Error in estimates of tissue material properties from shear wave dispersion ultrasound vibrometry.
Error in estimates of tissue material properties from shear wave dispersion ultrasound vibrometry.
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DOI：
10.1109/tuffc.2009.1097
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发表时间：
2009-04
期刊：
影响因子：
--
通讯作者：
Greenleaf JF
中科院分区：
文献类型：
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作者：
Urban MW;Chen S;Greenleaf JF
剪切波速度测量用于弹性成像以发现组织的剪切弹性和粘性。一种被称为剪切波色散超声振动测量（SDUV）的技术已经被引入，以使用剪切波速度的色散性质来局部估计组织的材料特性。剪切波是使用多频超声辐射力产生的，传播的剪切波在离激发点几毫米的地方测量。使用重复脉冲回波方法和卡尔曼滤波来测量剪切波速度，以在2个不同位置处找到谐波剪切波的相位。利用粘弹性Voigt模型和不同频率下的剪切波速测量值来求出组织的剪切弹性（μ1）和粘度（μ2）。本文的目的是报告在μ1和μ2的不同值范围内SDUV方法的准确度。利用振动散射介质的运动检测模型，分析了散射介质中振动相位的测量误差。为了评估SDUV方法的准确性，我们模拟了相位误差对剪切波速度和材料特性估计的影响，同时改变参数，如剪切刚度和粘度、剪切波振幅、剪切波测量之间的距离（Δr）、超声脉冲回波方法的信噪比（SNR）和测量的频率范围。我们在猪肌肉的一部分进行了实验，以评估上述参数的变化对估计的剪切波速度和材料特性测量，并验证误差预测模型。该模型表明，通过最大化剪切波振幅、脉冲回波SNR、Δr和用于剪切波测量的带宽，可以最大限度地减少剪切波速度和材料属性估计的误差。实验模型表明，当Δr = 3-6 mm，SNR ≥35 dB，频率范围为100 ~ 600 Hz，剪切波振幅从几微米量级到0.5 μm时，可获得最佳性能。该模型提供了一个基础，探索不同的参数相关的SDUV方法的实施。实验结果验证了模型的结论，可为深潜器的优化设计提供参考。
Shear wave velocity measurements are used in elasticity imaging to find the shear elasticity and viscosity of tissue. A technique called shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave velocity to locally estimate the material properties of tissue. Shear waves are created using a multifrequency ultrasound radiation force, and the propagating shear waves are measured a few millimeters away from the excitation point. The shear wave velocity is measured using a repetitive pulse-echo method and Kalman filtering to find the phase of the harmonic shear wave at 2 different locations. A viscoelastic Voigt model and the shear wave velocity measurements at different frequencies are used to find the shear elasticity (μ1) and viscosity (μ2) of the tissue. The purpose of this paper is to report the accuracy of the SDUV method over a range of different values of μ1 and μ2. A motion detection model of a vibrating scattering medium was used to analyze measurement errors of vibration phase in a scattering medium. To assess the accuracy of the SDUV method, we modeled the effects of phase errors on estimates of shear wave velocity and material properties while varying parameters such as shear stiffness and viscosity, shear wave amplitude, the distance between shear wave measurements (Δr), signal-to-noise ratio (SNR) of the ultrasound pulse-echo method, and the frequency range of the measurements. We performed an experiment in a section of porcine muscle to evaluate variation of the aforementioned parameters on the estimated shear wave velocity and material property measurements and to validate the error prediction model. The model showed that errors in the shear wave velocity and material property estimates were minimized by maximizing shear wave amplitude, pulse-echo SNR, Δr, and the bandwidth used for shear wave measurements. The experimental model showed optimum performance could be obtained for Δr = 3-6 mm, SNR ≥35 dB, with a frequency range of 100 to 600 Hz, and with a shear wave amplitude on the order of a few microns down to 0.5 μm. The model provides a basis to explore different parameters related to implementation of the SDUV method. The experiment confirmed conclusions made by the model, and the results can be used for optimization of SDUV.