Virtual colonoscopy using a new type of computed tomography scan is as effective as conventional colonoscopy for detecting precancerous growths, according to a study presented Monday at the annual meeting of the Radiological Society of North America in Chicago.
"Basically, an advance in the technology allows us, in a more automated fashion, to fly through a three-dimensional virtual reality view," says lead author Perry Pickhardt, M.D., associate professor of radiology at the University of Wisconsin Medical School. Previous tests looked at a two-dimensional slice to detect polyps in the colon, he says.
The study finds that use of the newer technique of virtual colonoscopy detects 93.8% of polyps at least 10 millimeters in diameter, 93.9% of polyps at least 8 millimeters in diameter and 88.7% of those at least 6 millimeters across. By comparison, traditional optical colonoscopy detects 87.5%, 91.5% and 92.3% of the three sizes of polyps, respectively.
Presented in October at the fourth International Symposium on Virtual Colonoscopy in Boston, the study also appears in this week?s New England Journal of Medicine. It is touted as the largest study of its kind, including 1,233 asymptomatic adults, aged 50 to 79, who were offered both virtual and optical colonoscopies.
Pickhardt says only about 50 medical centers currently have the new system that provides the three-dimensional image, but he predicts it will become more widespread within the year. He says the main reason implementation will not come overnight is the lack of third-party reimbursement for the procedure by Medicare and private payers.
People who receive the test now pay out of pocket whatever the market allows, Pickhardt says, which has been about $500 to $2,000.
"Once reimbursement comes into play, it will be a cost-effective strategy for evaluating the more healthy, asymptomatic patients," he says.
Virtual colonoscopy is for those who have the highest likelihood of not having a polyp, he continues. For those with a higher risk, Pickhardt maintains that conventional colonoscopy is the more appropriate first step.
"By screening healthy patients, over 90% can be given clean bill of health, leaving the smaller fraction that require removal by conventional colonoscopy," he says.
While Pickhardt says he is not an advocate of the "unproven" whole-body screening that is increasingly available at outpatient scanning centers, he says with proper training and proper systems, those centers could be one way to increase the availability of the new technique.
"The bottom line is all virtual colonoscopies are not created equal," Pickhardt says. "We really need to establish guidelines and practice standards so patients know they are getting a quality study."