Fig. 4

Heatmaps for cardiac pathology assessment on PSIR images. A, B: Subject without cardiac pathology. A shows the late gadolinium phase sensitive inversion recovery (PSIR) image. B shows a heatmap generated by overlaying a gradient-weighted class activation map (Grad-CAM) with the PSIR image. Red indicates higher activation, and blue indicates lower activation. The heatmap shows that the model mainly focused on the myocardial septum for its decision. This was classified by the deep learning model as normal with 86% certainty. C, D: Subject with chronic myocardial infarction. C shows the late gadolinium phase sensitive inversion recovery (PSIR) image. D shows a heatmap generated by overlaying a gradient-weighted class activation map (Grad-CAM) with the PSIR image. Red indicates higher activation, and blue indicates lower activation. The heatmap shows that the model mainly focused on the myocardium of the left ventricle, exhibiting wall thinning and an increase in signal intensity. The deep learning model diagnosed a cardiac pathology with 99% certainty