SAN DIEGO – A colonoscopy capsule that requires no bowel preparation safely detected pedunculated and sessile polyps as small as 7 mm in a feasibility study of 54 volunteers.
The capsule scans the colon with very-low-dose X-rays, and the images are converted to high-resolution three-dimensional reconstructions that physicians can review remotely in about 10 minutes, said Dr. Nadir Arber of the Integrated Cancer Prevention Center at Tel Aviv Sourasky Medical Center. “All 54 capsules were excreted naturally, without discomfort or side effects,” he reported at the annual Digestive Disease Week.
Bowel preparation is the most common reason for skipping a colonoscopy, and poor preparation leads to missed adenomas on conventional screens, Dr. Arber noted. “A colorectal cancer screening method that would generate structural data of the colon, without cathartic cleansing or diet restrictions, would offer an attractive alternative for many patients,” he said.
This capsule is no larger than others that have been approved, but it uses low-dose X-rays to circumvent the need for bowel preparation. Patients swallow the capsules and go about their day while wearing tracking patches on their lower backs that transmit (nonionizing) radiofrequency data to a localization system. This system determines when a capsule has reached the colon. At this point, the capsule is activated and begins emitting X-rays, but only when it is moving, Dr. Arber said. Because the capsule usually is not moving, radiation exposure is minimized. Also, an axis-positioning system reconciles the location of the capsule with the colonic wall to prevent movement artifacts.
The 54 volunteers in the study were 45-75 years old. The capsules took an average of 66 hours to move through the entire alimentary tract, with a standard deviation of 37 hours. If swallowed before the first meal of the day, the transit time averaged 51 hours, with a standard deviation of 25 hours. The total radiation dose per procedure averaged 0.03 mSv (standard deviation, 0.0007 mSv), which is equivalent to one dental or chest X-ray, Dr. Arber said.
Examples of reconstructed lesions included a 12 × 4 mm flat sessile polyp, a double-headed polyp with heads measuring 7 and 15 mm, and a 25-mm polyp in the sigmoid colon. “In humans, 7-mm polyps are well within the detection capability of the system,” he said.
He and his associates are planning multicenter studies to compare adenoma detection by the capsule with traditional colonoscopy. Reconstructing long pedunculated polyps might be difficult because of image distortion, Dr. Arber acknowledged.
He reported that his spouse or partner has received consulting fees from Check-Cap Ltd., the maker of the capsule.