Frameless stereotactic neurosurgery using intraoperative magnetic resonance imaging: Stereotactic brain biopsy

OBJECTIVE: To assess the application accuracy of intraoperative magnetic re sonance imaging for frameless stereotactic surgery, and to evaluate the per formance of intraoperative magnetic resonance imaging for the brain biopsy, a standard stereotactic procedure. METHODS: A series of spatial coordinate and phantom experiments were perfor med to analyze the application accuracy of the system. A prospective analys is of 68 consecutive patients undergoing stereotactic brain biopsy was then performed. RESULTS: The spatial coordinate experiments revealed a mean overall error i n acquisition of 0.2 mm. The phantom experiments demonstrated a 1:1 correla tion between the magnetic resonance image of a stereotactically guided prob e and its relationship to a target and the actual relationship of the probe and target. Sixty-eight brain biopsies were successfully performed in all intracranial compartments except the sella. The radiographic abnormality wa s localized successfully in all patients (100%). Sixty-six (97.1%) of the b iopsies yielded diagnostic tissue. Two biopsies (2.9%) were complicated by intraparenchymal hemorrhage. One expanding temporal lobe hemorrhage was eva cuated by immediate craniotomy in the magnet with no postoperative sequelae . A deep hemorrhage from a lymphoma was managed conservatively with interva l resolution of symptoms. There were no infections. There was no perioperat ive mortality. CONCLUSION: Intraoperative magnetic resonance imaging allows excellent targ et localization, provides true real-time imaging to account for anatomic ch anges during surgery, and permits intraoperative confirmation that the biop sy needle has reached the targeted lesion. Immediate postoperative imaging in the operating room allows assessment of adverse events and the potential for immediate management of hemorrhagic complications.