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UW Researcher finds 3-D Virtual Colonoscopy is more sensitive than conventional procedure

A new technology aimed at the second-deadliest cancer in the nation is both more sensitive and less invasive than the conventional screening method.

If colon cancer is caught in the early stages, it's 90 percent curable. Until now, conventional colonoscopy has been the standard mode of screening for colon cancer, but because of the uncomfortable nature of the procedure, many individuals opt to not have one done at all - but this may soon change.

Three-dimensional computed tomography (CT) colonography, also known as Virtual Colonoscopy, is more sensitive and less invasive than conventional colonoscopy in screening average-risk patients, according to research to be presented December 1 in Chicago at the 89th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA).

The article will be published in the December 1 issue of the New England Journal of Medicine, and also will be featured on their Web site. The new technology allows radiologists to obtain 3-D images from different angles, providing a "movie" of the interior of the colon without having to insert a scope.

"The findings of this study should establish virtual colonoscopy as a viable screening option," said Perry J. Pickhardt, MD (pictured, above left), associate professor of radiology at University of Wisconsin Medical School, radiologist at UW Hospital and Clinics and lead author of the study from National Naval Medical Center in Bethesda, Md.

Colonic polyps are benign growths that may develop into colon cancer if not removed. Many people resist screening because of the discomfort caused by conventional colonoscopy and other tests. In recent years, radiologists have begun using CT colonography to screen for polyps. Although less invasive, until now the procedure primarily used 2-D CT slices (images) for polyp detection, which are likely less sensitive.

"Fly-Through" Imaging

With the addition of 3-D "fly-through" images, virtual colonoscopy sees the whole picture, providing precise and detailed images of the colon's interior in a minimally invasive manner. With virtual colonoscopy, there is no risk of bleeding or of perforating the colon. There is no need for intravenous sedation, and the procedure is less costly than conventional colonoscopy. It also is more convenient, taking 15 minutes or less, because patients need not recover from sedation.

Identifying Polyps

For example, virtual colonoscopy detected 92.6 percent of polyps eight millimeters and larger, whereas conventional colonoscopy detected 89.5 percent of such polyps. Two malignant polyps were present, and virtual colonoscopy detected both of them, while conventional colonoscopy missed one.

Most polyps that are missed at virtual colonoscopy are small (five millimeters or smaller) and are of little or no clinical importance, according to Dr. Pickhardt. Virtual colonoscopy is able to identify occasional polyps that are located behind folds in the colon lining and may be missed by conventional colonoscopy. Virtual colonoscopy is strictly a diagnostic procedure and is best suited for average-risk individuals 50 to 70 years of age.

Source: University of Wisconsin Health Sciences

You can discuss more about Gastroenterology & Endoscopy and related topics in our Gastroenterology & Endoscopy Group.