CTC (virtual colonoscopy) is a thin slice CT scan of the abdomen after adequate bowel preparation and colon insufflation in which data are reconstructed providing axial, multiplanar, and endoluminal views, in order to visualize internal colonic wall. Several studies have shown that CTC is a valuable tool to evaluate proximal colon after incomplete colonoscopy, and American Gastroenterologists Association (AGA) recognized that CTC is indicated for adults with failed colonoscopy. However the role of CTC after incomplete colonoscopy in a population-based screening context should be investigated deeper.
A research article to be published on July 28, 2008 in the World Journal of Gastroenterology addresses this question. The research team led by Dr. Sali and his colleagues in the University of Florence reported the results of CTC systematically performed in subjects with positive FOBT and incomplete colonoscopy in the context of a population-based screening programme.
From April 2006 to April 2007 43,290 individuals who adhered to the regional screening programme for the prevention of colorectal cancer underwent FOBT test, which was positive in 4.3% of the subjects. 77.7% of these subjects underwent colonoscopy. 7.2% of the colonoscopies were incomplete and 42 of these subjects underwent CTC. In these subjects CTC correctly identified 2 colonic masses and 20 polyps.
In conclusion, the data showed that in the context of a screening program with FOBT CT colonography is accurate for the detection of colonic masses or polyps equal or greater than 10 mm and should replace double contrast barium enema (DCBE) for evaluation of the non visualized part of the colon after incomplete colonoscopy.