Quantification of Blood Volume Flow using Ultrasound

描述(申请人提供)：这项研究建议使用一种新开发的三维超声方法来测量体积血流量。这一发展将使各种临床应用受益，包括心输出量的估计、脑血管疾病的监测和妊娠期间胎儿宫内生长受限(IUGR)的评估。目前使用的方法要么是有创的(即插入Swan-Ganz导管)，要么是精度有限(即未知的多普勒角度、血管几何形状和血流分布)。因此，本项目的目标是验证一种角度无关、健壮的体积流量测量技术的性能，该技术可以在当前的临床扫描仪架构中实施。3D/4D超声系统的出现使这一前景成为现实，这项研究将有助于将无创超声体积流量测量推向临床应用。该方法利用了超声系统中常用的多普勒法。因为超声成像已经扩展到3D，所以可以通过血管定义表面，其中多普勒速度的总和将产生体积流量。这种方法不需要流动方向(与角度无关)或血管几何形状的先验知识，只需要表面与感兴趣的血管完全相交。与以前的方法相比，这是一个实质性的改进，包括本项目最初提出的方法，并使用已被证明在临床血流速度测量中准确的多普勒信息。这是将这种测量扩展到3D，并认识到这种扩展提供了体积流动所需的信息。这项技术已经在犬类模型中展示了稳态的体积流量测量和体模的脉动流量测量以及动脉流量的测量。这项拟议的工作将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的流量测量技术进行直接比较，3)进行一项试验性研究，对接受透析的人体受试者的移植物中的流量进行量化。这些研究的成功结论将是验证一个适合临床使用的系统来测量血流量，并了解更广泛地实施该方法所需的基本多普勒处理。公共卫生相关性：体积血流量的测量在许多临床应用中是至关重要的，如果能够容易和可靠地获得该测量，将很容易在临床实践中使用。仅举一个例子，在所有中风中，通过颈动脉流向大脑的血流丢失已被确定为20%-30%的潜在原因。目前常用的测量血流变化的方法需要将测量设备插入到循环中，并伴随着相关的潜在并发症；然而，本文提出的3D超声成像方法将是非侵入性的，可能会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.