Background ^18F-fluorodeoxyglucose （FDG） is the most widely used radiotracer in tumor imaging,but its use for brain gliomas and recurrence is limited by the high ^18F-FDG uptake in normal brain tissue.^11C-methionine （MET） has low uptake in the normal brain tissue,providing potential advantages over ^18F-FDG.The aim of the study was to investigate the diagnostic value of ^11C-MET compared to ^18F-FDG positron emission tomography and computed tomography （PET/CT） in patients with suspected primary and residual/recurrent gliomas.Methods Eighty paired PET/CT scans using ^11C-MET and 18F-FDG were performed on 44 newly diagnosed patients with suspected gliomas and 36 post-operative patients with suspected residual/recurrent tumors.PET/CT results were evaluated by visual and semiquantitative analysis.The sensitivity,specificity and accuracy for detection of gliomas and residual/recurrent tumors were calculated using visual analysis.Tumor to contralateral normal gray matter （T/G） ratio was calculated for semiquantitative analysis.Results Final pathology of the 44 newly diagnosed patients included 26 gliomas （14 high-grade and 12 low-grade tumors） and 18 non-glioma benign lesions.Residual/recurrent gliomas were verified in 28 patients and excluded in 8/36 post-operative patients by subsequent histopathologic examination and/or clinical follow-up for more than six months.The sensitivity,specificity and accuracy of 11C-MET PET/CT were 88.5%,83.3% and 86.4% for gliomas and 96.4%,87.5% and 94.4% for residual/recurrent gliomas,respectively.The sensitivity,specificity and accuracy of 18F-FDG PET/CT were 50.0%,88.9% and 65.9% for gliomas and 46.4%,100.0% and 58.3% for residual/recurrent gliomas,respectively.11C-MET had a higher sensitivity than 18F-FDG （83.3% vs.33.3%,P=0.031） in low-grade gliomas,but had no significant difference in sensitivity from 18F-FDG for high-grade gliomas （92.9% vs.64.3%,P=0.219）.11C-MET T/G uptake ratios in high-grade gliomas,low-grade gliomas and benign lesions were 1.94±0
LI Dong-liXU Yi-kaiWANG Quan-shiWU Hu-bingLI Hong-sheng
