Sparse Coding Inspired LSTM and Self-Attention Integration for Medical Image Segmentation

Accurate and automatic segmentation of medical images plays an essential role in clinical diagnosis and analysis. It has been established that integrating contextual relationships substantially enhances the representational ability of neural networks. Conventionally, Long Short-Term Memory (LSTM) and Self-Attention (SA) mechanisms have been recognized for their proficiency in capturing global dependencies within data. However, these mechanisms have typically been viewed as distinct modules without a direct linkage. This paper presents the integration of LSTM design with SA sparse coding as a key innovation. It uses linear combinations of LSTM states for SA's query, key, and value (QKV) matrices to leverage LSTM's capability for state compression and historical data retention. This approach aims to rectify the shortcomings of conventional sparse coding methods that overlook temporal information, thereby enhancing SA's ability to do sparse coding and capture global dependencies. Building upon this premise, we introduce two innovative modules that weave the SA matrix into the LSTM state design in distinct manners, enabling LSTM to more adeptly model global dependencies and meld seamlessly with SA without accruing extra computational demands. Both modules are separately embedded into the U-shaped convolutional neural network architecture for handling both 2D and 3D medical images. Experimental evaluations on downstream medical image segmentation tasks reveal that our proposed modules not only excel on four extensively utilized datasets across various baselines but also enhance prediction accuracy, even on baselines that have already incorporated contextual modules. Code is available at https://github.com/yeshunlong/SALSTM.