Computed tomographic colonography and conventional colonoscopy for colon diseases: a prospective, blinded study.
OBJECTIVE
Computed tomographic (CT) colonography or virtual colonoscopy is a new diagnostic method for the colon and rectum, developed on the basis of spiral computed axial tomography and employing virtual reality technology. The aim of this study was to determine the sensitivity, specificity, and diagnostic accuracy of CT colonography compared with colonoscopy in a prospective, blinded study in one single institution in Italy.


METHODS
Ninety-nine patients randomly selected among those attending the open-access endoscopy unit for diagnostic colonoscopy underwent colonoscopy and spiral CT. The images obtained were transmitted to generate the virtual colonoscopy pictures. A supervisor compared the results with the findings of conventional colonoscopy.


RESULTS
CT colonography diagnosed seven of eight tumors, one being missed because the patient had been inadequately prepared. In 28 patients, CT colonography identified 26 polyps of 45 (57.8% sensitivity, 92.6% specificity, 86.7% positive predictive value), regardless of their size. The sensitivity in detecting colonic polyps was 31.8% (7/22) in the first 25 cases and 91.6% (11/12) in the last 20 patients. CT colonography missed one flat adenoma, some angioectasias and colonic lesions because of portal hypertension in one patient, Crohn's disease ulcers in two patients, and ulcerative colitis lesions in three.


CONCLUSIONS
CT colonography shows poor sensitivity for identifying colonic polyps and does not always detect neoplastic lesions. Flat lesions are impossible to see by this method.
Department of Internal Medicine, H. Valduce-Como, Italy.
G
G
Spinzi
G
G
Belloni
A
A
Martegani
A
A
Sangiovanni
C
C
Del Favero
G
G
Minoli
D003108:Colonic Diseases / Q000175:diagnosis* / Q000453:epidemiology; D003110:Colonic Neoplasms / Q000175:diagnosis / Q000453:epidemiology; D003111:Colonic Polyps / Q000175:diagnosis / Q000453:epidemiology; D003113:Colonoscopy; D006801:Humans; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011897:Random Allocation; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014584:User-Computer Interface