Airway Segmentation and Luminal Analysis

Airway segmentation and airway luminal area measurements were obtained using SYNAPSE VINCENT software (FUJIFILM Medical, Tokyo, Japan)⁵. The segmental bronchus was defined as the 3rd generation airway. Following automatic luminal segmentation of the airway tree, all branches of the 3rd to 6th generation airways in all segments were manually identified by tracking from the 3rd to the 6th generation [5 (link), 21 (link)]. For each branch, cross-sectional images perpendicular to the longitudinal center line of the lumen were generated, and the lumen areas and internal diameters in the middle third portion were automatically measured and averaged. The mean lumen area for each generation airway was calculated in all segments.