Information for Patients
Virtual Colonography (CT Colonography)
Colon polyps have been shown to be the precursor lesions for most colon cancers. Identification and removal of colon polyps before they become cancerous is the goal of colon screening. Radiologists at the VCU Medical Center are among the first in Virginia to test and use a more patient-friendly method of screening for colon polyps. Virtual colonography (VC) or CT Colonography (CTC) are noninvasive treatments that use computed tomography (CT) scanning to determine whether or not colon polyps are present.
What makes VC or CTC a good option for screening?
The procedure is noninvasive, safe, quick – lasting only a few minutes – and does not require sedation. Due to the twists and turns in the large intestine, navigating a colonoscope during a standard colonography can be difficult. VC, however, allows an evaluation of the entire colon, without the risks, such as bowel perforation, or complications from sedation associated with standard colonography.
VC is accurate in identifying significant polyps and is attractive to many patients who are simply not willing to undergo the more invasive traditional colonography.
How accurate is VC compared to conventional colonography?
Early studies show that VC is comparable to conventional colonography in terms of identifying polyps six millimeters or greater in size. Physicians at the VCU Medical Center use VC as a diagnostic tool to confirm or rule out the possibility of cancer. If large polyps are identified, traditional colonoscopy is required for biopsy and removal.
What can I expect when I have VC?
Patients who have VC will undergo bowel preparation one day prior to the exam, as they would for standard colonoscopy.
The VC procedure itself calls for the patient to lie on the CT scan table while the colon is partially inflated using a tiny air tube. Two five-second CT scans are performed, one with the patient on his or her back and the other with the patient lying on his or her stomach. In less than five to ten minutes, the examination is complete; no sedatives are required for this screening method.
Using data acquired from the CT scans, two-dimensional and three-dimensional images of the colon are obtained. VC relies on specially developed computer software to recreate the inside of the patient’s colon, allowing a “fly-through” or “virtual” evaluation of the colon that provides the precise location and size of colon polyps or masses.
Why is it so important to be screened?
Research shows that less than 40 percent of those who should be screened actually do so. Left undetected, colon polyps larger than seven to 10 millimeters are at risk of developing into colon cancer. If polyps are removed early on, colon cancer is preventable.
According to the American Cancer Society, cancers of the colon and rectum combined are the second leading cause of cancer-related deaths overall and the third most common cancer for both men and women. Screening and early removal of colon polyps can prevent the development of cancer. Although there are high-risk determinants, 75 percent of all colon cancer cases occur in people with no known predisposing factors.
For more information about virtual colonography, call the Department of Radiology at (804) 828-4467.