端到端学习动态MRI的自适应采样、重建与配准,提升运动图像质量与精度。
Deep End-to-end Adaptive k-Space Sampling, Reconstruction, and Registration for Dynamic MRI
- 基于深度学习的自适应采样,按需捕获关键动态数据
- 联合优化重建与配准,实现欠采样下高精度形变场估计
- 模块可插拔,适用于心脏成像与放疗引导等临床场景
动态MRI在心脏功能评估、器官运动追踪和放疗引导中具有重要应用,但受时间限制及呼吸、心搏等生理运动影响,完全采样动态k空间数据通常不可行。这导致欠采样,降低重建图像质量,进而影响形变场估计,阻碍动态图像与静态参考图像的配准。该配准对运动校正、治疗规划和定量分析(如心脏影像、磁共振引导放疗)至关重要。为此,我们提出一种端到端深度学习框架,集成自适应动态k空间采样、重建与配准。方法首先通过深度学习实现动态k空间的自适应采样,优化数据采集以捕捉特定病例的关键信息;随后利用深度学习重建模块生成利于准确估计形变场的图像;最后由配准模块计算动态图像与静态参考图像间的形变场。整个框架独立于具体重建与配准模块,支持即插即用。通过监督与无监督损失函数联合训练,实现全链路端到端优化。控制实验与消融研究验证了各组件有效性,表明每一步选择均有助于从欠采样动态数据中稳健估计运动。
原文摘要 · Abstract (English)
Dynamic MRI enables a range of clinical applications, including cardiac function assessment, organ motion tracking, and radiotherapy guidance. However, fully sampling the dynamic k-space data is often infeasible due to time constraints and physiological motion such as respiratory and cardiac motion. This necessitates undersampling, which degrades the quality of reconstructed images. Poor image quality not only hinders visualization but also impairs the estimation of deformation fields, crucial for registering dynamic (moving) images to a static reference image. This registration enables tasks such as motion correction, treatment planning, and quantitative analysis in applications like cardiac imaging and MR-guided radiotherapy. To overcome the challenges posed by undersampling and motion, we introduce an end-to-end deep learning (DL) framework that integrates adaptive dynamic k-space sampling, reconstruction, and registration. Our approach begins with a DL-based adaptive sampling strategy, optimizing dynamic k-space acquisition to capture the most relevant data for each specific case. This is followed by a DL-based reconstruction module that produces images optimized for accurate deformation field estimation from the undersampled moving data. Finally, a registration module estimates the deformation fields aligning the reconstructed dynamic images with a static reference. The proposed framework is independent of specific reconstruction and registration modules allowing for plug-and-play integration of these components. The entire framework is jointly trained using a combination of supervised and unsupervised loss functions, enabling end-to-end optimization for improved performance across all components. Through controlled experiments and ablation studies, we validate each component, demonstrating that each choice contributes to robust motion estimation from undersampled dynamic data.
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