Figure 7. In bar graph, each pair of bars depicts the mean Az value and mean best classification accuracy achieved with a proposed morphologic feature when applied to four collections of lesion boundaries. Each collection comprised one of the four sets of lesion boundaries in the first set of US images and the lesion boundaries in the second set of US images. Error bars indicate 1 SD. At the 5% significance level, the first four features (ie, NSPD, LI, ENS, and ENC) are better than the other three. Moreover, the performances of NSPD, LI, and ENC are the same with the first set of US images and with all 271 images.