以CT图像为基础的冠状动脉狭窄处血流动力学研究

A Hemodynamic Study of Stenosed Coronary Artery Based on CT Images

目的:冠状动脉粥样硬化好发于具有特殊几何构型的血管部位,提示血流动力学参数在粥样硬化形成方面起到重要作用。以往研究多局限于理想的血管模型,本文旨在探索以CT图像为基础构建个体化冠状动脉血流动力学模型的技术方法,对人体左冠状动脉前降支粥样硬化病变狭窄处进行计算流体动力学(computational fluid dynamics,CFD)数值模拟,探讨冠状动脉粥样硬化病变形成和发展的血流动力学机制。方法:用MIMICS软件读取CTA数据,以CT图像为基础进行冠状动脉三维几何建模,假设动脉血流为层流、不可压缩、牛顿流体,入口血液流速随时间周期性变化,应用有限体积法FLUENT软件进行血流数值模拟,分析与动脉粥样硬化形成、发展相关的血流动力学参数。结果:获得个体化左冠状动脉前降支狭窄处血管模型及血流动力学参数,数值模拟结果包括冠状动脉的血液流场、壁面压力(wall pressure WP)及壁面切应力(wall shear stress WSS)分布,可见狭窄段血管血液流速加快,WP降低、WSS增高,且在狭窄邻近区域出现低WSS区、较高的WP及血液湍流区域。结论:以CT图像为基础的CFD技术是在体评价人狭窄冠状动脉内血流动力学状况与冠状动脉粥样硬化病变之间关系的有效方法,能够更为真实的建立人体血管几何模型,为分析血流动力学参数与冠状动脉粥样硬化形成与发展的关系提供研究手段。

Objective： Coronary atherosclerosis shows a predilection in regions of arterial trees with geometrical particularities, which indicates that hemodynamic parameters are closely related to atherosclerosis formation. We aim to establish a patient-specific hemodynamic model based on CT images and to simulate numerically the local hemodynamics in anatomically realistic human stenosed lefl anterior descending （LAD） coronary artery using computational fluid dynamics （CFD） techniques, in order to investigate the hemodynamic mechanism of coronary atherosclerosis formation and progression. Methods： A 3D realistic model of the left coronary artery was reconstructed from DICOM format computed tornography angiography （CTA） images of a male patient. The geometry was reconstructed using medical image processing software MIMICS. A time-dependent pulsatile boundary condition was deployed at the inlet. Unsteady blood flow simulation was performed in real geometry of the artery with a finite volume method code. The bemodynamic parameters related with the formation and progression of atherosclerosis were analyzed. Results： A patient-specific vascular model was established and contours of hemodynamic parameters were displayed, including vectors of velocity, wall pressure （WP） and wall shear stress 0VSS） distributions. High blood flow velocity with low WP, high WSS were observed in the regions of stenosed LAD, while distributions of low WSS, high WP, blood turbulence were observed in the vicinity. Conclusion： CT image-based CFD is an effective method in elucidating in vivo the role of hemodynamics in the formation and progression of coronary artery atherosclerosis. R provides a more realistic way to establish human vascular models, in order to further study the relationship between hemodynamic parameters and atherosclerosis.