孤立性颈动脉粥样硬化斑块内膜长轴切面力学状态的初步超声研究

摘要

Objective To evaluate the mechanical homogeneity pattern of isolated carotid atherosclerotic plaque intima on longitudinal axis view using ultrasonic velocity vector imaging.Methods Fourty six patients with 48 isolated plaques were undergone the high frequency ultrasound scanning,the real-time two-dimensional longitudinal-axis gray scale view at the maximal thickness of the plaque was obtained in three complete cardiac cycles.A dedicated velocity vector imaging(ⅤⅤⅠ)workstation was used for the off-line dynamic two-dimensional gray-scale image analysis and mechanics parameter(i.e.,the peak strain and the absolute difference of the peak strain)assessment at the sites of the upper,middle and down stream separately.The length and direction distribution of the velocity vectors at the carotid atherosclerotic plaque intima were observed.Wilcoxon test was utilized for the comparison of the peak strain and the absolute difference of the peak strain between two sites.Results The chaos phenomenon of velocity vector distribution at the sites of plaque intima occurred significantly differed from those uniform velocity vectors at the reference sites.According to the two groups of the higher strain value side and the lower strain value side on the upper stream and the down stream of the plaque intima,the peak strain at the higher strain value side was significantly higher than the lower strain value side(P=0.000).There was a significantly difference between the absolute difference of peak strain from the higher strain value side to the middle stream point of the plaque intima and the absolute difference of peak strain from the lower strain value side to the higher strain value side of the plaque intima(P＜0.017).Conclusions The length and direction distribution of velocity vectors of the isolated carotid atherosclerotic plaque intima on longitudinal axis view are uneven,the mechanical heterogeneity pattern exists at the plaque intima and could be visualized and quantitatively evaluated using ultrasonic velocity vector imaging.%目的 超声评价孤立性颈动脉粥样硬化斑块长轴切面上中下游内膜位点力学状态.方法 经体表获取标准等长握力试验前后46例患者48个孤立性颈动脉粥样硬化斑块最大厚度长轴切面超声图像,观察颈动脉粥样硬化斑块长轴切面上中下游内膜运动速度向量变化,测取颈动脉粥样硬化斑块血管内膜分析位点应变峰值及应变峰值绝对差值.结果 二维速度向量图显示颈动脉粥样硬化斑块处内膜运动速度向量大小、方向紊乱不同步;等长握力试验前后斑块上下游内膜位点测值高端与测值低端应变峰值差异有统计学意义(P=0.000),斑块上下游内膜位点测值高端与中游内膜位点应变峰值绝对差值和斑块上下游位点间应变峰值绝对差值差异有统计学意义(P＜0.017).结论 孤立性颈动脉粥样硬化斑块长轴切面上中下游血管内膜机械运动速度向量变化方向具有不一致性,斑块内膜不同位点间应变峰值存在不一致并能够应用超声速度向量技术定性和定量评价.