arXiv:2507.11557eess.IVcs.AI2025-07被引 3

用小波潜空间扩散模型实现全身MR到CT精准转换,提升临床可用性。

3D Wavelet Latent Diffusion Model for Whole-Body MR-to-CT Modality Translation

  • 在小波潜空间进行三维扩散建模,融合小波残差模块增强细节重建。
  • 生成的CT图像与输入MR空间对齐,骨组织和软组织对比更清晰。
  • 适合用于MR-only放疗和PET/MR等需要高精度衰减图的临床场景。

磁共振(MR)成像在现代临床诊断中至关重要,正日益融入混合正电子发射断层扫描/磁共振(PET/MR)成像及仅基于MR的放疗等先进治疗流程。这些集成方法依赖于精确的辐射衰减估计,通常通过从MR扫描合成计算机断层扫描(CT)图像来生成衰减图。然而,现有的全身MR-to-CT合成方法常因生成的CT与输入MR图像空间对齐不佳,且图像质量不足,难以可靠用于下游临床任务。本文提出一种新型3D小波潜扩散模型(3D-WLDM),通过在学习的潜空间中进行模态转换,解决上述问题。通过在编码器-解码器架构中引入小波残差模块,增强了跨图像与潜空间的细粒度特征捕捉与重建能力。为保持扩散过程中的解剖完整性,我们分离结构与模态特异性特征,并锚定结构成分以防止形变。此外,在扩散模型中引入双跳接注意力机制,实现了高分辨率CT图像生成,显著改善了骨骼结构与软组织对比的表现。

原文摘要 · Abstract (English)

Magnetic Resonance (MR) imaging plays an essential role in contemporary clinical diagnostics. It is increasingly integrated into advanced therapeutic workflows, such as hybrid Positron Emission Tomography/Magnetic Resonance (PET/MR) imaging and MR-only radiation therapy. These integrated approaches are critically dependent on accurate estimation of radiation attenuation, which is typically facilitated by synthesizing Computed Tomography (CT) images from MR scans to generate attenuation maps. However, existing MR-to-CT synthesis methods for whole-body imaging often suffer from poor spatial alignment between the generated CT and input MR images, and insufficient image quality for reliable use in downstream clinical tasks. In this paper, we present a novel 3D Wavelet Latent Diffusion Model (3D-WLDM) that addresses these limitations by performing modality translation in a learned latent space. By incorporating a Wavelet Residual Module into the encoder-decoder architecture, we enhance the capture and reconstruction of fine-scale features across image and latent spaces. To preserve anatomical integrity during the diffusion process, we disentangle structural and modality-specific characteristics and anchor the structural component to prevent warping. We also introduce a Dual Skip Connection Attention mechanism within the diffusion model, enabling the generation of high-resolution CT images with improved representation of bony structures and soft-tissue contrast.

MR到CT扩散模型医学影像小波变换

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