Yuan Jianmin, Teng Zhongzhao, Feng Jiaxuan, Zhang Yongxue, Brown Adam J, Gillard Jonathan H, Jing Zaiping, Lu Qingsheng
Department of Radiology, University of Cambridge, Cambridge, CB2 0QQ, UK.
Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK.
Int J Numer Method Biomed Eng. 2015 Aug;31(8). doi: 10.1002/cnm.2722. Epub 2015 May 28.
Mechanical analysis has been shown to be complementary to luminal stenosis in assessing atherosclerotic plaque vulnerability. However, patient-specific material properties are not available and the effect of material properties variability has not been fully quantified. Media and fibrous cap (FC) strips from carotid endarterectomy samples were classified into hard, intermediate and soft according to their incremental Young's modulus. Lipid and intraplaque haemorrhage/thrombus strips were classified as hard and soft. Idealised geometry-based 3D fluid-structure interaction analyses were performed to assess the impact of material property variability in predicting maximum principal stress (Stress-P1 ) and stretch (Stretch-P1 ). When FC was thick (1000 or 600 µm), Stress-P1 at the shoulder was insensitive to changes in material stiffness, whereas Stress-P1 at mid FC changed significantly. When FC was thin (200 or 65 µm), high stress concentrations shifted from the shoulder region to mid FC, and Stress-P1 became increasingly sensitive to changes in material properties, in particular at mid FC. Regardless of FC thickness, Stretch-P1 at these locations was sensitive to changes in material properties. Variability in tissue material properties influences both the location and overall stress/stretch value. This variability needs to be accounted for when interpreting the results of mechanical modelling.
在评估动脉粥样硬化斑块易损性方面，力学分析已被证明是对管腔狭窄的补充。然而，患者特异性的材料属性不可得，且材料属性变异性的影响尚未得到充分量化。根据颈动脉内膜切除术样本的增量杨氏模量，将中膜和纤维帽（FC）条带分为硬、中、软三类。脂质和斑块内出血/血栓条带分为硬和软两类。进行了基于理想化几何形状的三维流固相互作用分析，以评估材料属性变异性对预测最大主应力（应力-P1）和拉伸（拉伸-P1）的影响。当FC较厚（1000或600 µm）时，肩部的应力-P1对材料刚度变化不敏感，而FC中部的应力-P1变化显著。当FC较薄（200或65 µm）时，高应力集中从肩部区域转移到FC中部，应力-P1对材料属性变化越来越敏感，尤其是在FC中部。无论FC厚度如何，这些位置的拉伸-P1对材料属性变化敏感。组织材料属性的变异性会影响应力/拉伸的位置和整体值。在解释力学建模结果时需要考虑这种变异性。
