Abstract： Objective To investigate the value of 18 F-FDG PET/CT combined with clinical data in the diagnosis of gallbladder carcinoma and to assess the role of 18F-FDG PET/CT in tumor staging.Methods 18F-FDG PET/CT and clinical data of 54 patients (28 males,26 females,age range 18-82 years) with suspected gallbladder carcinoma from March 2009 to March 2014 were retrospectively analyzed.The results of histopathology and clinical follow-up were taken as golden standard.The diagnostic value of 18F-FDG PET/CT for gallbladder carcinoma was determined by the qualitative and quantitative methods.Serum CEA,CA19-9 and WBC count were evaluated for discriminating 18F-FDG-avid malignant and benign diseases.According to the final clinical staging,the role of 18F-FDG PET/CT for tumor staging was assessed.Data were analyzed by two-sample t test,x2 test and McNemar test.Results (1) Gallbladder carcinoma was diagnosed in 27 cases and the gallbladder benign diseases in other 27 cases.18F-FDG PET/CT showed positive results in 42 patients including true positive in 27 patients and false positive in other ones.When focal high uptake of 18F-FDG in the gallbladder and SUVmax of 6.6 in the lesions were used as the qualitative and quantitative standards,the diagnostic sensitivity,specificity,and accuracy of the two methods for gallbladder carcinoma were 100％(27/27) vs 81.5％(22/27),44.4％(12/27) vs 70.4％(19/27),72.2％(39/54) vs 75.9％ (41/54),respectively (x2=3.711 and 0.193,both P＞0.05).There were no much difference for the positive rate of serum CEA and CA19-9 levels between the patients with early staged gallbladder carcinoma and those with 18F-FDG-avid benign diseases(x2 =0.529 and 0.045,both P＞0.05).However,the rate of increased WBC count in patients with 18F-FDG-avid benign diseases was significantly higher than that in patients with early staged gallbladder carcinoma (14/15 vs 1/6,x2 =12.343,P＜0.05).(2) Nearly 59.3％ (16/27) patients with gallbladder carcinoma were upstaged due to the findings by whole body 18F-FDG PET/CT.The sensitivity,specificity of 18F-FDG PET/CT for diagnosing lymph node metastases and distant metastases were 18/19,7/8 and 17/17,9/10,respectively.Conclusions 18F-FDG PET/CT has low specificity for differentiating 18F-FDG-avid gallbladder benign disease and early staged gallbladder carcinoma,but it may be beneficial to the diagnosis that combining PET/CT with WBC count.18F-FDG PET/CT is helpful for the staging of gallbladder carcinoma.