arXiv:2512.01135eess.IV2025-12

用多回波GRE数据生成高质量脑部T1加权图像,缩短扫描时间。

Diffusion-Based Synthesis of 3D T1w MPRAGE Images from Multi-Echo GRE with Multi-Parametric MRI Integration

  • 基于扩散模型融合铁敏感性QSM和R2*图作为物理先验
  • 合成图像在丘脑、苍白球等区域分割精度显著提升
  • 生成结果与真实图像在年龄/性别差异上高度一致,生物合理性强

多回波梯度回波(mGRE)序列可提供定量参数图,如定量磁化率成像(QSM)和横向弛豫率(R2*),对组织铁含量和髓鞘敏感。但传统结构形态学分析依赖独立的T1加权MPRAGE扫描,延长了扫描时间。本文提出一种深度学习框架,直接从mGRE数据合成高对比度3D T1w MPRAGE图像,优化神经影像采集流程。构建基于Fast-DDPM架构的多参数条件扩散模型,将铁敏感的QSM和R2*图作为物理先验,解决铁富集深灰质区域的对比度模糊问题。在175名健康受试者上训练并验证,性能通过感知指标与下游分割准确率评估,对比现有U-Net和GAN基线方法。特别地,通过复制人群水平年龄与性别相关的统计关联,评估合成图像的生物学合理性。所提方法显著优于基线,在亚皮质区域如丘脑和苍白球表现更优;关键的是,回归分析显示其在年龄相关萎缩率、衰老效应量及性别二态性模式上与真实图像高度一致。该扩散方法有效利用定量MRI先验,生成严格符合生物学规律的T1w图像,适用于可靠的临床形态分析,为从定量mGRE序列回溯生成结构对比提供了可行路径。

原文摘要 · Abstract (English)

Multi-echo Gradient Echo (mGRE) sequences provide valuable quantitative parametric maps, such as Quantitative Susceptibility Mapping (QSM) and transverse relaxation rate (R2*), sensitive to tissue iron and myelin. However, structural morphometry typically relies on separate T1-weighted MPRAGE acquisitions, prolonging scan times. We propose a deep learning framework to synthesize high-contrast 3D T1w MPRAGE images directly from mGRE data, streamlining neuroimaging protocols. We developed a novel multi-parametric conditional diffusion model based on the Fast-DDPM architecture. Unlike conventional intensity-based synthesis, our approach integrates iron-sensitive QSM and R2* maps as physical priors to address contrast ambiguity in iron-rich deep gray matter. We trained and validated the model on 175 healthy subjects. Performance was evaluated against established U-Net and GAN-based baselines using perceptual metrics and downstream segmentation accuracy. Uniquely, we assessed the biological plausibility of synthesized images by replicating population-level statistical associations with age and sex. The proposed framework significantly outperformed baselines, achieving superior perceptual quality and segmentation accuracy, particularly in subcortical regions like the thalamus and pallidum. Crucially, synthesized images preserved essential biological dependencies: regression analyses showed high concordance in age-related atrophy rates, aging effect sizes, and sexual dimorphism patterns compared to ground truth. By effectively leveraging quantitative MRI priors, our diffusion-based method generates strictly biologically plausible T1w images suitable for reliable clinical morphometric analysis. This approach offers a promising pathway to reduce acquisition time by deriving structural contrasts retrospectively from quantitative mGRE sequences.

3D图像合成扩散模型定量MRI神经影像

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