Cohort study of chest CT and clinical changes in 29 patients with coronavirus disease 2019 (COVID-19)

Objectives: To investigate the imaging findings and clinical time course of COVID-19 pneumonia.
Methods: A total of 113 baseline and follow-up CT scans from 24 January 2020 to 18 February 2020 were longitudinally collected from 29 confirmed COVID-19 patients in a single center. The changes in the clinical and laboratory characteristics, imaging features, lesion-to-muscle ratio (LMR), and pulmonary inflammation index (PII) at baseline, 1-6 days, 7-13 days, and ≥ 14 days were compared.
Results: Of the 29 COVID-19 patients enrolled, the baseline chest CT scan was obtained 3 ± 2 (0-9) days after the onset of symptoms, and each patient had an average of 4 ± 1 (3-5) CT scans with a mean interval of 5 ± 2 (1-14) days. The percentage of patients with fever, cough, shortness of breath, and myalgia obviously decreased at 7-13 days with regular treatment (p < 0.05). The lymphocyte count, C-reactive protein, interleukin-6, and oxygenation index worsened within 1-6 days but improved sharply at 7-13 days. Compared with those at the other three time points, the LMR, PII, and number of involved lobes at 1-6 days were the highest, and gradually improved after 7-13 days.
Conclusions: Lung lesion development on chest CT reflects the clinical time course of COVID-19 progression over 1-6 days, followed by clinical improvement and the resorption of lesions. CT imaging may be indicated when patients fail to improve within a week of treatment, but repeated chest CT may be unnecessary when the patients show improvements clinically.
Key points: • Chest CT reflects the development of coronavirus disease 2019 pneumonia (COVID-19). • COVID-19 usually shows progressive lesions over up to 9 days with subsequent resorption. • Unusual clinical time course of COVID-19 may indicate repeated chest CT.