Three-Dimensional Free-Breathing Ultrashort Echo Time (UTE) 1H MRI Regional Ventilation: Comparison With Hyperpolarized 129Xe MRI and Pulmonary Function Testing in Healthy Volunteers and People With Cystic Fibrosis

MRI can provide localized assessment of lung function for monitoring people with lung disease. Hyperpolarized Xe-129 MRI directly images pulmonary gas distribution but requires specialized hardware. Conventional 1H MRI acquisitions can also provide functional maps using free-breathing approaches. The purpose of this study is to evaluate regional ventilation derived from 3D ultrashort echo-time (UTE) H-1 MRI using Motion-Compensated Low-Rank constrained reconstruction (MoCoLoR), by comparing against Xe-129 MRI and pulmonary function testing as reference-standard. The study is retrospective in design. The study included 57 participants (25.4 +/- 15.8 years, 35 males and 22 females): 12 healthy volunteers, 20 pediatric, and 25 adult people with cystic fibrosis (CF) scanned between January 2022 and February 2023. Field strength/sequence: 3T; Xe-129: 2D multislice spoiled gradient-recalled sequence; UTE H-1: variable-density 3D radial sequence. K-means-based Xe-129 ventilation defect percent (VDP), forced expiratory volume in 1 s (FEV1), and lung clearance index (LCI) were evaluated against UTE H-1 VDP from a modified k-means method. The correspondence of ventilation defect maps from Xe-129 and UTE 1H was also evaluated. Statistical tests included the Pearson correlation coefficient (r) and t tests, with p < 0.05 considered significant. Xe-129 and UTE H-1 VDP were significantly correlated (r = 0.64, p = 9.1x10(-8)). Bland-Altman analysis showed a bias of -0.05 (p = 7.2x10(-5)) and limits of agreement of (0.07, -0.17). The Dice spatial accuracy of the UTE-based ventilation defect regions using Xe-129 as reference was 0.64 +/- 0.05. UTE H-1 VDP was significantly correlated with FEV1 (r = -0.54, p = 2.9x10(-4)) and LCI (r = 0.48, p = 5.9x10(-3)) and was significantly different between healthy and CF participants (p = 0.017), although the correlations and differences were stronger for Xe-129 VDP. UTE H-1 VDP correlated with Xe-129 VDP, FEV1, and LCI, and demonstrated high, consistent Dice spatial accuracy against Xe-129 VDP. UTE H-1 VDP captured variations in lung ventilation and has the advantage that it can be widely implemented on any MR system for evaluation and monitoring of patients with lung disease.