Accurate anomaly detection in brain MRI is crucial for early diagnosis of neurological disorders, yet remains a significant challenge due to the high heterogeneity of brain abnormalities and the scarcity of annotated data. Traditional one-class classification models require extensive training on normal samples, limiting their adaptability to diverse clinical cases. In this work, we introduce MadIRC, an unsupervised anomaly detection framework that leverages Inter-Realization Channels (IRC) to construct a robust nominal model without any reliance on labeled data. We extensively evaluate MadIRC on brain MRI
as the primary application domain, achieving a localization AUROC of 0.96 outperforming state-of-the-art supervised anomaly detection methods. Additionally, we further validate our approach on liverCT and retinal images to assess its generalizability across medical imaging modalities. Our results demonstrate that MadIRC provides a scalable, label-free solution for brain MRI anomaly detection, offering a promising avenue for integration into real-world clinical workflows.
