Radiographic features of COVID-19 based on an initial cohort of 96 patients in Singapore.

Khoo, Hau Wei; Hui, Terrence Chi Hong; Haja Mohideen, Salahudeen Mohamed; Lee, Yeong Shyan; Liew, Charlene Jin Yee; Kok, Shawn Shi Xian; Young, Barnaby Edward; Ong, Sean Wei Xiang; Kalimuddin, Shirin; Tan, Seow Yen; Loh, Jiashen; Chan, Lai Peng; Poh, Angeline Choo Choo; Wong, Steven Bak Siew; Leo, Yee-Sin; Lye, David Chien; Kaw, Gregory Jon Leng; Tan, Cher Heng

INTRODUCTION Chest radiographs (CXR) are widely used for the screening and management of the coronavirus disease 2019 (COVID-19). This paper determinates the radiographic features of COVID-19 based on an initial national cohort of patients. METHODS This is a retrospective review of swab-positive COVID-19 patients admitted to four different hospitals in Singapore between 22 January and 9 March 2020. Initial and follow-up CXR were reviewed by three experienced radiologists to identify the predominant pattern and distribution of lung parenchymal abnormalities. RESULTS In total, 347 CXR of 96 patients were reviewed. Initial CXR were abnormal in 41 out of 96 patients (42.7%). The mean time from onset of symptoms to CXR abnormality was 5.3 (range 1-21) days. The predominant pattern of lung abnormality was ground-glass opacity on initial CXR (51.2%) and consolidation on follow-up CXR (51.0%). Multifocal bilateral abnormalities in mixed central and peripheral distribution were seen in 63.4% and 59.2% of abnormal initial and follow-up CXR, respectively. The lower zones were involved in 90.2% of the initial CXR and 93.9% of the follow-up CXR. CONCLUSION In a cohort of swab-positive patients, including those identified from contact tracing, we found the incidence of CXR abnormality to be lower than previously reported. The most common pattern was ground-glass opacity or consolidation, but mixed central and peripheral involvement was more common than peripheral involvement alone.