BGS-Diff: Boundary-guided and scale-aware diffusion model for medical image synthesis
摘要
Medical imaging is essential for clinical diagnosis and biomedical research. However, data scarcity arising from privacy and security constraints limits downstream imaging tasks. Existing synthesis methods often suffer from blurred structures or unrealistic textures, primarily due to their limited ability to preserve anatomical boundaries and integrate multi-scale features effectively. To address these challenges, we propose BGS-Diff, a diffusion-based network that improves global edge similarity through two novel components: a Boundary Guidance Module (BGM) and a Scale-aware Attention Fusion Module (SAFM). The BGM integrates differentiable Canny edge extraction as an end-to-end feature enhancement mechanism, combining multi-scale convolution, channel attention, and dense connections to adaptively calibrate anatomical boundaries prior to latent diffusion. In contrast to conventional fixed-weight fusion strategies, the SAFM employs content-adaptive dynamic weight allocation across multi-window self-attention branches to capture heterogeneous multi-scale medical features. We evaluate our method on three public medical image datasets: PH2 (skin lesions), BUSI (breast ultrasound), and COVID-19 (chest X-ray). Compared to the baseline, our approach achieves state-of-the-art performance, reducing FID by 105.8, 133.6, and 97.9, and LPIPS by 0.09, 0.08, and 0.05 on the three datasets, respectively. These results demonstrate its robustness and potential as a data augmentation tool for downstream medical image analysis under data-limited conditions.