Harmonic Doppler Ultrasound Embolus Characterization

描述(由申请人提供)： 这项建议是开发一种功率M型多普勒超声设备，用于监测大脑基底动脉的血流，以观察栓子事件，并将这些栓子表征为气泡或颗粒。这种设备在几个医疗程序导致血栓进入大脑的场所具有重要价值。在使用体外循环的手术中，栓子特征的实质性临床意义被发现，许多结果研究记录了短期和长期认知能力下降。与体外循环相关的卒中中约有三分之一是术中的[L]，其中大部分是栓塞术。目前，直到患者从麻醉中苏醒并在重症监护病房表现出神经功能障碍，才能认识到栓塞的效果，而采取预防或治疗行动已经为时已晚。因此，术中超声对栓子成分的区分对于通过治疗或改进手术方法或技术来适当地响应栓塞术的类型具有重要价值。这一建议是基于成功的体外(流动体模)和体内(人体人工心脏瓣膜栓子的特征)的可行性实验，多普勒超声识别气泡和颗粒。这项技术的关键要素是：(1)能够处理来自运动散射体的基波和二次谐波反射的多普勒频移的高动态范围多普勒超声平台，以及(2)在基波和二次谐波频率下具有相似灵敏度模式的换能器。建议的工作是通过改进探头设计，增强来自栓子的基波和二次谐波回波的信号处理，并将表征结果以易于理解的图像格式呈现给操作员，从而进一步发展这些关键要素。在这项计划中开发的系统将在血流循环、人类大脑中动脉的动物模型以及接受经颅多普勒评估卵圆孔未闭的存在和严重程度的人体受试者上进行一系列实验。这些测试将包括观察单个栓子和栓子阵雨，这些栓子的大小和组成各不相同。这项工作预计将改善目标心脏手术应用中的神经学结果，第三阶段合作伙伴已准备好并等待将该技术推向市场。

DESCRIPTION (provided by applicant): This proposal is to develop a power M-mode Doppler ultrasound device for monitoring blood flow in the basal arteries of the brain for embolic events, and characterizing these emboli as gas bubbles or particulates. This device is of significant value in several venues where medical procedures result in emboli going to the brain. Substantial clinical significance of embolus characterization is found in surgeries utilizing cardiopulmonary bypass, for which numerous outcomes studies have documented short and long term cognitive decline. Approximately one third of strokes associated with CPB are intra operative[l], a majority of which are embolic. The effects of embolization are currently not appreciated until the patient comes out of anesthesia and manifests neurologic deficits in the intensive care unit, which is too late to take preventive or therapeutic action. Ultrasound differentiation of embolus composition during surgery is therefore of great value for appropriately responding to the type of emboliziation with therapy or modification in surgical approach or technique. This proposal is based on successful in vitro (flow phantom) and in vivo (characterization of emboli from prosthetic heart valves in a human subject) feasibility experiments for Doppler ultrasound discrimination of gas bubbles and particulates. The critical elements for this technology are: (1) a high dynamic range Doppler ultrasound platform capable of processing Doppler shifts from fundamental and second harmonic reflections from moving scatterers and (2) a transducer with similar sensitivity patterns at both fundamental and second harmonic frequencies. The proposed work is to further develop these critical elements by refinement of probe design, enhancement of signal processing of the fundamental and second harmonic echoes from emboli, and presentation of the characterization results to the operator in an easily appreciated image format. The system developed in this proposal will be tested in a series of experiments on a flow loop, an animal model of the human middle cerebral artery, and on human subjects undergoing Tran cranial Doppler evaluation for presence and severity of patent foramen ovale. These tests will include observation of single emboli and embolus showers, with variable embolus size and composition. This work is anticipated to result in improved neurological outcomes in the targeted heart surgery application, and a Phase III partner is ready and waiting to take the technology to market.