Oxygen-enhanced MRI and multiple breath washout with Short extension reveal cystic fibrosis lung disease progression despite triple modulator therapy

Introduction The current cystic fibrosis (CF) care era, while hugely welcome, raises new challenges, particularly the need for more sensitive pulmonary outcome measures. Seeking further optimisation, we previously developed a Short extension to multiple breath washout measure (MBW ShX ) which captures previously overlooked, under-ventilated lung units but lacks regional information. Functional lung MRI addresses this limitation. We hypothesised these measures would be more sensitive to change in tracking CF lung disease than usual clinical respiratory function tests. Methods Forty-six people with (pw)CF, median age 15 (range 6–55) years were recruited to a single-centre study. While clinically stable, pwCF performed OE-MRI, MBW+/- ShX and spirometry at baseline and at 6 monthly intervals over 18 months of follow-up. A subgroup of pwCF (n=20) and age-matched healthy controls (HC, n=20) performed two repeatability visits within 6 weeks. Results OE-MRI/MBW ShX were well tolerated, differentiated HC and CF groups, and were repeatable with negligible differences between two visits