Comparison of 18F-FDG and 11C-MET PET imaging in the preoperative grading of neuroepithelioma and their correlation with Ki67

Objective: To compare the value of 18F-fluorodeoxyglucose (FDG) and 11C-methionine (MET) PET in the preoperative grading of neuroepithelioma and the correlation with Ki67. Methods: Thirty-nine cases with neuroepithelioma proved by pathology were examined with 18F-FDG and 11C-MET PET preoperatively. Both images were analysed visually and semiquantitatively, and also correlated the pathologic grading with Ki67 labelling index (LI). Results: (1) Visual analysis: 22/23 high-grade tumors showed 18F-FDG hypermetabolism and 14/16 low-grade tumors showed 18F-FDG moderate-metabolism or hypometabolism. All cases except 1 low-grade tumor case showed 11C-MET hypermetabolism. (2) Semiquantitative analysis: 18F-FDG PET showed significant differences between various grades (P<0.05), except between grade I and II tumors, 11C-MET PET showed differences only between grade II and IV tumors(P<0.01) not in others. Both 18F-FDG and 11C-MET showed positive correlation with Ki67 LI, but in subgroups of grade II and III tumors only 11C-MET showed correlation with Ki67 LI. Conclusions: Visual and semi- quantitative grading with 18F-FDG in neuroepithelioma is better than that with 11C-MET. 11C-MET is of great value in detecting low-grade tumors and delineating its boundary. The uptake of 11C-MET denotes more significantly with the proliferation activity than 18F-FDG. (authors)