Multiorgan Segmentation Using Coherent Propagating Level Set Method Guided by Hierarchical Shape Priors and Local Phase Information

Abstract

In this chapter, we introduce an automatic multiorgan segmentation method using a hierarchical-shape-prior-guided level set method. The hierarchical shape priors are organized according to the anatomical hierarchy of the human body, so that the children structures are always contained by the parent structure. This hierarchical approach solves two challenges of multiorgan segmentation. First, it gradually refines the prediction of the organs' position by locating and segmenting the larger parent structure. Second, it solves the ambiguity of boundary between two attaching organs by looking at a large scale and imposing the additional shape constraint of the higher-level structures. To improve the segmentation accuracy, a model-guided local phase term is introduced and integrated with the conventional region-based energy function to guide the level set propagation. Finally, a novel coherent propagation method is implemented to speed up the model-based level set segmentation. In the VISCERAL Anatomy challenge, the proposed method delivered promising results on a number of abdominal organs.

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“…The local phase is referred to the argument of complex number. 8 The local properties (amplitude and phase) are extracted from a 1D signal f(x) represented in its analytic form. An analytical signal is a linear combination of the original signal f(x) and its Hilbert's transform f H (x) as shown in Equation ( 4):…”

“…In many applications, researchers obtained similar results to the learning approach by applying classical methods. 3,7,8 In general, the automatic and semiautomatic segmentation methods are based on the graph cut, 9 fuzzy CMeans, 10 region growing methods. 11 For instance, Ahammed Muneer and Pranav 12 proposed a semiautomated segmentation using region growingassociated morphological operations.…”

“…Kafali et al 18 used local phase to improve reconstruction for multiacquisition images which reduce noise. A remarkable approach was proposed by Wang and Smedby 8 for an automatic multiorgan segmentation. This approach is based on a coherent level set method, guided by hierarchical shape prior and local phase information.…”

“…The local phase in the complex plane8 176 slices, which have dimensions of 256 × 256 Pixels. The used algorithms are developed in the MATLAB environment.…”