31P MR spectroscopic imaging in preoperative embolization therapy of meningiomas

Purpose: P-31 NIR spectroscopic imaging (P-31 SI) was evaluated in a clinical study as a method for monitoring presurgical devascularization of meningiomas. The aim was to assess noninvasively metabolic alterations in tumor and in healthy brain tissue before and after embolization. Methods: Localized P-31 MR spectra of the brain were obtained by means of 2D-SI (voxel size: 36 cm(3)) using a 1,5-T whole-body NIR tomograph. Results: Eleven of 19 patients with intracranial meningiomas examined in this study underwent preoperative embolization therapy; eight patients were examined before and after treatment. After embolization, alterations of pH and of the concentrations of high-energy phosphates (nucleoside-5' triphosphate = NTP, phosphocreatine = PCr), inorganic phosphate (P-i), and membrane constituents were observed in the tumors. A tendency of [P-i] increase and decrease of [NTP], [PCr], and pH predominated, which is explained by ischemic processes after,tumor devascularization. Conclusion: P-31 SI is applicable in clinical:studies and detects alterations of phosphate metabolism in a meningioma after embolization.