Nonrigid registration of medical image by linear singular blending techniques

In this paper, a nonrigid registration method is presented for accommodating local shape variation when matching monomodal images or multimodal images. Affine transformation is adopted in global registration while local deformation is described by a free-form deformation based on a linear singular blending (LSB) B-spline, which can enhance the shape-control capability of the B-spline. This capability is derived from the blending parameters defined at the B-spline control points. The local deformation of images can be controlled by changing positions of the control points or altering values of blending parameters. Two voxel-based similarity measures, the SSD for monomodal images and mutual information for multimodal images are used. Experiments on simulated and real data have been performed to evaluate the accuracy of our method. We have also compared the results of the proposed approach to those obtained by affine and B-spline registration techniques. The results indicate that the proposed method is much better to describe the deformation than the affine algorithm and B-spline techniques.