129Xe MRI as a measure of clinical disease severity for pediatric asthma

Background: Measurement of regional lung ventilation with hyperpolarized Xe-129 magnetic resonance imaging (Xe-129 MRI) in pediatric asthma is poised to advance our understanding of disease mechanisms and pathophysiology in a disorder with diverse clinical phenotypes. Xe-129 MRI has not been investigated in a pediatric asthma cohort. Objective: We hypothesized that Xe-129 MRI is feasible and can demonstrate ventilation defects that relate to and predict clinical severity in a pediatric asthma cohort. Methods: Thirty-seven children (13 with severe asthma, 8 with mild/moderate asthma, 16 age-matched healthy controls) aged 6 to 17 years old were imaged with Xe-129 MRI. Ventilation defect percentage (VDP) and image reader score were calculated and compared with clinical measures at baseline and at follow-up. Results: Children with asthma had higher VDP (P=.002) and number of defects per image slice (defects/slice) (P=.0001) than children without asthma. Children with clinically severe asthma had significantly higher VDP and number of defects/slice than healthy controls. Children with asthma who had a higher number of defects/slice had a higher rate of health care utilization (r=0.48; P=.03) and oral corticosteroid use (r=0.43; P=.05) at baseline. Receiver-operating characteristic analysis demonstrated that the VDP and number of defects/slice were predictive of increased health care utilization, asthma, and severe asthma. VDP correlated with FEV1 (r=20.35; P=.04) and FEV1/forced vital capacity ratio (r=20.41; P=.01). Conclusions: Xe-129 MRI correlates with asthma severity, health care utilization, and oral corticosteroid use. Because delineation of clinical severity is often difficult in children, Xe-129 MRI may be an important biomarker for severity, with potential to identify children at higher risk for exacerbations and improve outcomes.

Automated summary

The use of Xe-129 MRI to measure lung ventilation can help understand the severity of asthma pathology, predict disease severity, and is of significant value in the management of pediatric asthma patients.