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A Graph-Based Multi-Scale Approach with Knowledge Distillation for WSI Classification

Abstract: The usage of Multi Instance Learning (MIL) for classifying Whole Slide Images (WSIs) has recently increased. Due to their gigapixel size, the pixel-level annotation of such data is extremely expensive and time-consuming, practically unfeasible. For this reason, multiple automatic approaches have been raised in the last years to support clinical practice and diagnosis. Unfortunately, most state-of-the-art proposals apply attention mechanisms without considering the spatial instance correlation and usually work on a single-scale resolution. To leverage the full potential of pyramidal structured WSI, we propose a graph-based multi-scale MIL approach, DAS-MIL. Our model comprises three modules: i) a self-supervised feature extractor, ii) a graph-based architecture that precedes the MIL mechanism and aims at creating a more contextualized representation of the WSI structure by considering the mutual (spatial) instance correlation both inter and intra-scale. Finally, iii) a (self) distillation loss between resolutions is introduced to compensate for their informative gap and significantly improve the final prediction. The effectiveness of the proposed framework is demonstrated on two well-known datasets, where we outperform SOTA on WSI classification, gaining a +2.7% AUC and +3.7% accuracy on the popular Camelyon16 benchmark.


Bontempo, Gianpaolo; Bolelli, Federico; Porrello, Angelo; Calderara, Simone; Ficarra, Elisa "A Graph-Based Multi-Scale Approach with Knowledge Distillation for WSI Classification" IEEE TRANSACTIONS ON MEDICAL IMAGING, pp. 1 -10 , 2024 DOI: 10.1109/TMI.2023.3337549

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