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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 process of real three-dimensional anatomy of human abdominal aorta and iliac artery based on clinically acquired enhanced CT image data to improve the reliability of computational fluid dynamics (CFD) calculation results and to compare and analyze the blood flow of normal iliac artery and iliac artery thrombosis Within the blood flow, in order to clarify the formation of atherothrombosis provide a theoretical basis. Methods Patient A was 40 years old and had normal abdominal and aortic arteries. Patient B was 60 years old and had a normal abdominal aorta but partial thrombosis of the left aorta and thrombus of the left internal iliac artery. The CT images are in the format of the Digital Imaging and Communications in Medicine (DICOM) format with a 0.5 mm interlayer spacing and a planar resolution of 512 × 512 for each image and a pixel size of 0.5 mm. The medical post-processing software was used to reconstruct the two-dimensional image data of the augmented CT acquired by clinical practice and then converted into computer-aided design (CAD) model for numerical calculation in the general finite element analysis software ANSYS and directly performed CFD simulation calculation . Results The hemodynamic parameters of subjects A and B at different time points during the cardiac cycle were obtained by calculation. B The average wall shear stress (0.576 6 ± 0.009 0, 3.260 2 ± 0.032 0) in the region of interest of the left and right iliac arteries was significantly different from the mean wall shear stress in the region of interest of the left and right iliac arteries in study A (1.269 8 ± 0.008 0, 1.3993 2 ± 0.011 0). Conclusion Through the improvement of the CFD simulation method, the three-dimensional model of irregular blood vessels after the thrombosis is obtained which is more close to the physiological anatomical features. By comparing the calculated results of the A and B study objects, the complicated blood flow conditions such as low flow velocity, Stress and other phenomena and the formation of atherosclerotic thrombosis exists a certain relationship.