Improving the computational modeling of coiled cerebral aneurysms through synchrotron microtomography

在这里，我们试图提高弹簧圈栓塞脑动脉瘤的血流动力学建模的准确性。这一目标 由于脑动脉瘤的患病率，其破裂时的预后不良，以及治疗 失败率（导致动脉瘤复发和脑出血或需要再次治疗的风险） 高达25%。血流动力学被认为会影响动脉瘤治疗结果，但标准 弹簧圈动脉瘤内此类力的计算流体动力学（CFD）建模方法（称为 “多孔介质技术”）容易出错。提高弹簧圈栓塞动脉瘤CFD建模的准确性将 加强患者特异性CFD的预测价值，这可以提高动脉瘤治疗疗效， 减少死亡和残疾，以及与多次住院相关的医疗保健费用。 该项目建立在我们正在进行的NIH资助的专业知识，在创建脑动脉瘤的CFD模型， 并与欧洲同步加速器研究机构合作，开发一种改进的计算流体动力学方法 可应用于临床环境的盘绕脑动脉瘤的建模。首先，我们将创造高保真 基于患者特定动脉瘤解剖结构的3D打印动脉瘤模型，并将其商业化- 实际患者治疗中使用的可用动脉瘤弹簧圈。这些螺旋动脉瘤模型将 使用同步加速器X射线显微断层扫描技术，以12 µm的分辨率进行扫描，提供 复杂的线圈几何形状。这些图像将被纳入临床相关血流动力学的CFD模型中 变量，并将被视为其他建模技术进行比较的参考标准。 然后，我们将使用标准多孔 中等技术来表示线圈质量。该技术将复杂的线圈几何形状简化为 均匀孔隙率的材料，我们的初步分析表明，这是一个显着的误差来源， 计算血流动力学变量。我们将通过将这些CFD模型与 参考使用显微断层扫描创建的标准CFD模型。 然后，我们将采用多尺度展开技术的均匀化，其中复杂的 线圈质量的结构由更好地近似磁导率的宏观方程表示。我们 将开发一套校正因子（“线圈建模工具包”），可用于未来的CFD模型， 弹簧圈栓塞动脉瘤的准确性优于标准多孔介质技术。 最后，我们将通过使用线圈建模工具包来确定该技术的改进精度， 创建一组新动脉瘤的CFD模型，不需要3D打印和显微断层扫描。 我们将这些结果与参考标准进行比较（使用CFD和使用体外流量测量 通过3D打印模型），并量化使用线圈建模工具包获得的准确性提高。 准确性的提高将加强动脉瘤治疗CFD研究的临床影响。

Here we seek to improve the accuracy of hemodynamic modeling of coiled cerebral aneurysms. This goal is significant due to the prevalence of cerebral aneurysms, their dismal prognosis when ruptured, and treatment failure rates (resulting in aneurysm recurrence and risk of either brain hemorrhage or need for retreatment) of up to 25%. Hemodynamic forces are thought to influence aneurysm treatment outcomes, but the standard method of computational fluid dynamics (CFD) modeling of such forces within coiled aneurysms (termed the “porous medium technique”) is error-prone. Improving the accuracy of CFD modeling of coiled aneurysms will strengthen the predictive value of patient-specific CFD, which could improve aneurysm treatment efficacy and reduce death and disability, as well as health care costs associated with multiple hospitalizations. This project builds on our ongoing NIH-funded expertise at creating CFD models of brain aneurysms, and a partnership with the European Synchrotron Research Facility, to develop an improved method of CFD modeling of coiled cerebral aneurysms that can be applied in a clinical setting. First, we will create high-fidelity 3D-printed aneurysm models based on patient-specific aneurysm anatomy, and place the same commercially- available aneurysm coils used in actual patient treatment into each model. These coiled aneurysm models will be scanned at 12 µm resolution using synchrotron x-ray microtomography, providing detailed 3D images of the complex coil geometry. These images will be incorporated into CFD models of clinically relevant hemodynamic variables, and will be considered a reference standard to which other modeling techniques are compared. Then, we will create a new set of CFD models of the same aneurysms, using the standard porous medium technique to represent the coil mass. This technique simplifies the complex coil geometry into a material of uniform porosity, which our preliminary analysis suggests is a source of significant error in the calculation of hemodynamic variables. We will quantify this error by comparing these CFD models to the reference standard CFD models created using microtomography. Then, we will employ the homogenization of multiple scale expansions technique, in which the complex structure of the coil mass is represented by macroscopic equations that better approximate permeability. We will develop a set of corrective factors (a “coil modeling toolkit”) that can be used in future CFD models of coiled aneurysms with better accuracy than the standard porous medium technique. Finally, we will determine the improved accuracy of this technique by using the coil modeling toolkit to create CFD models of a new set of aneurysms, for which 3D-printing and microtomography are not required. We will compare these results to the reference standard (both using CFD and using in vitro flow measurements through 3D-printed models) and quantify the improvement in accuracy gained using the coil modeling toolkit. This improved accuracy will strengthen the clinical impact of CFD studies of aneurysm treatment.