@conference {1252, title = {Spectral clustering to model deformations for fast multimodal prostate registration}, booktitle = {International Conference on Pattern Recognition (ICPR)}, year = {2012}, month = {Nov 2012}, pages = {2622 - 2625}, publisher = {IEEE}, organization = {IEEE}, type = {Conference paper}, address = {Tsukuba, Japan}, abstract = {

This paper proposes a method to learn deformation parameters off-line for fast multimodal registration of ultrasound and magnetic resonance prostate images during ultrasound guided needle biopsy. The registration method involves spectral clustering of the deformation parameters obtained from a spline-based nonlinear diffeomorphism between training magnetic resonance and ultrasound prostate images. The deformation models built from the principal eigen-modes of the clusters are then applied on a test magnetic resonance image to register with the test ultrasound prostate image. The deformation model with the least registration error is finally chosen as the optimal model for deformable registration. The rationale behind modeling deformations is to achieve fast multimodal registration of prostate images while maintaining registration accuracies which is otherwise computationally expensive. The method is validated for 25 patients each with a pair of corresponding magnetic resonance and ultrasound images in a leave-one-out validation framework. The average registration accuracies i.e. Dice similarity coefficient of 0.927 {\textpm} 0.025, 95\% Hausdorff distance of 5.14 {\textpm} 3.67 mm and target registration error of 2.44 {\textpm} 1.17 mm are obtained by our method with a speed-up in computation time by 98\% when compared to Mitra et al. [7].

}, isbn = {978-1-4673-2216-4 }, url = {http://hal.archives-ouvertes.fr/docs/00/71/09/43/PDF/ICPR_Jhimli.pdf}, author = {Jhimli Mitra and Zoltan Kato and Soumya Ghose and Desire Sidibe and Robert Mart{\'\i} and Xavier Llad{\'o} and Oliver Arnau and Joan C Vilanova and Fabrice Meriaudeau}, editor = {Jan-Olof Eklundh and Yuichi Ohta and Steven Tanimoto} } @article {1248, title = {A spline-based non-linear diffeomorphism for multimodal prostate registration.}, journal = {MEDICAL IMAGE ANALYSIS}, volume = {16}, year = {2012}, note = {UT: 000309694100015ScopusID: 84866118888doi: 10.1016/j.media.2012.04.006}, month = {Aug 2012}, pages = {1259 - 1279}, type = {Journal article}, abstract = {

This paper presents a novel method for non-rigid registration of transrectal ultrasound and magnetic resonance prostate images based on a non-linear regularized framework of point correspondences obtained from a statistical measure of shape-contexts. The segmented prostate shapes are represented by shape-contexts and the Bhattacharyya distance between the shape representations is used to find the point correspondences between the 2D fixed and moving images. The registration method involves parametric estimation of the non-linear diffeomorphism between the multimodal images and has its basis in solving a set of non-linear equations of thin-plate splines. The solution is obtained as the least-squares solution of an over-determined system of non-linear equations constructed by integrating a set of non-linear functions over the fixed and moving images. However, this may not result in clinically acceptable transformations of the anatomical targets. Therefore, the regularized bending energy of the thin-plate splines along with the localization error of established correspondences should be included in the system of equations. The registration accuracies of the proposed method are evaluated in 20 pairs of prostate mid-gland ultrasound and magnetic resonance images. The results obtained in terms of Dice similarity coefficient show an average of 0.980+/-0.004, average 95\% Hausdorff distance of 1.63+/-0.48mm and mean target registration and target localization errors of 1.60+/-1.17mm and 0.15+/-0.12mm respectively.

}, isbn = {1361-8415}, doi = {10.1016/j.media.2012.04.006}, author = {Jhimli Mitra and Zoltan Kato and Robert Mart{\'\i} and Oliver Arnau and Xavier Llad{\'o} and Desire Sidibe and Soumya Ghose and Joan C Vilanova and Josep Comet and Fabrice Meriaudeau} }