Effect of Blood Transfusion on Cerebral Hemodynamics and Vascular Topology Described by Computational Fluid Dynamics in Sickle Cell Disease Patients.

The main objective of this study was to demonstrate that computational fluid dynamics (CFD) modeling can be used to study the contribution of covert and overt vascular architecture to the risk for cerebrovascular disease in sickle cell disease (SCD) and to determine the mechanisms of response to therapy such as chronic red blood cell (cRBC) transfusions. We analyzed baseline (screening), pre-randomization and study exit magnetic resonance angiogram (MRA) images from 10 (5 each from the transfusion and observation arms) pediatric sickle SCD participants in the silent cerebral infarct transfusion (SIT) trial using CFD modeling. We reconstructed the intracranial portion of the internal carotid artery and branches and extracted the geometry using 3D Slicer. We cut specific portions of the large intracranial artery to include segments of the internal carotid, middle, anterior, and posterior cerebral arteries such that the vessel segment analyzed extended from the intracranial beginning of the internal carotid artery up to immediately after (~0.25 inches) the middle cerebral artery branching point. Cut models were imported into Ansys 2021R2/2022R1 and laminar and time-dependent flow simulation was performed. Change in time averaged mean velocity, wall shear stress, and vessel tortuosity were compared between the observation and cRBC arms. We did not observe a correlation between time averaged mean velocity (TAMV) and mean transcranial Doppler (TCD) velocity at study entry. There was also no difference in change in time average mean velocity, wall shear stress (WSS), and vessel tortuosity between the observation and cRBC transfusion arms. WSS and TAMV were abnormal for 2 (developed TIA) out of the 3 participants (one participant had silent cerebral infarctions) that developed neurovascular outcomes. CFD approaches allow for the evaluation of vascular topology and hemodynamics in SCD using MRA images. In this proof of principle study, we show that CFD could be a useful tool and we intend to carry out future studies with a larger sample to enable more robust conclusions.

本研究的主要目的是证明计算流体动力学（CFD）建模可用于研究隐匿性和显性血管结构对镰状细胞病（SCD）脑血管疾病风险的影响，并确定对诸如慢性红细胞（cRBC）输血等治疗的反应机制。我们使用CFD建模分析了沉默性脑梗死输血（SIT）试验中10名（输血组和观察组各5名）儿童镰状SCD参与者的基线（筛查）、随机分组前和研究结束时的磁共振血管造影（MRA）图像。我们重建了颈内动脉及其分支的颅内部分，并使用3D Slicer提取了几何形状。我们切割了颅内大动脉的特定部分，包括颈内动脉、大脑中动脉、大脑前动脉和大脑后动脉的节段，使得所分析的血管节段从颈内动脉的颅内起始处延伸至大脑中动脉分支点之后紧邻处（约0.25英寸）。切割后的模型被导入Ansys 2021R2/2022R1，并进行了层流和时间相关的血流模拟。比较了观察组和cRBC输血组之间时间平均平均流速、壁面剪切应力和血管迂曲度的变化。我们在研究开始时未观察到时间平均平均流速（TAMV）与平均经颅多普勒（TCD）流速之间的相关性。观察组和cRBC输血组之间在时间平均平均流速、壁面剪切应力（WSS）和血管迂曲度的变化上也没有差异。在出现神经血管结局的3名参与者中，有2名（发生短暂性脑缺血发作）的WSS和TAMV异常（1名参与者有沉默性脑梗死）。CFD方法允许使用MRA图像评估SCD中的血管拓扑结构和血流动力学。在这项原理验证研究中，我们表明CFD可能是一种有用的工具，并且我们打算在未来进行更大样本的研究，以得出更可靠的结论。