Évaluation préopératoire comparative de 43 gliomes de grade II et III par TEP au 18F-FDG et à la 18F-DOPA : corrélation aux données histologiques et moléculaires

Abstract

ObjectiveTo characterize and compare the biological information brought by 18F-FDG and 18F-FDOPA, analyzed separately and together, in relation with prognostic factors including histological and molecular factors in the preoperative assessment of grade II and III gliomas. MethodsForty-three patients who underwent 18F-FDG and 18F-FDOPA PET in the preoperative assessment of glioma have been retrospectively included (35 grade II and 8 grade III). 18F-FDG and 18F-FDOPA uptakes were determined using qualitative method for 18F-FDG and semi-quantitative method for 18F-FDOPA (tumor/striatum ratio), and were compared with demographic (age, sex), surgical (type of surgery, localization) histological, immunohistochemistrical (histology, grade, Ki-67 index) and molecular characteristics (IDH mutation, 1p19q codeletion, p53 mutation and “triple negative” status). To analyze the relative impact of the two radiopharmaceuticals, we have divided the patients according to the different possible combinations of 18F-FDG and 18F-FDOPA PET to create 3 groups: group −/−, group −/+ and group +/+. ResultsA positive 18F-FDG uptake was associated with a higher Ki-67 index (P=0.021). Using tumor/striatum ratio, a higher 18F-FDOPA uptake was associated with presence of IDH mutation (P=0.037) and presence of 1p19q codeletion (P=0.030). There was a positive correlation between Ki-67 index and tumor/striatum ratio (r=0.33; P=0.029). Comparing group −/− and group −/+, there was more frequently presence of 1p19q codeletion in group −/+ than in group −/− (P=0.008). The same applies to IDH mutation (P=0.028). Comparing group −/− and group +/+, there were more frequently a lower Ki-67 index (P=0.006) in group −/−. ConclusionThe two 18F-FDG and 18F-FDOPA PET brought separately information about cellular proliferation. 18F-FDOPA PET could bring additional information on the molecular side of the tumor. Finally, the association between 18F-FDG and 18F-FDOPA PET could give more information about cellular proliferation and presence of 1p19q codeletion and IDH mutation.