Quantifying hepatic shear modulus in vivo using acoustic radiation force
Quantifying hepatic shear modulus in vivo using acoustic radiation force
复制标题
DOI：
10.1016/j.ultrasmedbio.2007.10.009
复制
发表时间：
2008-04-01
影响因子：
2.9
通讯作者：
Nightingale, K. R.
中科院分区：
文献类型：
--
作者：
Palmeri, M. L.;Wang, M. H.;Nightingale, K. R.
剪切波在组织中传播的速度可用于量化组织的剪切模量。正如许多研究小组所示，剪切波可以使用聚焦的、脉冲的、声辐射力激励在组织内产生，并且所产生的位移响应可以通过时间进行超声跟踪。本报告的工作有两个目标：（i）开发和验证一种算法，以量化辐射力引起的剪切波速度，超声检测的位移数据，其在存在差的位移信噪比的情况下是稳健的，以及（ii）将该算法应用于人体志愿者体内采集的数据集，以证明使用该方法定量肝脏剪切模量的临床可行性组织纵向研究。这项工作的最终临床应用是在纤维化和脂肪变性的情况下无创量化肝脏硬度。在该算法中，响应于激励区域外的脉冲声辐射力的时间到峰值的位移数据被用来表征材料的剪切波速，其被用来重建材料的剪切模量。该算法的开发和验证使用有限元方法模拟。通过在模拟位移场上使用该算法，剪切模量（mu）范围为1.3-5 kPa的材料的重建精确到0.3kPa以内，而更刚性的剪切模量范围为10-16 kPa的材料的重建精确到1.0kPa以内。超声跟踪位移数据，这在位移估计中引入抖动，并不妨碍使用该算法来重建准确的剪切模量。通过使用在体内数据采集肋间在20名志愿者的身体质量指数范围从正常到肥胖，肝剪切模量已重建0.9和3.0 kPa之间，平均精度为+/- 0.4 kPa。这些重建的肝脏模量与文献中报道的一致（mu = 0.75-2.5 kPa），精度相似（+/- 0.3 kPa）。在105天的时间内，在9个不同的日期对两名志愿者进行了重复的肋间肝脏剪切模量重建，第一名志愿者的平均剪切模量为1.9 +/- 0.50 kPa（1.3-2.5 kPa），第二名志愿者的平均剪切模量为1.8 +/- 0.4 kPa（1.1-3.0 kPa）。迄今为止的模拟和体内数据表明，该方法能够产生准确和可重复的肝脏硬度测量值，并且作为量化肝脏硬度的临床工具似乎很有前途。
The speed at which shear waves propagate in tissue can be used to quantify the shear modulus of the tissue. As many groups have shown, shear waves can be generated within tissues using focused, impulsive, acoustic radiation force excitations, and the resulting displacement response can be ultrasonically tracked through time. The goals of the work herein are twofold: (i) to develop and validate an algorithm to quantify shear wave speed from radiation force-induced, ultrasonically-detected displacement data that is robust in the presence of poor displacement signal-to-noise ratio and (ii) to apply this algorithm to in vivo datasets acquired in human volunteers to demonstrate the clinical feasibility of using this method to quantify the shear modulus of liver tissue in longitudinal studies. The ultimate clinical application of this work is noninvasive quantification of liver stiffness in the setting of fibrosis and steatosis. In the proposed algorithm, time-to-peak displacement data in response to impulsive acoustic radiation force outside the region of excitation are used to characterize the shear wave speed of a material, which is used to reconstruct the material's shear modulus. The algorithm is developed and validated using finite element method simulations. By using this algorithm on simulated displacement fields, reconstructions for materials with shear moduli (mu) ranging from 1.3-5 kPa are accurate to within 0.3 kPa, whereas stiffer shear moduli ranging from 10-16 kPa are accurate to within 1.0 kPa. Ultrasonically tracking the displacement data, which introduces jitter in the displacement estimates, does not impede the use of this algorithm to reconstruct accurate shear moduli. By using in vivo data acquired intercostally in 20 volunteers with body mass indices ranging from normal to obese, liver shear moduli have been reconstructed between 0.9 and 3.0 kPa, with an average precision of +/- 0.4 kPa. These reconstructed liver moduli are consistent with those reported in the literature (mu = 0.75-2.5 kPa) with a similar precision (+/- 0.3 kPa). Repeated intercostal liver shear modulus reconstructions were performed on nine different days in two volunteers over a 105-day period, yielding an average shear modulus of 1.9 +/- 0.50 kPa (1.3-2.5 kPa) in the first volunteer and 1.8 +/- 0.4 kPa (1.1-3.0 kPa) in the second volunteer. The simulation and in vivo data to date demonstrate that this method is capable of generating accurate and repeatable liver stiffness measurements and appears promising as a clinical tool for quantifying liver stiffness.