129Xe Gas-Transfer MRI RBC-to-Barrier Ratio in Post-Acute COVID19 Syndrome: Clinically-relevant?

Post-acute COVID19 syndrome (PACS) is an umbrella term for a syndrome of symptoms persisting at least 12 weeks post COVID19 infection. Preliminary studies in PACS patients post-hospitalization revealed abnormally low 129 Xe RBC-to-barrier ratios, but the clinical relevance of this is not well-understood. We acquired 129 Xe gas-transfer MRI, spirometry, diffusing-capacity-of-the-lung for carbon-monoxide (DL CO ) and same-day CT in 39 participants including 30 PACS and 9 never-COVID19 controls. The 129 Xe MRI RBC-to-barrier ratio was significantly related to DL CO and significantly lower in both never-hospitalized and ever-hospitalized PACS patients compared to never-COVID19 controls.