Analysis of thin-section CT in patients with coronavirus disease (COVID-19) after hospital discharge

Abstract

Purpose: To analyze clinical and thin-section computed tomographic (CT) data from the patients with coronavirus disease (COVID-19) to predict the development of pulmonary fibrosis after hospital discharge.

Materials and methods: Fifty-nine patients (31 males and 28 females ranging from 25 to 70 years old) with confirmed COVID-19 infection performed follow-up thin-section thorax CT. After 31.5±7.9 days (range, 24 to 39 days) of hospital admission, the results of CT were analyzed for parenchymal abnormality (ground-glass opacification, interstitial thickening, and consolidation) and evidence of fibrosis (parenchymal band, traction bronchiectasis, and irregular interfaces). Patients were analyzed based on the evidence of fibrosis and divided into two groups namely, groups A and B (with and without CT evidence of fibrosis), respectively. Patient demographics, length of stay (LOS), rate of intensive care unit (ICU) admission, peak C-reactive protein level, and CT score were compared between the two groups.

Results: Among the 59 patients, 89.8% (53/59) had a typical transition from early phase to advanced phase and advanced phase to dissipating phase. Also, 39% (23/59) patients developed fibrosis (group A), whereas 61% (36/59) patients did not show definite fibrosis (group B). Patients in group A were older (mean age, 45.4±16.9 vs. 33.8±10.2 years) (P = 0.001), with longer LOS (19.1±5.2 vs. 15.0±2.5 days) (P = 0.001), higher rate of ICU admission (21.7% (5/23) vs. 5.6% (2/36)) (P = 0.061), higher peak C-reactive protein level (30.7±26.4 vs. 18.1±17.9 mg/L) (P = 0.041), and higher maximal CT score (5.2±4.3 vs. 4.0±2.2) (P = 0.06) than those in group B.

Conclusions: Pulmonary fibrosis may develop early in patients with COVID-19 after hospital discharge. Older patients with severe illness during treatment were more prone to develop fibrosis according to thin-section CT results.

Keywords: COVID-19; X-ray computed; coronavirus; severe acute respiratory syndrome; tomography.

Fig. 1

Example of CT image slices of a male COVID-19 patient of 32 years old. (a) CT scan performed 5 days after admission. Images show a focal ground-glass opacity in the lower lobe of the left lung. (b) Follow-up CT taken after discharge (or obtained on day 27 after admission to hospital). The lesion was basically absorbed, leaving a little GGO. This patient was enrolled in group B.

Fig. 2

Example of CT image slices of a male COVID-19 patient of 65 years old. (a) CT scan performed 2 days after admission. Images show ground-glass opacity (GGO) in the posterior basal segment of the right lower lobe, with the lesion located subpleural region. (b) CT images obtained 10 days after admission. Lesions Increased with higher density and thickening of the interlobular septum. (c) Follow-up CT scan (obtained at day 36 after admission and 18 days after discharge) shows visible parenchymal bands, irregular interface, and traction bronchiectasis, which indicates fibrosis. The patient was enrolled in group A.