Karmonik Christof, Anderson Jeff R, Elias Saba, Klucznik Richard, Diaz Orlando, Zhang Yi Jonathan, Grossman Robert G, Britz Gavin W
Cerebrovascular Center, Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA; MRI Core, Houston Methodist Research Institute, Houston, Texas, USA.
MRI Core, Houston Methodist Research Institute, Houston, Texas, USA.
World Neurosurg. 2017 Sep;105:775-782. doi: 10.1016/j.wneu.2017.06.042. Epub 2017 Jun 15.
Hemodynamics in cerebral aneurysms are currently investigated toward clinical efficacy using nonstandardized computational simulation techniques. At the same time, flow patterns and velocities are accessible by 4-dimensional phase contrast magnetic resonance imaging (4D pcMRI). Complexity of protocol design and imaging duration has limited the use of this technique in clinical imaging. A new approach is presented to overcome these limitations.
Three-dimensional (3D) replicas of 2 cerebral aneurysms were fabricated by fused deposition prototyping (3D printing) and imaged using 4D pcMRI while connected to a magnetic resonance imaging-compatible continuous flow loop. Acquisition parameters were optimized with imaging times not to exceed 10 minutes. Six patients harboring cerebral aneurysms with sizes ranging from 4.7 to 13.8 mm were imaged with the optimized 4D pcMRI protocol. After treatment with the pipeline embolization device (PED), 4D pcMRI examinations were repeated in 3 patients.
In all cases, major flow patterns were visualized well; smaller aneurysms posed a challenge because of limited spatial resolution, whereas larger aneurysms contained regions of low velocity resulting in limited contrast in the flow-sensitive images. After PED placement, ordered aneurysmal flow was disrupted and intra-aneurysmal velocity was reduced on average by 24.5% (range, 12.9-31.5%). Exploratory statistical analysis yielded a positive significant correlation (P < 0.01) between changes in inflow velocity and posttreatment intra-aneurysmal flow velocity.
4D pcMRI flow imaging in cerebral aneurysms within a time frame suitable for clinical imaging applications is feasible with optimized acquisition parameters, thereby enabling quantification of intra-aneurysmal flow changes after flow diverter device treatment.
目前正使用非标准化的计算模拟技术研究脑动脉瘤的血流动力学，以评估其临床疗效。与此同时，通过四维相位对比磁共振成像（4D pcMRI）可获取血流模式和速度。然而，方案设计的复杂性和成像持续时间限制了该技术在临床成像中的应用。本文提出一种新方法以克服这些限制。
通过熔融沉积成型（3D打印）制作了2个脑动脉瘤的三维（3D）模型，并在连接到磁共振成像兼容的连续血流环时使用4D pcMRI进行成像。优化采集参数，使成像时间不超过10分钟。对6例患有大小在4.7至13.8毫米之间脑动脉瘤的患者采用优化的4D pcMRI方案进行成像。在用管道栓塞装置（PED）治疗后，对3例患者重复进行4D pcMRI检查。
在所有病例中，主要血流模式均能清晰显示；较小的动脉瘤由于空间分辨率有限而带来挑战，而较大的动脉瘤包含低速区域，导致血流敏感图像中的对比度受限。放置PED后，动脉瘤内的有序血流被破坏，动脉瘤内平均流速降低了24.5%（范围为12.9 - 31.5%）。探索性统计分析显示，流入速度变化与治疗后动脉瘤内血流速度之间存在显著正相关（P < 0.01）。
通过优化采集参数，在适合临床成像应用的时间范围内对脑动脉瘤进行4D pcMRI血流成像可行，从而能够量化分流装置治疗后动脉瘤内血流的变化。
