PDF(Pubmed)
Abstract：
Introduction: Computational fluid dynamics (CFD) assess biological systems based on specific boundary conditions. We propose modeling more advanced hemodynamic metrics, such as core line length (CL) and critical points which characterize complexity of flow in the context of cerebral vasculature, and specifically cerebral veins during the physiologically evolving early neonatal state of vein of Galen malformations (VOGM). CFD has not been applied to the study of arteriovenous shunting in Vein of Galen Malformations but could help illustrate the pathophysiology of this malformation. Methods: Three neonatal patients with VOGM at Boston Children\'s Hospital met inclusion criteria for this study. Structural MRI data was segmented to generate a mesh of the VOGM and venous outflow. Boundary condition flow velocity was derived from PC-MR sequences with arterial and venous dual velocity encoding. The mesh and boundary conditions were applied to model the cerebral venous flow. We computed flow variables including mean wall shear stress (WSSmean), mean OSI, CL, and the mean number of critical points (nCrPointsmean) for each patient specific model. A critical point is defined as the location where the shear stress vector field is zero (stationary point) and can be used to describe complexity of flow. Results: The division of flow into the left and right venous outflow was comparable between PC-MR and CFD modeling. A high complexity recirculating flow pattern observed on PC-MR was also identified on CFD modeling. Regions of similar WSSmean and OSImean (<1.3 fold) in the left and right venous outflow channels of a single patient have several-fold magnitude difference in higher order hemodynamic metrics (> 3.3 fold CL, > 1.7 fold nCrPointsmean). Specifically, the side which developed JBS in each model had greater nCrPointsmean compared to the jugular bulb with no stenosis (VOGM1: 4.49 vs. 2.53, VOGM2: 1.94 vs. 0, VOGM3: 1 vs. 0). Biologically, these regions had subsequently divergent development, with increased complexity of flow associating with venous stenosis. Discussion: Advanced metrics of flow complexity identified in computational models may reflect observed flow phenomena not fully characterized by primary or secondary hemodynamic parameters. These advanced metrics may indicate physiological states that impact development of jugular bulb stenosis in VOGM.
摘要：
简介：计算流体动力学（CFD）根据特定的边界条件评估生物系统。我们建议对更先进的血液动力学指标进行建模，例如核心线长度（CL）和临界点，这些临界点在脑血管系统的背景下表征流动的复杂性，特别是在盖伦畸形（VOGM）的生理演变的早期新生儿静脉状态期间的脑静脉。CFD尚未应用于Galen畸形静脉的动静脉分流研究，但可以帮助说明该畸形的病理生理学。方法：波士顿儿童医院的3例VOGM新生儿患者符合本研究的纳入标准。将结构MRI数据分段以生成VOGM和静脉流出物的网格。边界条件流速来自具有动脉和静脉双速度编码的PC-MR序列。网格和边界条件用于对脑静脉流量进行建模。我们计算了流量变量，包括平均壁面剪应力(WSSmean)，意思是OSI，CL,和每个患者特定模型的平均临界点数(nCrPointsmean)。临界点定义为剪切应力矢量场为零的位置（固定点），可用于描述流动的复杂性。结果：在PC-MR和CFD建模之间，左右静脉流出的血流划分具有可比性。在CFD建模中还确定了在PC-MR上观察到的高复杂性再循环流动模式。单个患者的左静脉流出通道和右静脉流出通道中相似的WSSmean和OSImean（<1.3倍）的区域在高阶血液动力学指标中具有几倍的幅度差异（>3.3倍CL，>1.7倍nCrPointsmean)。具体来说,与无狭窄的颈静脉球相比，在每个模型中形成JBS的一侧的nCrPointsmean更大（VOGM1：4.49vs.2.53，VOGM2：1.94vs.0，VOGM3：1与0).生物学,这些地区后来有了不同的发展，与静脉狭窄相关的流量复杂性增加。讨论：计算模型中确定的流量复杂性的高级度量可能反映了观察到的流量现象，这些现象未完全由主要或次要血液动力学参数表征。这些高级度量可以指示影响VOGM中颈静脉球狭窄发展的生理状态。
