RT Journal Article SR Electronic T1 Effect of ELX/TEZ/IVA treatment on lung ventilation in children with cystic fibrosis – comprehensive assessment using spirometry, MBW, structural and functional lung MRI JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 3919 DO 10.1183/13993003.congress-2022.3919 VO 60 IS suppl 66 A1 Streibel, C A1 Willers, C C A1 Pusterla, O A1 Bauman, G A1 Bieri, O A1 Stranzinger, E A1 Brabandt, B A1 Latzin, P A1 Kieninger, E YR 2022 UL http://erj.ersjournals.com/content/60/suppl_66/3919.abstract AB Background: With the introduction of cystic fibrosis transmembrane conductance regulator (CFTR)-modulator treatment in patients with cystic fibrosis (CF) a new era of milder lung disease started. Thus, sensitive parameters are needed to comprehensively monitor disease course. Functional lung matrix-pencil decomposition (MP)-MRI is a promising tool that allows calculating quantitative impairment of ventilation and perfusion.Aim: To assess applicability of structural and functional MRI to monitor treatment effects in patients with CF after starting ELX/TEZ/IVA treatment.Methods: 23 children with CF underwent lung function tests (spirometry, multiple breath washout), structural and functional (matrix pencil, MP) MRI before and after starting ELX/TEZ/IVA treatment (mean (range) treatment 4.6 (0.5 to 10.2) months). Main outcomes were changes in FEV1, lung clearance index (LCI), Eichinger score and defect percentage of ventilation (VDP) and perfusion (QDP).Results: We observed a significant improvement in lung function and structural and functional MRI parameters upon ELX/TEZ/IVA treatment (mean; 95%-CI from paired t-test): delta FEV1 1.13 (0.63 to 1.62) z-Scores, p<0.001; delta LCI -0.94 (-1.75 to -0.14), p=0.024; delta VDP [% of impairment] -5.87 (-8.43 to -3.32), p<0.001; delta QDP [% of impairment] -4.08 (-6.15 to -2.02), p<0.001; delta Eichinger score -3.90 (-5.15 to -2.65), p<0.001.Conclusion: Both structural and functional MRI are suitable tools to monitor treatment effects of ELX/TEZ/IVA therapy in patients with CF.FootnotesCite this article as Eur Respir J 2022; 60: Suppl. 66, 3919.This article was presented at the 2022 ERS International Congress, in session “-”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).