Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
Department of Medical Sciences Industry, Chang Jung Christian University, Tainan, Taiwan.
BMC Neurol. 2020 Jun 20;20(1):251. doi: 10.1186/s12883-020-01831-z.
The purpose of this study was to clarify the effect of asymmetric COW variants on carotid flow changes, and proposed an easy estimate of the representative carotid flow volume for accurate numerical simulation.
A total of 210 healthy adults receiving magnetic resonance angiography and carotid duplex sonography were included. Three anterior cerebral artery asymmetry (AA) groups were defined based on the diameter ratio difference (DRD) of bilateral A1 segments: AA1 group, one-side A1 aplasia; AA2, A1 DRD ≥ 50%; AA3, A1 DRD between 10 and 50%. Similarly, 3 posterior communicating artery (PcomA) asymmetry (PA) groups were defined: PA1 group, one fetal-origin posterior cerebral artery and absent contralateral PcomA; PA2, PcomA DRD ≥ 50%; PA3, PcomA DRD between 10 and 50%.
With A1 asymmetry, the ICA diameter of the dominant A1 is significantly greater than the contralateral side. Significant differences of bilateral ICA flow were present in the AA1 and AA2 groups (mean flow difference 42.9 and 30.7%, respectively). Significant bilateral ICA diameter and flow differences were only found in the PA1 group. Linear regression analysis of ICA diameter and flow found a moderately positive correlation between ICA diameter and flow in all AA groups, with a 1 mm increment in vessel diameter corresponding to a 62.6 ml increment of flow volume. The product of bilateral ICA diameter and flow volume difference (ICA-PDF) could be a potential discriminator with a cutoff of 4.31 to predict A1 asymmetry ≥50% with a sensitivity of 0.81 and specificity of 0.76.
The study verifies that A1 asymmetry causes unequal bilateral carotid inflow, and consequently different bilateral ICA diameters. Adjustment of the inflow boundary conditions according to the COW variants would be necessary to improve the accuracy of numerical simulation.
本研究旨在阐明不对称颈内动脉（ICA）虹吸段（COW）变异对颈动脉血流变化的影响，并提出一种简单的代表性颈动脉血流量估计方法，以实现准确的数值模拟。
共纳入 210 名接受磁共振血管造影和颈动脉双功能超声检查的健康成年人。根据双侧 A1 段直径比差（DRD），将 3 组前交通动脉（A1）不对称（AA）定义为：AA1 组，单侧 A1 发育不全；AA2 组，A1 DRD≥50%；AA3 组，A1 DRD 介于 10%至 50%之间。同样，根据 3 组后交通动脉（PcomA）不对称（PA）定义为：PA1 组，单侧起源于后交通动脉且对侧无 PcomA；PA2 组，PcomA DRD≥50%；PA3 组，PcomA DRD 介于 10%至 50%之间。
在 A1 不对称中，优势 A1 的颈内动脉直径明显大于对侧。AA1 和 AA2 组双侧颈内动脉血流存在显著差异（平均血流差异分别为 42.9%和 30.7%）。仅在 PA1 组发现双侧颈内动脉直径和血流存在显著差异。颈内动脉直径和血流的线性回归分析发现，所有 AA 组的颈内动脉直径与血流之间呈中度正相关，血管直径增加 1mm 对应血流体积增加 62.6ml。双侧颈内动脉直径和血流体积差的乘积（ICA-PDF）可能是一种潜在的鉴别指标，其截点值为 4.31，可预测 A1 不对称≥50%，其敏感性为 0.81，特异性为 0.76。
本研究验证了 A1 不对称导致双侧颈动脉流入不等，进而导致双侧颈内动脉直径不同。根据 COW 变异调整流入边界条件对于提高数值模拟的准确性是必要的。
