Deforming a preoperative volume to better represent the intraoperative scene

Soft-tissue deformation can be a problem if a pre-operative modality is used to help guide a surgical or an interventional procedure. We present a method which can warp a pre-operative CT image to represent the intra-operative scene shown by an interventional fluoroscopy image. The method is a novel combination of a 2D-3D image registration algorithm and a deformation algorithm which allows rigid bodies to be incorporated into a non-linear deformation based on a radial basis function. The 2D-3D registration algorithm is used to obtain information on relative vertebral movements between pre-operative and intra-operative images. The deformation algorithm uses this information to warp the pre-operative image to represent the intra-operative scene more accurately. Images from an aortic stenting procedure were used. The observed deformation was 5 degree flexion and 5 mm lengthening of the lumbar spine. The vertebral positions in the warped CT volume represent the intra-operative scene more accurately than in the pre-operative CT volume. Although we had no gold- standard with which to assess the registration accuracy of soft-tissue structures, the position of soft-tissue structures within the warped CT volume appeared visually realistic.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.