颈动脉粥样硬化斑块上中下游短轴切面内膜位点的超声径向力学研究

Study of radial mechanical pattern at isolated carotid plaque intima using ultrasonic velocity vector imaging

目的定量分析孤立性颈动脉粥样硬化斑块上中下游短轴切面内膜位点力学状态。方法获取标准等长握力试验前后46例患者47个孤立性颈动脉粥样硬化斑块上中下游切面和无斑块参考段血管切面实时二维动态灰阶超声图像,导入2D VVI工作站脱机分析,观察血管内膜运动速度向量变化,测取斑块上中下游及参考段切面内膜分析位点径向应变峰值及峰值绝对差值,进行比较分析。结果握力试验前后斑块内膜运动速度向量大小和方向紊乱不同步;斑块上游、中游及下游短轴切面斑块两侧肩部内膜位点径向应变峰值测值高端和测值低端差异有统计学意义(P≤0.001);斑块上中下游短轴切面斑块肩部内膜位点径向应变峰值测值低端与顶部内膜位点径向应变峰值绝对差值和双侧肩部间内膜位点径向应变峰值绝对差值具有显著性统计学差异(P<0.017)。结论孤立性颈动脉粥样硬化斑块上中下游内膜不同位点间存在明显的径向不均衡力学状态。

Objective To make quantitative analysis of the intima radial mechanical pattern of carotid atherosclerotic plaque in different short axis view at different intima points. Methods Forty-six patients with 47 isolated plaques underwent high frequency ultrasound scanning to achieve real-time two-dimensional gray scale ultrasonic dynamic images in serial short axis view of plaque intima （the upper, middle and down stream of the plaque intima） before and after the standard grip strength test separately. A dedicated velocity vector imaging workstation was used for the off-line images analysis, derived the radial mechanics parameter at different plaque intima points （the peak strain and the absolute difference of the peak strain）, Wilcoxon test was used to compare the peak strain and the absolute difference of the peak strain between the different points. Results The chaos and the asynchrony of radial velocity vectors were observed at the sites of plaque intima before and after the grip strength test, the peak strain at the higher strain value side was significantly higher than that at the lower side （P≤0.001） at all the upper, middle and down stream intima points of the plaque. There was significant difference between the absolute difference of peak strain from the lower strain value side to the middle point of the plaque intima and the absolute difference of peak strain from the lower strain value side to the higher side of the plaque intima （P〈0.017） also at all the upper, middle and down stream intima points of the plaque. Conclusion The radial heterogeneous and asymmetrical mechanical pattern exists at the plaque intima.