Determinants of Intracranial Aneurysm Growth

摘要： 颅内动脉瘤呈现出巨大的死亡或毁灭性伤害风险，无论是由于集体效应还是 大出血。首次发现的动脉瘤大小不一。然而，人们对此知之甚少 关于随着时间推移动脉瘤的进展速度。长期以来，人们一直怀疑血液动力学力量 在动脉瘤的发生和破裂中起着重要作用，但据我们所知，还没有文献报道 这表明，动脉瘤的哪些血流动力学描述可以预测未来的增长。 国际未破裂颅内动脉瘤研究的最新结果表明， 试图修补直径小于7毫米的动脉瘤超过了介入的好处。 因此，现在有一群患有囊性颅内动脉瘤的患者没有接受治疗， 以及谁可以通过非侵入性成像进行追踪。这些患者是更广泛的患者群体中的一部分 颅内循环动脉瘤，目前尚无安全有效的干预措施。 这个项目的目标是用非侵入性磁共振每两年监测一次这类患者 成像。使用从患者特定的体内成像获得的边界值(几何和速度)， 将进行计算流体动力学(CFD)模拟以确定血流动力学条件 在每个动脉瘤中。动脉瘤腔体积和/或腔内血栓体积随时间的进展 将通过共同注册的系列成像研究进行测量。不同候选人之间的关系 将寻找血流动力学变量和观察到的动脉瘤生长情况。具体来说，我们假设， 指定较低的壁面剪应力阈值，则壁面剪应力低于的表面积越大 这个阈值越大，随着时间的推移，动脉瘤体积就会增加。 除了使用已经建立的标准方法外，我们还将开发新的成像能力， 并将对整个血管区域的流速进行更全面的测量 利息。我们的CFD方法将被扩展到模拟非牛顿效应，以及体内的速度 将使用测量结果来选择最适合的型号。随着这些新工具的问世，他们 将被用来提高我们方法的准确性。这个项目代表了翻译研究方面的努力。 针对神经血管疾病的一个重要组成部分。 公共卫生相关性：这项研究将确定颅内动脉瘤的生长与 和血液动力学力量。这些信息将被用来指导临床医生进行哪些介入治疗 可能会被考虑，以及何时可能最好地实施。

Abstract: Intracranial aneurysms present a formidable risk of death or devastating injury either from mass effect or hemorrhage. Aneurysms are detected with a broad range of sizes on first presentation. However, little is known about the rate of progression of aneurysms over time. It has long been suspected that hemodynamic forces play an important role in the genesis and rupture of aneurysms, but there is, to our knowledge, no literature that demonstrates which hemodynamic descriptors of an aneurysm are predictive of future growth. Recent results from the International Study of Unruptured Intracranial Aneurysms demonstrate that the risk of attempting a repair of aneurysms smaller than 7 mm in diameter exceeds the benefit from that intervention. There is now, therefore, a group of patients with saccular intracranial aneurysms who are not being treated, and who can be followed by non-invasive imaging. These patients are part of a broader group of patients with aneurysms of the intracranial circulation for whom there are no safe and effective interventions. The goal of this project is to monitor such patients on a bi-annual basis with non-invasive Magnetic Resonance Imaging. Using boundary values (geometric and velocity) obtained from patient-specific in-vivo imaging, Computational Fluid Dynamics (CFD) simulations will be performed to determine the hemodynamic conditions in each aneurysm. Progression over time in aneurysm lumen volume and/or volume of intralumenal thrombus will be measured from co-registered serial imaging studies. A relationship between different candidate hemodynamic variables and observed aneurysm growth will be sought. Specifically, we hypothesize that, specifying a low wall shear stress threshold value, the larger the surface area is with wall shear stress below that threshold value the greater will be the increase in aneurysm volume over time. In addition to using the standard methodology already established, we will develop new imaging capabilities, and will implement more comprehensive measurements of flow velocities throughout the vascular territory of interest. Our CFD methods will be extended to model non-Newtonian effects, and the in-vivo velocity measurements will be used to select which model is most suitable. As these new tools become available they will be used to improve the accuracy of our methods. This project represents an effort in translational research directed at an important component of neurovascular disorders. Public Health Relevance: This study will determine the relationship between growth of intracranial aneurysms and hemodynamic forces. That information will be used to guide clinicians as to what interventional treatments might be considered, and when they might best be implemented.