Determinants of Intracranial Aneurysm Growth

描述（由申请人提供）：颅内动脉瘤存在因占位效应或出血导致死亡或毁灭性损伤的巨大风险。首次就诊时检测到的动脉瘤尺寸范围很广。然而，关于动脉瘤随时间推移的进展率知之甚少。长期以来，人们一直怀疑血流动力学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流动力学描述符可以预测未来的生长。来自未破裂颅内动脉瘤国际研究的最新结果表明，尝试修复直径小于7 mm的动脉瘤的风险超过了该介入治疗的获益。因此，现在有一组囊状颅内动脉瘤患者没有接受治疗，并且可以通过非侵入性成像进行随访。这些患者是更广泛的颅内循环动脉瘤患者组的一部分，对这些患者没有安全有效的干预措施。该项目的目标是通过非侵入性磁共振成像每两年监测一次此类患者。使用从患者特定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，以确定每个动脉瘤中的血流动力学条件。将通过共同配准的系列成像研究测量动脉瘤管腔体积和/或管腔内血栓体积随时间的进展。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。具体而言，我们假设，指定低壁剪切应力阈值，壁剪切应力低于该阈值的表面积越大，动脉瘤体积随时间的增加越大。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领域实施更全面的流速测量。我们的计算流体力学方法将扩展到非牛顿效应的模型，并在体内的速度测量将用于选择哪种模型是最合适的。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的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。 该项目将深入了解动脉瘤进展的潜在机制，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.