Unprepped CT Colonography

It is our objective to improve the performance of CTC in the prepared colon, and to validate CTC in the unprepared colon for the detection of colorectal neoplasia. The cost-effectiveness ratio of CTC in the unprepared colon will compare favorably with other colorectal screening test.

To improve the diagnostic performance of CTC in the prepared colon using improved spatial resolution, advanced image displays, and computer-assisted diagnosis, and to optimize diagnostic performance of CTC in the unprepared colon for colorectal polyp detection using electronic stool subtraction and computer-aided diagnostic techniques. To estimate the sensitivity and specificity of CTC in the unprepared colon for clinically important colorectal neoplasms (large adenomas ≥ 1 cm) and to compare such estimates with colonoscopy. To survey patient acceptance of CTC in the unprepared colon, and to assess implications for health care costs and cost-effectiveness of CTC in the unprepared colon in comparison with other approaches.

Mayo Clinic patients scheduled for colonoscopy.

• 1
  485 patients,who have an average risk (asymptomatic and without colon screening in the last 5 years) or those who have a high risk for colon cancer (strong family history of colon cancer or polyps and/or personal history of colon cancer or polyps).
• 2
  160 patients, with a known colorectal lesion at or greater than 1 cm.
• 3
  610 patients, who are of average risk for colon cancer (asymptomatic and no colon cancer screening in the last 5 years).

• MacCarty RL, Johnson CD, Fletcher JG, Wilson LA. Occult colorectal polyps on CT colonography: implications for surveillance. AJR Am J Roentgenol. 2006 May;186(5):1380-3.
• Johnson CD, Fletcher JG, MacCarty RL, Mandrekar JN, Harmsen WS, Limburg PJ, Wilson LA. Effect of slice thickness and primary 2D versus 3D virtual dissection on colorectal lesion detection at CT colonography in 452 asymptomatic adults. AJR Am J Roentgenol. 2007 Sep;189(3):672-80.

Inclusion Criteria:

Average risk or higher for colorectal cancer and scheduled for colonoscopy with any of the following indications:

• Prior colorectal cancer, prior colorectal adenoma, strong family history of colorectal neoplasia, iron deficiency.
• Age ≥ 40 -100 years
• Known or highly suspected primary colorectal neoplasms > 10 mm (n = 160)
• Higher than average risk for colorectal cancer and scheduled for colonoscopy with any of the following indications: prior colorectal cancer, prior colorectal adenoma, strong family history of colorectal neoplasia, iron deficiency.

Exclusion Criteria:

• Less than 1/2 of colorectum remaining
• Inflammatory bowel disease (Crohns, Chronic Ulcerative Colitis)
• Familial Polyposis
• Melena, hematochezia