Hierarchical Compositionality in Hyperbolic Space for Robust Medical Image Segmentation

Ainkaran Santhirasekaram, Mathias Winkler, Andrea G. Rockall, Ben Glocker

Abstract: Deep learning based medical image segmentation models need to be robust to domain shifts and image distortion for the safe translation of these models into clinical practice. The most popular methods for improving robustness are centred around data augmentation and adversarial training. Many image segmentation tasks exhibit regular structures with only limited variability. We aim to exploit this notion by learning a set of base components in the latent space whose composition can account for the entire structural variability of a specific segmentation task. We enforce a hierarchical prior in the composition of the base components and consider the natural geometry in which to build our hierarchy. Specifically, we embed the base components on a hyperbolic manifold which we claim leads to a more natural composition. We demonstrate that our method improves model robustness under various perturbations and in the task of single domain generalisation.