Ct features of patients with COVID-19 pneumonia at three months following infection

Rationale: The long term evolution of Covid-19 pneumonia has still little been evaluated. We herein describe CT features that persist 3 months after Covid-19 symptom onset and correlate them to the extent of disease at diagnosis. Methods: Monocentric retrospective study including consecutive patients with Covid-19 confirmed by RT-PCR who presented to Bichat Hospital, Paris, France, between March and May 2020, and had a follow-up chest-CT 3 months later as part of their usual care. Chest CT analysis at 3 months evaluated ground-glass opacities (GGO, graded according to their extent and density), reticulations, bronchial distortion, honeycombing, band-like atelectasis and air trapping. The grade of persistent GGO and the presence of any sign suggestive of fibrosis were correlated to the extent of disease at presentation.Results;Any residual opacity was observed in 99/142 patients (70%). GGO, band-like atelectasis and reticulations were the most frequent findings, in 87/142 (61%), 53/142 (37%) and 40/142 (28%) patients, respectively. Signs that may suggest a fibrosing evolution, including bronchial distortion and distorted reticulations, were observed in 17/142 patients (12%), whereas no case showed honeycombing. Air trapping was present in 12 out of 80 patients (15%) who had an expiratory CT. The grade of GGO and the presence of reticulations at 3 months were highly correlated to the extent of disease at presentation (p<0.0001 and p=0.020, Kruskall Wallis) but signs suggestive of fibrosis were not (p=0.15)Conclusion: Residual opacities are frequent 3 months after Covid-19 pneumonia onset, chest CT mostly showing GGO, band-like atelectasis and reticulations. Signs that may suggest a fibrosing evolution are observed in only 12% of patients.