One year stability and sex differences in a 5 path analysis of the normal human airway tree via QCT: SPIROMICS cohort

Background: SPIROMICS cohort includes baseline (V1) and year 1 (V2) airway metrics along 5 lobar paths in normal non-smokers using quantitative CT (QCT). Aim: Establish airway measurement ranges for normal non-smokers and assess 1-year measurement stability. Methods: 181 normals (67 F, 114 M) were evaluated at full inspiration. Analysis (Apollo® 2.0, VIDA Diagnostics) included airway segmentation, labeling, and measurements. Metrics include wall thickness (WT), luminal diameter (D), and path-based Pi10. V1/V2 and Male (M)/Female (F) differences were assessed. Results: WT and D at segmental airways (LB1, LB10, RB1, RB4, RB10) stayed consistent between V1 and V2 with tight confidence intervals (CI) for differences. E.g., RB1: conf. int. (-0.04, 0.04) mm for lumen diameter, (-0.02, 0.01) mm for WT. Significant differences were found for D and WT between F and M (all segments). Mean D difference: 0.71 mm, mean WT difference: 0.14 mm. Pi10 values for each path were consistent between V1 and V2 with tight CI. Pi10. Pi10 for only the LB10 and RB1 showed significant (P=0.025) F/M differences: 3.66(F) vs. 3.77(M) and 3.77(F) vs. 3.86(M) respectively. Conclusions : Airway measurements remained stable. D and WT showed significant differences between F and M. Pi10 F vs. M differences were found only for the LB10 and RB1 paths.