High-field strength interventional magnetic resonance imaging for pediatric neurosurgery

Background: Interventional magnetic resonance (MR) imaging allows neurosurgeons to interactively perform surgery using MR guidance. High-field (1.5-Tesla) strength imaging provides exceptional visualization of intracranial and spinal pathology. The full capabilities of this technology for pediatric neurosurgery have not been defined or determined. Materials and Methods: From January 1997 through June 1998, 10 of 85 cases performed in the interventional MR unit were in the pediatric population (mean age 8.3, median 8, range 2-15 years). Procedures included 2 brain biopsies, 5 craniotomies for tumor, 2 thoracic laminectomies for syringomyelia, and placement of a reservoir into a cystic brainstem tumor. The biopsies and reservoir placement were performed using MR-compatible equipment. Craniotomies and spinal surgery were performed with conventional instrumentation outside the 5-Gauss magnetic footprint. Interactive and intraoperative imaging was performed to assess the goals of surgery. Results: Both brain biopsies were diagnostic for cerebral infarct and anaplastic astrocytoma and the reservoir was optimally placed within the tumor cyst. Of the 5 tumor resections, all were considered radiographically complete. One biopsy patient and 1 tumor resection patient experienced transient neurological deficits after surgery. The patient with the thoracic syrinx required reoperation when the syringosubarachnoid shunt migrated into the syrinx 3 months after initial placement. No patient sustained a postoperative hemorrhage. Tumor histologies found at craniotomy were craniopharyngioma, ganglioglioma, and 3 low-grade gliomas. No evidence of tumor progression has been seen in any of these patients at a mean follow-up of 5.3 (range 4-8) months. The goals of the procedure were achieved in all 10 cases. There were no untoward events experienced related to MR-compatible instrumentation or intraoperative patient monitoring, despite the present inability to monitor core body temperature. Conclusions: 1.5-Tesla interventional MR is a safe and effective technology for assisting neurosurgeons to achieve the goals of pediatric neurosurgery. Preliminary results suggest that surgical resection of histologically benign tumors is enhanced in the interventional MR unit. The incidence of surgically related morbidity is low.