title: CT colonography without cathartic preparation: feasibility study.
abstract: OBJECTIVE
  To evaluate methods for contrast material labeling of stool in the unprepared colon for computed tomographic (CT) colonography and to determine their sensitivity for polyp detection.
  
  
  METHODS
  Fifty-six patients with suspected or known polyps were assigned to five groups. Two to seven doses of 225 mL of dilute contrast material were orally administered during 24 or 48 hours. Transverse CT images were assessed for effectiveness of stool labeling. Colonoscopy was performed in all patients and was the standard. Two radiologists blinded to prior imaging and colonoscopic results assessed polyp detection.
  
  
  RESULTS
  For each group, average stool labeling scores and ranges were as follows: 24 hour two dose, 16% and 8%-21%; 24 hour five dose, 53% and 27%-66%; 48 hour four dose, 38% and 22%-48%; 48 hour six dose, 68% and 54%-77%; and 48 hour seven dose, 88% and 75%-98%. Sensitivity for the two radiologists for the identification of patients with polyps 1 cm or larger for each group was as follows: 24 hour two dose, 50% and 67%; 24 hour five dose, 100% and 100%; 48 hour four dose, 58% and 75%; 48 hour six dose, 56% and 67%; and 48 hour seven dose, 100% and 80%.
  
  
  CONCLUSIONS
  Ingestion of contrast material adequately labels stool for lesion identification; a 48-hour lead time and multiple doses of contrast material are required. Sensitivity for polyp detection in patients with adequate stool labeling approaches the sensitivity for polyp detection in prepared colons.
authors.affiliation: Department of Diagnostic Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Callstrom
authors.forename: C D
authors.initials: CD
authors.lastname: Johnson
authors.forename: J G
authors.initials: JG
authors.lastname: Fletcher
authors.forename: J E
authors.initials: JE
authors.lastname: Reed
authors.forename: D A
authors.initials: DA
authors.lastname: Ahlquist
authors.forename: W S
authors.initials: WS
authors.lastname: Harmsen
authors.forename: K
authors.initials: K
authors.lastname: Tait
authors.forename: L A
authors.initials: LA
authors.lastname: Wilson
authors.forename: K E
authors.initials: KE
authors.lastname: Corcoran
mesh_terms: D001466:Barium Sulfate; D002400:Cathartics; D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000453:epidemiology; D003113:Colonoscopy; D003287:Contrast Media; D003974:Diatrizoate Meglumine; D005240:Feasibility Studies; D005243:Feces; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D002400:Cathartics; D003287:Contrast Media; D001466:Barium Sulfate; D003974:Diatrizoate Meglumine