Multiobject segmentation using coupled shape space models

Due to noise and artifacts often encountered in medical images, segmenting objects in these is one of the most challenging tasks in medical image analysis. Model-based approaches like statistical shape models (SSMs) incorporate prior knowledge that supports object detection in case of in-complete evidence from image data. In this paper, we present a method to increase information of the object's shape in problematic image areas by incorporating mutual shape information from other entities in the image. This is done by using a common shape space of multiple objects as additional restriction. Two different approaches to implement mutual shape information are presented. Evaluation was performed on nine cardiac images by simultaneous segmentation of the epi- and endocardium of the left heart ventricle using the proposed methods. The results show that the segmentation quality is improved with both methods. For the better one, the average surface distance error is approx. 40% lower.