OBJECTIVE: To identify utility of chest computed tomography severity score (CT-SS) as an additional tool to COVID-19 pneumonia imaging classification in assessing severity of COVID-19 . STUDY
DESIGN: Descriptive analytical study Place and Duration of Study: Armed Forces Institute of Radiology and Imaging, (AFIRI) Rawalpindi, from April 2020 to June 2020 .
METHODOLOGY: Five hundred suspected COVID-19 cases referred for high resolution computed tomography - chest were included in the study . Cases were categorised by radiological findings using COVID-19 pneumonia imaging classification, proposed in the radiological society of North America expert consensus statement on reporting chest CT findings related to COVID-19 . CT-SS was calculated for all scans . Patients were clinically classified according to disease severity as per 'Diagnosis And Treatment Program of Pneumonia of New Coronavirus Infection' recommended by China's National Health Commission . The relationships between radiological findings, CT-SS, and clinical severity were explored .
RESULTS: Based on the radiological findings , 298 cases were graded as typical , 34 as indeterminate , 15 as atypical, and 153 as negative for pneumonia . The apical and posterior basal segments of lower lobes were most commonly involved . The CT-SS showed higher values in patients of severe group as compared to those in moderate group (p <0.05). CT-SS threshold for recognising severe COVID-19 was 18.5 (area under curve , 0.960), with 84.3% sensitivity and 92.5% specificity .
CONCLUSION: In coherence with COVID-19 pneumonia imaging classification, CT-SS may provide a comprehensive and objective assessment of COVID-19 severity . Key Words: COVID-19, COVID-19 pneumonia, CT-SS, High resolution computed tomography.