Added Value of the Chest CT Features in Diagnosis of Patients with Corona Virus 2019 (COVID-19) in Early and Late Phase of the Disease with CO-RADS Assessment

Abstract Background: An outbreak of coronavirus disease caused by a novel coronavirus (SARS-CoV-2) began in December 2019 in Wuhan in central China. RT-PCR (reverse-transcription-polymerase chain reaction) is the gold standard test in the diagnosis of patients with COVID 19 but due to the shortage of its kits, Chest CT is considered a vital com-ponent in the diagnostic algorithm of these patients. Aim of Study: This study aim to assess the usefulness of chest CT features in diagnosis of patients in early and late phase of COVID-19 infection with assessment of these features with CORADS and determine the relation of the CO-RADS and the phase of the disease. Patients and Methods: Chest CT of 290 patients who confirmed laboratory by RT-PCR to be infected with COVID 19 were reviewed retrospectively for common CT findings, then we investigate the relation between the initial CT scan and symptoms onset [early, 0-4 days (n=143), late, 5-12 days (n=147)]. After that we assessed these features in correlation to CO-RADS. Results: The number of early phase group was 143 (49.3%) while the late phase group was 147 (50.7%) patients. Regarding CO-RADS class, there were 45, 47, 18, 11, and 169 patients have CO-RADS class 1, 2, 3, 4, and 5, respectively. Seventy-eight (54.5%) patients who were imaged in the early phase had a normal CT scan, while CT findings such as, mixed ground glass (GGO) and consolidative opacities (74.1%) with peripheral and central distribution, bilateral lung involvement (93.2%), and multilobar affection (91.8%), were statistically significant in late phase group (p < 0.001). Patients with late phase of COVID 19 have significantly higher CO-RADS score (³4) than those in early phase. Also fever, cough and dyspnea (respiratory symptoms) were common in high CO-RADS score (>!4) than in low CO-RADS score. Conclusions: RT-PCR is mandatory for the diagnosis of patients suspected to have COVID 19 in an early phase of illness with normal CT chest or low CORADS score !93. Bilateral GGO and consolidative opacities, multilobar affection, with peripheral and central lesion distribution, in chest CT of patients imaged in a late phase of the disease or high CORADS score ³4 encourage the radiologists to suggest COVID 19 as a possible diagnosis with confidence in the case global pan-demic and shortage of PCR kits supply.