Evaluating post-bronchodilator response in well-controlled paediatric severe asthma using hyperpolarised 129Xe-MRI: A pilot study.

Abstract

INTRODUCTION\nPulmonary function tests (PFTs) are the main objective measures used to assess asthma in children. However, PFTs provide a global measure of lung function. Hyperpolarised xenon-129 magnetic resonance imaging (129Xe-MRI) can assess lung function spatially. This cross-sectional cohort study aimed to evaluate the use of 129Xe-MRI in detecting ventilation abnormalities in children with well-controlled severe asthma pre- and post-bronchodilator (BD).\n\n\nMETHOD\nSix healthy children (aged 11\xa0±\xa03) and six with well-controlled severe asthma (14\xa0±\xa01) underwent spirometry, multiple breath washout (MBW), and 129Xe-MRI. These tests were repeated post-BD in the asthma cohort. Image analysis was performed in MATLAB. Wilcoxon signed-rank test, repeated measures analysis of variance (ANOVA), and Spearman s rank correlation coefficient were used for statistical analysis.\n\n\nRESULTS\nA significantly higher number of ventilation defects were found in the asthma cohort pre-BD compared to the healthy participants and post-BD within the asthma cohort (p\xa0=\xa00.02 and 0.01). A greater number of wedge-shaped defects were detected in the asthma cohort pre-BD compared to healthy participants and post-BD within the asthma cohort (p\xa0=\xa00.01 and 0.008, respectively). 129Xe ventilation defect percentage (VDP) and coefficient of variation (CoV) were significantly higher in the asthma cohort pre-BD compared to the healthy cohort (p\xa0=\xa00.006 for both). VDP and CoV were reduced significantly post-BD in the asthma cohort, to a level where there was no longer a significant difference between the two cohorts.\n\n\nCONCLUSION\n129Xe-MRI is a sensitive marker of ventilation inhomogeneity in paediatric severe asthma and may potentially be used as a biomarker to assess disease progression and therapeutic response.