OBJECTIVE. The objective of our study was to investigate whether an increasing num�ber of computer-aided detection (CAD) false-positives decreases reader sensitivity, specific�ity, and confidence for nonexpert readers of CT colonography (CTC).
MATERIALS AND METHODS. Fifty CTC data sets (29 men; mean age, 65 years), 25 of which contained 35 polyps > 5 mm, were selected in which CAD had 100% polyp sen�sitivity at two sphericity settings (0 and 75) but differed in the number of false-positives. The data sets were read by five readers twice: once at each sphericity setting. Sensitivity, speci�ficity, report time, and confidence before and after second-read CAD were compared using the paired exact and Students / test, respectively. Receiver operating characteristic (ROC) curves were generated using reader confidence (1-100) in correct case classification (normal or abnormal).
RESULTS. CAD generated a mean of 42 (range, 3-118) and 15 (range, 1-36) false-posi�tives at a sphericity of 0 and 75, respectively. CAD at both settings increased per-patient sen�sitivity from 82% to 87% (p = 0.03) and per-polyp sensitivity by 8% and 10% for a sphericity of 0 and 75, respectively (p
CONCLUSION. CAD has the potential to increase the sensitivity of readers inexperi�enced with CTC, although specificity may be reduced. An increased number of CAD-gener-ated false-positives does not negate any beneficial effect but does reduce efficiency.