REGIONAL GLUCOSE-METABOLISM AND HISTOPATHOLOGY OF GLIOMAS - A STUDY BASED ON POSITRON EMISSION TOMOGRAPHY-GUIDED STEREOTAXIC BIOPSY

BACKGROUND, Positron emission tomography (PET) with F-18-2-fluoro-2-de oxy-D-glucose (FDG) is widely applied to the study of gliomas. The his tology of most gliomas is regionally heterogeneous. The relationship b etween histologic features and glucose metabolism evaluated by PET wit h FDG may therefore vary within the limits of the tumor. PET with FDG integrated in the planning of stereotactic brain biopsy allows precise comparison between local FDG uptake and histology. Using this approac h, the authors investigated whether glucose metabolism of gliomas is r elated to anaplasia, and whether PET with FDG detects metabolic hetero geneity that parallels histologic heterogeneity of gliomas. METHODS, A total of 161 biopsy samples collected from 20 PET-guided procedures p erformed in patients with gliomas (8 low grade astrocytomas, 8 anaplas tic astrocytomas, 1 anaplastic oligoastrocytoma, and 3 glioblastomas) were analyzed for the presence or absence of 8 histologic features. St ereotactic coordinates were used to calculate the metabolic rate of gl ucose (MRGlu) in the region of each biopsy sample. Gray and white matt er MRGlu were used to define four metabolic grades that were compared with local histology. RESULTS. The difference in MRGlu expressed as mi cromoles per 100 g per minute was highly significant between anaplasti c and nonanaplastic samples; the median +/- quartile deviation was 23 +/- 16 in anaplastic samples and 18 +/- 5 in nonanaplastic samples (P < 0.005). Even more significant differences were found when MRGlu was normalized to the cortex or to the white matter. Metabolic grades were different in anaplastic and nonanaplastic samples (P < 0.0001). Appro ximately 75% of samples metabolically graded 3 or 4 demonstrated signs of anaplasia, compared with 10% of samples graded 0 or 1. CONCLUSIONS , FDG uptake in gliomas is anatomically heterogeneous and is regionall y related to the presence of anaplasia. (C) 1996 American Cancer Socie ty.