Liver shear wave vibroelastography

肝病影响着全世界数亿人。肝炎和脂肪肝疾病是亚洲和北美人口的主要问题。肝脏疾病的管理严重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僵硬度的增加，通常由医生通过触诊进行定性评估。通过组织病理分析（从活检芯针提取的组织样本中获得的放大切片），可以定量评估肝脏疾病的进展水平，从0期（正常）到4期（肝硬化），但这需要针活检。通过测量组织中横波的传播速度，也可以在没有活检的情况下测量肝组织的“体积”特性。目前，可以通过对组织施加敲打来测量波的传播，就像一个温和的锤子动作，然后用超声波测量产生的波前的速度。在另一种技术中，敲击可以由临床超声换能器本身产生。最后，通过使用磁共振弹性成像技术，也可以测量整个肝脏体积内肝纤维化的局部状态，这种技术将稳定的振动应用于组织，并将整个组织体积的波形可视化。波形可以定量地与组织刚度相关。我们的目标是通过模拟磁共振弹性成像技术，证明我们可以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，获取由机械振动器引入肝脏的稳态波模式的三维图像。我们将从超声中获得肝脏硬度图像，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通过比磁共振弹性成像简单得多的检查对肝脏体积进行深度成像。它的成功实施有可能对肝脏疾病的管理产生重大影响。

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.