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International Journal of Biomedical Imaging
Volume 2011 (2011), Article ID 891585, 16 pages
http://dx.doi.org/10.1155/2011/891585
Research Article

Diffeomorphic Registration of Images with Variable Contrast Enhancement

1Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Universitè Catholique de Louvain (UCL), 1348 Louvain-la-Neuve, Belgium
2Department of Radiation Oncology and Laboratory of Radiobiology and Radiation Protection (RBNT), Universitè Catholique de Louvain (UCL), 1200 Brussels, Belgium

Received 30 April 2010; Revised 28 July 2010; Accepted 24 September 2010

Academic Editor: James G. Nagy

Copyright © 2011 Guillaume Janssens et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Nonrigid image registration is widely used to estimate tissue deformations in highly deformable anatomies. Among the existing methods, nonparametric registration algorithms such as optical flow, or Demons, usually have the advantage of being fast and easy to use. Recently, a diffeomorphic version of the Demons algorithm was proposed. This provides the advantage of producing invertible displacement fields, which is a necessary condition for these to be physical. However, such methods are based on the matching of intensities and are not suitable for registering images with different contrast enhancement. In such cases, a registration method based on the local phase like the Morphons has to be used. In this paper, a diffeomorphic version of the Morphons registration method is proposed and compared to conventional Morphons, Demons, and diffeomorphic Demons. The method is validated in the context of radiotherapy for lung cancer patients on several 4D respiratory-correlated CT scans of the thorax with and without variable contrast enhancement.