TvaraNet: A Lightweight Mamba Neural Network for Real-Time Medical Image Segmentation

Abstract

Medical image segmentation models based on vision mamba architectures have recently shown strong performance with improved efficiency over convolutional and transformer-based models. However, existing lightweight and ultralight variants often suffer from boundary degradation and inconsistent shape prediction, thereby limiting their clinical reliability. We propose TvaraNet, an extremely lightweight segmentation network designed to preserve boundary fidelity under strict efficiency constraints. TvaraNet contains only 0.037M parameters and requires only 0.060 GFLOPs, enabling deployment in resource-constrained environments. The architecture introduces two core lightweight modules. Parallel Skip Mamba Averaging (PASMA) enhances long-range dependency modeling by injecting globally aggregated channel context into Mamba blocks. Dilated Asymmetric Spatial Mixer Attention (DASMA) improves boundary-aware feature refinement in skip connections through efficient multi-scale spatial modulation. In addition, training-time regularization strategies, including an Adaptive Gated Gradient Reversal Layer (AGGRL), an adaptive Singular Value Decomposition (SVD) loss, and a Boundary-weighted Cross-Entropy loss (BWCE), are employed to suppress redundant features and emphasize object boundaries without adding inference overhead. Experiments on ISIC-17, ISIC-18, and a spinal segmentation dataset demonstrate that TvaraNet consistently outperforms existing lightweight models and achieves competitive or superior boundary-aware performance compared to heavier architectures. Notably, it improves mean IoU by +1.50, +1.42, and +3.35 over Ultralight VMUNet on the respective datasets, establishing TvaraNet as a practical solution for boundary-consistent medical image segmentation on edge and low-resource platforms. Code is available at: \url{https://github.com/MindsLab-GitHub/TvaraNet}