Virtual Colonoscopy Helpful in Cancer Screening

Virtual colonoscopy compares well with conventional colonoscopy in detecting large polyps, New York-based researchers report in the medical journal Radiology.

They concede that the detection rate is lower for smaller lesions, but point out that if patients undergo screening every five years, “missing small lesions is likely to be clinically insignificant.” Despite its name, virtual colonoscopy is more like an x-ray than a conventional colonoscopy. With the test, special CT scans of the colon are taken and then reconstructed with computer software to generate images similar to those seen with conventional colonoscopy. Lastly, the virtual test doesn’t require the insertion of a long camera tube into the rectum. “The examination is well tolerated, does not require sedation and can be certainly used in patients who are unwilling to undergo conventional colonoscopy or in patients with underlying medical conditions that make conventional colonoscopy risky,” lead investigator Dr. Michael Macari told Reuters Health. Macari of Tisch Hospital, NYU Medical Center and colleagues also note that the use of the evolving CT technique may increase public acceptance and thus increase the number of patients who undergo colon cancer screening. To compare the results of the two screening approaches, the researchers studied 68 men who were deemed to be of average risk and were older than 50 years. They underwent virtual colonoscopy followed by conventional colonoscopy on the same day. A total of 98 polyps were detected with conventional colonoscopy. Virtual colonoscopy detected all three polyps that were at least 10 millimeters in diameter, but usually missed the 95 smaller polyps. In a few cases, the virtual test indicated the presence of polyps when, in fact, there were none. The researchers conclude that the method “is a sensitive and specific test for detecting colorectal polyps 10 millimeters and larger.” (Source: Radiology: Reuters Health: David Douglas: MedLine Plus: March 2004.)