Quantitative CT Evaluation of Bronchiectasis Improvement in Cystic Fibrosis after CFTR-Modulator Therapy

Purpose To assess whether elexacaftor-tezacaftor-ivacaftor (ETI) therapy improves bronchiectasis in cystic fibrosis at CT and to identify associated factors. Materials and Methods This retrospective study included consecutive patients with cystic fibrosis (CF) from two reference centers (between January 2020 and January 2025). Pulmonary function testing was performed, including forced expiratory volume in 1 second as percentage predicted (FEV₁%p), and CT was performed at three time points: 2 years before ETI (Y-2), at initiation of ETI (Y0), and 1 year after ETI (Y1). Bronchiectasis was assessed quantitatively and visually for shape and regional extent. Comparisons of paired medians were done using the Friedman test. Results A total of 106 patients were included (median age, 19 years [IQR, 12-29]; 59 male patients; median FEV₁%p, 80% [IQR, 55-99]). Of these 106 patients, 101 (95.3%) had mild-to-moderate disease severity, with FEV₁%p greater than 40%. Bronchiectasis normalized volumes increased between Y-2 (7.6 [IQR, 2-19]) and Y0 (15.3 [IQR, 5.6-32]) but decreased at Y1 (3.6 [IQR, 0.6-25]; <i>P</i> < .001). Bronchiectasis improved in 74 of 106 patients (69.8%), including 18 of 106 (16.9%) with complete resolution and 56 of 106 (52.9%) with partial reduction, with a median volume reduction of 64% and six resolved segments per patient. Bronchiectasis improvement was associated with younger age (<i>P</i> < .001), cylindric CT pattern (<i>P</i> < .001), fewer CT abnormalities (<i>P</i> < .001), and greater FEV1%p increase (<i>P</i> = .03). Younger age, lower <i>Pseudomonas aeruginosa</i> colonization, and lower CT mucus volume were independent predictors of bronchiectasis improvement (<i>R²</i> = 0.50; <i>P</i> < .001). Conclusion Bronchiectasis improvement occurred after ETI treatment in a substantial fraction of patients with predominantly mild-to-moderate CF. Improvement was linked to younger age and better disease status at ETI initiation, supporting early intervention. <b>Keywords:</b> CT-Quantitative, Tracheobronchial Tree, Chronic Obstructive Pulmonary Disease <i>Supplemental material is available for this article.</i> © RSNA, 2025.