Using StyleGAN for Visual Interpretability of Deep Learning Models on Medical Images

TL;DR

This paper introduces a novel interpretability method using StyleGAN to generate synthetic image variations in the latent space, providing more insightful explanations of model predictions for medical images than traditional heatmaps.

Contribution

The paper presents a new approach that leverages StyleGAN's latent space to interpret deep learning models on medical images by showing how input modifications affect predictions.

Findings

Method produces more informative explanations than GradCAM.

Enables discovery of new biomarkers and model biases.

Validates approach on histology and radiology images.

Abstract

As AI-based medical devices are becoming more common in imaging fields like radiology and histology, interpretability of the underlying predictive models is crucial to expand their use in clinical practice. Existing heatmap-based interpretability methods such as GradCAM only highlight the location of predictive features but do not explain how they contribute to the prediction. In this paper, we propose a new interpretability method that can be used to understand the predictions of any black-box model on images, by showing how the input image would be modified in order to produce different predictions. A StyleGAN is trained on medical images to provide a mapping between latent vectors and images. Our method identifies the optimal direction in the latent space to create a change in the model prediction. By shifting the latent representation of an input image along this direction, we can produce a series of new synthetic images with changed predictions. We validate our approach on histology and radiology images, and demonstrate its ability to provide meaningful explanations that are more informative than GradCAM heatmaps. Our method reveals the patterns learned by the model, which allows clinicians to build trust in the model's predictions, discover new biomarkers and eventually reveal potential biases.