Quantitative assessment of airway dimensions in young children with cystic fibrosis lung disease using chest computed tomography

ObjectiveTo evaluate lung disease progression using airway and artery (AA) dimensions on chest CT over 2-year interval in young CF patients longitudinally and compare to disease controls cross-sectionally. MethodsRetrospective analysis of pressure controlled end-inspiratory CTs, 12 routine baseline (CT1) and follow up (CT2) from AREST CF cohort; 12 disease controls with normal CT. All visible AA-pairs were measured perpendicular to the airway axis. Inner and outer airway diameters and wall (outer-inner radius) thickness were divided by adjacent arteries to compute A(in)A-, A(out)A-, and A(WT)A-ratios, respectively. Differences between CF and control data were assessed using mixed effects models predicting AA-ratios per segmental generation (SG). Power calculations were performed with 80% power and ?=0.05. ResultsCF, median age CT1 2 years; CT2 3.9 years, 5 males. Controls, median age 2.9 years, 10 males. Total of 4798 AA-pairs measured. Cross-sectionally: A(in)A-ratio showed no difference between controls and CF CT1 or CT2. A(out)A-ratio was significantly higher in CF CT1 (SG 2-4) and CT2 (SG 2-5) compared to controls. A(WT)A-ratio was increased for CF CT1 (SG 1-5) and CT2 (SG 2-6) compared to controls. CF longitudinally: A(in)A-ratio was significantly higher at CT2 compared to CT1. Increase in A(out)A-ratio at CT2 compared to CT1 was visible in SG 4. Sample sizes of 21 and 58 would be necessary for 50% and 30% A(out)A-ratio reductions, respectively, between CF CT2 and controls. ConclusionAA-ratio differences were present in young CF patients relative to disease controls. A(out)A-ratio as an objective parameter for bronchiectasis could reduce sample sizes for clinical trials.