Comparison of registration accuracy of skin- and bone-implanted fiducials for frameless stereotaxis of the brain: a prospective study.

The registration accuracy of skin- and bone-implanted fiducials using a frameless stereotactic system were analyzed prospectively.Twenty-eight patients underwent resection of intra-axial neoplasmas after both skin- and bone-implantable fiducial markers were placed. Both sets of fiducials were independently co-registered to a magnetic resonance imaging data set acquired preoperatively using the ISG Viewing Wandtrade mark. Root mean square errors were recorded as an objective measure of registration accuracy of the two types of fiducials.Root mean square errors of bone-implanted fiducials registration were lower than those of skin fiducials; however, this difference was not statistically significant (p = 0.206).The registration accuracy of skin- and bone-implanted fiducials appears to be similar. Still, bone-implanted fiducials may be advantageous compared to skin fiducials when re-registration of the patient-image space is desired intraoperatively such as during major drift in the patient's position or after surgical repositioning.