Multisite Hyperpolarized 129Xe MRI Study of Pediatric Primary Ciliary Dyskinesia

Background: Primary ciliary dyskinesia (PCD) is a mucociliary clearance disease with significant lung morbidity. Commonly used lung function (LFxn) measures include FEV₁pp (spirometry) and LCI (multiple breath washout (MBW)). Hyperpolarized ¹²⁹Xe MRI (XeMRI) is an emerging approach that uses an inhaled gas to visualize ventilation and measure ventilation defect percent (VDP). It is a sensitive LFxn marker in CF but still under investigation in PCD. Objective: Determine the feasibility and intraday reliability of XeMRI in pediatric PCD across 2 sites. Methods: Participants were recruited from 2 PCD centers, if they had a confirmed PCD diagnosis, >6 years, and able to perform reproducible spirometry. Participants were excluded if medically unstable or on supplemental oxygen.  Participants underwent repeat intraday LFxn testing (spirometry, MBW, XeMRI). Results: 12 participants were enrolled. Repeat LFxn testing demonstrated good reliability in FEV₁pp, LCI and VDP; intraclass correlations >0.9. VDP had a significant and good correlation with LCI (R²=0.81, p<0.01) but not FEV₁pp (R²=0.37, p=0.04).  Intraday XeMRI scans showed changing ventilation defects (Figure). Conclusions: In PCD, XeMRI is feasible and harmonizable across institutions. VDP correlates with LCI and is reliable. Intraday scans reveal shifting ventilation defects and ongoing research is needed to understand the mechanisms and significance of this finding.