This study aims to measure three parameters of the airways: airway length(in mm), AWT(in mm), and ALA(in mm2). Specifically, we assessed the length of seven major airway sites, which include the trachea, right main bronchus(RMB), right superior lobe bronchus(RSLB), right middle lobe bronchus(RMLB), left main bronchus(LMB), left superior lobe bronchus(LSLB), and left inferior lobe bronchus(LILB). Following our established guidelines for dividing the central airway (Figure S2) [15 (link)], we measured the AWT and ALA at seven specific locations, including zones I to III and V to VIII (midpoint position of each zone) within the central airway. Additionally, we quantified the SCA (in degrees).
Airway parameters were measured in the study through 3D reconstruction of the airway tree from CT images using SYNAPSE 3D, an image analysis software developed by Fujifilm Medical Co., Ltd, Tokyo, Japan (Figure 1) [16 (link), 17 (link)]. The airway centreline was constructed using the minimum spanning tree generated by SYNAPSE 3D. The airway length was measured directly or indirectly (Figure 1B, Table S1). Additionally, the inner and outer contours of the seven selected airway locations were extracted using the graph cut method to calculate AWT and ALA (Figure 1A). The SCA was determined by measuring the airway centreline angles of the right and left main bronchus (Figure 1A).