REGISTRATION OF HEAD VOLUME IMAGES USING IMPLANTABLE FIDUCIAL MARKERS

In this paper, me describe an extrinsic-point-based, interactive image guided neurosurgical system designed at Vanderbilt University, Nashvi lle, TN, as part of a collaborative effort among the Departments of Ne urological Surgery, Computer Science, and Biomedical Engineering, Mult imodal image-to-image (II) and image-to-physical (IF) registration is accomplished using implantable markers, Physical space tracking is acc omplished with optical triangulation. We investigate the theoretical a ccuracy of point-based registration using numerical simulations, the e xperimental accuracy of our system using data obtained with a phantom, and the clinical accuracy of our system using data acquired in a pros pective clinical trial by six neurosurgeons at four medical centers fr om 158 patients undergoing craniotomies to resect cerebral lesions, We can determine the position of our markers with an error of approximat ely 0.4 mm in X-ray computed tomography (CT) and magnetic resonance (M R) images and 0.3 mm in physical space, The theoretical registration e rror using four such markers distributed around the head in a configur ation that is clinically practical is approximately 0.5-0.6 mm, The me an CT-physical registration error for the phantom experiments is 0.5 m m and for the clinical data obtained with rigid head fixation during s canning is 0.7 mm, The mean CT-MR registration error for the clinical data obtained without rigid head fixation during scanning is 1.4 mm, w hich is the highest mean error that we observed, These theoretical and experimental findings indicate that this system is an accurate naviga tional aid that can provide real-time feedback to the surgeon about an atomical structures encountered in the surgical held.