129 Xe and Free-Breathing 1 H Ventilation MRI in Patients With Cystic Fibrosis: A Dual-Center Study

Abstract

Background: Free-breathing ¹ H ventilation MRI shows promise but only single-center validation has yet been performed against methods which directly image lung ventilation in patients with cystic fibrosis (CF).

Purpose: To investigate the relationship between ¹²⁹ Xe and ¹ H ventilation images using data acquired at two centers.

Study type: Sequence comparison.

Population: Center 1; 24 patients with CF (12 female) aged 9-47 years. Center 2; 7 patients with CF (6 female) aged 13-18 years, and 6 healthy controls (6 female) aged 21-31 years. Data were acquired in different patients at each center.

Field strength/sequence: 1.5 T, 3D steady-state free precession and 2D spoiled gradient echo.

Assessment: Subjects were scanned with ¹²⁹ Xe ventilation and ¹ H free-breathing MRI and performed pulmonary function tests. Ventilation defect percent (VDP) was calculated using linear binning and images were visually assessed by H.M., L.J.S., and G.J.C. (10, 5, and 8 years' experience).

Statistical tests: Correlations and linear regression analyses were performed between ¹²⁹ Xe VDP, ¹ H VDP, FEV₁ , and LCI. Bland-Altman analysis of ¹²⁹ Xe VDP and ¹ H VDP was carried out. Differences in metrics were assessed using one-way ANOVA or Kruskal-Wallis tests.

Results: ¹²⁹ Xe VDP and ¹ H VDP correlated strongly with; each other (r = 0.84), FEV₁ z-score (¹²⁹ Xe VDP r = -0.83, ¹ H VDP r = -0.80), and LCI (¹²⁹ Xe VDP r = 0.91, ¹ H VDP r = 0.82). Bland-Altman analysis of ¹²⁹ Xe VDP and ¹ H VDP from both centers had a bias of 0.07% and limits of agreement of -16.1% and 16.2%. Linear regression relationships of VDP with FEV₁ were not significantly different between ¹²⁹ Xe and ¹ H VDP (P = 0.08), while ¹²⁹ Xe VDP had a stronger relationship with LCI than ¹ H VDP.

Data conclusion: ¹ H ventilation MRI shows large-scale agreement with ¹²⁹ Xe ventilation MRI in CF patients with established lung disease but may be less sensitive to subtle ventilation changes in patients with early-stage lung disease.

Evidence level: 2 TECHNICAL EFFICACY: Stage 2.

Keywords: MRI; cystic fibrosis; proton; ventilation; xenon-129.