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ProtoDiv: Prototype-guided Division of Consistent Pseudo-bags for Whole-slide Image Classification

Rui Yang, Pei Liu, Luping Ji

TL;DR

ProtoDiv tackles the data scarcity and weak labeling challenge in whole-slide image (WSI) classification by augmenting training data with pseudo-bags that are guided by bag prototypes. It introduces mean-based and attention-based prototypes to produce a cosine-distance–driven partitioning of patch features, yielding phenotype-diverse yet representative pseudo-bags that preserve the parent bag distribution. The approach is designed as a plug-and-play augmentation for existing MIL methods and demonstrates consistent AUC gains across seven baselines on TCGA-Lung and TCGA-BRCA, with efficient division times and intuitive visualizations of prototype separation. Overall, ProtoDiv enhances generalization in WSI MIL by maintaining phenotype consistency while safely increasing data size through adaptive pseudo-bag generation.

Abstract

Due to the limitations of inadequate Whole-Slide Image (WSI) samples with weak labels, pseudo-bag-based multiple instance learning (MIL) appears as a vibrant prospect in WSI classification. However, the pseudo-bag dividing scheme, often crucial for classification performance, is still an open topic worth exploring. Therefore, this paper proposes a novel scheme, ProtoDiv, using a bag prototype to guide the division of WSI pseudo-bags. Rather than designing complex network architecture, this scheme takes a plugin-and-play approach to safely augment WSI data for effective training while preserving sample consistency. Furthermore, we specially devise an attention-based prototype that could be optimized dynamically in training to adapt to a classification task. We apply our ProtoDiv scheme on seven baseline models, and then carry out a group of comparison experiments on two public WSI datasets. Experiments confirm our ProtoDiv could usually bring obvious performance improvements to WSI classification.

ProtoDiv: Prototype-guided Division of Consistent Pseudo-bags for Whole-slide Image Classification

TL;DR

ProtoDiv tackles the data scarcity and weak labeling challenge in whole-slide image (WSI) classification by augmenting training data with pseudo-bags that are guided by bag prototypes. It introduces mean-based and attention-based prototypes to produce a cosine-distance–driven partitioning of patch features, yielding phenotype-diverse yet representative pseudo-bags that preserve the parent bag distribution. The approach is designed as a plug-and-play augmentation for existing MIL methods and demonstrates consistent AUC gains across seven baselines on TCGA-Lung and TCGA-BRCA, with efficient division times and intuitive visualizations of prototype separation. Overall, ProtoDiv enhances generalization in WSI MIL by maintaining phenotype consistency while safely increasing data size through adaptive pseudo-bag generation.

Abstract

Due to the limitations of inadequate Whole-Slide Image (WSI) samples with weak labels, pseudo-bag-based multiple instance learning (MIL) appears as a vibrant prospect in WSI classification. However, the pseudo-bag dividing scheme, often crucial for classification performance, is still an open topic worth exploring. Therefore, this paper proposes a novel scheme, ProtoDiv, using a bag prototype to guide the division of WSI pseudo-bags. Rather than designing complex network architecture, this scheme takes a plugin-and-play approach to safely augment WSI data for effective training while preserving sample consistency. Furthermore, we specially devise an attention-based prototype that could be optimized dynamically in training to adapt to a classification task. We apply our ProtoDiv scheme on seven baseline models, and then carry out a group of comparison experiments on two public WSI datasets. Experiments confirm our ProtoDiv could usually bring obvious performance improvements to WSI classification.
Paper Structure (16 sections, 5 equations, 5 figures, 3 tables)

This paper contains 16 sections, 5 equations, 5 figures, 3 tables.

Figures (5)

  • Figure 1: An overview of ProtoDiv. One WSI is used as an example to explain how our ProtoDiv works in MIL framework: extract patch features, calculate bag prototype, divide bag into pseudo-bags for training, and aggregate to get a final prediction.
  • Figure 2: Visualization of the attention prototypes in TCGA-BRCA (left) and TCGA-Lung (right) test set by using t-SNE vandermaaten08a. ABMIL is adopted as the baseline model.
  • Figure 3: Visualization of the phenotype and pseudo-bag generated by our ProtoDiv. (a) is the original WSI. (b) shows the cluster prototypes via ProtoDiv. (c) gives the pseudo-bags generated via ProtoDiv. Each color indicates one specific phenotype or pseudo-bag in (b) and (c). More results are shown in our supplementary material.
  • Figure 4: All phenotypes and their respective patches, as a supplement to the Figure 3 in our main context. Patches are clustered into different tissue phenotypes for subsequent pseudo-bag generation.
  • Figure 5: Visualization of the phenotype and pseudo-bag generated by our ProtoDiv. (a) is the original WSI. (b) shows the cluster prototypes via ProtoDiv. (c) gives the pseudo-bags generated via ProtoDiv. Each color indicates one specific phenotype or pseudo-bag in (b) and (c), respectively. The patches of three selected phenotypes are also shown at the bottom of each row.