This retrospective study was approved by our institutional review board and the requirement for informed consent was waived. A database search between March 1, 2020 and April 26, 2020 was performed to identify patients with COVID-19 and who had chest CT scans. Inclusion criteria were as follows,adult patients (age ≥ 18 years),
patients who had positive RT-PCR tests for COVID-19,
patients who had two consecutive unenhanced chest CTs (obtained at hospital admission and follow-up).