GOLD-associated shape variations in central airway tree assessed via QCT

Background: We seek to evaluate an automated method developed to assess central airway shape (cross-sectional and longitudinal) variations in the context of a multi-center study, SPIROMICS, seeking to evaluate phenotypes of COPD. Methods: 717 subjects (GOLD 1: 28, GOLD 2: 275, GOLD 3: 293, GOLD 4: 121) randomly selected from SPIROMICS baseline scans. Matching TLC and RV datasets were analyzed (VIDA Diagnostics) with a focus on the trachea and the left and right mainstem bronchi (LMB, RMB). Measurements included: extent of concave sections and deviation from circularity in lumen cross-sections, and straightness along the airway centerline. Results: Concavity and circularity: there is a significant increase in concavity and decrease in circularity between TLC and RV for all GOLD groups. Kruskal-Wallis test indicates significant concavity and circularity differences at RV in the trachea and LMB between GOLD groups 2 and 4, as well as 3 and 4. Straightness: statistically significant but physically small change in straightness between TLC and RV for all three major airways. Significant differences at RV in straightness across GOLD groups for trachea and LMB, but not for RMB. Conclusions: Central airway shapes change significantly across the vital capacity with distinctly different shape changes detectable across GOLD status.