New software aids virtual colonoscopy

From Chicago, at a meeting of the Radiological Society of North America

POLYP ON SCREEN. A computer program highlights a precancerous growth (blue) in the colon. Summers

Radiologists can use a new computer program to spot dangerous growths in the colon without probing inside the body, researchers report. The software could make virtual colonoscopy a more dependable alternative to conventional colonoscopy.

In the standard method, an optical probe passes along the length of the colon. That carries a small risk of injury and is more unpleasant—but, according to some studies, more accurate—than the virtual method, in which a computer images the colon using abdominal X rays.

Ronald M. Summers of the National Institutes of Health in Bethesda, Md., and his colleagues designed software that augments virtual exams. It discriminates precancerous polyps from healthy tissue by assessing the shape and density of suspicious areas along the colon. Such computer-aided detection (CAD) programs provide doctors examining diagnostic images with “a second set of eyes,” says Summers.

The researchers performed both types of colonoscopy on 792 healthy volunteers. The methods picked up the same number of polyps that were at least 1 centimeter wide and therefore appropriate for removal. Optical colonoscopy identified more smaller polyps, but researchers disagree on whether those growths need to be removed.

“CAD works well for the most worrisome types and sizes of polyps,” Summers concludes.

The program raised red flags about some growths that weren’t polyps, but the researchers who conducted the virtual colonoscopies knew to ignore most of that input. The study also revealed two tumors, one of which would have been missed without CAD.

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