What is the virtual colonoscopy ?

The principle of the virtual colonoscopy

The principle of the virtual colonoscopy is to go over an abdominal part of the body with a scanner to recreate the colon in a 2 and 3 dimension synthesis image. The scanner views the abdomen in cuts. The image treatment stations allow the radiologist to study these cuts in 2D but also in 3D and even realize a virtual colonoscopy. The can move as they wish through the colon as if they had a remote controlled camera.

Preparation: a preparation is necessary before going over the body with the scanner. Its main goals are to mark the stools and the waist liquids to help the radiologist to achieve his analysis. Therefore the preparation consists of a contrast product of a laxative. However, some preparations do not need any laxative. These need a special diet 24-28 hours before the examination: either a liquid diet or a diet with special food.

The colorectal cancer

Between 1980 and 2000 in France the number of colo-rectal cancers (CRC) went from 23 900 to 36 000 and the standardized incidence from 33 to 39 and from 22 to 25 for 105 inhabitants respectively for men and women, i.e. an incidence increase of a 16% in 20 years.
At the same time the yearly number of deaths by CRC increased a 22% going from 14 727 to 15 973.

In Canada in 2001 the number of CRC increased from some 4500 cases to 17000 from 1972 to 2001. The numbers of deaths was of 7000 in 2001. In 2004, of the 19100 new CRC cases and 8300 of these have died.

In the United States, 112340 of CRC and 41420 of rectum cancer cases have been listed in 2007 with 52180 deaths.

According to studies, around a 40% of the CRC are mortal.

This trend is the same in all Europe and generally speaking for “rich countries”.

The screening

The screening:

According to studies, the screening of the cancer of colon at the age of 50 by screening and polyp removal reduces of a 85-90 % the risk of CRC.
Screening techniques:

Screening by analyzing the hidden blood in the excrements: this screening still gives at present deceiving accuracy results with about a 50% of false positives and 50% of false negatives.

Screening by optical colonoscopy: this technique brings satisfying results from 80% to 89 % of detected polyps that are larger than 8 mm? But this technique presupposes general anaesthesia and is an invasive act. The main risks are the following:
-Risk of perforation: around 3 perforations of 1000 cases.
-Risk of iatrogenic contamination
-Risk due to general anaesthesia.

Some studies pretend that each general anaesthesia brings one less year of life.

Screening by virtual colonoscopy: this technique brings at present the best results with, for the Viatronix console, according different studies a 91 % to 100 % of detected polyps of 6 mm or larger.