Conventional colonoscopy is the best available method for detection of colorectal cancer and its precursors. However, it is invasive and not without risk.
Computed tomographic colonography (CTC), or "virtual colonoscopy", has been reported to be reasonably accurate in the diagnosis of colorectal tumors in studies performed at expert centers.
CTC involves the examination of computer-generated images of the colon constructed from data obtained from an abdominal computed tomographic examination.
|The accuracy of computed tomographic colonography varied considerably between centers.|
|Journal of the American Medical Association|
In this study, Dr Peter Cotton of the Medical University of South Carolina, Charleston, and colleagues assessed the accuracy of CTC in a large number of participants from multiple centers.
They included 615 patients aged 50 years or older who were referred for routine, clinically indicated colonoscopy at 9 major hospital centers between 2000 and 2001.
The CTC was performed before the standard colonoscopy and results were compared.
The researchers found that the sensitivity of CTC for detecting participants with one or more lesions ≥ 6 mm was 39% and for lesions ≥ 10 mm it was 55%.
These results were significantly lower than those for conventional colonoscopy, which has sensitivities of 99% and 100%, respectively.
The accuracy of CTC varied considerably between centers and did not improve as the study progressed.
Dr Cotton's team concluded, "Our results indicate that CTC using these techniques is not ready for routine use at this time, as many others have concluded".
"There is an obvious need for continuing collaboration between radiologists and gastroenterologists in further evaluation of this exciting new technology".
"If and when results do justify widespread introduction, similar multidisciplinary collaboration will be needed to ensure its efficient application".
In an accompanying editorial, Dr David Ransohoff, of the University of North Carolina, Chapel Hill, writes, "The biggest near-term problem for virtual colonoscopy is that it may be implemented too widely without sufficient regard for current technological problems that affect sensitivity".
"The level of sensitivity and specificity that virtual colonoscopy can achieve, in some specialized situations, is known".
"Yet the differences between what virtual colonoscopy can do and what it will do if applied in ordinary practice circumstances are so great that physicians must be cautious".
"There are many important steps yet to be taken in learning how to implement this new technology appropriately."