Liver fibrosis is a kind of chronic damage of the liver. The progression of liver fibrosis will result in cirrhosis which is one of the top 10 causes of death in the western world. Recently, a device developed based on transient ultrasound elastography shows promising results for liver stiffness measurement. However, this device does not provide enough visual guidance for the liver being tested during measurement. We aim to design and validate a transient elastography system with real-time B-mode ultrasound imaging for liver fibrosis assessment. Our development is based on a conventional B-mode ultrasound scanner, which consists of a B-mode ultrasound probe fixed along the axis of a mechanical vibrator. The induced shear wave propagates through the liver tissue. During measurement, B-modr ultrasound imaging is generated in real-time to view the morphological information and dynamic motion of the tissue, and an A-mode ultrasound with a frame rate of 6000 f/s is generated to track the propagation of shear wave within a selected region. The propagation speed of the shear wave is related to the tissue stiffness and thus Young's modulus can be calculated. The system was tested using a series of custom-made phantoms with different stiffness and the results were compared with those measured by an existing transient elastography system and mechanical testing. The results showed that the elasticity measured by our new method agreed well with those obtained by other methods. For the preliminary in vivo assessment, the Young's modulus of a normal male subject is 5.8 kPa and 7.5 ±2.1 kPa obtained by the existing and our systems, respectively. In summary, we have successfully developed a transient ultrasound elastography system with real-time B-mode imaging for the assessment of liver fibrosis. Further evaluation of the system is being conducted.%肝纤维化是一种慢性的肝脏损害,严重的损害更会导致肝硬化.肝硬化在西方是前十位导致死亡的病.最近,超声瞬时弹性测量被用来评估肝脏硬度,取得较好的结果.然而,在测量过程中,目前的设备不能提供足够的图像引导来确定肝脏的位置.所以,我们的目标是设计和验证一台实时B超图像引导下的瞬时弹性成像系统.我们的研发是基于传统的B型超声扫描系统,而B型超声探头被安装在机械振动器的轴心上.振动会产生弹性剪切波,并在肝脏组织中传播.当测量时,实时B超图像会生成以查看组织的静态和动态信息.另外,6000帧/s的实时A型超声也会用以追踪在选定位置弹性剪切波的传播.弹性剪切波的传播速度是与组织的弹性相关的,所以我们能够计算出杨氏模量.我们以自制的不同弹性的仿体进行了一系列的测试,将得出的结果与现有的瞬时弹性测量系统和传统力学测培作比较,得出的结果相当符合.另外,对于正常人体的初步测试,现有的系统和我们系统测出的杨氏模量分别为5.8 kPa和(7.5±2.1)kPa.我们已经成功地研发了实时B超引导下的瞬时弹性测量系统对肝纤维化的评估.进一步的评估正在进行中.
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