Departmental Papers (BE)

Document Type

Journal Article

Date of this Version

August 2008

Abstract

There are several medical application areas that require the segmentation and separation of the component bones of joints in a sequence of images of the joint acquired under various loading conditions, our own target area being joint motion analysis. This is a challenging problem due to the proximity of bones at the joint, partial volume effects, and other imaging modality-specific factors that confound boundary contrast. In this article, a two-step model-based segmentation strategy is proposed that utilizes the unique context of the current application wherein the shape of each individual bone is preserved in all scans of a particular joint while the spatial arrangement of the bones alters significantly among bones and scans. In the first step, a rigid deterministic model of the bone is generated from a segmentation of the bone in the image corresponding to one position of the joint by using the live wire method. Subsequently, in other images of the same joint, this model is used to search for the same bone by minimizing an energy function that utilizes both boundary - and region-based information. An evaluation of the method by utilizing a total of 60 data sets on MR and CT images of the ankle complex and cervical spine indicates that the segmentations agree very closely with the live wire segmentations, yielding true positive and false positive volume fractions in the range 89%–97% and 0.2%–0.7%. The method requires 1–2 minutes of operator time and 6–7 min of computer time per data set, which makes it significantly more efficient than live wire - the method currently available for the task that can be used routinely.

Comments

Copyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. Reprinted in Medical Physics, Volume 35, Issue 8, August 2008, pages 3637-3649.

Publisher URL: http://dx.doi.org/10.1118/1.2953567

Keywords

MRI, image segmentation, live wire, model-based segmentation, kinematics

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Date Posted: 18 August 2008

This document has been peer reviewed.