[11C]methionine positron emission tomography for the evaluation of pancreatic exocrine function in chronic pancreatitis

Positron emission tomography (PET) can be used for the quantitative analysis of amino acid metabolism. The aim of this study was to investigate whether pancreatic exocrine function can be evaluated by [C-11]methionine PET in chronic pancreatitis (CP) patients. Dynamic PET scan of the pancreas and liver was performed in eight healthy subjects and seven patients with CP after intravenous (i.v.) injection of [C-11]methionine. Simultaneously, duodenal juice was collected with the background of continuous i.v, administration of secretin (125 ng/kg/h). The radioactivity ratio of the pancreas to that of the liver (PLR) was calculated by regions of interest (ROI) analysis. Amylase output and bicarbonate concentration were measured in the duodenal aspirates. The PLR of CP patients was significantly lower than that of healthy subjects at all time points after methionine injection. The PLRs at 4.5 minutes (PLR4.5) after methionine injection were positively correlated with the amylase output, mean bicarbonate concentration, and volume of duodenal aspirates (R = 0.74, 0.69, 0.46). It is concluded that [C-11]methionine PET would be a noninvasive method for the evaluation of exocrine pancreatic function, which may represent total amino acids uptake of viable acinar cells in the pancreas.