arXiv:2503.01075eess.IVcs.AI2025-03被引 14

用动态扩散法修复医学影像,减少假结构,提升重建精度。

Tackling Hallucination from Conditional Models for Medical Image Reconstruction with DynamicDPS

  • 结合条件与无条件扩散模型,动态选择反向过程起点。
  • 仅用5%采样步数,使关键组织体积估计误差降低15%以上。
  • 无需微调,适配各类条件模型,解决医学影像幻觉问题。

幻觉是指重建图像中不存在于真实图像的虚假结构,是数据驱动的条件模型在医学图像重建中的主要挑战。我们提出动态扩散修复框架DynamicDPS,通过结合无条件扩散模型与数据一致性约束,在多样化数据集上训练,有效抑制幻觉。方法先用条件模型生成初始重建,再通过自适应扩散逆问题求解器进行优化;动态选择每样本的最优起始时间点,并采用Wolfe线搜索调整步长,兼顾效率与图像保真度。该方法利用扩散先验和数据一致性,系统性减少任意条件模型输出的幻觉。在低场磁共振成像增强任务中验证,合成与真实数据均显示其显著降低幻觉,关键组织体积估计相对准确率提升超15%,且仅需基线扩散模型5%的采样步数。作为模型无关、免微调的方法,DynamicDPS为医学影像幻觉问题提供稳健解决方案。代码将于发表后公开。

原文摘要 · Abstract (English)

Hallucinations are spurious structures not present in the ground truth, posing a critical challenge in medical image reconstruction, especially for data-driven conditional models. We hypothesize that combining an unconditional diffusion model with data consistency, trained on a diverse dataset, can reduce these hallucinations. Based on this, we propose DynamicDPS, a diffusion-based framework that integrates conditional and unconditional diffusion models to enhance low-quality medical images while systematically reducing hallucinations. Our approach first generates an initial reconstruction using a conditional model, then refines it with an adaptive diffusion-based inverse problem solver. DynamicDPS skips early stage in the reverse process by selecting an optimal starting time point per sample and applies Wolfe's line search for adaptive step sizes, improving both efficiency and image fidelity. Using diffusion priors and data consistency, our method effectively reduces hallucinations from any conditional model output. We validate its effectiveness in Image Quality Transfer for low-field MRI enhancement. Extensive evaluations on synthetic and real MR scans, including a downstream task for tissue volume estimation, show that DynamicDPS reduces hallucinations, improving relative volume estimation by over 15% for critical tissues while using only 5% of the sampling steps required by baseline diffusion models. As a model-agnostic and fine-tuning-free approach, DynamicDPS offers a robust solution for hallucination reduction in medical imaging. The code will be made publicly available upon publication.

医学影像扩散模型幻觉抑制MRI增强

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