New imaging device could assist colonoscopy in detecting lesions

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The gold-standard colonoscopy can occasionally miss lesions, especially on the proximal aspect of haustral folds and flexures or behind the ileocecal valve. The Third Eye Retroscope (TER) could provide a retrograde view that complements the forward view of a standard colonoscope, according to initial results from a study presented this week at the American College of Gastroenterology (ACG) conference in Orlando, Fla.

D. K. Rex, MD, from the gastroenterology and hepatology division at the Indiana University Medical Center in Indianapolis, and colleagues conducted a multicenter study involves 14 endoscopists at eight U.S. sites. Investigators examined 214 patients (age 55-80) during screening colonoscopy using a TER from Avantis Medical Systems in Sunnyvale, Calif., in combination with a standard colonoscope (CF-Q160AL, CF-Q180AL or CF-H180AL from Olympus America).

After cecal intubation, the disposable TER was inserted through the instrument channel of the colonoscope, the researchers explained. As it emerged from the channel, the distal tip of the device turned 180 degrees to provide a retrograde view. During withdrawal, the two video images were observed side-by-side on a wide-screen monitor. For each polyp, the endoscopist indicated whether it was visible through the colonoscope or was detected with the colonoscope only because it was first detected with the TER.

In the initial 214 subjects, the investigators found that 203 polyps were identified with the standard colonoscope. With the TER, 27 additional polyps were detected, a 13.3 percent increase. With the colonoscope, 105 adenomas were found, and with the TER, 13 more adenomas were detected, a 12.4 percent increase.

Rex and colleagues said that the mean size of lesions detected with the TER was similar to mean size of lesions found with the colonoscope. In 21 individuals, at least one additional polyp was found, and in seven patients, the polyp detected with the TER was the only one found.

The researchers noted that every polyp that was initially detected with the TER was then located and removed with the colonoscope.

Rex and colleagues concluded that the initial results of the prospective study indicate that a retrograde-viewing device revealed areas that are hidden from the forward-viewing colonoscope and allowed detection of 13.3 percent additional polyps, including 12.4 percent additional adenomas.