Medical image registration based on mutual information combined with gradient similarity.

To solve the drawback that typical mutual information-based registration neglects the spatial information of images, a new medical image registration method is developed by combining mutual information with gradient similarity. The gradient similarity of each pair of corresponding points includes direction similarity and module similarity. The summation of the similarity term for all sample pairs gives the gradient similarity of two registration images, which is multiplied by the mutual information to form the final registration metric. Registration functions are analyzed and compared, applying in different transform such as translation, rotation and sub-sampling of 2D multi-modal images, respectively. Experimental results show that the new method performs better than typical mutual information in robustness and precision. [ABSTRACT FROM AUTHOR]