Delayed structural cerebral sequelae has been reported following cranial radiation therapy (CRT) to children with primary brain tumors, but little is known about potential functional changes. Twenty-four patients were included, diagnosed and treated at a median age of 11 years, and examined after a median recurrence free survival of 16 years by MRI and Positron Emission Tomography using the glucose analog 2-18F-fluoro-2-deoxy-D-glucose (18FDG). Three patients were not analyzed further due to diffuse cerebral atrophy, which might be related to previous hydrocephalus. Twenty-one patients were evaluable and regional cerebral metabolic rate for glucose (rCMRglc) was estimated in nontumoral brain regions in 12 patients treated with surgery alone and 9 patients treated with both surgery and CRT. Furthermore 10 normal controls matched for age at examination were included. Patients treated with both surgery and CRT had a general decreased rCMRglc compared to normal controls and patients treated with surgery alone, significantly (p < 0.05) in 5 of 11 regions of interest. No difference was found in rCMRglc between normal controls and patients treated with surgery alone. We conclude that there is a general reduction in rCMRglc in long-term recurrence free survivors of childhood primary brain tumors treated with CRT in high doses (44-56 Gy).

Our study did not show a gain of PET compared with structural imaging in the prospective evaluation of GBM. We found a difference in metabolic increase and tumor growth between the two treatment regimens, although this finding has limited relevance due to the design of the study.