title: Evaluation of low-density neutral oral contrast material in PET/CT for tumor imaging: results of a randomized clinical trial.
abstract: OBJECTIVE
  The objective of this study was to determine the impact on image quality and risks in terms of artifacts and side effects of a low-density barium-based suspension as oral contrast material for CT during PET/CT examinations of an oncologic patient population.
  
  
  METHODS
  Eighty-five patients (51 men and 34 women; mean age, 53 years; age range, 21-87 years) were prospectively randomized to receive either 0.1% barium sulfate oral suspension or no oral contrast material during PET/CT. Patients in the oral contrast group were given 1,350 mL over 60-75 minutes. The (18)F-FDG PET component of each examination was reviewed for the presence of artifacts by two nuclear medicine physicians and was classified as adequate (no presence of artifactual focal FDG uptake attributed to attenuation-correction errors) or inadequate (focal uptake in attenuation-correction PET images with no corresponding uptake in non-attenuation-corrected PET images). Two radiologists reviewed the CT studies and scored the degree of bowel opacification using a 5-point scale, ranging from 0 for no opacification (i.e., not possible to delineate the bowel structures from the surrounding tissues) to 4 for excellent opacification (i.e., bowel structure identifiable and bowel wall clearly visible). The attenuation values (in Hounsfield units) were recorded in the stomach, duodenum, mid jejunum, and terminal ileum for quantitative analysis. Interobserver variability was assessed using kappa coefficients.
  
  
  RESULTS
  None of the patients who received oral contrast material experienced side effects. All 85 PET examinations were considered adequate with no observable artifacts. The mean bowel opacification scores of the oral contrast group (2.59 and 2.93) as evaluated by radiologists 1 and 2, respectively, were significantly higher (p < 0.01) than those of the control group (1.55 and 1.59). The level of attenuation achieved in the contrast group was significantly higher than in the control group. The interobserver variability was moderate (kappa = 0.32).
  
  
  CONCLUSIONS
  The use of low-density neutral oral contrast material for CT during combined FDG PET/CT studies significantly improves visualization of the bowel structures compared with no contrast material without causing side effects or clinically detectable errors in the attenuation correction of the FDG PET study.
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, 1620 Tremont St., 3rd Fl., Radiology Ste., Boston, MA 02120, USA. hotero@partners.org
authors.forename: Hansel J
authors.initials: HJ
authors.lastname: Otero
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Yap
authors.forename: Michael A
authors.initials: MA
authors.lastname: Patak
authors.forename: Sukru M
authors.initials: SM
authors.lastname: Erturk
authors.forename: David A
authors.initials: DA
authors.lastname: Israel
authors.forename: Ciaran J
authors.initials: CJ
authors.lastname: Johnston
authors.forename: Chris
authors.initials: C
authors.lastname: Sakellis
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Rybicki
authors.forename: Annick D
authors.initials: AD
authors.lastname: Van den Abbeele
authors.forename: Pablo R
authors.initials: PR
authors.lastname: Ros
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D001466:Barium Sulfate / Q000008:administration & dosage; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006689:Hodgkin Disease / Q000175:diagnosis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007422:Intestines / Q000000981:diagnostic imaging; D008228:Lymphoma, Non-Hodgkin / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D016037:Single-Blind Method; D013270:Stomach / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media; D001466:Barium Sulfate