129Xe red blood cell chemical shift and T2* in patients hospitalised due to COVID-19 with and without residual lung abnormalities seen on CT

Motivation: Previous studies show red blood cell (RBC) chemical shift, RBC T2* and M T2* may be sensitive to alveolar-capillary diffusion. Goal(s): To determine whether these 129Xe MRI measures are associated with markers of clinical function in patients hospitalised due to COVID-19. Approach: Patients hospitalised due to COVID-19 with and without residual lung abnormalities (RLAs) had 6 month and 1 year MRI. RBC chemical shift, RBC T2* and M T2* were calculated from dissolved phase 129Xe MRI. Results: RBC chemical shift correlates with TLCO Z-score in patients with RLAs. RBC T2*and M T2* were significantly longer in patients with RLAs, compared to patients without. Impact: RBC chemical shift is sensitive to alveolar-capillary diffusion abnormalities in patients with residual lung abnormalities following COVID-19 and may enable more sensitive monitoring of gas transfer abnormalities in these patients.