CT COLONOGRAPHY WITH 3-DIMENSIONAL PROBLEM-SOLVING FOR DETECTION OF COLONIC POLYPS

OBJECTIVE. We performed CT colonography in patients referred for conve ntional colonoscopy, interpreted the axial images, and used commercial ly available software to reconstruct endoluminal perspective views to differentiate polyps from folds. SUBJECTS AND METHODS. We prospectivel y examined 44 patients (27 men and 17 women; mean age, 58 years old) w ith CT colonography by interpreting the axial images and using three-d imensional rendering for problem solving only. The CT scans were inter preted by two radiologists who were unaware of patients' histories as revealed by colonoscopic findings. The findings on colonography were c ompared with those of conventional colonoscopy to determine sensitivit y specificity, time spent on interpretation, and confidence of interpr etation. RESULTS. Colonoscopy showed normal findings in 28 patients an d 22 polyps in the remaining 16 patients. Six polyps were 8 mm or larg er, three were 5-7 mm, and 13 were 5 mm or smaller. The findings of th e two observers revealed an overall sensitivity of 50% and 38%, respec tively, and a specificity of 93% and 86%, respectively. Sensitivity fo r polyps larger than 8 mm was 83% and specificity was 100% for both ob servers. The average amount of time spent on interpretation was 28 min 30 sec (range, 14-65 min). Both observers used the endoluminal view f or differentiating folds from polyps in 23 (52%) of 44 patients, which had only minimal impact on interpretation time. CONCLUSION. CT colono graphy can be performed and the images interpreted using currently ava ilable hardware and software by initially using the axial images to se arch for polyps of significant size. Endoluminal views should be used only when necessary to help distinguish normal folds from fixed raised lesions that are suggestive of polyps.