Karmonik C, Klucznik R, Benndorf G
Radiology, The Methodist Hospital Research Institute, 6565 Fannin, Houston, TX 77030, USA.
Rofo. 2008 Mar;180(3):209-15. doi: 10.1055/s-2008-1027135.
Computational fluid dynamics (CFD) simulations are increasingly used to model cerebral aneurysm hemodynamics. We investigated the capability of phase contrast magnetic resonance imaging (pcMRI), guided by specialized software for optimal slice definition (NOVA, Vassol Inc.) as a non-invasive method to measure intra-aneurysmal blood flow patterns in-vivo. In a novel approach, these blood flow patterns measured with pcMRI were qualitatively compared to the ones calculated with CFD.
The volumetric inflow rates into three unruptured cerebral aneurysms and the temporal variations of the intra-aneurysmal blood flow patterns were recorded with pcMRI. Transient CFD simulations were performed on geometric models of these aneurysms derived from 3D digital subtraction angiograms. Calculated intra-aneurysmal blood flow patterns were compared at the times of maximum and minimum arterial inflow to the ones measured with pcMRI and the temporal variations of these patterns during the cardiac cycle were investigated.
In all three aneurysms, the main features of intra-aneurysmal flow patterns obtained with pcMRI consisted of areas with positive velocities components and areas with negative velocities components. The measured velocities ranged from approx. +/- 60 to +/- 100 cm/sec. Comparison with calculated CFD simulations showed good correlation with regard to the spatial distribution of these areas, while differences in calculated magnitudes of velocities were found.
CFD simulations using inflow boundary conditions measured with pcMRI yield main features of intra-aneurysmal velocity patterns corresponding to intra-aneurysmal measurements performed with pcMRI. Thus, pcMRI may become a valuable complementary technique to CFD simulations to obtain in-vivo reference data for the study of aneurysmal hemodynamics. More data is needed to compare and fully explore the capabilities of both methods.
计算流体动力学（CFD）模拟越来越多地用于模拟脑动脉瘤血流动力学。我们研究了在专门用于优化切片定义的软件（NOVA，Vassol公司）指导下的相位对比磁共振成像（pcMRI）作为一种测量体内动脉瘤内血流模式的非侵入性方法的能力。在一种新方法中，将通过pcMRI测量的这些血流模式与通过CFD计算的血流模式进行定性比较。
用pcMRI记录流入三个未破裂脑动脉瘤的体积流入率以及动脉瘤内血流模式的时间变化。对从3D数字减影血管造影获得的这些动脉瘤的几何模型进行瞬态CFD模拟。将计算得到的动脉瘤内血流模式在动脉流入最大和最小时与用pcMRI测量的血流模式进行比较，并研究这些模式在心动周期中的时间变化。
在所有三个动脉瘤中，通过pcMRI获得的动脉瘤内血流模式的主要特征包括具有正速度分量的区域和具有负速度分量的区域。测量的速度范围约为±60至±100厘米/秒。与计算得到的CFD模拟结果比较表明，这些区域的空间分布具有良好的相关性，同时发现速度计算值存在差异。
使用通过pcMRI测量的流入边界条件进行的CFD模拟产生的动脉瘤内速度模式的主要特征与用pcMRI进行的动脉瘤内测量结果相对应。因此，pcMRI可能成为CFD模拟的一种有价值的补充技术，以获得用于研究动脉瘤血流动力学的体内参考数据。需要更多数据来比较和充分探索这两种方法的能力。
