SHEAR-MODE TRANSCRANIAL ULTRASOUND IMAGING

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。该项目的目的是使用一种新的超声波方法，为血流成像、检测出血和诊断某些脑部疾病提供低成本和便携的方法。颅骨的变形和低信噪比严重限制了经颅多普勒等现有临床设备的使用。信号退化是由颅骨的反射、折射、衰减和散射引起的。然而，我们最近的工作表明，在某些条件下，使用大入射角可以以较小的失真和较高的信号幅度通过颅骨传播超声波。数值和实验研究都表明，这是由于颅骨中诱导的剪切模式行为所致。初步数据显示，通过头骨获得的高角度信号比纵向信号的失真要小。我们正致力于通过横波而不是纵向声学模式在颅骨中传播，从而实质性地改进经颅超声。这项研究正在测试经颅剪切模式在一些成像问题上的应用，包括血管检测、肿瘤检测、组织形态和脑出血。这项工作可能会提供一种可以在临床上操作的非电离成像方法，同时将一种新技术引入医学和生物成像。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The aim of the project is to use a new ultrasound method to provide a low cost, and portable methods for imaging blood flow, detecting hemorrhaging, and diagnosing certain brain disorders. Distortion and low signal to noise ratios (SNR) caused by the skull have severely limited the use of existing clinical devices such as trancranial Doppler. Signal degradation is caused by reflection, refraction, attenuation, and scattering by the skull. Our recentwork, however, indicates that under certain conditions it is possible to propagate ultrasound through the skull with reduced distortion and higher signal amplitudes by using high incident angles. Both numeric and experimental investigation indicate this is due to the behavior of shear modes induced in the skull bone. Preliminary data shows that a signal obtained through the skull at high angles is less distorted than a longitudinal one. we are working toward substantial improvement of transcranial ultrasound by propagating through the skull as a shear wave as opposed to a longitudinal acoustic mode. The investigation is testing the application of the transcranial shear mode to a number of imaging problems including the vessel detection, tumor detection, tissue morphology, and hemorrhaging in the brain. The work could potentially offer a non-ionizing imaging method that could in operate clinically, while introducing a new technique into medical and biological imaging.