Spatial Information Encoded Mutual Information for Nonrigid Registration

We propose a new nonrigid registration method based on a unified framework of encoding spatial information in entropy measures. The encoding of spatial information improves nonrigid registration against the problems caused by intensity distortion where the registration using traditional mutual information (MI) is challenged. Using this encoding framework, we derive the new registration method, spatial information encoded mutual information (SIEMI). SIEMI registration has a similar computation complexity as the registration using traditional MI measures, but works significantly better in the nonrigid cases. We validated the registration method using brain MRI and dynamic contrast enhanced MRI of the liver. The results showed that the proposed method performed significantly better than the normalized mutual information registration.