Vascular Modelling of Complex Flow in Aneurysms and Endovascular Devices

血管血流模型和测量平台为探索血管几何形状(如脑动脉瘤)中的复杂血流，包括介入设备的影响提供了关键工具。典型的动脉瘤血管内介入治疗包括插入弹簧圈、支架或分流装置，其目的是在动脉瘤内实现血流停滞和血栓形成。特定设备实施的结果取决于体内的流动条件，即流量、压力梯度和下游阻抗，这些因素关键地决定了设备的影响和潜在的并发症。人们也越来越认识到，扰动和类湍动的流动条件在血管病理中发挥着重要作用，特别是通过壁面切应力的低和多方向振荡。粒子图像测速(PIV)是一种重要的基准测量工具，它通过分析激光激发的荧光微粒的图像，在流动的横截面上提供瞬时速度矢量测量。PIV提供了高时间和空间分辨率的3D速度矢量映射，因此它唯一能够捕获3D流动扰动，如涡流脱落、高频振荡和向湍流样流动的转变，如血管模型中的。我们的目标是开发一个集成的脑血管血流模拟平台，其中包括我们的高分辨率PIV系统，该系统将能够根据患者特定的动脉瘤几何形状快速测试血管内设备。我们将开发快速3D打印透明患者特定动脉瘤几何图形的方法。这些模型将被整合到脑血管流动系统中，能够根据需要以预测性的方式改变下游阻抗，以再现患者特定的压力和流动波形。建议的系统将包括迄今为止最高水平的生理现实主义，具有患者特定的几何和波形、顺应性血管、非牛顿流体以及高时间和空间分辨率来捕捉流动不稳定性。

Vascular flow models and measurement platforms provide a critical tool for exploring complex flow in vascular geometries such as brain aneurysms, including the effects of interventional devices. Typical endovascular interventions for aneurysms include insertion of coils, stents, or flow diverters, which aim to achieve flow stagnation and thrombosis within the aneurysm. The outcome of a particular device implementation is dependent upon in vivo flow conditions namely flow rates, pressure gradients, and downstream impedances that critically determine device impact and potential complications. It is also increasingly recognized that disturbed and turbulent-like flow conditions play a fundamental role in vascular pathology, particularly through low and multidirectional oscillations in wall shear stress. Particle image velocimetry (PIV) is an essential benchmarking tool that provides instantaneous velocity vector measurements in a cross-section of flow via analysis of images of fluorescent micro-particles excited by laser illumination. PIV offers high temporal and spatial resolution mapping of 3D velocity vectors, and it is thus uniquely able to capture 3D flow disturbances, such as vortex shedding, high-frequency oscillations, and transition to turbulent-like flow, such as in vascular models. We aim to develop an integrated cerebrovascular flow simulation platform including our high-resolution PIV system that will enable the rapid testing of endovascular devices in patient-specific aneurysm geometries. We will develop methodology for the rapid 3D-printing of transparent patient-specific aneurysm geometries. These models will be incorporated into a cerebrovascular flow system with the capacity to vary downstream impedances in a predictive fashion as necessary to reproduce patient-specific pressure and flow waveforms. The proposed system will include the highest level of physiological realism to date, with patient-specific geometries and waveforms, compliant vessels, non-Newtonian fluid, and high temporal and spatial resolution to capture flow instabilities.