Comparison of phase-resolved functional lung (PREFUL) and hyperpolarized Xe MRI for longitudinal monitoring of lung function in pediatric cystic fibrosis following elexacaftor/tezacaftor/ivacaftor.

BACKGROUND

Phase-resolved functional lung (PREFUL) MRI offers a more accessible alternative to hyperpolarized Xe MRI (Xe-MRI) for monitoring treatment response in pediatric cystic fibrosis (CF), but longitudinal comparisons are limited.

OBJECTIVE

To assess longitudinal lung function changes following elexacaftor/tezacaftor/ivacaftor (ETI) treatment initiation in CF children using PREFUL MRI, in comparison with Xe-MRI and pulmonary function tests (PFTs).

MATERIALS AND METHODS

PREFUL MRI, Xe-MRI, and PFTs were performed in 14 CF patients (median [IQR] age 15 [14-16.5] years old) at baseline and 1 month, 6 months, 12 months, and 24 months following initiation of ETI treatment. Ventilation and defect percentage (VDP) was derived from PREFUL MRI (regional ventilation VDP, VDP; regional-flow volume loop cross-correlation VDP, VDP; and the combination of VDP and VDP, VDP) and Xe-MRI (VDP) maps. Perfusion defect percentage (QDP) was derived from normalized perfusion maps and, with VDP, determined the percentage of healthy ventilation-perfusion matching (VQM). Significance of 1-month treatment changes was determined using the Wilcoxon-signed rank test and was correlated between metrics using Spearman ranked correlation.

RESULTS

All PREFUL measures significantly improved (P < 0.01) 1-month post-treatment in agreement with changes in Xe-MRI VDP and PFTs (P < 0.03). The absolute change in VDP and VDP significantly correlated with VDP (r ≥ 0.62, P < 0.02), unlike VDP (P = 0.35). The change in QDP did not correlate with any metric (P > 0.10). PREFUL MRI and Xe-MRI measures showed minimal changes 1 to 24 months post-treatment (median changes = -2.3% to 1.4%), in agreement with PFTs.

CONCLUSION

PREFUL MRI detects longitudinal treatment-related changes in pulmonary ventilation and perfusion in CF children post ETI.