18 months computed tomography follow-up after Covid-19 interstitial pneumonia

Abstract

Background: Our aim is to evaluate the possible persistence of lung parenchyma alterations, in patients who have recovered from Covid-19.

Design and methods: We enrolled a cohort of 115 patients affected by Covid-19, who performed a chest CT scan in the Emergency Department and a chest CT 18 months after hospital discharge. We performed a comparison between chest CT scan 18 months after discharge and spirometric data of patients enrolled. We obtained quantitative scores related to well-aerated parenchyma, interstitial lung disease and parenchymal consolidation. A radiologist recorded the characteristics indicated by the Fleischner Society and "fibrotic like" changes, expressed through a CT severity score ranging from 0 (no involvement) to 25 (maximum involvement).

Results: 115 patients (78 men, 37 women; mean age 60.15 years old ±12.52). On quantitative analysis, after 18 months, the volume of normal ventilated parenchyma was significantly increased (16.34 points on average ±14.54, p<0.0001). Ground-glass opacities and consolidation values tend to decrease (-9.80 and -6.67 points, p<0.0001). On semiquantitative analysis, pneumonia extension, reactive lymph nodes and crazy paving reached statistical significance (p<0.0001). The severity score decreased by 2.77 points on average (SD 4.96; p<0.0001). There were not statistically significant changes on "fibrotic-like" changes correlated with level of treatment and there was not a statistically significant correlation between CT lung score and spirometric results obtained 18 months after discharge.

Conclusions: Patients recovered from Covid-19 seem to have an improvement of ventilated parenchyma and "fibrotic-like" alterations. The level of treatment does not appear to influence fibrotic changes.

Figure 1.

Participant flow diagram.

Figure 2.

CT scan of a 45-year-old man analyzed with 3D slicer. a) The axial thin-section scan shows ground-glass opacities highlighted in yellow by the operator. Then, the program calculates the volume of the healthy lung parenchyma, the percentage of lung parenchyma occupied by the ground-glass opacities, and the percentage of consolidation. b,c) Coronal and sagittal thin-section scan, red areas indicate consolidation.

Figure 3.

Chest CT findings of COVID-19 pneumonia. a) Traction bronchiectasis. b) Ground-glass opacities. c) Pleural effusion.

Figure 4.

Statistical model of correlation between fibrotic score and respiratory therapy.

Figure 5.

Subdivision according to parenchymal bands severity degree at 18 months CT. a) No visible alterations. b) Mild parenchymal bands. c) Moderate degree. d) Severe parenchymal bands.

Figure 6.

CT scan of a 69-year-old man with severe COVID-19 pneumonia. a,c) The axial and coronal thin-section scans, performed at our Emergency Department, showed multiple bilateral ground-glass opacities and parenchymal consolidation. b,d) The axial and coronal thin-section scans obtained 547 days after the first acquisition showed the persistence of some parenchymal bands.