An octahedral shear strain-based measure of SNR for 3D MR elastography.
An octahedral shear strain-based measure of SNR for 3D MR elastography.
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DOI：
10.1088/0031-9155/56/13/n02
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发表时间：
2011-07-07
影响因子：
3.5
通讯作者：
Paulsen KD
中科院分区：
文献类型：
--
作者：
McGarry MD;Van Houten EE;Perriñez PR;Pattison AJ;Weaver JB;Paulsen KD
针对 MR 弹性成像提出了基于八面体剪切应变（3D 应变状态的任何平面中的最大剪切应变）的信噪比 (SNR) 测量，其中通常使用基于运动的 SNR 测量。通过剪切应力的定义，剪切应变 γ 与剪切模量 μ 直接相关，τ = μγ。因此，决定运动数据质量的重要因素是应变中的噪声，而不是运动中的噪声。研究发现运动和应变 SNR 测量与明胶模型和人类乳房的 MRE 相关。对根据测量的运动数据重建的体模的刚度分布进行分析，揭示了应变和运动 SNR 的阈值，其中 MRE 刚度估计值与独立机械测试相匹配。猫脑的 MRE 显示两种 SNR 测量值之间的相关性明显较低。应变 SNR 测量有一个阈值，高于该阈值重建的刚度值在不同情况下是一致的，而运动 SNR 测量则没有提供有用的阈值，这主要是由于刚体运动效应。
A signal to noise ratio (SNR) measure based on the octahedral shear strain (the maximum shear strain in any plane for a 3D state of strain) is presented for MR elastography, where motion-based SNR measures are commonly used. The shear strain, γ, is directly related to the shear modulus, μ, through the definition of shear stress, τ = μγ. Therefore, noise in the strain is the important factor in determining the quality of motion data, rather than the noise in the motion. Motion and strain SNR measures were found to be correlated for MRE of gelatin phantoms and human breast. Analysis of the stiffness distributions of phantoms reconstructed from the measured motion data revealed a threshold for both strain and motion SNR where MRE stiffness estimates match independent mechanical testing. MRE of the feline brain showed significantly less correlation between the two SNR measures. The strain SNR measure had a threshold above which the reconstructed stiffness values were consistent between cases, whereas the motion SNR measure did not provide a useful threshold, primarily due to rigid body motion effects.