Landmark-Guided Surface Matching and Volumetric Warping for Improved Prostate Biopsy Targeting and Guidance

We present a composite method for landmark-guided surface matching and volumetric non-rigid registration, with an application to prostate biopsy. The two-step method, based primarily on finite element and thin-plate spline techniques, consists of a boundary matching process, followed by a volumetric warping step. In practice, the boundary matching method allows for registration of anatomical surfaces, such as prostate gland capsules, in a way that is bijective, i.e. one-to-one and onto. The novelty of this approach is that it allows for the exact matching of pre-specified corresponding landmark points on the two surfaces to be matched. The second step, volumetric warping, is presented as an extension of our previous work in prostate registration, having been improved to address the problem of non-bijectivity (the “flipping” of tetrahedra) which can result from the linear-elastic modelling of the deformation. We discuss the use of our method for the registration of pre-operative magnetic resonance (MR) imaging for improved targeting and visualization during MR-guided prostate biopsy. Although presented within the context of prostate MR image registration, our composite surface matching and volumetric registration method has general applicability to other organs and imaging modalities such as CT and ultrasound.