CT colonography

Extracolonic findings: outside the colon. Major areas of concern that Medicare has that we have sufficiently addressed. Additional cost per CTC exam it is reasonable as it ranges $28.00 per CTC exam. 

Additional Screening Opportunities

• Extracolonic cancers
• Aneurysm screening
• Osteoporosis
• Hepatic steatosis
• Visceral fat analysis 

Decreasing the cathartic is going to be very important. Gastroenterologists would agree that getting rid of laxative would bring more patients in for screening. At reduced bowel preparation using two liter peg and comparing it to magnesium citrate, we found that two liter peg patients is equally effective in bowel cleansing and had better tagging quality.  Also, the interpretation times were shorter with two liter peg solution.  Two liter peg solution is specifically made by particular manufacturer, which makes it more expensive so is an issue dissemination

• View of larger areas of the colon which means shorter interpretation times
• Intuitive, easier to learn that would decrease reader fatigue
• Improve sensitivity and specificity
• Ability to incorporate: Tagging and subtraction:  Tagging: a substance that helps distinguish between stool in the colon and abnormalities during CTC; CAD (computer aided detection) for polyps is available for the standard views but has not been implemented for many of the novel displaying.

1. CTC is validated as an effective, safe, screening test
2. Benefits of CTC screening outweigh the radiation risks. Current techniques decrease radiation dose by up to 60% (≤3mSv= annual background dose)
3. CTC is supported as a screening tool by the ACS and FDA
4. ACR CTC Registry (NRDR) is in place for monitoring of CTC quality and safety

Major Private Payers Covering Screening CTC

• United Healthcare
• Cigna
• Anthem
• Blue Cross/Blue Shield
• BC of California, Wellmark BC/ BS of New Jersey, Empire BC, BC/BS of North Carolina

Reasons for denial was due to that they didn’t know enough about

• Radiation dose
• Extracolonic (Outside the colon) findings
• Performance in Medicare age patients 

• Stevenson G. Canadian Association Radiol J 2008; 59: 174-82
  • “It beginning to seem rather irresponsible to continue to offer routine DCBE examinations…More than 90 Canadian radiology departments have bought the necessary CO2 insufflators so there is clearly great interest.”
• Blachar et al. Israel Medical Association Journal 2008; 10: 707

ACRIN 6664: National CTC Trial (N Engl J Med 2008; 359:1207-1217)

• Multi-institutional (15 sites)-academic and private
• Feb 2005-Dec 2006
• ≥50 years asx, screening asymptomatic (without symptoms) patients
• 15 patients, 2531 patients
• Radiologist certification to read cases:
  • >500 cases already: 90% accuracy
  • <500 cases: 1 day training course +90% accuracy
  • Otherwise additional 20 cases for testing

After the patient is scanned, the data is transferred to high end computer work station that is loaded with specific software that allows us to generate 2D and 3D images of the colon. A fly through can be down through the 3D image. We can manipulate the data 360 degrees and rotate in anyway we want.  It also allows for doctors to roll through walls without additional radiation.  Also, there is the option of automated measurement.

Thin slice-low dose 

• Must use low dose protocol
• Effective mAs 50
• kV 120
• Pitch 6
• Collimation 1 mm

Effective radiation dose similar to BE

• 5.0 mSv for males
• 7.8 mSv for females

(Macari et al. Radiology 2002; 224-383)

Radiation Exposure