A hierarchical nonrigid image registration technique based on local deformations

We introduce a new technique for nonrigid registration for medical images based on a hierarchical composition of local deformations. The local deformation model is analyzed in order to guarantee continuity, differentiability and a one-to-one transformation by constraining the parameters of the spatial transformation. The performance of our technique was validated with synthetic images, and MR images. The proposed method was always able to improve the similarity criterion, the normalized mutual information, where accuracy was determined strongly by the resolution and dimensions of the involved domains. The searching strategy was carried out with a hybrid genetic algorithm.