An Airway Tree-shape Model for Geodesic Airway Branch Labeling

We present a mathematical airway tree-shape framework where airway trees are compared using geodesic distances. The framework consists of a rigorously defined shape space for treelike shapes, endowed with a metric such that the shape space is a geodesic metric space. This means that the distance between two tree-shapes can be realized as the length of the geodesic, or shortest deformation, connecting the two shapes. By computing geodesics between airway trees, as well as the corresponding airway deformation, we generate airway branch correspondences. Correspondences between an unlabeled airway tree and a set of labeled airway trees are combined with a voting scheme to perform automatic branch labeling of segmented airways from the challenging EXACT’09 test set. In spite of the varying quality of the data, we obtain robust labeling results.