The ventilation defect percent (VDP), measured from hyperpolarized (HP) ¹²⁹Xe magnetic resonance imaging (MRI), is sensitive to functional changes in cystic fibrosis (CF) lung disease. The purpose of this study was to measure and compare VDP from HP ¹²⁹Xe MRI acquired at two institutions in stable pediatric CF subjects with preserved lung function.

This retrospective analysis included 26 participants from two institutions (18 CF, 8 healthy, age range 10–17). Pulmonary function tests, N₂ multiple breath washout (to measure lung clearance index, LCI), and HP ¹²⁹Xe MRI were performed. VDP measurements were compared between two trained analysts using mean-anchored linear binning. Correlations were investigated for VDP compared to the forced expiratory volume in one second (FEV₁) and LCI.

VDP measurements agreed for the two analysts with an intraclass correlation coefficient of 0.99. In the combined dataset, VDP measured by Analyst 1 was 5.96 ± 1.82% and 15.96 ± 6.76% for the healthy and CF groups, respectively (p = .0004). Analyst 2 showed similar differences between healthy and CF (p = .0003). VDP measured by either analyst was shown to correlate with FEV₁ (R² = 0.33, p = .003; and R² = 0.26, p = .009 for Analysts 1 and 2, respectively) and LCI (R² = 0.76, p < .0001; and R² = 0.77, p < .0001 for Analysts 1 and 2, respectively).

HP ¹²⁹Xe MRI provides a robust measurement of ventilation heterogeneity in stable pediatric CF subjects at two sites. Since measurements performed at two sites yielded similar VDP values with near-identical values between different analysts, implementation of the technique in multi-center trials in CF appears feasible.