1992 Volume 1 Issue 1 Pages 55-63
The authors discuss a new system that has been developed for intraoperative spatial monitoring. Named the "NEURO-SAT", it is comprised of frameless iso-centric stereotactic mechanism and a three-dimensional (3-D) digitizer. The 3-D digitizer's multi-articulated arm has three joints that form Cartesian coordinates, two quadrant arcs that form an iso-center system, a microdrive, and a probe holder. This frameless iso-centric mechanism is useful for open stereotaxy. Further, routine CT- or MRI-guided stereotactic surgery also is possible, due to the system's high level of accuracy. Before surgery, CT and/or MR images are acquired after placing three or four external markers on the scalp. Then, using an image scanner, CT or MR images are entered into a computer and stored on a floppy disk. After the patient's head has been fixed on the operating table, NEURO-SAT is used to read the spatial points of these external markers on the scalp. During the procedure, the coordinates on the patient's head are automatically entered into the computer and matched with those of the NEURO-SAT and the CT/MR images on the CRT display. The authors have used this system in 31 cases of an open craniotomy and 41 cases of burr hole surgery, both types of surgery having been carried out by using the stereotactic function and the 3-D spatial monitoring function in parallel. Errors in mechanical accuracy of this system were under 0.8 mm, and the maximum error during operation is presumed not to have exceeded 2 mm. Because of these results, it is felt that this new system provides a more dependable method for performing image-guided surgery than currently available conventional instruments.
