Fig. 3.

Patient-specific airway model and representative Y-branch models created from magnetic resonance image segmentation. We select regions of interest in each transverse plane image and segment the airway boundaries with splines. We then stack the images to create a three-dimensional surface model of the inner airway wall. From the surface model, we create volume models of five representative Y-branches, which we mesh with more than 300,000 hexahedral elements and 1,000,000 degrees of freedom.