ACG: Colonoscopy May Have High-Tech Future

LAS VEGAS, Oct. 31 -- Pill-sized cameras, self-navigating endoscopes, and other high-tech gadgetry may one day supplant or augment conventional colonoscopy for colon cancer detection, according to a technology review presented here.

At an industry-sponsored symposium held in conjunction with the American College of Gastroenterology meeting, Jacques Van Dam, M.D., Ph.D., of Stanford offered a glimpse into the high-tech future of colonoscopy.

While conventional colonoscopy remains the gold standard for detecting colon cancer, Dr. Van Dam cited some drawbacks. For example, currently used colonoscopes are prone to "looping" upon insertion, which causes patient discomfort and interferes with the procedure, he said.

In addition, conventional colonoscopy still misses more than a quarter of small polyps (those 5 mm or less), especially those on the "backside" of a tissue fold, he said.

In one study comparing the results of 465 patients who underwent two conventional colonoscopies in the same day, the procedure missed 26% of polyps smaller than 5 mm, 13% of polyps 5mm to 10 mm, and 2.1% of those 10 mm or greater, Dr. Van Dam noted. The study was published in the February issue of the American Journal of Gastroenterology.

Dr. Van Dam discussed several investigational devices that promise to improve on conventional colonoscopy.

1) The Aer-O-Scope

One of these was the Aer-O-Scope, a disposable, self-propelling, self-navigating endoscope made by G.I. View of Ramat Gan in Israel. The device, which provides a 360-degree view, captures high-resolution video pictures of the colon walls and transmits them in real time to a computer monitor.

Because advancement through the colon and retraction are largely automated with this device, it requires minimal training and skill to operate, Dr. Van Dam said.

In a pilot feasibility study of 12 healthy volunteers (ages 20 to 43), the device achieved cecal intubation in 10 of the 12. The average intubation time was 14 minutes. The procedure was well-tolerated, with two patients requesting analgesia and four complaining of bloating and swelling, Dr. Van Dam said.

2) The PillCam

Another investigational device is the PillCam, made by Given Imaging of Yoqneam in Israel. The capsule measures 11 mm by 32 mm, roughly the size of a large vitamin pill. The capsule has tiny cameras at each end which capture four images per second for up to 10 hours.

The patient swallows the PillCam with a glass of water and also takes prokinetic agents to help move the capsule along the digestive tract. The images are transmitted to a workstation for video review.

This procedure requires no sedation, and "it has the potential to improve compliance with colorectal cancer screening for patients unable or unwilling to undergo standard colonoscopy," Dr. Van Dam said.

In a study presented at the ACG meeting here, Blair Lewis, M.D., of Mount Sinai in New York, reported that of 25 patients who underwent the PillCam procedure, 22 passed the camera through the rectum within 10 hours. The average time was four hours. The other three patients passed the device in less than 25 hours.

3) The'Third Eye' Retroscope

Finally, Dr. Van Dam discussed the "Third Eye" Retroscope, a device made by Avantis Medical Systems, Inc. of Sunnyvale, Calif. This imaging device is passed through the instrument channel of a standard colonoscope until it extends beyond the colonoscope's tip. As the device emerges, it automatically turns around 180 degrees to aim backward toward the tip of the colonoscope. As the colonoscope is withdrawn from the colon, the "Third Eye" comes along with it, providing a continuous backward view to complement the forward view of the colonoscope.

A non-clinical study published in Gastrointestinal Endoscopy suggests that this device may perform better than standard colonoscopy in detecting polyps "hiding" on folds, Dr. Van Dam said. In this study, three anatomical models of the colon were prepared with multiple simulated polyps. About one-third of the simulated polyps were obvious and roughly two-thirds were located on the proximal aspect of folds.

Six endoscopists examined each model with both a standard colonoscope and one assisted by the Third Eye. Standard colonoscopy detected only 12% of the "hidden" simulated polyps, compared with an 81% detection rate for standard colonoscopy plus the Third Eye (P