Diagnostic Performance of Chest CT for SARS-CoV-2 Infection in Individuals with or without COVID-19 Symptoms

Background: The use of chest CT for coronavirus disease 2019 (COVID-19) diagnosis or triage in health care settings with limited severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) capacity is controversial. COVID-19 Reporting and Data System (CO-RADS) categorization of the level of COVID-19 suspicion might improve diagnostic performance. Purpose: To investigate the value of chest CT with CO-RADS classification to screen for asymptomatic SARS-CoV-2 infections and to determine its diagnostic performance in individuals with COVID-19 symptoms during the exponential phase of viral spread. Materials and Methods: In this secondary analysis of a prospective trial, from March 2020 to April 2020, parallel SARS-CoV-2 PCR and CT with categorization of COVID-19 suspicion was performed with CO-RADS for individuals with COVID-19 symptoms and control participants without COVID-19 symptoms admitted to the hospital for medical emergencies unrelated to COVID-19. CT with CO-RADS was categorized on a five-point scale from 1 (very low suspicion) to 5 (very high suspicion). Area under the receiver operating curve (AUC) was calculated in symptomatic versus asymptomatic individuals to predict positive SARS-CoV-2 PCR, and likelihood ratios for each CO-RADS score were used for rational selection of diagnostic thresholds. Results: A total of 859 individuals (median age, 70 years; interquartile range, 52-81 years; 443 men) with COVID-19 symptoms and 1138 control participants (median age, 68 years; interquartile range, 52-81 years; 588 men) were evaluated. CT with CO-RADS had good diagnostic performance (P < .001) in both symptomatic (AUC, 0.89) and asymptomatic (AUC, 0.70) individuals. In symptomatic individuals (42% PCR positive), CO-RADS 3 or greater detected positive PCR with high sensitivity (89%, 319 of 358) and specificity of 73%. In asymptomatic individuals (5% PCR positive), a CO-RADS score of 3 or greater detected SARS-CoV-2 infection with low sensitivity (45%, 27 of 60) but high specificity (89%). Conclusion: CT with Coronavirus Disease 2019 Reporting and Data System (CO-RADS) had good diagnostic performance in symptomatic individuals, supporting its application for triage. Sensitivity in asymptomatic individuals was insufficient to justify its use as a first-line screening approach. Incidental detection of CO-RADS 3 or greater in asymptomatic individuals should trigger testing for respiratory pathogens. (C) RSNA, 2020