The Study On Mechanical Property Of Plaque Based On High-resolution Ultrasound Imaging

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.