Meshram N H, Mitchell C C, Wilbrand S M, Dempsey R J, Varghese T
Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, 53706.
Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin, 53706.
Biomed Phys Eng Express. 2019;5(3). doi: 10.1088/2057-1976/ab15c9. Epub 2019 Apr 17.
Carotid plaque rupture can result in stroke or transient ischemic attack that can be devastating for patients. Ultrasound strain imaging provides a noninvasive method to identify unstable plaque likely to rupture. Axial, lateral and shear strains in carotid plaque have been shown to be linked to carotid plaque instability. Recently, there has been interest in using principal strains, which do not depend on angle of insonification of the carotid artery for quantifying instability in plaque along the longitudinal view. In this work relationships between angle dependent axial, lateral and shear strain along with axis independent principal strains are compared. Three strain indices were defined, 1) Average Mean Strain (AMS), 2) Maximum Mean Strain (MMS) and 3) Mean Standard Deviation (MSD) to identify relationships between these five strain image types in a group of 76 i patients. The maximum principal strain demonstrated the highest strain values when compared to axial strain for all patients with a linear regression slope of 1.6 and a y intercept of 2.4 percent strain for AMS. The maximum shear strain when compared to shear strain had a slope of 1.15 and a y intercept of 0.21 percent for AMS. Next, the effect of insonification angle, which is the angle subtended by the artery at the location of plaque was studied. Patients were divided into three sub groups, i.e. less than 5 degrees (n = 31), between 5 and 10 degrees (n = 24) and above 10 degrees (n = 21). The angle of insonification did not make a significant difference between the three angle groups when comparing the relationship between the angle dependent and independent strain values.
颈动脉斑块破裂可导致中风或短暂性脑缺血发作，这对患者来说可能是毁灭性的。超声应变成像提供了一种非侵入性方法来识别可能破裂的不稳定斑块。颈动脉斑块中的轴向、横向和剪切应变已被证明与颈动脉斑块不稳定性有关。最近，人们对使用主应变产生了兴趣，主应变不依赖于颈动脉的超声入射角，用于量化纵向视图中斑块的不稳定性。在这项工作中，比较了角度相关的轴向、横向和剪切应变与与轴无关的主应变之间的关系。定义了三个应变指数：1）平均平均应变（AMS），2）最大平均应变（MMS）和3）平均标准差（MSD），以确定一组76例患者中这五种应变图像类型之间的关系。与所有患者的轴向应变相比，最大主应变显示出最高的应变值，AMS的线性回归斜率为1.6，y轴截距为2.4%应变。与剪切应变相比，最大剪切应变的斜率为1.15，AMS的y轴截距为0.21%。接下来，研究了超声入射角（即斑块位置处动脉所对的角度）的影响。患者被分为三个亚组，即小于5度（n = 31）、5至10度（n = 24）和大于10度（n = 21）。在比较角度相关和独立应变值之间的关系时，超声入射角在三个角度组之间没有显著差异。
