Active Shape Model for Contour Detection of Anatomical Structure

This chapter introduces an active shape model (ASM) for contour detection of anatomical structures. It presents the review of deformable models and ASM. The 2D deformable models can be categorized into two classes: free-form models and parametrical models. Free-form models are only constrained by some general local constraints. As there is no global structure, the models can represent arbitrary shapes. Parametrically deformable models are able to describe a specific characteristic shape by a set of parameters. The chapter describes the method of ASM. ASM is a parametric deformable model that a combines point distribution model (PDM) and an iterative refinement procedure. The chapter investigates two applications of ASM: the boundary detection of optic disk in fundus images and lens structure detection in lens images. Experiments show that the ASM is suitable for the boundary detection of anatomical structures.