Correlation of Hyperpolarised Xenon-129 Magnetic Resonance Imaging (129Xe-MRI) of the Lung with Multi-Breath Washout (MBW) in Children with Severe Asthma

Abstract

Introduction: Asthma is the most common chronic disease in children. MBW-derived lung clearance index (LCI), a global measure of ventilation inhomogeneities, is increasingly used in paediatric patients to complement spirometry, the current gold-standard pulmonary function test. 129Xe-MRI, a functional imaging technique, can assess regional lung function, including regional ventilation inhomogeneities. A strong correlation between VDP and LCI in CF and a weaker one in mild asthma has been shown previously. Aim: We aimed to assess the feasibility of 129Xe-MRI in children with severe asthma. Method: 129Xe-MR lung images were acquired on a 3T Siemens MRI scanner during a breath-hold of up to 16-seconds. Images were analysed in MatLab, calculating the ventilation defect percentage (VDP) regionally. Results: Nine healthy children (mean age 10.6) and four with severe asthma (mean age 14.1) were recruited. All completed the scan. VDP was 15 times greater in the asthma cohort (p=0.02), in whom VDP correlated strongly with LCI (Pearson’s correlation r=0.99, p=0.018) and mildly with FEV1 (r=0.22). Conclusion: 129Xe-MRI is feasible in children with severe asthma and VDP correlates strongly with LCI. 129Xe-MRI is a non-ionising technique and may potentially be used as a biomarker to assess disease progression and therapeutic response. (ClinicalTrials.gov ID NCT02740868)