CT colonography with computer-aided detection: Automated recognition of ileocecal valve to reduce number of false-positive detections

The ileocecal valve (ICV) is a common cause of false-positive detections of polyps at computed tomographic (CT) colonography with computer-aided detection (CAD). The authors developed a CAD algorithm for differentiating, the' ICV from a true polyp and evaluated this algorithm by using two colonoscopy-confirm ed CF colonography data sets. Data sets 1 and 2 consisted of the data obtained at CT colonographic examinations performed in 20 -and 40 patients, respectively. Forty of these patients had at least one polyp 1 cm or larger. For data set 1, the proposed ICV recognition algorithm eliminated three of nine (33%; 95% confidence interval [CI]: 8%, 70%) false-positive CAD detections that were attributable to the ICV and none of the true-positive polyp detections. For data set 2, with use of identical parameters, the algorithm eliminated 11 of 18 (610/6; 95% CI: 36%, 83%) falsepositive detections that were attributable to the ICV and none of the truepositive detections. The thresholds used -to recognize the lCV were a mean internal Uattenuation of less than - 124 HU and a volume of greater than 1.5 cm(2). The proposed algorithm successfully recognized the lCV and eliminated it in some cases. This result is clinically important because, by reducing the frequency of a common cause of false-positive'detections, this algorithm may improve the efficiency of physicians who use CAD. (C) RSNA, 2004.