Department of Neurosurgery, Nagoya University Graduate School of Medicine, Showa-ku, Aichi, Japan.
Acta Neurochir (Wien). 2012 Jun;154(6):993-1001. doi: 10.1007/s00701-012-1305-5. Epub 2012 Mar 4.
Hemodynamics in intracranial aneurysms is thought to play an important role in their growth and rupture. Usual computed fluid dynamics (CFD) based on three-dimensional (3D) computed tomographic (CT) angiography requires a time-consuming process for analysis. Magnetic resonance fluid dynamics (MRFD) based on MR images is a new tool for analyzing flow dynamics and a promising method for obtaining such information more easily. We compared the data from MRFD and CFD and studied the clinical feasibility of MRFD.
A total of 15 aneurysms, including two ruptured ones, in 15 patients were investigated with MR imaging and 3D-CT angiography. The flow data of MRFD and CFD, 3D stream lines, flow velocity profile and wall shear stress (WSS) were extracted from the image reconstruction and were compared each other.
Both flow dynamics images showed quite similar 3D flow pattern and WSS map. However, the calculated value of maximum WSS was quite different and there was no significant correlation. Further, in one ruptured case, CFD showed less visualization to evaluate the intra-aneurysmal flow. Interestingly, one delayed rupture case showed a particular flow pattern with abnormal secondary flow in the bottom of the aneurysm before rupture, which might suggest the specific finding of rupture risk.
MRFD is a valuable and less invasive tool to evaluate aneurysmal fluid dynamics. It can be obtained from the usual MRI examination without contrast medium and exposure to radiation. Although there is a problem of consistency of the absolute value of WSS between MRFD and conventional CFD, it may be useful to predict the risk of enlargement or rupture of aneurysms based on the information of the similar distribution of WSS and flow patterns. The quantifiable analysis and establishment of a meaningful threshold for high risk should be further studied.
颅内动脉瘤的血流动力学被认为在其生长和破裂中起着重要作用。基于三维（3D）计算机断层血管造影术（CTA）的常规计算流体动力学（CFD）分析需要耗时的过程。基于磁共振成像（MRI）的磁共振流体动力学（MRFD）是一种分析流动动力学的新工具，也是一种更容易获得此类信息的有前途的方法。我们比较了 MRFD 和 CFD 的数据，并研究了 MRFD 的临床可行性。
对 15 例患者的 15 个动脉瘤（包括 2 个破裂动脉瘤）进行了 MRI 和 3D-CTA 检查。从图像重建中提取了 MRFD 和 CFD 的流量数据、3D 流线、流速分布和壁面剪切应力（WSS），并相互比较。
两种血流动力学图像均显示出非常相似的 3D 流型和 WSS 图。然而，计算得到的最大 WSS 值差异较大，且无显著相关性。此外，在一个破裂病例中，CFD 显示出对评估瘤内血流的可视化效果较差。有趣的是，一个迟发性破裂病例在破裂前的动脉瘤底部显示出异常的二次流，这可能提示了破裂风险的特定发现。
MRFD 是一种评估动脉瘤血流动力学的有价值的、微创的工具。它可以从常规 MRI 检查中获得，无需造影剂和辐射暴露。尽管 MRFD 和传统 CFD 之间的 WSS 绝对值的一致性存在问题，但根据 WSS 和流型分布的相似信息，它可能有助于预测动脉瘤的扩大或破裂风险。需要进一步研究可量化分析和建立有意义的高危阈值。
