FS-DANet: Dual-Domain Signal Enhancement and Dynamic Spatial Calibration for Gastric Ultrasound Artifact Mitigation

Accurate automatic segmentation of gastric cancer in ultrasound images is crucial for early diagnosis and treatment. However, this task remains challenging due to severe speckle noise, tissue deformation, and the high computational cost of fully supervised models in real-time clinical workflows. While few-shot reference-guided methods offer an efficient alternative, they often struggle with cross-frame feature alignment under low-quality ultrasound signals. To overcome these limitations, we propose FS-DANet, a Frequency-Spatial Dual-domain Awareness and Dynamic Adaptation Network. FS-DANet first adopts a Dual-Frequency Disentangled Block (DFDB) to explicitly separate stochastic noise from anatomical structures in the frequency domain. A Mask-Guided Feature Calibration (MGFC) module is then introduced to suppress background artifacts and establish precise cross-frame correspondences using the support mask as an anchor. Furthermore, an Iterative Deformable Adaptation (IDA) decoder is employed to progressively reconstruct irregular lesion boundaries at the pixel level. Extensive experiments on a proprietary Gastric Cancer Ultrasound (GCUI) dataset and the public BUSI dataset demonstrate that FS-DANet consistently achieves superior performance over state-of-the-art reference-guided methods. In particular, it obtains Dice coefficients of 75.41% and 74.19% on the GCUI and BUSI datasets, respectively, even surpassing fully supervised baselines under a single-reference setting. These findings suggest that FS-DANet can substantially improve segmentation accuracy in complex ultrasound environments and holds strong potential for clinical application in personalized diagnosis.