Vachutka Jaromir, Sedlackova Zuzana, Furst Tomas, Herman Miroslav, Herman Jan, Salzman Richard, Dolezal Ladislav
1 Department of Medical Biophysics, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic.
2 Department of Radiology, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc, Olomouc, Czech Republic.
Ultrason Imaging. 2018 Nov;40(6):380-393. doi: 10.1177/0161734618793837. Epub 2018 Aug 12.
Shear wave imaging is considered to be more precise and less operator dependent when compared with strain imaging. It enables quantitative and reproducible data (Young's modulus of the imaged tissue). However, results of shear wave imaging can be affected by a variety of different factors. The aim of this study is to evaluate the effect of the pressure applied by the ultrasound probe during examination on the measured values of Young's modulus. The effect of the tissue compression on the results of the real-time shear wave elastography was evaluated via the gelatine phantom measurements, via the ex vivo experiments with pig liver, and via the in vivo measurements of the thyroid gland stiffness on healthy volunteers. The results of our measurements confirmed that the measured value of Young's modulus increases with the increasing pressure applied on the imaged object. The highest increase was observed during the ex vivo experiments (400%), and the lowest increase was detected in the case of the phantom measurements (8%). A two- to threefold increase in Young's modulus was observed between the minimum and maximum pressure in the case of the in vivo elastography measurements of thyroid gland. The Veronda-Westman theoretical model was used for the description of the tissue nonlinearity. We conclude that tissue compression by the force exerted on the probe can significantly affect the results of the real-time shear wave elastography measurements. Minimum pressure should be used when measuring the absolute value of Young's modulus of superficial organs.
与应变成像相比，剪切波成像被认为更精确且对操作者的依赖性更小。它能够提供定量且可重复的数据（成像组织的杨氏模量）。然而，剪切波成像的结果可能会受到多种不同因素的影响。本研究的目的是评估超声探头在检查过程中施加的压力对杨氏模量测量值的影响。通过明胶模型测量、猪肝离体实验以及对健康志愿者甲状腺硬度的体内测量，评估了组织压缩对实时剪切波弹性成像结果的影响。我们的测量结果证实，杨氏模量的测量值随着对成像对象施加压力的增加而增加。在离体实验中观察到的增加幅度最大（400%），而在模型测量中检测到的增加幅度最小（8%）。在甲状腺的体内弹性成像测量中，在最小和最大压力之间观察到杨氏模量增加了两到三倍。使用Veronda-Westman理论模型来描述组织的非线性。我们得出结论，探头施加的力引起的组织压缩会显著影响实时剪切波弹性成像测量的结果。在测量浅表器官杨氏模量的绝对值时应使用最小压力。
