Figure 4

Class activation mapping of four cardiac diseases. (a) Class activation maps are generated by mapping back to the previous convolutional layer and the calculation formula listed on the right. (b–e) Examples of class activation mapping localized the lesion region of ASD in (b), DCM in (c), HCM in (d), and prior MI in (e), respectively. The heatmaps of each second row from (b–e) represented the regions of interest (ROI) automatically identified by class activation mapping.