Fig. 1

Measurement procedure using a CT-3D imaging workstation. The bronchus to be measured was selected on the left CT image, and a bronchial pathway was created by automatic extraction (top). The bronchial cross section at the specified position is displayed and the inner and outer diameters are marked (bottom left). The inner and outer diameters, WA%, and T/D ratio were automatically calculated for the 4th-8th generations of bronchi (bottom right). L: lumen diameter, T: wall thickness, D: overall bronchial diameter. In the measurement screen, multiple measurements of T, D, and L are made, and their average are calculated