Intra- and Inter-visit Repeatability of 129 Xenon Multiple-Breath Washout MRI in Children With Stable Cystic Fibrosis Lung Disease.

Background: Multiple-breath washout (MBW) ¹²⁹ Xe MRI (MBW Xe-MRI) is a promising technique for following pediatric cystic fibrosis (CF) lung disease progression. However, its repeatability in stable CF needs to be established to use it as an outcome measure for novel therapies.
Purpose: To assess intravisit and intervisit repeatability of MBW Xe-MRI in healthy and CF children.
Study Type: Prospective, longitudinal cohort study.
Subjects: A total of 18 pediatric subjects (7 healthy, 11 CF).
Field Strength/sequence: A 3 T/2D coronal hyperpolarized (HP) ¹²⁹ Xe images using GRE sequence.
Assessment: All subjects completed MBW Xe-MRI, pulmonary function tests (PFTs) (spirometry, nitrogen [N ₂ ] MBW for lung clearance index [LCI]) and ventilation defect percent (VDP) at baseline (visit 1) and 1-month after. Fractional ventilation (FV), coefficient of variation (CoV _FV ) maps were calculated from MBW Xe-MRI data acquired between intervening air washout breaths performed after an initial xenon breath-hold. Skewness of FV and CoV _FV map distributions was also assessed.
Statistical Tests: Repeatability: intraclass correlation coefficients (ICC), within-subject coefficient of variation (CV%), repeatability coefficient (CR). Agreement: Bland-Altman. For correlations between MBW Xe-MRI, VDP and PFTs: Spearman's correlation. Significance threshold: P < 0.05.
Results: For FV, intravisit median [IQR] ICC was high in both healthy (0.94 [0.48, 0.99]) and CF (0.83 [0.04, 0.97]) subjects. CoV _FV also had good intravisit ICC in healthy (0.92 [0.42, 0.99]) and CF (0.79 [0.02, 0.96]) subjects. Similarly, for FV, intervisit ICC was high in health (0.94 [0.68, 0.99]) and CF (0.89 [0.61, 0.97]). CoV _FV also had good intervisit ICC in health (0.92 [0.42, 0.99]) and CF (0.78 [0.26, 0.94]). FV had better intervisit repeatability than VDP. CoV _FV correlated significantly with LCI (R = 0.56). Skewness of FV distributions significantly distinguished between cohorts at baseline.
Data Conclusion: MBW Xe-MRI had high intravisit and intervisit repeatability in healthy and stable CF subjects. CoV _FV correlated with LCI, suggesting the importance of ventilation heterogeneity to early CF.
Evidence Level: 1.
Technical Efficacy: Stage 2.
(© 2023 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)