3-D Virtual Colonoscopy Is More Sensitive Than Conventional Procedure
One of the yuckiest medical screening tests we have may be the screening colonoscopy,
recommended for all adults over age 50 as an early detection tool for colon
cancer, the second highest cancer killer of men and women. Patients too often
go to great lengths to avoid having this test, which involves inserting a scope
through the rectum (usually under gentle sedation) and also involves an comprehensive
"cleansing" preparation the day before the procedure. Despite the discomfort-physical
and psychological-with this procedure, it can be truly life-saving, but researchers
have long sought a more socially acceptable and less invasive alternative.
A new procedure, 3-D virtual colonoscopy, may provide that alternative.
A prospective multi-center trial was to evaluate the benefits of the 3-D virtual
colonoscopy as compared with traditional colonoscopy. Published in the New
England Journal of Medicine (12/1/03), this study found that 3-D virtual
colonoscopy is more sensitive than conventional colonoscopy in screening average-risk
patients. Virtual colonoscopy is less costly, less invasive and less time-consuming
than conventional colonoscopy. Also called "three-dimensional computed tomography
(CT) colonography", this new technology allows radiologists to obtain 3-D images
from different angles, providing a "movie" of the interior of the
colon without having to insert a scope.
Within the past few years, radiologists have used CT colonography to screen
for colon polyps. Although less invasive, until now the procedure primarily
used 2-D CT images to detect polyps, which are less sensitive. With the addition
of 3-D images, virtual colonoscopy provides a more complete picture, creating
precise and detailed images of the interior of the colon in a non-invasive manner.
With virtual colonoscopy, there is no risk of bleeding or of perforating the
colon. Unlike traditional colonoscopy, there is no need for intravenous sedation,
and the procedure is less costly than conventional colonoscopy. It also is more
convenient, taking 15 minutes or less, because patients don't need to recover
Colon polyps are benign growths that may develop into colon cancer if not removed.
Many people resist screening because of the discomfort caused by conventional
colonoscopy and other tests. The disadvantage of virtual screening over traditional
colonoscopy, however, is that if a patient is found to have a polyp or a suspicious
area needed biopsy, a follow-up procedure would be required; with traditional
colonoscopy, biopsies or polyp removal can be done during the same procedure.
For this study, researchers performed both conventional and virtual colonoscopy
on 1,233 asymptomatic adults, 97.4 percent of whom were at average risk of having
colonic polyps. Overall, virtual colonoscopy detected more than 90 percent of
significant polyps. For example, virtual colonoscopy detected 92.6 percent of
polyps 8 mm and greater, whereas conventional colonoscopy detected 89.5 percent
of such polyps. Two malignant polyps were present, and virtual colonoscopy detected
both of them, while conventional colonoscopy missed one.
The findings of this study establish virtual colonoscopy as a viable screening
option and may encourage more adults to seek testing. A recent commentary in
the Journal of the American Medical Association (JAMA) advised that
colon screening with any test is recommended for anyone over the age
Created: 1/16/2004  - Donnica Moore, M.D.