髂主动脉血栓后与正常髂主动脉血流动力学数值模拟对比分析

Comparison of hemodynamics in iliac aortic with thrombosis and normal iliac aortic based on numerical simulation

目的简化基于临床采集的增强CT图像数据进行人体腹主动脉及髂动脉真实三维解剖结构的过程,提高计算流体力学(CFD)计算结果的可靠性,并对比分析正常髂动脉和髂动脉血栓后血管内血流情况,为阐明动脉粥样硬化血栓的形成机制提供理论依据。方法患者A为40岁男性,腹主动脉及髂动脉正常;患者B为60岁女性,腹主动脉正常,但左髂主动脉部分血栓及左髂内动脉血栓。CT图像为医学数字成像与通信标准(DICOM)格式,层间距为0.5 mm,每片图像的平面分辨率为512×512,像素大小为0.5mm。应用医学后处理软件对通过临床采集的增强CT二维图像数据进行三维重构,然后在通用有限元分析软件ANSYS中转换成可用于数值计算的计算机辅助设计(CAD)模型并直接进行CFD模拟计算。结果通过计算可得到A、B研究对象在心动周期内不同时刻的血流动力学参数。B研究对象左和右髂动脉感兴趣区域的平均壁面切应力(0.576 6±0.009 0,3.260 2±0.032 0)明显区别于A研究对象左和右髂动脉感兴趣区域的平均壁面切应力(1.269 8±0.008 0,1.393 2±0.011 0)。结论通过CFD模拟方法的改进,得到更加接近生理解剖特征的血栓后不规则血管三维立体模型,并通过对比A、B研究对象的计算结果,分析了复杂的血流情况如低流速、低壁面切应力等现象与动脉粥样硬化血栓的形成机制存在一定的关系。

Objective To simplify the processing of three-dimensional structure of abdominal aorta and iliac arteries based on clinical enhanced CT image data and improve the reliability of computational fluid dynamic（CFD） results,and study the athemthrombosis formation mechanism by comparing the blood flow in normal iliac artery and the iliac artery with thrombosis.Methods Patient A,male,40-year-old,with normal abdominal aorta and iliac arteries;patient B,female,60-year-old,with normal abdominal aorta and athemthrombosis in left iliac arteries.CT image was presented in the format of the digital imaging and communications in medicine（DICOM）,with layer distance of 0.5 mm,plane resolution of 512 × 512 and pixel size of 0.5 mm.The two-dimensional image of enhanced CT was put into medical image post-processing software to reconstruct three-dimensional model,which was subsequently converted into computer aided design（CAD） model and the simulation in finite element analysis software ANSYS was performed.Results The hemodynamic parameters of patient A and B at different time during a cardiac cycle should be calculated.The average wall shear stresses at the specific interest locations of the left（0.576 6 ± 0.009 0） and right（3.260 2 ± 0.032 0） iliac artery of patient B were significantly different from that at the specific interest locations of the left（1.269 8 ± 0.008 0） and right（1.393 2 ± 0.011 0） iliac artery of patient A.Conclusion It is demonstrated that a more reliable three-dimensional model of the irregular artery with thrombosis could be obtained by using the improved CFD simulation method.The relationship between the complex phenomenon in iliac artery（such as low blood flow,low wall shear stress and so on） and the formation mechanism of athemthrombosis were also investigated.