Longitudinal lung function assessment of patients hospitalised with COVID-19 using 1 H and 129 Xe lung MRI
Abstract
Introduction
Microvascular abnormalities and impaired gas transfer have been observed in patients with COVID-19. The progression of pathophysiological pulmonary changes during the post-acute period in these patients remains unclear.
Methods
Patients who were hospitalised due to COVID-19 pneumonia underwent a pulmonary 1 H and 129 Xe MRI protocol at 6, 12, 25 and 51 weeks after hospital admission. The imaging protocol included: ultra-short echo time, dynamic contrast enhanced lung perfusion, 129 Xe lung ventilation, 129 Xe diffusion weighted and 129 Xe 3D spectroscopic imaging of gas exchange.
Results
9 patients were recruited and underwent MRI at 6 (n=9), 12 (n=9), 25 (n=6) and 51 (n=8) weeks after hospital admission. Patients with signs of interstitial lung damage at 3 months were excluded from this study. At 6 weeks after hospital admission, patients demonstrated impaired 129 Xe gas transfer (RBC:M) but normal lung microstructure (ADC, Lm D ). Minor ventilation abnormalities present in four patients were largely resolved in the 6–25 week period. At 12 week follow up, all patients with lung perfusion data available (n=6) showed an increase in both pulmonary blood volume and flow when compared to 6 weeks, though this was not statistically significant. At 12 week follow up, significant improvements in 129 Xe gas transfer were observed compared to 6-week examinations, however 129 Xe gas transfer remained abnormally low at weeks 12, 25 and 51. Changes in 129 Xe gas transfer correlated significantly with changes in pulmonary blood volume and TL CO Z-score.
Conclusions
This study demonstrates that multinuclear MRI is sensitive to functional pulmonary changes in the follow up of patients who were hospitalised with COVID-19. Impairment of xenon transfer may indicate damage to the pulmonary microcirculation.
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