Brain biopsy using high-field strength interventional magnetic resonance imaging

OBJECTIVE: Lesions within the brain are commonly sampled using stereotactic techniques. The advent of interventional magnetic resonance imaging (MPI) now allows neurosurgeons to interactively investigate specific regions, wit h exquisite observational detail. We evaluated the safety and efficacy of t his new surgical approach. METHODS: Between January 1997 and June 1998, 35 brain biopsies were perform ed in a high-field strength interventional MRI unit. All biopsies were perf ormed using MRI-compatible instrumentation. Interactive scanning was used t o confirm accurate positioning of the biopsy needle within the region of in terest. Intraoperative pathological examination of the biopsy specimens was performed to verify the presence of diagnostic tissue, and intra- and post operative imaging was performed to exclude the presence of intraoperative h emorrhage. Recently, magnetic resonance spectroscopic targeting was used fo r six patients. RESULTS: Diagnostic tissue was obtained in all 35 brain biopsies and was us ed in therapeutic decision-making. Histological diagnoses included 28 prima ry brain tumors (12 glioblastomas multiforme, 9 oligodendrogliomas, 2 anapl astic astrocytomas, 2 astrocytomas, 1 lymphoma, and 1 anaplastic oligodendr oglioma), 1 melanoma brain metastasis, 1 cavernous sinus meningioma, 1 cere bral infarction, 1 demyelinating process, and 3 cases of radiation necrosis . In all cases, magnetic resonance spectroscopy was accurate in distinguish ing recurrent tumors (five cases) from radiation necrosis (one case). No pa tient sustained clinically or radiologically significant hemorrhage, as det ermined by intraoperative imaging performed immediately after the biopsy. O ne patient (3%) suffered transient hemiparesis after a pontine biopsy for i nvestigation of a brain stem glioma. Another patient developed scalp cellul itis, with possible intracranial extension, 3 weeks after the biopsy; this condition was effectively treated with antibiotic therapy. Three patients w ere discharged on the day of the biopsy. CONCLUSION: Interventional 1.5-T MRI is a safe and effective method for eva luating lesions of the brain. Magnetic resonance spectroscopic targeting is likely to augment the diagnostic yield of brain biopsies.