Abstract
Neural network-based classification methods are often criticized for their lack of interpretability and explainability. By highlighting the regions of the input image that contribute the most to the decision, saliency maps have become a popular method to make neural networks interpretable. In medical imaging, they are particularly well-suited for explaining neural networks in the context of abnormality localization. Nevertheless, they seem less suitable for classification problems in which the features that allow distinguishing classes are spatially correlated and scattered. We propose here a novel paradigm based on Disentangled Variational Auto-Encoders. Instead of seeking to understand what the neural network has learned or how prediction is done, we seek to reveal class differences. This is achieved by transforming the sample from a given class into the “same” sample but belonging to another class, thus paving the way to easier interpretation of class differences. Our experiments in the context of automatic sex determination from hip bones show that the obtained results are consistent with expert knowledge. Moreover, the proposed approach enables us to confirm or question the choice of the classifier or eventually to doubt it.