S19 Gas exchange imaging using dissolved-phase 129Xe MRI in post COVID cohorts

Résumé fourni par la source

Introduction Hyperpolarised 129Xe MRI allows quantitative and regionally sensitive measurement of gas exchange. The objective of this work is to characterise longitudinal lung function abnormalities using hyperpolarised 129Xe MRI in patients hospitalised due to COVID-19. Methods A comprehensive 1H and 129Xe 1.5T MRI protocol has been implemented in two longitudinal studies of patients hospitalised due to COVID-19, up to 2 years after hospitalisation: i) with normal or near-normal CT[1] ii) with abnormal CT consistent with signs of interstitial lung damage at 12 weeks post-hospitalisation as part of the XMAS study[2]. Matching MRI protocols were performed in both studies including dissolved phase xenon imaging, from which the fraction of xenon dissolved in the pulmonary red blood cells compared to the xenon dissolved in the pulmonary membrane is calculated (RBC:M) as a measure of xenon gas transfer. PFTs were also performed. Longitudinal and group comparisons were assessed using non parametric tests. Results 8 patients with normal CT (6 months, n=7; 1 year, n=8; 2 years: n=5) and 25 patients with abnormal CT were recruited (6 months, n= 16; 1 year, n=14; 2 year, n=6). Patients with normal CT showed abnormal xenon gas transfer (RBC:M) with no longitudinal change between 6 months and 1 year. TLCO Z-score was normal in 7/7 patients at 6 months, 7/8 patients at 1 year and 3/3 patients with data available at 2 years. Patients with abnormal CT had significantly greater xenon gas transfer impairment at 1 year (6 months: p=0.056, 1 year: p=0.032) and lower TLCO Z-score predicted than patients, with normal TLCO Z-score in 4/16, 3/16, and 1/6 patients with data available at 6 months, 1 year and 2 years respectively. Conclusions Xenon gas transfer can detect ongoing abnormalities in patients hospitalised due to COVID-19 up to two years after hospitalisation, including in patients with normal CT and PFTs. Please refer to page A283 for declarations of interest related to this abstract.

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