Vascular Modelling of Complex Flow in Aneurysms and Endovascular Devices

血管流动模型和测量平台为探索复杂的血管几何结构（如脑动脉瘤）提供了重要的工具，包括介入装置的影响。动脉瘤的典型血管内介入包括置入线圈、支架或分流器，其目的是在动脉瘤内实现血流停滞和血栓形成。特定装置实施的结果取决于体内流动条件，即流速、压力梯度和下游阻抗，这是决定装置影响和潜在并发症的关键因素。******人们也越来越认识到，扰动和湍流样流动条件在血管病理学中起着重要作用，特别是通过壁面剪切应力的低和多向振荡。粒子图像测速（PIV）是一种重要的基准测试工具，它通过分析受激光照射激发的荧光微粒子的图像，提供流动截面的瞬时速度矢量测量。PIV提供三维速度矢量的高时间和空间分辨率映射，因此它能够独特地捕获三维流动干扰，如漩涡脱落，高频振荡，以及向湍流样流动的过渡，如血管模型。******我们的目标是开发一个集成的脑血管流模拟平台，包括我们的高分辨率PIV系统，该系统将能够在患者特定的动脉瘤几何形状中快速测试血管内装置。我们将开发透明的特定患者动脉瘤几何形状的快速3d打印方法。这些模型将被整合到脑血管流系统中，该系统有能力以预测的方式改变下游阻抗，以重现患者特定的压力和流量波形。该系统将包括迄今为止最高水平的生理真实感，具有患者特定的几何形状和波形、顺应性血管、非牛顿流体，以及高时间和空间分辨率，以捕获血流不稳定性。

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.