Mapping of the cortical motor hand area with functional MR imaging and MR imaging-guided laser-induced interstitial thermotherapy of brain tumors. Work in progress.

PURPOSE: To localize the cortical motor hand area with functional magnetic resonance (MR) imaging before and after MR imaging--guided laser-induced interstitial thermotherapy of tumors in the precentral brain region to control energy delivery and to improve safety. MATERIALS AND METHODS: Functional MR images were obtained in eight patients (five men, three women; aged 27-63 years) while they flexed their fingers. MR imaging--guided laser-induced interstitial thermotherapy was terminated when there was less than 8-12 mm between the border of the laser-induced lesion and the motor hand area anterior aspect. RESULTS: Seven patients had a statistically significant localized change in signal intensity in the central region of the contralateral hemisphere. This area was a spotlike circumscribed focus in three patients and scattered over a larger zone in four patients. Persistent deficits did not occur after thermotherapy in any patient. In three patients, onset of reversible perifocal edema in the motor hand area coincided with the development of hemiparesis, which completely resolved. No patient had activity within the tumor on functional MR images. CONCLUSION: Functional MR imaging findings can be used to prevent neurologic damage during MR imaging--guided laser-induced interstitial thermotherapy.