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

Objective: To 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. Methods: Retrospective 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 AinA-, AoutA-, and AWTA-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 ɑ = 0.05. Results: CF, 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: AinA-ratio showed no difference between controls and CF CT1 or CT2. AoutA-ratio was significantly higher in CF CT1 (SG 2-4) and CT2 (SG 2-5) compared to controls. AWTA-ratio was increased for CF CT1 (SG 1-5) and CT2 (SG 2-6) compared to controls. CF longitudinally: AinA-ratio was significantly higher at CT2 compared to CT1. Increase in AoutA-ratio at CT2 compared to CT1 was visible in SG ≥4. Sample sizes of 21 and 58 would be necessary for 50% and 30% AoutA-ratio reductions, respectively, between CF CT2 and controls. Conclusion: AA-ratio differences were present in young CF patients relative to disease controls. AoutA-ratio as an objective parameter for bronchiectasis could reduce sample sizes for clinical trials.

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