Determinants of Intracranial Aneurysm Growth

描述（由申请人提供）：颅内动脉瘤存在巨大的死亡风险或因肿块效应或出血造成的毁灭性伤害。动脉瘤在第一次出现时被发现的大小范围很广。然而，随着时间的推移，人们对动脉瘤的发展速度知之甚少。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，没有文献表明动脉瘤的血液动力学描述符可以预测未来的生长。来自国际未破裂颅内动脉瘤研究的最新结果表明，尝试修复直径小于7毫米的动脉瘤的风险超过了这种干预的益处。因此，现在有一群患有囊状颅内动脉瘤的患者没有接受治疗，他们可以接受非侵入性成像。这些患者是颅内循环动脉瘤患者的一部分，他们没有安全有效的干预措施。该项目的目的是监测这类患者一年两次的基础上，无创磁共振成像。利用从患者特异性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，以确定每个动脉瘤的血流动力学状况。动脉瘤腔体积和/或腔内血栓体积随时间的进展将通过联合登记的系列影像学研究来测量。将寻求不同候选血流动力学变量与观察到的动脉瘤生长之间的关系。具体来说，我们假设，指定一个较低的壁面剪应力阈值，壁面剪应力低于该阈值的表面积越大，随着时间的推移，动脉瘤体积的增加越大。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，并将在整个感兴趣的血管区域内实施更全面的流速测量。我们的CFD方法将扩展到非牛顿效应的模型，并使用体内速度测量来选择最合适的模型。随着这些新工具的出现，它们将被用来提高我们方法的准确性。该项目代表了针对神经血管疾病重要组成部分的转化研究的努力。公共卫生相关性：本研究将确定颅内动脉瘤生长与血流动力学力之间的关系。这些信息将用于指导临床医生考虑哪些介入治疗，以及何时最好实施这些治疗。该项目将深入了解动脉瘤发展的潜在机制，并有助于指导这种毁灭性疾病的治疗。

DESCRIPTION (provided by applicant): 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 intraluminal 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 a 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. The project will provide insight into the underlying mechanisms of aneurysm progression and could help in guiding treatment for this devastating condition.