Background: Identification of cancer or inflammatory bowel disease in the intestinal tract by PET/computed tomography (CT) imaging can be hampered by physiological uptake of 18F-fluorodeoxyglucose (18F-FDG) in the normal colon. Previous work has localized this 18F-FDG uptake to the intestinal lumen, predominantly occupied by bacteria. We sought to determine whether pretreatment with an antibiotic could reduce 18F-FDG uptake in the healthy colon.
Patients and methods: Thirty patients undergoing restaging PET/CT for nongastrointestinal lymphoma were randomly selected to receive rifaximin 550 mg twice daily for 2 days before their scan (post-rifaximin). Their PET/CT images were compared with those from their prior study (pre-rifaximin). Cecal maximum standard uptake value (SUVmax) and overall colonic 18F-FDG uptake were compared between scans. All PET/CT images were blindly scored by a radiologist. The same comparison of sequential scans was also undertaken in 30 patients who did not receive antibiotics.
Results: Thirty post-rifaximin scans were compared with 30 pre-rifaximin scans in the same patients. SUVmax in the cecum was significantly lower in the patient’s post-rifaximin scans than in their pre-rifaximin scans (P=0.002). The percentage of scans with greater than grade 1 colonic 18F-FDG uptake was significantly lower in the post-rifaximin scans than in the pre-rifaximin scans (P<0.05). In contrast, there was no significant difference in the paired sequential scans from control patients, nor a reduction in the percentage of scans with greater than grade 1 colonic 18F-FDG uptake.
Conclusion: This pilot study shows that treatment with rifaximin for 2 days before PET/CT scanning can significantly reduce physiological 18F-FDG uptake in the normal colonic lumen.
aDivision of Nuclear Medicine and Molecular Imaging, Department of Radiology
bDivision of Gastroenterology, Department of Medicine
cDivision of Hematology and Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
dDepartment of Medicine, Universidad Autónoma de Barcelona (UAB), Barcelona, Spain
* Gerald M. Kolodny and Alan C. Moss contributed equally to the writing of this article.
This data was presented previously at the Society of Nuclear Medicine and Molecular Imaging Annual Meeting, June 2013.
Correspondence to Alan C. Moss, MD, Division of Gastroenterology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02115, USA Tel: +1 617 667 3197; fax: +1 617 667 1171; e-mail: firstname.lastname@example.org
Received March 10, 2014
Accepted June 20, 2014