Comparısion of multı-slice computed tomografic colonography and conventional colonoscopy ın detection of colorectal polyps and masses

Colorectal cancers are the 3rd most common type of cancer and 2nd leading cause of cancer death in the United States. Colorectal cancer screening, detects colorectal cancers at an earlier stage, reduces colorectal cancer mortality. Although a variety of colon screening tests such as fecal occult blood testing, double-contrast barium enema, sigmoidoscopy, colonoscopy are available, none is ideal and also they are expensive, invasive and not easily tolerable techniques. Virtual colonoscopy and computed tomographic colonography are promising to be the primary, non-invasive method of screening of colorectal cancers. The aim of our study is determine the diagnostic efficiency, advantage and disadvantage of virtual colonoscopy in detection of colorectal pathologies.The accuracy of MDCT colonography depends on; good colon cleaning and distention, well-known variations of the colon and the normal anatomic structure, the prone and supine positions, with thin-slice MDCT imaging the evaluation of the combined 2D and 3D images. In our study sixty four patients who underwent MDCT colonography (virtual colonography) and video colonoscopies between October 2010 and September 2011 were evaluated retrospectively. 8 patients were excluded because of not enough colon cleaning and distention.Video colonoscopy, 24 were applied to 56 patients (42.8%) as normal evaluated, in 32 patients (57.2%) 59 pathology was detected. The distribution of these pathologies; 36 polyps, 14 tumoral lesions, 4 cases nodular mucosa irregularities, reduction of haustral patterns, psödopolipoid formations in mucosa, 3 diverticulosis colli and 2 fistula pathology was found to be a total of 59.36 polyps were identified in Video colonoscopy. 25 of these 36 polyps were correctly identified with MDCT colonography (69.4%). All of 6 polyps which are 10 mm and larger (100%), 4 of 5 polyps which are between 6-9 mm (80%), 15 of 25 polyps which are 1-5 mm (60%) were identified correctly with MDCT colonography.CT colonography specificity of on 10 mm and larger polyps were found 100%, on polyps between 6-9 mm were found 100% and polyps under 5 mm were found 89%. Polyps under 5 mm positive predictive value were found 83%, in other polyps were found 100%.Polyps 5 mm and under, negative predictive value were found 70,5%, on polyps between 6-9 mm were found 96%, on 10 mm and larger polyps were found 100%. As a result; multi-slice CT colonography study might be a good alternative to other existing colorectal cancer screening tests because of; the High sensitivity on polyps larger than 10 mm, relatively safe and minimally invasive.