■缺血性中风,发病率很高,残疾,和死亡率,主要是由颈动脉粥样硬化斑块引起的。颈动脉几何结构的差异不可避免地导致局部血流动力学的变异性,在颈动脉粥样硬化的形成中起着关键作用。目前,颈动脉粥样硬化斑块形成的血流动力学和几何学联合机制尚不清楚。因此,这项研究使用四维(4D)流磁共振成像(MRI)表征了颈动脉粥样硬化斑块形成的几何和血流动力学特征。
■最终,本研究检查了61例患者的122条颈动脉。根据颈部血管超声(US)上颈动脉分叉处斑块的存在,颈动脉分为斑块组(N=69)和无斑块组(N=53).最大颈内动脉(ICA)内径与最大颈总动脉(CCA)内径之比(ICA-CCA直径比),分叉角,使用颈部三维飞行时间磁共振血管造影(3DTOF-MRA)测量弯曲度。同时,4D血流MRI用于获得以下颈动脉的血流动力学参数:容积流速,速度,壁面剪应力(WSS),和压力梯度(PG)。使用独立样本t检验比较斑块组和非斑块组之间的颈动脉几何形状和血液动力学变化。
■斑块组与无斑块组之间的ICA-CCA直径比没有显着差异(P=0.124),而分叉角度(P=0.005)和弯曲度(P=0.032)存在显著差异。斑块组分叉角大于无斑块组(60.70°±20.75°vs.49.32°±22.90°),弯曲度小于无斑块组(1.07±0.04vs.1.09±0.05)。两组在容积流速(P=0.351)和流速最大值(velocitymax)(P=0.388)方面无显著差异,但是轴向,圆周,和3DWSS值都有显著不同,包括它们的平均值(所有P值<0.001)和3DWSS的最大值(P<0.001),与平均轴向,圆周,3DWSS值,以及最大3DWSS值,在斑块组中较低。两组在最大PG值(P=0.030)和平均PG值(P=0.026)方面也存在显着差异。这些值在非斑块组大于斑块组。
■大的分叉角和低的颈动脉弯曲是该区域斑块形成的几何危险因素。低WSS和低PG值与颈动脉粥样硬化斑块形成有关。
UNASSIGNED: Ischemic stroke, which has a high incidence, disability, and mortality rate, is mainly caused by carotid atherosclerotic plaque. The difference in the geometric structures of the carotid arteries inevitably leads to the variability in the local hemodynamics, which plays a key role in the formation of carotid atherosclerosis. At present, the combined mechanisms of hemodynamic and geometric in the formation of carotid atherosclerotic plaque are not clear. Thus, this study characterized the geometric and hemodynamic characteristics of carotid atherosclerotic plaque formation using four-dimensional (4D) flow magnetic resonance imaging (MRI).
UNASSIGNED: Ultimately, 122 carotid arteries from 61 patients were examined in this study. According to the presence of plaques at the bifurcation of the carotid artery on cervical vascular ultrasound (US), carotid arteries were placed into a plaque group (N=69) and nonplaque group (N=53). The ratio of the maximum internal carotid artery (ICA) inner diameter to the maximum common carotid artery (CCA) inner diameter (ICA-CCA diameter ratio), bifurcation angle, and tortuosity were measured using neck three-dimensional time-of-flight magnetic resonance angiography (3D TOF-MRA). Meanwhile, 4D flow MRI was used to obtain the following hemodynamic parameters of the carotid arteries: volume flow rate, velocity, wall shear stress (WSS), and pressure gradient (PG). Independent sample t-tests were used to compare carotid artery geometry and hemodynamic changes between the plaque group and nonplaque group.
UNASSIGNED: The ICA-CCA diameter ratio between the plaque group and the nonplaque group was not significantly different (P=0.124), while there were significant differences in the bifurcation angle (P=0.005) and tortuosity (P=0.032). The bifurcation angle of the plaque group was greater than that of the nonplaque group (60.70°±20.75° vs. 49.32°±22.90°), and the tortuosity was smaller than that of the nonplaque group (1.07±0.04 vs. 1.09±0.05). There were no significant differences between the two groups in terms of volume flow rate (P=0.351) and the maximum value of velocity (velocitymax) (P=0.388), but the axial, circumferential, and 3D WSS values were all significantly different, including their mean values (all P values <0.001) and the maximum value of 3D WSS (P<0.001), with the mean axial, circumferential, 3D WSS values, along with the maximum 3D WSS value, being lower in the plaque group. The two groups also differed significantly in terms of maximum PG value (P=0.030) and mean PG value (P=0.026), with these values being greater in the nonplaque group than in the plaque group.
UNASSIGNED: A large bifurcation angle and a low tortuosity of the carotid artery are geometric risk factors for plaque formation in this area. Low WSS and low PG values are associated with carotid atherosclerotic plaque formation.