Study confirms CTC accuracy in polyp evaluation

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BOSTON--CT colonography (CTC) allows radiologists to predict, with a high degree of confidence, whether or not a polyp needs to be evaluated through colonoscopy or removed through polypectomy, according to a study presented today at the 2009 annual meeting of the American Roentgen Ray Society (ARRS).

The study included 479 patients with 739 CTC detected lesions. "In our study, we found that when a clinically important polyp is found with CT colonography, a corresponding polyp will be identified at colonoscopy greater than 90 percent of the time," according to the study's lead author Steven M. Wise, MD, from the University of Wisconsin School of Medicine and Public Health in Madison, Wis.

The researchers said that their study results showed that 91.6 percent detected on CTC were also found during optical colonoscopy or surgery. "This means that when a radiologist calls a CTC exam positive, the endoscopist can be confident that a treatable polyp is present. The CTC exam can also show the endoscopist where the polyp is located," Wise said.

Wise and colleagues found that Increased diagnostic confidence and a polypoid (nonflat) morphology correlate with a higher likelihood of finding a matching lesion at optical colonoscopy. Polyp size alone (6-9 mm vs. equal to 10 mm) had little effect on positive predictive value, being greater than 90 percent for both size categories.

"The results of this study add even more strength to the argument that CTC is an effective primary screening test for colon cancer that can be used to select out patients who will need colonoscopy and polypectomy. CTC is a good screening option for those patients who wish to avoid the sedation and higher complication rate associated with colonoscopy," he said.

"The finding that the vast majority of polyps found on CTC do represent true polyps will help better establish CTC as a first line screening test for colon cancer in clinical practice. Hopefully, this will increase the number of people screened for colon cancer and therefore enable early detection and prevention of this deadly disease," Wise said.