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"Generating Coefficients for Regularization Terms in Nonrigid Registration of Contrast-Enhanced MRI"

Xi Liang, R. Kotagiri, Q. Yang, Marius Staring and A. Pitman

Abstract

Nonrigid registration is a technique to recover spatial deformations between images. It can be formulated as an optimization problem to minimize the image dissimilarity. A regularization term is used to reduce undesirable deformations which are usually employed in a homogeneous or spatial-variant fashion. When spatial-variant regularization is used in nonrigid registration of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), the local coefficients have been determined by manual segmentation of tissues of interest. We propose a framework to generate regularization coefficients for nonrigid registration in DCE-MRI, where tumor locations are to be transformed in a rigid fashion. The coefficients are obtained by applying a sigmoid function on subtraction images from a pre-registration. All parameters in the function are automatically determined using k-means clustering. The validation study compares three regularization weighting schemes in nonrigid registrations: a constant coefficient for a volume-preserving term, binary coefficients obtained by manual segmentation and a real-value coefficients using the proposed method on a rigidity term. Evaluation is performed using displacements, intensity changes and volume changes of tumors on synthetic and clinical DCE-MR breast images. As a result, the registration using spatial-variant rigidity terms performs better than using homogeneous volume-preserving terms. For the coefficient generation methods of a rigidity term, the proposed method can replace the binary coefficients requiring manual tumor segmentation.

 

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Copyright © 2011 by the authors. Published version © 2011 by . Personal use of this material is permitted. However, permission to reprint or republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the copyright holder.

 

BibTeX entry

@inproceedings{Liang:2011,
author = "{Xi Liang and R. Kotagiri and Q. Yang and Marius Staring and A. Pitman}",
title = "{Generating Coefficients for Regularization Terms in Nonrigid Registration of Contrast-Enhanced MRI}",
booktitle = "{Medical Image Computing and Computer-Assisted Intervention, Workshop on Breast Image Analysis}",
editor = "{C. Tanner and J. Schnabel and N. Karssemeijer and Mads Nielsen and M. Giger and D.J. Hawkes}",
address = "{Toronto, Canada}",
pages = "{1 - 8}",
month = "{September}",
year = "{2011}",
}

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