CT appearances, patterns of progression, and follow-up of COVID-19: evaluation on thin-section CT

Abstract

Background: To retrospectively analyze CT appearances and progression pattern of COVID-19 during hospitalization, and analyze imaging findings of follow-up on thin-section CT.

Methods: CT findings of 69 patients with COVID-19 were evaluated on initial CT, peak CT, and pre-discharge CT. CT pattern were divided into four types on CT progression. Lesion percentage of pulmonary lobe (lobe score) was graded. Correlation analysis was made between scores and intervals. 53 patients were followed up by CT.

Results: Among 69 patients, 33.3% exhibited improvement pattern, 65.2% peak pattern, 1.5% deterioration pattern, and 0% fluctuation pattern. The lobe scores were positively correlated with most of intervals. It was more common to observe consolidation, pleural thickening and pleural effusion on the peak CT, and irregular line and reticulation on pre-discharge CT. The peak-initial interval were shortened when the initial CT with consolidation and pleural thickening. The intervals were extended when the irregular lines appeared on peak CT and reticulation on pre-discharge CT. Among 53 follow-up patients, 37.7% showed normal chest CT, and 62.3% showed viral pneumonia remained that mainly included GGO (100.0%) and irregular lines (33.3%).

Conclusions: COVID-19 displayed different appearances on CT as progressing. The peak pattern was the most common progression pattern. The CT appearances showed closely related to the intervals. The COVID-19 pneumonia can be remained or completely absorbed on CT with follow-up.

Keywords: COVID-19; Infectious disease medicine; Multidetector computed tomography; Pneumonia.

Fig. 1

Schematic diagram of different time intervals

Fig. 2

The intervals between the onset of symptoms and initial CT, peak CT, and pre-discharge CT

Fig. 3

Female, 50-year-old, COVID-19. a The initial CT obtained 4 days from onset of symptoms shows the round ground-glass opacity around the subpleural area of the right lower lobe. b The peak CT obtained 6 days later shows the large patchy ground-glass opacity and a few of consolidation around the subpleural area of the right lower lobe. c The pre-discharge CT obtained 14 days later shows reticulation, irregular lines, and pleura thickening. d. Axial CT. The follow-up CT obtained 64 days later shows a normal chest CT

Fig. 4

Male, 45-year-old, COVID-19. a Axial CT and (b) Volume Render (VR) Imaging. The initial CT and VR imaging obtained 7 days from onset of symptoms. The CT shows the patchy ground-glass opacity, crazy-paving pattern, irregular lines, and consolidation around the subpleural area, and pleura thickening. The VR imaging shows the lesions involve the bilateral lungs. c Axial CT and (d) VR Imaging. The peak CT and VR imaging obtained 3 days later. The CT shows that ground-glass opacity decrease, consolidation irregular lines, and pleural thickening increase, and bilateral pleura effusion occurred. The VR imaging shows the lesion size significantly increases. e Axial CT. The pre-discharge CT obtained 8 days later. The CT shows ground-glass opacity, irregular lines, and pleural thickening adhesions remain. f Axial CT. The follow-up CT obtained 34 days later shows a normal chest CT

Fig. 5

Female, 55-year-old, COVID-19. a The initial CT obtained 5 days from onset of symptoms shows the round ground-glass opacity (arrow) around the subplerual area of the left lower lobe. b The peak CT obtained 9 days later shows the large patchy consolidations and pleural thickening increase much more and air bronchograms are observed. c The pre-discharge CT obtained 8 days later shows consolidation, ground-glass opacity, irregular lines, reticulation, and pleura thickening. d The follow-up CT obtained 45 days later shows a few of ground-glass opacity remained in right middle lobe (arrow)

Fig. 6

The lobe score, ground-glass opacity score, and consolidation score on initial CT, peak CT, and pre-discharge CT

Fig. 7

The CT appearences on the initial CT, peak CT, and pre-discharge CT