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The assessment of short and long term changes in lung function in CF using 129 Xe MRI.

Research paper by Laurie J LJ Smith, Alex A Horsley, Jody J Bray, Paul J C PJC Hughes, Alberto A Biancardi, Graham G Norquay, Martin M Wildman, Noreen N West, Helen H Marshall, Jim M JM Wild

Indexed on: 08 Jul '20Published on: 08 Jul '20Published in: European Respiratory Journal



Abstract

Xe ventilation MRI is sensitive to detect early CF lung disease and response to treatment. Xe-MRI could play a significant role in clinical trials and patient management. Here we present data on the repeatability of imaging measurements and their sensitivity to longitudinal change. 29 children and adults with CF and a range of disease severity were assessed twice, a median [IQR] of 16.0 [14.4,19.5] months apart. Patients performed Xe-MRI, lung clearance index (LCI), body plethysmography and spirometry at both visits. Eleven patients repeated Xe-MRI in the same session to assess the within-visit repeatability. The ventilation defect percentage (VDP) was the primary metric calculated from Xe-MRI. At baseline, mean (sd) age=23.0 (11.1) years and FEV z-score=-2.2 (2.0). Median [IQR] VDP=9.5 [3.4,31.6]%, LCI=9.0 [7.7,13.7]. Within-visit and inter-visit repeatability of VDP was high. At 16 months there was no single trend of Xe-MRI disease progression. Visible Xe-MRI ventilation changes were common, which reflected changes in VDP. Based on the within-visit repeatability, a significant short-term change in VDP is >±1.6%. For longer-term follow up, changes in VDP of up to ±7.7% can be expected, or ±4.1% for patients with normal FEV. No patient had a significant change in FEV, however 59% had change in VDP >±1.6%. In patients with normal FEV, there were significant changes in ventilation and in VDP. Xe-MRI is a highly effective method for assessing longitudinal lung disease in patients with CF. VDP has great potential as a sensitive clinical outcome measure of lung function and endpoint for clinical trials. Copyright ©ERS 2020.