Comparison of 3D UTE free‐breathing lung MRI with hyperpolarized ¹²⁹Xe MRI in pediatric cystic fibrosis

Abstract Purpose To compare phase‐resolved functional lung (PREFUL) regional ventilation derived from a free breathing 3D UTE radial MRI acquisition to hyperpolarized 129 Xe‐MRI (Xe‐MRI), conventional 2D multi‐slice PREFUL MRI, and pulmonary function tests in pediatric cystic fibrosis (CF) lung disease. Methods Free‐breathing 3D UTE and 2D multi‐slice 1 H MRI as well as Xe‐MRI were acquired in 12 stable pediatric CF patients. Using PREFUL, regional ventilation (RVent) maps were calculated from the free‐breathing data. Ventilation defect percentage (VDP) was determined from 3D and 2D RVent maps (2D VDP RVent and 3D VDP RVent , respectively) and Xe‐MRI ventilation (VDP Xe ). VDP was calculated for the whole lung and for eight regions based on left/right, anterior/posterior, and superior/inferior divisions of the lung. Global and regional VDP was compared between the three methods using Bland–Altman analysis, linear mixed model‐based correlation, and one‐way analysis of variance and multiple comparisons tests. Results Global 3D VDP RVent , VDP Xe , and 2D VDP RVent were all strongly correlated (all R 2 > 0.62, p < 0.0001) and showed minimal, non‐significant bias (all <2%, p > 0.05). Three dimensional and 2D VDP RVent significantly correlated to VDP Xe in most of the separate lung regions ( R 2 = 0.18–0.74, p < 0.04), but showed lower inter‐agreement. The superior/anterior lung regions showed the least agreement between all three methods (all p > 0.12). Conclusion Absolute VDP assessed by 3D UTE PREFUL MRI showed good global agreement with Xe‐MRI and 2D multi‐slice PREFUL MRI in pediatric CF lung disease. Therefore, 3D UTE PREFUL MRI offers a sensitive and potentially more accessible alternative to Xe‐MRI for regional volumetric evaluation of ventilation.