【作者】 李帅；

【导师】 徐礼胜； 郑海荣；

【作者基本信息】 东北大学 ， 生物医学工程， 2016， 硕士

【摘要】 斑块力学特性作为研究动脉粥样硬化的重要因素,已经成为研究热点。已有研究发现应力相位角(SPA)会随着斑块狭窄程度的增大而呈现出更大的负值,这暗示着SPA和易损性之间有着某种联系。但到目前为止,由于缺乏同时测量壁面剪切力(WSS)和周向应变(CS)的合适工具,因此这一猜想还没有实验数据作为支撑。本文利用无创的超声生物力学方法来评估斑块力学特性,并通过体外仿体实验和动物体内实验对斑块力学特性与不同斑块形态之间的相关性进行了研究分析。为了对斑块形态进行分析,本文将体外仿体实验分成不同狭窄程度和不同长度两组。其中不同狭窄度分为30%、50%和70%(斑块长度相同,为8mm),不同长度为8mm、10mm和15mm(斑块狭窄度相同,为50%)。利用体外血管仿体实验装置进行体外实验,并通过高分辨率超声成像系统VevO2100获取体外仿体数据。随后使用超声力学算法对采集得到的体外仿体数据进行计算分析。结果发现随着斑块狭窄程度的增加,SPA的数值分别为-177.46 ±11.72°,-207.50 ± 10.90°和-227.68 ± 21.54°,WSR(壁面剪切率,曲线变化与WSS相同)从3.320增加到13.805。然而随着斑块长度的增加SPA的数值分别为-207.50±10.90°,-182.59 ±32.28° 和-174.98 ± 42.57°,WSR 从 9.594 下降到 2.023。由于所有的仿体都是基于相同的制作周期,因此不同血管仿体的应变(Strain)没有显著性差异。关于动物体内实验,本文使用的实验对象为ApoE基因敲除小鼠。对ApoE基因敲除小鼠进行高脂饲料(配方:脂肪21%。胆固醇0.5%)喂养,喂养时间为10个月。之后利用小鼠颈动脉实验平台进行体内实验,从而通过高分辨率超声成像系统Vevo2100获取小鼠颈动脉数据,再通过超声力学算法进行计算分析。在小鼠数据采集的过程中,根据斑块大小的不同(狭窄程度是否大于50%),将数据分成了两组:小斑块组和大斑块组。动物体内实验的结果与体外仿体实验结果相近:随着斑块严重程度的增加,SPA会更负,WSR增大而strain减小。总而言之,斑块越易损,SPA会更负,WSS增大而CS减小。更多还原

【Abstract】 Mechanical property of artery,as the key factor of the atherosclerosis,has attracted more and more concern on it.Previous studies through the simulation have indicated that stress phase angle(SPA)is more highly negative in where the stenosis is greater,and hypothesized that there may be a subtle relation between SPA and vulnerability.So far,there is no experimental data to support this hypothesis,probably due to the lack of a proper method for estimating wall shear stress(WSS)and circumferential strain(CS)simultaneously.Therefore,a non-invasive ultrasonic biomechanics method was utilized to measure the mechanical property in different types of the stenoses.In this study,vitro and vivo are both developed,questioning how the mechanical property including WSS,CS and SPA,which is the phase difference between WSS and CS,are affected by the severity and the length of the stenoses.Having performed the experiments in vitro,the data were obtained by high-resolution ultrasound imaging system,Vevo 2100,and calculated by ultrasonic mechanics method.In term of severity,three PVA-c phantoms with different stenotic plaques of 30%50%and 70%(all in the same length,8mm)were assembled in a pulsatile flow circuit and SPA were measured to be-177.46±11.72°,-207.50±10.90° and-227.68±21.54° respectively,where wall shear rate(WSR)rapidly grows from 3.320 to 13.805.In area of length,under the three kinds of stenotic plaques in PVA-c phantoms with 8mm,10mm and 15mm(all in the same stenosis degree,50%),SPA were respectively measured to be-207.50±10.90°,-182.59±32.28° and-174,98±42.57°,where WSR plummets from 9.594 to 2.023.CS in both group were slightly transforming because of their same freeze-thaw cycles.As for the experiments in vivo,the animals we used were ApoE rats,which fed with hypercholesterolemic diet(HCD,containing 21%fat and 0.15%cholesterol by weight)for almost 10 months.Having performed the experiments in vivo,the data were obtained by high-resolution ultrasound imaging system,Vevo 2100,and calculated by ultrasonic mechanics method.The results were consistent with the state in vitro that highly negative SPA,bigger WSR and smaller strain with the greater plaque,which could be the vulnerable one.更多还原