Hierarchical segmentation and identification of thoracic vertebra using learning-based edge detection and coarse-to-fine deformable model”, Med

Abstract. Precise segmentation and identification of thoracic verte-brae is important for many medical imaging applications whereas it remains challenging due to vertebra’s complex shape and varied neigh-boring structures. In this paper, a new method based on learned bone-structure edge detectors and a coarse-to-fine deformable surface model is proposed to segment and identify vertebrae in 3D CT thoracic images. In the training stage, a discriminative classifier for object-specific edge detection is trained using steerable features and statistical shape models for 12 thoracic vertebrae are also learned. In the run-time, we design a new coarse-to-fine, two-stage segmentation strategy: subregions of a vertebra first deforms together as a group; then vertebra mesh vertices in a smaller neighborhood move group-wise, to progressively drive the deformable model towards edge response maps by optimizing a prob-ability cost function. In this manner, the smoothness and topology of vertebra’s shapes are guaranteed. This algorithm performs successfully with reliable mean point-to-surface errors 0.95±0.91 mm on 40 volumes. Consequently a vertebra identification scheme is also proposed via mean surface meshes matching. We achieve a success rate of 73.1 % using a sin-gle vertebra, and over 95 % for 8 or more vertebra which is comparable or slightly better than state-of-the-art [1].