Accuracy
The ROC area was greater for mammography plus AWBU for both BIRADS (0.808 versus 0.701; F(1, 123) = 14.79, p < 0.001) and likelihood scores (0.810 versus 0.703; F(1, 85) = 17.88, p < 0.001) as estimated by multi-reader multi-case analyses. This is highlighted in Fig. 1 by ROC curves that are generated by averaging the results of separate ROC analyses for each reader. The BIRADS and likelihood AUC curves for mammography and mammography plus AWBU in both cases almost superimpose when confidence in malignancy by mammography is high, but when confidence in malignancy by mammography is low, as in the lower portions of the graphs, the curves in both cases diverge significantly. In both cases the mammography plus AWBU approaches the y-axis indicating better cancer recognition.
Fig. 1 Receiver operating characteristic curves averaged across 12 readers for mammography alone (circles and dashed line) and mammography plus AWBU (triangles and solid line)
Figure 2 shows the areas under the ROC curves for each reader and for the average of all readers as estimated by multi-reader multi-case analyses. These individual line graphs mirror the improvement in reader performance shown in Table 2.
Fig. 2 Changes in areas under the receiver operating characteristic curve(s) for each reader (hollow circles) and averaged across 12 readers (solid circles)
Similar to ROC areas, the figures of merit (FOM) were higher for mammography plus AWBU across all readers, compared with mammography alone using both the BIRADS scores (0.786 versus 0.613; F(1, 270) = 34.1, p < 0.001) and DMIST likelihood scores (0.791 versus 0.614; F(1, 238) = 37.9, p < 0.001) as accuracy indices.