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

Lin, Nancy Y; Roach, David J; Willmering, Matthew M; Walkup, Laura L; Hossain, Md Monir; Desirazu, Priyanka; Cleveland, Zackary I; Guilbert, Theresa W; Woods, Jason C

BACKGROUND Measurement of regional lung ventilation with hyperpolarized 129Xe magnetic resonance imaging (129Xe MRI) in pediatric asthma is poised to advance our understanding of disease mechanisms and pathophysiology in a disorder with diverse clinical phenotypes. 129Xe MRI has not been investigated in a pediatric asthma cohort. OBJECTIVE We hypothesized that 129Xe 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 severe asthma, 8 mild/moderate asthma, 16 age-matched healthy controls) aged 6-17 years-old were imaged with 129Xe MRI. Ventilation defect percentage (VDP) and image reader score were calculated and compared to clinical measures at baseline and at follow-up. RESULTS Children with asthma had higher VDP (p=0.002) and number of defects per image slice (defects/slice) (p=0.0001) 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 higher number of defects/slice had higher rate of healthcare utilization (r=0.48, p=0.03) and oral corticosteroid use (r=0.43, p=0.05) at baseline. ROC analysis demonstrated the number of defects/slice and VDP were predictive of increased healthcare utilization, asthma and severe asthma. VDP correlated with FEV1 (r=-0.35, p=0.04) and FEV1/FVC ratio (r=-0.41, p=0.01). CONCLUSION 129Xe MRI correlates with asthma severity, healthcare utilization, and oral corticosteroid use. As delineation of clinical severity is often difficult in children, 129Xe MRI may be an important biomarker for severity, with potential to identify children at higher risk for exacerbations and improve outcomes.