DT-MIL: Deformable Transformer for Multi-instance Learning on Histopathological Image

Learning informative representations is crucial for classification and prediction tasks on histopathological images. Due to the huge image size, whole-slide histopathological image analysis is normally addressed with multi-instance learning (MIL) scheme. However, the weakly supervised nature of MIL leads to the challenge of learning an effective whole-slide-level representation. To tackle this issue, we present a novel embedded-space MIL model based on deformable transformer (DT) architecture and convolutional layers, which is termed DT-MIL. The DT architecture enables our MIL model to update each instance feature by globally aggregating instance features in a bag simultaneously and encoding the position context information of instances during bag representation learning. Compared with other state-of-the-art MIL models, our model has the following advantages: (1) generating the bag representation in a fully trainable way, (2) representing the bag with a high-level and nonlinear combination of all instances instead of fixed pooling-based methods (e.g. max pooling and average pooling) or simply attention-based linear aggregation, and (3) encoding the position relationship and context information during bag embedding phase. Besides our proposed DT-MIL, we also develop other possible transformer-based MILs for comparison. Extensive experiments show that our DT-MIL outperforms the state-of-the-art methods and other transformer-based MIL architectures in histopathological image classification and prediction tasks. An open-source implementation of our approach can be found at https://github.com/yfzon/DT-MIL.