Diphenoxylate / Atropine to Decrease Bowel Activity During F-18 FDG PET

2-[18F]-fluoro-2-deoxyD-glucose positron emission tomography (FDG PET) has proven to be a valuable clinical tool for the staging and surveillance of lymphoma.1-6 Occasionally, lymph nodes in the mesentery and retroperitoneum can be difficult to distinguish from normal bowel activity on PET scans despite three-plane and cine maximal image projection (MIP) imaging. This uncertainty limits the clinical usefulness of PET in some cases of lymphoma.7-8 In addition, bowel activity can also hinder interpretation of PET scans in other types of solid tumors including melanoma and colorectal cancer.6,9,10 Our goal is to determine how well diphenoxylate/atropine 5mg/0.05mg (Lomotil) decreases bowel activity and how this decrease impacts clinical decision-making, specifically for lymphoma staging and surveillance. This is a prospective, randomized, double-blinded study involving 60 patients undergoing PET scans for newly diagnosed or recurrent, untreated lymphoma.