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