title: Rifaximin suppresses background intestinal 18F-FDG uptake on PET/CT scans.
abstract: 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 F-fluorodeoxyglucose (F-FDG) in the normal colon. Previous work has localized this F-FDG uptake to the intestinal lumen, predominantly occupied by bacteria. We sought to determine whether pretreatment with an antibiotic could reduce F-FDG uptake in the healthy colon.
  
  
  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 F-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 F-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 F-FDG uptake.
  
  
  CONCLUSIONS
  This pilot study shows that treatment with rifaximin for 2 days before PET/CT scanning can significantly reduce physiological F-FDG uptake in the normal colonic lumen.
authors: 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.
authors: Elisa
authors: E
authors: Franquet
authors: Mathew R
authors: MR
authors: Palmer
authors: Anne E
authors: AE
authors: Gifford
authors: Daryl J
authors: DJ
authors: Selen
authors: Yih-Chieh S
authors: YC
authors: Chen
authors: Neda
authors: N
authors: Sedora-Roman
authors: Robin M
authors: RM
authors: Joyce
authors: Gerald M
authors: GM
authors: Kolodny
authors: Alan C
authors: AC
authors: Moss
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002432:Cecum / Q000000981:diagnostic imaging / Q000378:metabolism; D015331:Cohort Studies; D003106:Colon / Q000000981:diagnostic imaging / Q000378:metabolism; D004347:Drug Interactions; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012294:Rifamycins / Q000494:pharmacology*; D000078262:Rifaximin
chemical_list: D000900:Anti-Bacterial Agents; D019275:Radiopharmaceuticals; D012294:Rifamycins; D019788:Fluorodeoxyglucose F18; D000078262:Rifaximin