Medial Models of Populations of Nearly Tubular Objects

Many structures in the world and several in the human body are nearly tubular in shape, i.e., have approximately circular cross-sections. Examples are portions of blood vessels, the colon and the whole head and neck. The method of modeling populations of slab-like objects as medial objects and segmentation using statistical shape and appearance models has been shown to be successful for several structures. However, the medial surface of a tubular object degenerates to a curve, and the statistics of even nearly tubular objects represented as slabs will typically be unstable. In this paper, we detail the representation, geometry and means of computing statistics of a population of nearly tubular medial models. We test our method on CTs of real rectums.