MRI may make colon cancer screening more tolerable
NEW YORK (Reuters Health) - The use of magnetic resonance imaging, or MRI, may offer a more tolerable alternative to conventional colonoscopy in screening for colon cancer, new research suggests.
With MRI colonography, images are taken of the colon that resemble those seen with colonoscopy. Unlike colonoscopy, however, this screening method does not require the insertion of a long tube in the rectum.
Moreover, with use of a special technique called "fecal tagging," patients do not need to undergo the uncomfortable bowel cleansing required with conventional colonoscopy.
The new findings indicate that MRI colonography can accurately detect polyps that have the potential for becoming cancerous. However, improvements are needed to better detect small polyps, according to the report in the journal Gut.
These findings are from a study of 315 adults older than 50 years who underwent MRI colonography screening. Two days before screening, the subjects drank a liquid that "tagged" any stool in the bowel, allowing the stool to be virtually removed from the colonographic images to makes it easier for doctors to look for polyps.
No bowel cleansing agents were given, although rectal water enema was administered during imaging to expand the bowel. No sedative or analgesic medications were given.
The findings on MRI colonography were compared with those obtained with conventional colonoscopy.
Dr. Christiane A. Kuehle, from University Hospital Essen in Germany, and colleagues found that MRI colonography was fairly good at detecting polyps greater than 5 millimeters in diameter. By contrast, MRI colonography nearly always missed smaller polyps.
While the results are encouraging, the researchers believe that conventional colonoscopy will remain the first choice screening method for colon cancer. An important advantage of conventional colonoscopy is that polyps that are detected can be removed or biopsied during the procedure.
"However, for patients unwilling to undergo colonoscopy, MRI colonography should be regarded as an attractive alternative."
SOURCE: Gut, August 2007.
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