With regard to CT colonography (CTC) for detection of colorectal polyps and neoplasms, the ICSI Technology Assessment Committee finds:
CTC is a safe procedure with minor side effects reported. The use of an intravenous contrast agent would potentially increase the morbidity and/or mortality.
To date, there are no data on the value of CTC in a screening population and CTC should not be considered as a screening tool. However, based on the performance of CTC in high-risk patients, CTC is potentially useful for patients who are unwilling to undergo conventional colonoscopy or other procedures, who have failed conventional colonoscopy (incomplete examination of colon), or who cannot be sedated.
CTC studies (after full bowel preparation) of patients who are either at high risk for colorectal cancer or who are symptomatic have yielded sensitivity values of 38% to 96% and specificity values of 63% to 100% with conventional colonoscopy as the gold standard. Higher sensitivity and specificity values have been reported for larger lesions (>=10 mm) (Conclusion Grade II). The proficiency of the persons reading the CTC images also influences the findings.
For patients with symptoms, CTC appears to be superior, in terms of detection of colorectal polyps and neoplasms, to no examination or a fecal occult blood test and comparable to a flexible sigmoidoscopy examination. Unless a colonoscopy can be done on the same day as CTC, a second bowel preparation would be required to obtain tissue samples from lesions identified on CTC.
With the present data acquisition and interpretation protocols, CTC is not as sensitive or specific as conventional colonoscopy.