Effect of atropine and sincalide on the intestinal uptake of F-18 fluorodeoxyglucose

Purpose: Variable diffuse intestinal uptake of F-18 fluorodeoxyglucose (FDG ) is commonly seen in patients undergoing positron emission tomography (PET ) imaging. Diffuse high uptake can obscure a lesion, whereas occasional hig h focal uptake can mimic a lesion. The cause of intestinal FDG uptake and t he parameters that influence the level of uptake are unknown. Methods: We hypothesized that intestinal FDG uptake may result from smooth muscle peristalsis. We tested our hypothesis by comparing FDG uptake at bas eline and after administration of two drugs (atropine and sincalide) that a re known to affect intestinal motility. We performed FDG PET scans in rando m order in five healthy male volunteers without medication, after intramusc ular administration of atropine, aid after intravenous administration of si ncalide. Results: Qualitative comparison of the images before and after both medicat ions did not show any significant difference in the level of intestinal FDG uptake, Conclusions: We conclude that intestinal FDG uptake is probably not caused by peristalsis. Mucosal uptake may be an alternative explanation.