Intraoperative Prostate Tracking with Slice-to-Volume Registration in MR

A slice-to-volume registration algorithm, to be used for prostate tracking, is presented. The technique is designed to provide patient tracking information for prostate biopsy performed under MR guidance. Interventional MR slices are acquired from a static physical plane just prior to needle insertion. These slices are registered to a high resolution volume of the patient. Registration is performed at two resolutions, with the result of the low resolution registration used as the initial alignment of the high resolution step. Two versions of the algorithm are implemented: registration with a transverse slice and registration with intersecting transverse and sagittal slices. Validation is performed on five high resolution patient data sets. After segmentation of the prostate, an interventional MR slice is simulated and subsequently translated and rotated from its original position. Registration performed to recover the original position resulted in average target registration errors below 1 mm, for both the single transverse slice and the combination of a transverse and a sagittal slice.