CT colonography without cathartic preparation: Feasibility study

PURPOSE: To evaluate methods for contrast material labeling of stool in the unprepared colon for computed tomographic (CT) colonography and to determi ne their sensitivity for polyp detection. MATERIALS AND METHODS: Fifty-six patients with suspected or known polyps we re 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 ima ges were assessed for effectiveness of stool labeling. Colonoscopy was perf ormed in all patients and was the standard. Two radiologists blinded to pri or imaging and colonoscopic results assessed polyp detection. RESULTS: For each group, average stool labeling scores and ranges were as f ollows: 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%; a nd 48 hour seven dose, 88% and 75%-98%. Sensitivity for the two radiologist s for the identification of patients with polyps 1 cm or larger for each gr oup 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%; an d 48 hour seven dose, 100% and 80%. CONCLUSION: Ingestion of contrast material adequately labels stool for lesi on identification; a 48-hour lead time and multiple doses of contrast mater ial are required. Sensitivity for polyp detection in patients with adequate stool labeling approaches the sensitivity for polyp detection in prepared colons.