Virtual vs. optical colonoscopy in symptomatic gastroenterology out-patients: the case for virtual imaging followed by targeted diagnostic or therapeutic colonoscopy.

AIM To compare virtual colonoscopy with optical colonoscopy findings in symptomatic patients. BACKGROUND Computer tomographic colonography is an alternative to optical colonoscopy. Studies have shown that two-dimensional computer tomographic colonography does not have sufficient sensitivity. Three-dimensional computerized tomographic virtual colonoscopy compares well with optical colonoscopy for colorectal neoplasia screening in asymptomatic individuals. METHODS One hundred patients aged 50 and older underwent same day virtual colonoscopy and optical colonoscopy. The endoscopists were unaware of the radiologist's report until the withdrawal phase of the endoscopy when segmental unblinding occurred. The virtual colonoscopy and optical colonoscopy findings were compared by using the unblinded optical colonoscopy as the reference standard. RESULTS Pancolonic endoluminal virtual colonoscopy was achieved in 99 patients. Optical colonoscopy caecal intubation occurred in 91 patients. Direct comparison was possible in 90 patients. Both techniques revealed the three cancers detected. Virtual colonoscopy revealed 11 polyps > or = 6 mm diameter in nine patients. Optical colonoscopy revealed 10 polyps > or = 6 mm diameter in nine patients with a further 15-mm polyp discovered after segmental unblinding. CONCLUSION In symptomatic patients, three-dimensional virtual colonoscopy is equivalent to optical colonoscopy for diagnosing colon cancer and clinically significant polyps. A case can be made for three-dimensional virtual colonoscopy as a primary modality followed if necessary by same day-targeted optical colonoscopy.