Comparison assessment of virtual colonoscopy and conventional colonoscopy

Background: CT colonoscopy is a rapidly spreading method for the evaluation of colonic disorders. This diagnostic method is able to detect colorectal cancer and adenomas with 82–87% sensitivity and 92–94% specificity.

Aims: To compare the diagnostic value of virtual endoscopy with a new autodissection program and conventional colonoscopy.

Patients and Methods: 554 patients with abdominal pain and a history of colorectal cancer were studied during a 5 years period (401 women, 153 men, age 55±37 years) before conventional colonoscopy. During the evaluation the colon was divided into 6 segments (sigmoid colon, descending colon, splenic flexure, transverse colon, hepatic flexure, ascending colon with the cecum). Segments seen by both method were compared. CT colonoscopy was performed with a 64 slice multislice instrument (General Electric, USA) with low dose values. For the optimal distension of the colon supine and prone positions were both applied. The radiologist was blinded to the colonoscopic results.

Results: One thousand one hundred and fifty-three colonic segments were evaluated. One hundred and thirty-five pathologic findings were detected. These included 35 tumors, 82 polyps, 29 strictures and 125 diverticula. For the detection of colonic polyps larger than 5mm, the sensitivity, the specificity, the positive and negative predictive values of virtual colonoscopy were 80.5, 99, 89, and 99 percent respectively. For the detection of diverticula these were 95.2, 98.2, 73, and 93 percent. All tumors and strictures were detected.

Conclusion: The evaluation of the colon by autodissection programme assisted virtual colonoscopy can be quickly performed. In addition it was able to improve specificity and sensitivity of the method.