AIM:To investigate the role of 18 F-fluorodeoxyglucose positron emission tomography(FDG-PET) in the diagnosis of small pancreatic cancer. METHODS:This study involved 31 patients with proven invasive ductal cancer of the pancreas.The patients were divided into 3 groups according to the maximum diameter of the tumor:TS1(maximum tumor size≤2.0 cm) ,TS2(>2.0 cm and≤4.0 cm) or TS3-4(>4.0 cm) .The relationships between the TS and various diagnostic tools,including FDG-PET with dual time point evaluation,were analyzed. RESULTS:The tumors ranged from 1.3 to 11.0 cm in diameter.Thirty of the 31 patients(97%) had a positive FDG-PET study.There were 5 patients classified as TS1,15 as TS2 and 11 as TS3-4.The sensitivity of FDG-PET,computed tomography(CT) and magnetic resonanceimaging(MRI) were 100%,40%,0%in TS1,93%,93%,89%in TS2 and 100%,100%,100%in TS3-4. The sensitivity of FDG-PET was significantly higher in comparison to CT and MRI in patients with TS1(P< 0.032) .The mean standardized uptake values(SUVs) did not show a significant difference in relation to the TS(TS1:5.8±4.5,TS2:5.7±2.2,TS3-4:8.2±3.9) ,respectively.All the TS1 tumors(from 13 to 20 mm) showed higher SUVs in FDG-PET with dual time point evaluation in the delayed phase compared with the early phase,which suggested the lesions were malignant. CONCLUSION:These results indicate that FDG-PET with dual time point evaluation is a useful modality for the detection of small pancreatic cancers with a diameter of less than 20 mm. AIM: To investigate the role of 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the diagnosis of small pancreatic cancer. METHODS: This study involved 31 patients with proven invasive ductal cancer of the pancreas. The patients were divided into 3 groups (maximum tumor size <2.0 cm), TS2 (> 2.0 cm and <4.0 cm) or TS3-4 (> 4.0 cm). The relationships between the TS and various diagnostic tools, including RESULTS: The tumors ranged from 1.3 to 11.0 cm in diameter. Thirty of the 31 patients (97%) had a positive FDG-PET study. There were 5 patients classified as TS1, 100%, 40%, 0% in TS1, 93%, 93%, 89% in TS2 The sensitivity of FDG-PET was significantly higher in comparison with CT and MRI in patients with TS1 (P <0.032). The mean standardized uptak (SUVs) did not show a significant difference in relation to the TS (TS1: 5.8 ± 4.5, TS2: 5.7 ± 2.2, TS3-4: 8.2 ± 3.9), respectively. All the TS1 tumors (from 13 to 20 mm ) showed higher SUVs in FDG-PET with dual time point evaluation in the delayed phase compared with the early phase, which suggested the lesions were malignant. CONCLUSION: These results indicate that FDG-PET with dual time point evaluation is a useful modality for the detection of small pancreatic cancers with a diameter of less than 20 mm.