphadenopathy. (b) Distribution of the involvement: Laterality, craniocaudally distribution, number of the lobes involved, percentage of involvement in each lobe. Then the CT severity score (0-25) was calculated following the semi-quantitative scoring system which depends on the visual . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted June 27, 2021. ; https://doi.org/10.1101/2021.06.25.21259523 doi: medRxiv preprint assessment of the each 5 lung lobes (0-0%; -<5%; 2-5 to 25%; 3-26 to 50%; 4-51 to 75%; 5-> 75% ) that was initially proposed by Pan et al. [10] 

In this cross-sectional study total of 43 RT-PCR positive COVID-19 cases were included.

Among the study cohort 26 (60.5%) had positive Chest CT scan findings (Figure 1-3) . The positive Chest CT had mostly bilateral (65.3%) and multifocal (77%) lesion. 92% of them had ground glass opacities ( Table 1 ).

The median global CT score of the abnormal CT scan chest was 3.5 (Interquartile range; 2-6).

The mean CT score value was significantly higher (5.3±2.6 vs 3.0± 1.0) in bilateral lung disease.

The ratio of upper to lower lobe involvement was 2:3. The patients with normal CT scan had higher mean cycle threshold (CT) value of RT-PCR test than abnormal chest CT scan group (23.8 vs 21.7;). However, the difference was statistically not significant. One patient developed mild COVID-19 symptoms (cough and headache) during follow up.

. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted June 27, 2021. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted June 27, 2021. 

Pneumonia is primary manifestation of the COVID-19 disease. WHO has classified symptomatic COVID-19 infection into mild cases, pneumonia, severe pneumonia, and critical disease (sepsis, septic shock and or ARDS). In a large cohort of population based study the 30-40% were asymptomatic young adults. The virus can be cultured from infected individual as early as six days prior to the developments of symptoms. Whereas it takes at leas a week for CT scan to detect changes in lung parenchyma. [11] [12] [13] [14] Screening CT chest had positivity rate of 1.6%. [15] In RT-PCR confirmed COVID-19 cases HRCT help in prognostication, evaluating the disease progression and monitoring the response to therapy. [16] With RT-PCR as reference, the sensitivity, specificity, accuracy of chest CT in indicating COVID-19 infection were 97%, 25% and 68% respectively, the accuracy of which is higher in age more than 60 years. Studies have shown that Bilateral lung (90%) involvement with ground glass opacities (46-50%) and mixed GOO along with consolidation (44-50%), and consolidation only (25%) were the most common pattern in Chest CT scan characteristics of COVID-19

patients. [12, 14, 16, 1716 ] Similar pattern of Ground glass opacities (95%) and consolidation (5%) with predominantly bilateral, sub pleural, and multiple lesion were described among asymptomatic cases. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted June 27, 2021. ; damage (DAD), diffuse thrombotic alveolar microvascular occlusion, and inflammatory mediator-associated airway inflammation. [17, 20, 21, 20] The median CT severity score in this study was 3.5 with range (range, 1-11). Francone et all found significant positive correlation (p< 0.0001) of CT score between age of patient, inflammatory biomarkers, and with severity of the disease. CT score >18 has hazard ratio of 8.33 (95% CI, 3.19-21.7) for COVID-19 related mortality. [22] The significance of CT score in asymptomatic patients is yet to be evaluated in short and long term follow up.

Based on SARS-COV-1 data of 2003 two third of the survivors suffered from TGF-β-mediated pulmonary fibrosis and SARS-COV-2 is expected to share similar chronic sequel. [23, 24] . CT chest is widely available modality to assess and follow the pulmonary changes in COVID-19 patients both symptomatic and asymptomatic. During early 2020 asymptomatic or undocumented cases were responsible for 79% of the documented cases. [25] Probability of having incidental CT findings among asymptomatic cases is high due to ongoing progression of the pandemic. Though it is difficult to explain the temporal phase of CT changes in asymptomatic cases screening CT is recommended for all RT-PCR positive COVID-19 patients for the purpose of characterization of the findings and its long-term sequel.

[26] The study was conducted during first COVID-19 pandemic wave in Nepal when the average nation wide case positivity rate was 15.6%. Study with large sample size and follow up scan add more to the scientific evidence on radiological features of asymptomatic COVID-19 cases. Study in a context of higher incidence rate can unfold different data and evidences.

Chest CT plays an important role in the diagnosis and management of the RT-PCR negative COVID suspected as well as RT-PCR positive asymptomatic COVID-19 cases. The long term sequel of the COVID-Lung is little known to us. The present evidences suggest that the COVID-19 asymptomatic cases should be followed clinically and radiologically in order to evaluate its outcome.

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We declare no conflict of interest or competing interests

Ethical approval for this study was taken from Institutional review board

Written consent taken

All authors consent to publication of this paper

All data is available for review by contacting Dr. Bikash Thapa

All author has made substantial contributions to the conception or design of the work; the acquisition, analysis, interpretation of data; and the creation of manuscript. BB agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted June 27, 2021. ;

Transmission of SARS-CoV-2: A Review of Viral, Host, and Environmental Factors

Accessed

Overview of Testing for SARS-CoV-2

Proportion of asymptomatic coronavirus disease 2019: A systematic review and meta-analysis

Household Transmission of SARS-CoV-2: A Systematic Review and Meta-analysis

Occurrence and transmission potential of asymptomatic and presymptomatic SARS-CoV-2 infections: A living systematic review and meta-analysis

Clinical Outcomes in 55 Patients With Severe Acute Respiratory Syndrome Coronavirus 2 Who Were Asymptomatic at Hospital Admission in Shenzhen

Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing

CT imaging and clinical course of asymptomatic cases with COVID-19 pneumonia at admission in Wuhan

Time Course of Lung Changes at Chest CT during Recovery from Coronavirus Disease 2019 (COVID-19)

Prevalence of Asymptomatic SARS-CoV-2 Infection : A Narrative Review

Clinical management of COVID-19: interim guidance [WHO-2019-nCoV-clinical-2020

Suppression of a SARS-CoV-2 outbreak in the Italian municipality of Vo'

Incidental chest computed tomography findings in asymptomatic Covid-19 patients. A multicentre Indian perspective

Chest CT-scan finding of asymptomatic COVID-19 pneumonia: a prospective 542 patients' single center study

CT in coronavirus disease 2019 (COVID-19): a systematic review of chest CT findings in 4410 adult patients

Correlation of Chest CT and RT-PCR Testing for Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases

Radiological findings from 81 patients with COVID-19 pneumonia in Wuhan, China: a descriptive study

Chest CT findings in cases from the cruise ship "Diamond Princess

Pulmonary pathology and COVID-19: lessons from autopsy. The experience of European Pulmonary Pathologists

Pathological study of the 2019 novel coronavirus disease (COVID-19) through postmortem core biopsies

Chest CT score in COVID-19 patients: correlation with disease severity and short-term prognosis

The long-term impact of severe acute respiratory syndrome on pulmonary function, exercise capacity and health status

Long-Term Respiratory and Neurological Sequelae of COVID-19

Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2)