Liver shear wave vibroelastography

肝病影响着全球数亿人。肝炎和脂肪肝是亚洲和北美人口的主要问题。肝脏疾病的治疗在很大程度上依赖于对肝组织物理变化的准确评估，这些变化表现为肝脏硬度的增加，通常由医生通过触诊进行定性评估。使用组织病理学分析(从活检芯针提取的组织样本中获得放大的切片)，可以定量评估肝病的进展程度，从0期(正常)到4期(肝硬变)，但这需要针刺活检。通过测量剪切波在组织中的传播速度，也可以在不进行活组织检查的情况下测量肝组织的“体积”特性。目前，波的传播可以通过对组织施加敲击，如轻微的锤子动作，并用超声波测量产生的波前的速度来测量。在另一种技术中，爆震可以由临床超声换能器本身产生。最后，还可以使用磁共振弹性成像来测量整个肝脏体积内肝纤维化的局部状态，这是一种对组织施加稳定振动并显示整个组织体积的波动模式的技术。波型可以定量地与组织硬度相关。我们的目标是表明，我们可以通过模仿磁共振弹性成像技术，用超声波测量肝纤维化的局部状态。为此，我们将与我们的工业合作伙伴合作，获取由机械振动器在肝脏中引入的稳态波动模式的三维图像。我们将从超声波获得肝脏硬度图像，并将它们与志愿者和少数患者的磁共振弹性成像产生的图像进行比较。我们提出的这项技术的优势是能够通过比磁共振弹性成像简单得多的检查来对肝脏体积进行深度成像。它的成功实施有可能对如何管理肝病产生重大影响。

Liver disease affects hundreds of millions of people worldwide. Hepatitis and fatty liver disease are major problems in Asian and North American populations. Liver disease management is critically dependent on an accurate assessment of physical changes in the liver tissue, which manifest themselves as an increase in the liver stiffness, typically assessed qualitatively by palpation by a physician. It is possible to quantitatively assess the level of advancement of liver disease, from stage 0 (normal) to stage 4 (cirrhosis), using tissue pathological analysis (magnified slides obtained from tissue samples extracted with a biopsy core needle), but this requires a needle biopsy. It is also possible to measure the "bulk" properties of the liver tissue without biopsy by using a measurement of the propagation speed of shear waves in tissue. Currently, the wave propagation can be measured by applying a knock, like a gentle hammer action, to tissue, and measuring the speed of the resulting wavefront with ultrasound. In an alternative technique, the knock can be generated by the clinical ultrasound transducer itself. Finally, it is also possible to measure the localized state of liver fibrosis throughout the volume of the liver by using magnetic resonance elastography, a technique in which a steady vibration is applied to tissue and the wave pattern throughout the tissue volume is visualized. The wave pattern can be quantitatively related to tissue stiffness. Our goal is to show that we can measure the localized state of liver fibrosis with ultrasound, by mimicking the magnetic resonance elastography technique. For this purpose, we will work with our industrial partner to acquire three-dimensional images of the steady-state wave pattern introduced in the liver by a mechanical vibrator. We will obtain liver stiffness images from ultrasound and we will compare them with those generated by magnetic resonance elastography in volunteers and in a small number of patients. The technique we propose has the advantage of being able to image the liver volume at depth, through a much simpler examination than by magnetic resonance elastography. Its successful implementation has the potential to make a significant impact on how liver disease management.