Introduction: COVID-19 pneumonia is often responsible for long-term radiological lung impairment.

Aims and objectives: This study investigates volumetric lung alterations in COVID-19-associated ARDS (CARDS) during the acute phase and evaluates quantitative radiological recovery at 1-year follow-up.

Methods: 34 patients (pts) without a history of chronic lung disease admitted to Vimercate Hospital Respiratory Intermediate Care Unit (RICU) with CARDS entered the study. Quantitative CT volumetric data were measured with Synapse 3D software and compared with a control group of 20 healthy subjects of the same age. Categorical data were expressed as frequencies and percentages, while continuous variables were represented using median values. Statistical significance was considered for p-value<0.05.

Results: Quantitative analysis pointed out that, during the acute phase, the normo-areated median lung volume (VA) of the 34 pts was 1746 ml, versus 5234 ml of the control group. At 1-year follow-up, pts with CARDS had a VA of 3974 ml, markedly increased compared with the acute phase (p<0.001), but still lower than healthy subjects (p<0.001).

Conclusions: During the acute phase pts with CARDS showed extremely compromised VA. Although it improved remarkably at 1-year follow-up, it remained significantly inferior than data obtained in the control group. Further studies are needed to evaluate if the loss of lung volumes remains permanently.