Temporal Lung Changes in High-resolution Chest Computed Tomography for Coronavirus Disease 2019

Objective: To evaluate temporal lung changes in coronavirus disease 2019 (COVID-19) in high-resolution computed tomography (HRCT) and to determine the appropriate computed tomographic (CT) follow-up time.

Methods: Eighty-six patients with two or more HRCT scans who were diagnosed with COVID-19 were included. The CT score and major CT findings were evaluated.

Results: Eighty-two (95.3%) patients had lesions on the initial HRCT scans. Most scans showed bilateral, multifocal lung lesions, with multiple lobes involved and diffuse distribution. For fifty-seven patients with type I (progress compared with the initial CT score), the CT score reached a peak at 12 days and the nadir at 36 days. For twenty-nine patients with type II (no progress compared with the initial CT score), the lowest CT score was reached at 23 days. On the final HRCT scans (>21 days), patients with a reticular pattern were older than those without a reticular pattern.

Conclusion: The appropriate follow-up time of CT scans is during the second week (approximately 12 days) and the fourth to fifth weeks (approximately 23-36 days) from the onset of illness. These times could help reduce the CT radiation dose and show timely changes in the course of the disease by CT.