Quantification of Blood Volume Flow using Ultrasound

描述（由申请人提供）：本研究拟采用一种新开发的三维超声方法测量血流量。广泛的临床应用将受益于这一发展，包括心排血量的估计，脑血管疾病的监测，以及妊娠期间宫内生长受限（IUGR）的评估。目前使用的方法要么是侵入性的（即插入Swan-Ganz导管），要么精度有限（即未知的多普勒角、血管几何形状和血流轮廓）。因此，该项目的目标是验证一种与角度无关的、稳健的、体积流量测量技术的性能，这种技术可以在当前的临床扫描仪架构中实现。3D/4D超声系统的出现使这一前景成为现实，该研究将有助于将无创超声体积流量测量推向临床应用。所提出的方法利用了超声系统中常用的多普勒发射。由于超声成像已扩展到3D，因此可以通过血管定义一个表面，其中多普勒速度的总和将产生体积流量。这种方法不需要先验的流向知识（不依赖于角度）或容器几何形状，只需要表面与感兴趣的容器完全相交。这是对先前方法的重大改进，包括本项目最初提出的方法，并使用多普勒信息，已被证明在临床血液速度测量中是准确的。这是对三维测量的扩展，并且实现了这种扩展提供了体积流动所需的信息。这项技术已经证明了在稳定状态下的体积流量测量和在狗模型中的脉冲流量和动脉流量。拟议的工作将1)在体内预期的一系列流动条件下验证这些结果；2)在动物研究中与标准流量测量技术进行直接比较；3)进行初步研究，量化接受透析的人类受试者移植物的流量。这些研究的成功结论将验证一个适合临床使用的测量血流量的系统，并了解更普遍实施该方法所需的基本多普勒处理。公共卫生相关性：血流量体积的测量在许多临床应用中都是至关重要的，如果测量结果能够轻松可靠地获得，将很容易在临床实践中使用。仅举一个例子，经颈动脉通向大脑的血液流动不足已被确定为20-30%中风的潜在原因。目前通常用于测量血流变化的方法需要将测量装置插入循环系统，并伴有相关的潜在并发症；然而，本文提出的3D超声成像方法是非侵入性的，可以提供更准确的体积流量测量。

DESCRIPTION (provided by applicant): This research proposes to use a newly developed 3D ultrasound method to measure volume blood flow. A wide variety of clinical applications would benefit from this development including estimation of cardiac output, monitoring of cerebrovascular diseases, and evaluation of intrauterine growth restriction (IUGR) during pregnancy. Methods currently used are either invasive (i.e. insertion of a Swan-Ganz catheter) or have limited accuracy (i.e. unknown Doppler angle, vessel geometry, and flow profile). Therefore the goal of this project is to verify the performance of an angle-independent, robust, volumetric flow measurement technique that can be implemented within current clinical scanner architecture. The advent of 3D/4D ultrasound systems has made this prospect a reality and the research will serve to move non-invasive ultrasonic volume flow measurements to clinical application. The method proposed takes advantage of the Doppler firings commonly used in ultrasound systems. Because ultrasound imaging has expanded to 3D, a surface can be defined through a vessel in which the summation of the Doppler velocities will yield the volume flow. This method requires no a priori knowledge of the flow direction (angle independent) or vessel geometry and only that the surface completely intersect the vessel of interest. This is a substantial improvement over previous methods including those originally proposed in this project and uses Doppler information that has proven to be accurate in clinical blood velocity measurements. This is an extension of such measurements to 3D and the realization that such an extension provides the information needed for volume flow. This technique has already demonstrated volume flow measurements in steady state and pulsatile flow in phantoms and in arterial flow in a canine model. The proposed work will 1) verify these results over a range of flow conditions anticipated in vivo 2) make direct comparisons to a standard flow measurement technique in animals studies and 3) perform a pilot study quantifying flow in grafts of human subjects undergoing dialysis. The successful conclusion of these studies will be the verification of a system suitable for clinical use in the measurement of volume blood flow and understanding of the fundamental Doppler processing needed for more general implementation of the method. PUBLIC HEALTH RELEVANCE: The measurement of volume blood flow is critical in many clinical applications and would be readily employed in clinical practice if the measurement could be obtained easily and reliably. As just one example, loss of blood flow through the carotid leading to the brain has been identified as a potential cause in 20-30% of all strokes. Current methods commonly used to measure changes in blood flow require the insertion of measurement devices into the circulation with the associated potential complications; however, the proposed 3D ultrasound imaging method proposed here would be noninvasive and may provide more accurate measurement of volume flow.