Real-time magnetic resonance-guided laser thermal therapy for focal metastatic brain tumors.

Objective: We report the initial results of a pilot clinical trial exploring the safety and feasibility of the first real-time magnetic resonance-guided laser-induced thermal therapy of treatment-resistant focal metastatic intracranial tumors.

Methods: Patients with resistant metastatic intracranial tumors who had previously undergone chemotherapy, whole-brain radiation therapy, and radiosurgery and who were recused from surgery were eligible for this trial. Under local anesthesia, a Leksell stereotactic head frame was used to insert a water-cooled interstitial fiberoptic laser applicator inside the cranium. In the bore of a magnetic resonance imaging (MRI) scanner, laser energy was delivered to heat the tumor while continuous MRI was performed. A computer workstation extracted temperature-sensitive information to display images of laser heating and computed estimates of the thermal damage zone. Posttreatment MRI scans were used to confirm the zone of thermal necrosis, and follow-up was performed at 7, 15, 30, and 90 days after treatment.

Results: In all cases, the procedure was well tolerated without secondary effect, and patients were discharged to home within 14 hours after the procedure. Follow-up imaging showed an acute increase in apparent lesion volume followed by a gradual and steady decrease. No tumor recurrence within thermal ablation zones was noted.

Conclusion: In this ongoing trial, a total of four patients have had six metastatic tumors treated with laser thermal ablations. Magnetic resonance-guided laser-induced thermal therapy appears to provide a new, efficient treatment for recurrent focal metastatic brain disease. This therapy is a prelude to the future development of closed-head interventional MRI techniques in neurosurgery.