Gamma knife radiosurgery for the treatment of cystic cerebral metastases.

Purpose: To assess the role of Gamma Knife radiosurgery (GKRS) in the treatment of nonsurgical cystic brain metastasis, and to determine predictors of response to GKRS.

Methods: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between 2006 and 2010. All lesions with a cystic component were identified, and volumetric analysis was done to measure percentage of cystic volume on day of treatment and consecutive follow-up MRI scans.