Use of Positron Emission Tomography in the Evaluation of Diffuse Intrinsic Brainstem Gliomas in Children

Background: Diffuse intrinsic brainstem gliomas (DIBSGs) in children remain difficult tumors to treat and have a very poor prognosis. Intensifying both chemotherapy and radiation programs have been attempted without success. Positron emission tomography (PET) has been used to differentiate benign from malignant tumors and may predict outcome. Objectives: To determine whether PET can characterize a specific metabolic pattern of DIBSGs and correlate this with patient survival. Methods: We conducted a retrospective review of patients with DIBSGs and PET scans at diagnosis. Data for (18)[F] fluorodeoxyglucose (FDG) and (11)C-methionine (CMET) PET scans were collected. Treatment and survival were reviewed. Results: We identified 30 patients with DIBSGs, 25 of whom had FDG and/or CMET PET scans. Scans showed both focal and generalized metabolic activity, and the patterns showed no correlation with survival. Patients with both FDG and CMET positive scans had a mean survival of 380 days, whereas those negative for both isotopes had a mean survival of 446 days. Conclusions: There was no specific PET pattern identified in this DIBSG cohort but a trend toward improved survival was noted with absence of FDG and CMET metabolism. Metabolically active areas may suggest potential sites for biopsy. We believe that biopsy is essential for improving therapy for this patient population.