Effect of CAD on radiologists' responses in distinction between malignant and benign pulmonary nodules on high-resolution CT

We carried out an observer performance study for evaluating the performance of 16 radiologists without and with a computer-aided diagnostic (CAD) scheme for determination of the likelihood of malignancy of lung nodules on HRCT in a database of 28 primary lung cancers and 28 benign nodules. The results of our observer study showed that radiologists' performance was improved with the CAD scheme, and their performance with the CAD scheme was greater than either radiologists alone or computer alone. Our purpose in this study was to analyze radiologists' responses with the CAD scheme in their task of differentiation between malignant and benign nodules on HRCT. Our results indicated that the average change in radiologists' ratings (difference between radiologists' ratings with the CAD scheme and radiologists' initial ratings) was strongly related to (A) the likelihood of malignancy (the computer output) and also (B) the difference of their initial ratings from the computer outputs, where the correlation coefficients were 0.93 and 0.90, respectively. Our detailed analysis showed that radiologists changed the majority of their ratings in agreement with the computer results, and the majority of these changes contributed to the improvement in their performance. They were able to maintain some of their correct ratings despite incorrect computer results. For some cases, they increased their confidence in their judgments above the computer output. Thus, the improvement in radiologists' performance above the computer performance was produced by the synergistic effect of the radiologists' decision making and the computer outputs.