基于磁共振成像的颈动脉粥样硬化斑块局部血流动力学平台研究

Assessment of hemodynamic changes near carotid atherosclerotic plaques by using magnetic resonance imaging and computational fluid dynamics

目的 建立颈动脉MRI和计算流体力学相结合的研究平台,分析颈动脉粥样硬化斑块结构学和血流动力学改变,以探讨血流动力学因素在斑块稳定性评价中的价值.方法 共13例颈动脉粥样硬化性脑血管病患者接受颈动脉MRI和增强磁共振血管成像检查,根据斑块形态分析斑块周围血流动力学参数变化.结果 共检出颈内动脉粥样硬化斑块15例次,Ⅳ～Ⅴ型5例次、Ⅵ型8例次、Ⅶ型l例次、Ⅷ型1例次.斑块周围血流动力学参数分别为管壁切应力（79.86± 57.83） Pa、静态压（-7586.81±9313.83） Pa、血流速度（2.76± 1.81） m/s,与正常对照组相比,斑块周围管壁切应力呈不均匀升高、静态压不均匀下降,斑块邻近血流为层流、呈喷射状,血流速度明显增加,且差异具有统计学意义（均P=0.000）.结论 颈动脉MRI与计算流体力学相结合可以实现对颈动脉粥样硬化斑块结构学和血流动力学的综合分析,从而揭示了血流动力学因素可以影响颈动脉粥样硬化斑块的发展和稳定性.

Objective To establish a platform by using carotid MRI and computational fluid dynamics （CFD） to assess hemodynamic changes around carotid atherosclerotic plaques.Methods Thirteen patients with carotid atherosclerosis were recruited in this study.Six volunteers were regarded as normal controls.All the patients and volunteers underwent carotid MRI and contrast-enhanced magnetic resonance angiography （CEMRA）.Carotid MRI was used to visualize the plaque structures and components.All plaques were divided into different types according to plaque components.CEMRA images were used to obtain three-dimensional （3D） models of carotid bifurcations,whose boundary conditions were specified using CFD front-end software,and then the mesh file of the 3D models were obtained to import to CFD software to visualize hemodynamic maps,including wall shear stress （WSS）,static pressure and blood velocity.Results Fifteen diseased internal carotid arteries （ICAs） were assessed.According to the MRI appearance of the plaques,the types of these plaques were from Ⅳ-Ⅴ to Ⅷ.All of these were vulnerable plaques which caused irregular stenosis of ICAs.The WSS,static pressure and blood velocity were （79.86± 57.83） Pa,（-7586.81 ± 9313.83） Pa,（2.76±1.81） m/s,respectively in the diseased ICAs group and （2.52 ± 0.58） Pa,（-71.65 ± 30.89） Pa,（0.21 ± 0.06） m/s,respectively in the normal control group.In the diseased ICAs group WSS was elevated heterogenously and static pressure was decreased heterogenously near the plaques.The blood velocity near the plaques was increased but still streamlined.Statistical significant differences were shown for WSS,static pressure and blood velocity between 2 groups （P =0.000,for all）.Conclusions The platform combining MRI and CFD can be used to analyze the plaque structures and fluid dynamic change near the plaques,suggesting hemodynamics plays an important role in the plaque progression and vulnerability.