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 high focal uptake can mimic a lesion. The cause of intestinal FDG uptake and the 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 baseline and after administration of two drugs (atropine and sincalide) that are known to affect intestinal motility. We performed FDG PET scans in random order in five healthy male volunteers without medication, after intramuscular administration of atropine, and after intravenous administration of sincalide.
Results: Qualitative comparison of the images before and after both medications 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.