Train-Free Segmentation in MRI with Cubical Persistent Homology
Anton François, Raphaël Tinarrage
TL;DR
This work tackles MRI segmentation without training data by leveraging cubical persistent homology. A three-module pipeline localizes the whole object, identifies a geometrically distinctive subset via persistent cycles, and deduces remaining components, enabling interpretable segmentations in glioblastoma, cardiac, and fetal cortical plate cases. Results show competitive performance with unsupervised baselines in some tasks and highlight limitations when topological assumptions fail, while offering clear avenues for integration with deep learning. The approach promises applicability in scarce-data settings and provides topological guarantees and explainability for clinical use.
Abstract
We present a new general framework for segmentation of MRI scans based on Topological Data Analysis (TDA), offering several advantages over traditional machine learning approaches. The pipeline proceeds in three steps, first identifying the whole object to segment via automatic thresholding, then detecting a distinctive subset whose topology is known in advance, and finally deducing the various components of the segmentation. Unlike most prior TDA uses in medical image segmentation, which are typically embedded within deep networks, our approach is a standalone method tailored to MRI. A key ingredient is the localization of representative cycles from the persistence diagram, which enables interpretable mappings from topological features to anatomical components. In particular, the method offers the ability to perform segmentation without the need for large annotated datasets. Its modular design makes it adaptable to a wide range of data segmentation challenges. We validate the framework on three applications: glioblastoma segmentation in brain MRI, where a sphere is to be detected; myocardium in cardiac MRI, forming a cylinder; and cortical plate detection in fetal brain MRI, whose 2D slices are circles. We compare our method with established supervised and unsupervised baselines.
