arXiv:2507.23224eess.IVeess.SP2025-07

E-M算法优化5维心脏MRI重建,显著减少运动伪影。

EMORe: Motion-Robust 5D MRI Reconstruction via Expectation-Maximization-Guided Binning Correction and Outlier Rejection

  • 用期望最大化框架动态修正数据分箱与剔除异常值
  • 仿真与真人实验均提升图像清晰度与分箱准确率
  • 适合对运动伪影敏感的心脏MRI临床应用

我们提出EMORe,一种自适应重建方法,旨在提升自由运行、自由呼吸自门控5维心脏磁共振成像(MRI)的运动鲁棒性。传统基于自门控的运动分箱在心律与呼吸信号提取不准确及突发整体运动时,常导致残留运动伪影,影响临床应用。EMORe通过在期望-最大化(EM)框架中集成自适应箱间校正与显式异常值剔除,交替执行E步与M步直至收敛。E步中,通过修正有效数据误分箱并将其余运动污染数据转入专用异常值箱,实现概率(软)分箱优化;M步则利用优化后的软分箱更新图像估计。模拟5维MRXCAT人体模型验证显示,与标准压缩感知重建相比,EMORe在不同水平模拟整体运动下,峰值信噪比、结构相似性指数、边缘锐度和分箱准确率均有显著提升。13名志愿者体内验证进一步证实其鲁棒性,在控制咳嗽诱发运动场景下,显著增强血心肌边界锐度并减少运动伪影。尽管计算复杂度略有增加,但其对整体运动伪影的强适应性极大提升了5维心脏MRI的临床适用性与诊断信心。

原文摘要 · Abstract (English)

We propose EMORe, an adaptive reconstruction method designed to enhance motion robustness in free-running, free-breathing self-gated 5D cardiac magnetic resonance imaging (MRI). Traditional self-gating-based motion binning for 5D MRI often results in residual motion artifacts due to inaccuracies in cardiac and respiratory signal extraction and sporadic bulk motion, compromising clinical utility. EMORe addresses these issues by integrating adaptive inter-bin correction and explicit outlier rejection within an expectation-maximization (EM) framework, whereby the E-step and M-step are executed alternately until convergence. In the E-step, probabilistic (soft) bin assignments are refined by correcting misassignment of valid data and rejecting motion-corrupted data to a dedicated outlier bin. In the M-step, the image estimate is improved using the refined soft bin assignments. Validation in a simulated 5D MRXCAT phantom demonstrated EMORe's superior performance compared to standard compressed sensing reconstruction, showing significant improvements in peak signal-to-noise ratio, structural similarity index, edge sharpness, and bin assignment accuracy across varying levels of simulated bulk motion. In vivo validation in 13 volunteers further confirmed EMORe's robustness, significantly enhancing blood-myocardium edge sharpness and reducing motion artifacts compared to compressed sensing, particularly in scenarios with controlled coughing-induced motion. Although EMORe incurs a modest increase in computational complexity, its adaptability and robust handling of bulk motion artifacts significantly enhance the clinical applicability and diagnostic confidence of 5D cardiac MRI.

5D MRI运动伪影自门控EM算法

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