title: Oral contrast medium in PET/CT: should you or shouldn't you?
abstract: OBJECTIVE
  It has been suggested that the use of computed tomography (CT) positive contrast agents has led to attenuation-induced artefacts on 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT) systems. Consequently, centres may withhold the use of such agents. Whilst there is theoretical evidence to support the aforementioned claim, the clinical relevance of the induced artefacts has not been widely established. Moreover, the potential benefits of bowel enhancement on PET/CT have yet to be formally evaluated. We therefore prospectively examined PET/CT studies to assess whether the use of oral contrast medium induces clinically relevant artefacts and whether the use of these agents is diagnostically helpful.
  
  
  METHODS
  Over a 2-month period, 18F-FDG PET/CT images were prospectively reviewed from 200 patients following Gastrografin administration 2 h prior to examination. Both a radiologist and a nuclear medicine physician reviewed the images for contrast medium-mediated clinically relevant artefacts. Artefacts were sought on the CT attenuation-corrected images and were compared with the appearance on non-attenuated-corrected images. The number of examinations in which the oral contrast aided image interpretation was also noted.
  
  
  RESULTS
  There were no oral contrast medium-induced clinically significant artefacts. In 38 of the 200 patients, oral contrast aided image interpretation (owing to differentiation of mass/node from bowel, discrimination of intestinal wall from lumen or definition of the anatomy of a relevant site). In 33 of these 38 patients, the anatomical site of interest was the abdomen/pelvis.
  
  
  CONCLUSIONS
  The use of oral contrast medium in 18F-FDG PET studies should not be withheld as it improves image interpretation and does not produce clinically significant artefacts.
authors.affiliation: Institute of Nuclear Medicine, Middlesex Hospital, University College London, Mortimer Street, London, W1T 3AA, UK. drashleygroves@hotmail.com
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Groves
authors.forename: Irfan
authors.initials: I
authors.lastname: Kayani
authors.forename: John C
authors.initials: JC
authors.lastname: Dickson
authors.forename: Caroline
authors.initials: C
authors.lastname: Townsend
authors.forename: Ian
authors.initials: I
authors.lastname: Croasdale
authors.forename: Rizwan
authors.initials: R
authors.lastname: Syed
authors.forename: Nagesh
authors.initials: N
authors.lastname: Nagabushan
authors.forename: Sharon F
authors.initials: SF
authors.lastname: Hain
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ell
authors.forename: Jamshed B
authors.initials: JB
authors.lastname: Bomanji
mesh_terms: D000008:Abdominal Neoplasms / Q000175:diagnosis*; D000284:Administration, Oral; D016477:Artifacts; D003287:Contrast Media; D003974:Diatrizoate Meglumine / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D010386:Pelvic Neoplasms / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D003974:Diatrizoate Meglumine