CARDIOVASCULAR FLOW DYNAMICS--IN VIVO IMAGING STUDIES

本项目重点研究使用新出现的强大的无创超声成像技术来量化心血管结构和功能病理。利用流体动力学原理，描述了心脏结构异常和病理生理流动事件的时间和空间方面，并对其进行了量化验证。在心功能障碍的临床治疗中，定量准确的评估对心功能障碍的诊断、预后和治疗具有重要意义。此外，非侵入性评估在经济上是可取的。为了达到这些目的，今年的努力扩展了前几年的研究，包括：1)在离体动物研究中，实际左心室容积与实时三维超声心动图计算的左心室容积之间存在很强的相关性。2)在体内，与电磁流量探头法和磁共振成像法相比，实时三维超声心动图的根尖旋转6面测量方法与计算左室容积的参考标准具有良好的相关性。3)实时三维超声心动图在左室不对称，即存在左室动脉瘤时，也可用于量化左室容积。4)利用实时三维彩色多普勒垂直于血流的独特c面成像左室流出道横断面空间流速分布。5)对左室流出道横断面彩色图像流速数据进行空间积分，得到峰值流速。因此，在没有任何关于流速几何分布的假设的情况下，估计峰值流量是可能的。6)通过应用时间平均因子校正低估，电磁流量计测量的参考流速与实时三维彩色多普勒超声心动图之间具有很好的一致性。这些研究已经出版或正在出版中。正在进行的研究使用三维结构成像和三维多普勒血流成像使用慢性主动脉和二尖瓣反流动物模型。

This project emphasizes studies using newly emerging robust non invasive ultrasonic imaging technologies for quantifying structural and functional cardiovascular pathology. Using hydrodynamic principles, temporal and spatial aspects of cardiac structural abnormalities and pathophysiologic flow events are described and their quantification validated. In the clinical management of cardiac dysfunction, quantitativelyaccurate assessment is of major importance for diagnosis, prognosis and therapy. Non invasive assessment is, in addition, economically desirable. To these ends, the current year's efforts have extended previous years' studies to include: 1) In ex vivo animal studies, a strong correlation was validated between actual left ventricular volumes and those calculated with real-time, three-dimensional echocardiography. 2) In vivo, apically rotated 6 plane measurement methods with real-time, three-dimensional echocardiography correlated well with reference standards for calculating left ventricular volumes when compared with electromagnetic flow probe methods and magnetic resonance imaging. 3) Real-time, three-dimensional echocardiography was also validated for quantifying left ventricular volumes in the presence of left ventricular asymmetry, i.e. in the presence of left ventricular aneurysms. 4) Using real-time, three-dimensional color Doppler with its unique c-plane, which is perpendicular to flow, the cross-sectional spatial velocity distributions in the left ventricular outflow tract were imaged. 5) Peak flow rates were obtained by spatially integrating the velocity data from the cross-sectional color images of the left ventricular outflow tract. Thus, estimations of peak flow rates were possible without any assumptions about flow velocity geometric distribution. 6) By applying a temporal averaging factor to correct for underestimation, there was an excellent agreement between reference flow rate by electromagnetic flow meter and real-time, three-dimensional color Doppler echocardiography. These studies have been published or are in press. On-going studies using three-dimensional structural imaging and three-dimensional Doppler flow imaging use animal models of chronic aortic and mitral regurgitation.