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基于几何不变性表征的磁共振深度成像方法综述

A Review of Deep MRI Reconstruction Methods Based on Geometry-Invariant Representations

  • 摘要: 近年来,基于模型驱动深度学习的加速重建已成为磁共振快速成像的重要技术路径,其关键在于利用神经网络学习表达能力更强的图像先验,以约束欠采样条件下的病态逆问题。除稀疏性、低秩性等常规先验外,磁共振图像中还存在器官形态、组织边界、结构对称性和运动形变等几何结构信息。这类信息在个体差异、成像条件和运动状态变化中具有相对稳定性与一致性,可概括为几何不变性表征。显式引入并有效利用几何不变性表征,能够为重建过程提供结构约束,提升重建结果的解剖合理性、鲁棒性和跨场景泛化能力,已成为磁共振深度成像先验建模中的重要研究方向。因此,本文围绕几何不变性表征的建模与利用,系统梳理了等变卷积网络、参数化卷积和形变卷积等方法的研究进展,总结其在网络结构、卷积核表示和采样机制层面的几何先验引入方式,以期为磁共振深度成像中的结构先验设计提供参考。

     

    Abstract: In recent years, accelerated reconstruction based on model-driven deep learning has become an important technical route for fast magnetic resonance imaging. Its key idea is to learn more expressive image priors using neural networks, thereby constraining the ill-posed inverse problem under undersampled conditions. In addition to conventional priors such as sparsity and low-rankness, magnetic resonance images also contain geometric structural information, including organ morphology, tissue boundaries, structural symmetry, and motion-induced deformation. Such information exhibits relative stability and consistency across individual anatomical variations, imaging conditions, and motion states, and can be summarized as geometric invariance representation. Explicitly introducing and effectively utilizing geometric invariance representation can provide structural constraints for the reconstruction process, improve the anatomical plausibility, robustness, and cross-scenario generalization of reconstructed results, and has become an important research direction in prior modeling for deep magnetic resonance imaging. Therefore, this review focuses on the modeling and utilization of geometric invariance representation, systematically summarizes the research progress of equivariant convolutional networks, parameterized convolutions, and deformable convolutions, and discusses how these methods introduce geometric priors at the levels of network architecture, convolutional kernel representation, and sampling mechanism, with the aim of providing reference for structural prior design in deep magnetic resonance imaging.

     

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