Background Managing patients with primary ciliary dyskinesia(PCD) is challenging due to limited therapeutic options and lack of sensitive, disease-specific outcome measures. Hyperpolarized 129-xenon MRI(XeMRI) is an emerging imaging modality that quantifies ventilation heterogeneity using the ventilation defect percent(VDP). In other obstructive lung diseases, VDP has demonstrated increased sensitivity compared to conventional lung function measures; however, its utility in PCD has not been established. Objectives In PCD, (i)determine the feasibility of XeMRI, (ii)evaluate the same-day repeatability of VDP and (iii)explore the relationship between VDP with lung clearance index(LCI 2.5 ) and forced expiratory volume in 1-second, z-score(FEV1z). Methods In this cross-sectional observational study, participants >6 years-old with confirmed PCD, were recruited from two Canadian PCD centers. Participants underwent lung function testing to measure FEV1z and LCI 2.5 . XeMRI was performed twice within 30–60 min to measure VDP. Intraclass correlation coefficient(ICC) and Bland-Altman plots(B&A) were used to assess same-day repeatability of VDP. Linear correlation between VDP with FEV1z and LCI 2.5 evaluated their relationships. Results 16 participants completed the study. In all participants, the VDP was elevated (VDP>2.3) with a median VDP of 11.05%(IQR: 4.83–13.67%). Same-day repeat XeMRI VDP had an ICC>0.95 and B&A showed good agreement. VDP positively correlated with LCI 2.5 (r=0.89, p< 0.05) and negatively correlated with FEV1z(r=0.6, p< 0.05). Conclusions XeMRI is a feasible imaging modality to capture lung disease in PCD. VDP has excellent same-day repeatability and correlated strongly with LCI 2.5 . Moreover, VDP was more sensitive at detecting lung function impairments than LCI 2.5 and FEV1z, demonstrating its potential as a sensitive outcome measure in PCD.
Wee et al. (Thu,) studied this question.