Metabolic response of glioblastoma to superselective intra-arterial cerebral infusion of bevacizumab: A proton MR spectroscopic imaging study

BACKGROUND AND PURPOSE: SIACI of bevacizumab has emerged as a promising novel therapy in the treatment of recurrent GB. This study assessed the potential of ¹H-MRS as an adjunctive technique in detecting metabolic changes reflective of antiproliferative effects of targeted infusion of bevacizumab in the treatment of GB. MATERIALS AND METHODS: Eighteen patients enrolled in a phase I/II study of SIACI of bevacizumab for treatment of recurrent GB were included. Concurrent MR imaging and ¹H-MRS scans were performed before and after treatment. Five distinct morphologic ROIs were evaluated for structural and metabolic changes on MR imaging and ¹H-MRS, which included enhancing, nonenhancing T2 hyperintense signal abnormality, and multiple control regions. Pre- and post-SIACI of bevacizumab peak areas for NAA, tCho, tCr, as well as tCho/tCr and tCho/NAA ratios, were derived for all 5 ROIs and compared using the Wilcoxon signed-rank test. RESULTS: A significant median decrease of 25.99% (range -55.76 to 123.94; P = .006) in tCho/NAA was found post-SIACI of bevacizumab relative to pretreatment values in regions of enhancing disease. A trend-level significant median decrease of 6.45% (range -23.71 to 37.67; P = .06) was noted in tCho/NAA posttreatment in regions of nonenhancing T2-hyperintense signal abnormality. CONCLUSIONS: The results of this ¹H-MRS analysis suggest that GB treatment with SIACI of bevacizumab may be associated with a direct antiproliferative effect, as demonstrated by significant reductions of tCho/NAA after the intervention.