Adaptive non-rigid registration of real time 3D ultrasound to cardiovascular MR images.

We present a new method to non-rigidly co-register a real-time 3D ultrasound volume slice to a cardiovascular MR image. The motivation for our research is to assist a clinician to automatically fuse the information from multiple imaging modalities for the early diagnosis and therapy of cardiac disease. The local phase presentation of both images is utilized as an image descriptor of the "featureness". The local deformation of ventricles is modeled by a polyaffine transformation. The anchor points (or control points) used in the polyaffine transformation are automatically detected and refined by calculating a local mis-match measure based on phase mutual information. The registration process is built in an adaptive multi-scale framework to maximize the phase-based similarity measure by optimizing the parameters of the polyaffine transformation. Registration results have demonstrated that this novel method is superior to our prior work, yielding an accurate registration to local cardiac regions.