实时超声弹性成像技术评价兔颈动脉易损斑块的价值

Value of real-time elastography in evaluating rabbit carotid artery vulnerable plaque

目的探讨实时超声弹性成像技术在评价兔颈动脉易损斑块中的应用价值。方法选取30只雄性新西兰大耳白兔，体质量2．0～3．0kg，经高脂喂养1周，球囊损伤兔右侧颈总动脉造模成功后随机分成2组，分别继续高脂喂养6周、12周，经耳缘静脉麻醉后，对兔右侧颈总动脉进行常规超声及实时超声弹性成像检查，获得兔颈动脉斑块弹性应变值并进行统计学分析。检查完成后，采用空气栓塞法猝死实验兔，将球囊损伤处兔颈总动脉分离、固定后进行病理学检查，根据美国心脏病学会（AHA）分级标准对斑块进行病理学分级，将实时超声弹性检查结果与病理学结果进行对比分析。结果实时超声弹性成像技术不同操作者间重复性好，对斑块进行分级与AHA病理学分级一致性好。Cohen’s κ=0．803（95％可信区间0．669-0．938）。斑块内部渲染为不同颜色的区域弹性应变值差异具有统计学意义（P〈0．0001）。应用弹性应变值来估测斑块内部存在脂质坏死核心的敏感性和特异性分别为88．0％和81．6％。ROC曲线下面积为0．902（95％可信区间0．810-0．959，P〈0．0001）。绪论实时超声弹性成像技术可以显示兔颈动脉斑块内部的弹性特征，对斑块进行分级评价；并可以通过弹性应变值来评估斑块内部是否存在脂质坏死核心，从而有助于评价斑块的稳定性。

Objective To explore the clinical value of real-time elastography in evaluating rabbit carotid vulnerable plaque. Methods Thirty male New Zealand rabbits （weighted from 2.0 to 3.0 kg） were all fed with high cholesterol diet for one week before balloon injury of their right common carotid arteries. Then they were categorized randomly into two groups which were continued fed by high cholesterol diet for 6 and 12 weeks, respectively. Ultrasound and real-time elastography of their right common carotid arteries were applied after their anesthesia by ear marginal vein. Strains of the carotid plaques were measured and analyzed statistically by two independent experienced sonographers. All the rabbits were sacrificed by air embolism method after all the examinations. The atherosclerotic rabbit common carotid lesions were dissected, fixed for pathologic examination, and graded according to the standard of American Heart Association （AHA）, which were compared with the real-time elastography findings. Results Real-time elastography had well repeatability between different operators. Consistency between elastography and the AHA pathology was quite good, with the Cohen＇s kappa = 0.803 （95% CI 0.659 to 0.938）. Strains of different regions in a plaque had statistically significant difference （ P 〈0.000 1）. By using strain higher than 0.37%, the sensitivity and specificity of detecting a lipid core were 88.0% and 81.6%, and area under ROC curve was 0.902 （95% CI 0.810 - 0.959, P 〈0.0001）. Conclusions Real-time elastography can display the inner elastic characteristics of the rabbit carotid plaques, and may help evaluate the grading of a plaque. The strain value may help detect a necrotic core, thereby help evaluate the stability of a plaque.