A Framework of Vertebra Segmentation Using the Active Shape Model-Based Approach

Mohammed Benjelloun,Saïd Mahmoudi,Fabian Lecron

doi:10.1155/2011/621905

Mohammed Benjelloun, Saïd Mahmoudi + Show 1 more

Open Access

https://doi.org/10.1155/2011/621905

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Abstract

We propose a medical image segmentation approach based on the Active Shape Model theory. We apply this method for cervical vertebra detection. The main advantage of this approach is the application of a statistical model created after a training stage. Thus, the knowledge and interaction of the domain expert intervene in this approach. Our application allows the use of two different models, that is, a global one (with several vertebrae) and a local one (with a single vertebra). Two modes of segmentation are also proposed: manual and semiautomatic. For the manual mode, only two points are selected by the user on a given image. The first point needs to be close to the lower anterior corner of the last vertebra and the second near the upper anterior corner of the first vertebra. These two points are required to initialize the segmentation process. We propose to use the Harris corner detector combined with three successive filters to carry out the semiautomatic process. The results obtained on a large set of X-ray images are very promising.

Highlights

In some circumstances, it is not easy for humans to distinguish objects in X-ray images from their background
In this paper we presented a vertebra segmentation method using an Active Shape Model recognition approach
The Active Shape Model segmentation method is composed of two phases: a modeling phase, aiming to create a mean shape model, and a searching phase

Summary

Introduction

It is not easy for humans to distinguish objects in X-ray images from their background. The chosen landmarks are positioned around each contour in such a manner to distribute the total variance existing in the training set Another variation of the ASM method is Active Appearance Model (AAM) which is largely described in the scientific literature [16]. Several publications [18,19,20,21,22] propose different methods to extract vertebra contours from X-ray images, like polar signature, template matching, active contours, and Discrete Dynamic Contour Model or Harris Detector. We propose a semiautomatic method allowing to ideally place the mean shape on the vertebrae to be segmented We achieve this task by using the Harris corner detector followed by a series of filters aiming to detect the two anterior corners of each vertebra on the X-ray image.

Method Overview

Results

Conclusion