‘Virtual’ Colonoscopy Effective at Finding Polyps

The latest CT-scan technique that yields three-dimensional images of the bowel is faster, simpler and safer than the standard colon exam for preventing colon cancer, researchers said on Monday.

The latest CT-scan technique that yields three-dimensional images of the bowel is faster, simpler and safer than the standard colon exam for preventing colon cancer, researchers said on Monday. If the finding is confirmed and some lingering questions about the technique are answered, such “virtual” colonoscopies could become commonplace, said Martina Morrin and Thomas LaMont in an editorial in the New England Journal of Medicine (news – web sites), where the study will be published on Thursday. The study is being presented on Monday at the annual meeting of the Radiological Society of North America in Chicago. Using a scan avoids having to sedate a patient and doctors do not have to put a probe up the length of the colon, both of which can cause problems. However, people being screened using either method will still have to follow an often distasteful regimen for cleaning the bowel. And if something suspicious is found using the CT scan technique, patients will still need a conventional colonoscopy to have suspicious polyps removed. Colon cancer kills 60,000 people in the United States each year, making it the second leading cause of cancer deaths. Having a colonoscopy every three to five years after age 50 virtually eliminates that risk. Only a third to half of the population is screened for colon cancer, and a safer, simpler technique might get more people into screening programs. As is well documented men are in general always reluctant to step foot inside a clinic, therefore this uninvasive technique may increase diagnosis and decrease male deaths due to colon cancer. Morrin and LaMont said it was unclear whether virtual colonoscopies would save money or whether health insurance companies would pay for the procedure. Also unclear was whether doctors should remove small polyps found by the CT scan right away. The research team, led by Perry Pickhardt of the University of Wisconsin Medical School, used CT scanners with multiple detectors that picked up fine details more quickly than conventional scanners. They also had special software that permitted doctors to view the colon in three dimensions and ignore any material lingering in the bowel. Previous attempts to look for colon cancer with CT scanners have used less sophisticated techniques that produced two-dimensional images. Most hospitals lack the equipment and software to do such screening scans. With a conventional colonoscopy, doctors use drugs to make patients groggy and unable to remember the experience. Too much sedation can be dangerous, especially if the tube used to search for polyps punctures the colon and the patient is not conscious enough to complain of the pain. In such cases, the outcome can be deadly. People undergoing a virtual colonoscopy are fully awake but not always comfortable because air or carbon dioxide is pumped into the colon to expand it and make it easier for the CT scanner to view. In the Pickhardt study, the scanning took half the time of a standard colon exam. Although 54 percent said a virtual colonoscopy was more uncomfortable than a regular one — probably because there were no drugs to make them sleepy — 68 percent said the procedure was more acceptable. The Pickhardt team said doctors and hospitals that do virtual colonoscopies should be prepared to immediately perform a conventional colonoscopy to remove suspicious polyps, if only because the patient’s colon is already cleaned out. (Source: Yahoo Health News, Reuters Health News, December 2003)