Monitoring the effects of BCNU chemotherapy Wafers (Gliadel®) in glioblastoma multiforme with proton magnetic resonance spectroscopic imaging at 3.0 Tesla

Carmustine wafers (Gliadel(R) Wafer) are implanted at resection in some patients with high-grade gliomas. Studies suggest that proton magnetic resonance spectroscopic imaging (H-1 MRSI) demonstrates early changes predictive of future failure or response to systemic chemotherapy. This study explores H-1 MRSI as a means to assess peri-tumoral tissue response post-resection and Gliadel(R) implantation in patients with high-grade gliomas. Pilot H-1 MRSI data are presented that demonstrate noninvasive, serial monitoring of metabolic changes at the tumor site following Gliadel(R) implantation. Three patients with newly diagnosed glioblastoma multiforme (GBM) underwent MRI and H-1 MRSI at 3.0 Tesla prior to resection and at 3 - 5 and >= 12 weeks postoperatively. Baseline MRS spectra of tumor tissue from all patients were characterized by marked increases of choline (CHO) and lactate ( LAC), and a decrease of N-acetylaspartate (NAA), typical of GBM compared with normal contra-lateral brain tissue. Postoperatively, spectra were analyzed from the resection cavity and peri-tumoral regions and compared with normal tissue from the contra-lateral brain at baseline. In 2 of 3 patients, peri-tumoral NAA/CRE increased and CHO/NAA decreased compared to contra-lateral brain at 3 - 5 weeks compared with baseline following Gliadel(R) therapy and surgery but prior to radiotherapy. This study indicates that H-1 MRSI has the ability to localize regions of heterogeneous response following Gliadel treatment. Although data are limited, these results suggest that metabolic indicators of outcome can be successfully monitored pre- and post-surgical resection and Gliadel implantation with H-1 MRSI. Additional study of patients receiving Gliadel(R) Wafers using H-1 MRSI may serve to aid clinicians in assessing tumor regression and gauging efficacy of this chemotherapy treatment.