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群的主要问题。肝脏疾病管理严重依赖于对肝脏组织中的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。可以使用组织病理学分析（从用活检芯针提取的组织样品获得的放大载玻片）定量评估肝病从0期（正常）到4期（肝硬化）的进展水平，但这需要针吸活检。还可以通过测量组织中剪切波的传播速度来测量肝脏组织的“整体”特性而无需活检。目前，波的传播可以通过对组织施加敲击（如轻轻的锤子动作）并用超声波测量所得波前的速度来测量。在替代技术中，爆震可以由临床超声换能器本身产生。最后，还可以通过使用磁共振弹性成像来测量整个肝脏体积中的肝纤维化的局部状态，磁共振弹性成像是一种将稳定振动施加到组织并且使整个组织体积中的波图案可视化的技术。波型可以与组织硬度定量相关。我们的目标是证明我们可以通过模拟磁共振弹性成像技术，用超声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，通过机械振动器采集肝脏中引入的稳态波图案的三维图像。我们将从超声获得肝脏硬度图像，并将其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。我们提出的技术的优点是能够成像肝脏体积的深度，通过一个简单得多的检查比磁共振弹性成像。它的成功实施有可能对肝病管理产生重大影响。

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.