BACKGROUBD: In some patients it is impossible to differentiate between mass forming chronic pancreatitis and adenocarcinoma of the head of the pancreas using standard anatomical imaging. Positron emission tomography using 2-[18F]fluoro-2deoxy-D-glucose (18FDG-PET) and 1-[11C]-acetate (11C-acetate-PET) are methods taking advantage of the metabolic differences in benign and malignant tissues. 18FDG-PET has been proposed to provide high sensitivity and diagnostic accuracy in the differentiation between malignant and benign pancreatic masses whereas the usefulness of 11C-acetate-PET alone or in combination with 18FDG-PET has not been determined. Objective: To assess the ability 18FDG-PET and 11C-acetate-PET to differentiate chronic pancreatitis from pancreatic adenocarcinoma in patients presenting with a pancreatic mass.
METHODS: 20 patients (12 M, 8 F; mean age ±SD 59.7±11 yrs, range 38-77 yrs) with a pancreatic mass of unclear etiology were prospectively included. All patients underwent 18FDG-PET and 18 of them 11C-acetate-PET. The scans were evaluated qualitatively and quantitatively; the later using calculated regional standardized uptake value (SUV). Receiver operating characteristic (ROC) curve analysis was used for evaluation of the results Final diagnosis was established using histopathologic evaluation of resected specimen, biopsy, and in 2 patients clinical follow-up.
RESULTS: The final diagnosis was adenocarcinoma of the pancreas in 12 patients (60%) and chronic pancreatitis in 8. Qualitative evaluation of 18FDG-PET imaging revealed 3 false-negative and 1 false-positive results. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 75%, 88%, 90%, 70%, and 80%, respectively. The cut-off SUV to differentiate malignant from benign disease was calculated to be 3.6 demonstrating a sensitivity of 91,7% and a specificity of 75%. There was no significant difference between the qualitative and quantitative results 11C-acetate-PET did not improve the overall results.
CONCLUSIONS: We could not confirm previous reports of high sensitivity and diagnostic accuracy of 18FDG-PET imaging for differentiating adenocarcinoma of the pancreas from chronic pancreatitis in patients presenting with a pancreatic mass. No additional diagnostic benefit could be demonstrated using 11C-acetate-PET.
