No abstract

Neuronavigation allows very precise intracranial and spinal surgery. The problem of brain shift during the navigation procedures has been solved by intraoperative image acquisition. The use of neuronavigation was shown to improve the postoperative quality of life of patients suffering from brain and spinal tumors.

The combination of intraoperative computerized tomography and spinal navigation allows easy navigation with a high application accuracy of 0.8 mm +/- 0.4 mm (SD) at the target point (measured in experiments with a plastic spine model). The possibility of performing an intraoperative quality check on demand markedly improves the safety of these procedures.

Objective: We report on the first successful incorporation of intraoperative computerized tomography in spinal navigation procedures.Materials and Methods: All operations were performed with the aid of a Tomoscan M mobile CT system (Philips Medical Systems, Eindhoven, The Netherlands). The system comprises a mobile gantry, a mobile patient examination table, and a mobile workstation. Three different navigation systems were used: the EasyGuide (Philips Medical Systems, Eindhoven, The Netherlands), the Surgical Tool Navigator (Zeiss, Oberkochen, Germany), and a prototype of an ultrasound navigation system developed by ourselves (IVS GbR, Chemnitz, Germany). All surgical operations were performed with the patient positioned on the mobile table of the CT system. Following dorsal preparation of the vertebral region, the surgeon implanted small titanium screws in the vertebrae to serve as fiducial markers. Image data acquisition and image-to-patient registration were performed after implantation of the marker screws. The pedicle screws were inserted using the navigation system, and the position of each implant was confirmed by intraoperative CT scans.Results: To date, 35 patients with various spine disorders have been operated upon using the technique described, and 161 pedicle screws have been inserted. There were no misplacements of pedicle screws. In three (1.9 %) cases we observed lateral perforation (maximum 2 mm) of the lateral pedicle wall. We achieved a registration error of 0.85 mm (RMSE) ؎ 0.42 mm (SD).Conclusions: The combination of intraoperative computerized tomography and spinal navigation allows easy navigation with a high application accuracy of 0.8 mm ؎ 0.4 mm (SD) at the target point (measured in experiments with a plastic spine model). The possibility of performing an intraoperative quality check on demand markedly improves the safety of these procedures.