I. Introduction
This paper reports the development of rigid and deformable image registration algorithms for providing intraoperative motion compensation in MRI-guided prostatic needle placement procedures. We propose to position the patient such that his prostate lies in the scanner's isocenter and acquire multiple statically set slices in this position. It is posited that full 6-DOF motion of the prostate can be recovered through the registration of a target planning MR volume and multiple MR slices acquired immediately before and after needle insertion. Orthogonal tracking slices are acquired with ordinary anatomical imaging sequences through the scanner's console.