The Effects of the Computer-Aided Diagnostic System on the Diagnostic Performance

点击翻译按钮获取中文摘要

As the baseline study for studying the effects of computer-aided diagnosis (CAD) on diagnostic performance, we have investigated how to superimpose the simulated nodule on plain chest X-ray images and on chest CT images. Based on these studies, we have developed the tool for digitally superimposing the simulated nodules, and have empirically derived the method to get the images with the superimposed nodules.To evaluate the effects of CAD output as a "second opinion" on detection performance, we have made the 5 plain chest X-ray images including from 15 to 19 superimposed nodules per one image. For these 5 images, we have applied the experimental CAD system, and we have got the CAD outputs. From these CAD outputs, we have made the simulated CAD outputs with a sensitivity of 47.6% and a specificity of 87.2% ; that sensitivity and specificity were calculated for the square fields on the chest X-ray images.Two radiologists read the 5 chest X-ray soft-copy images with the CAD outputs and without them, and reported their probability judgments regarding the presence of nodules in the square fields on the chest X-ray images. The diagnostic performance was evaluated with receiver operating characteristic (ROC) analysis and the Brier score. The conclusion was the following : 1) The probability regarding the presence of nodules increased both for the true positive cases and for the false positive cases. Therefore, from the ROC analysis, the diagnostic performance with the aid of CAD outputs were the same as that without it. 2) According to the Brier scores, the diagnostic performance with the aid of CAD outputs were better than that without it ; however, this difference was not statistically significant.Further, we have also studied the resampling method and the evaluation method of diagnostic performance by using the ROC analysis and the Brier score.