Department of Vascular Surgery, Imperial College, London, United Kingdom.
J Vasc Surg. 2013 Mar;57(3):609-618.e1; discussion 617-8. doi: 10.1016/j.jvs.2012.09.045. Epub 2013 Jan 18.
To test the hypothesis that the size of a juxtaluminal black (hypoechoic) area (JBA) in ultrasound images of asymptomatic carotid artery plaques predicts future ipsilateral ischemic stroke.
A JBA was defined as an area of pixels with a grayscale value <25 adjacent to the lumen without a visible echogenic cap after image normalization. The size of a JBA was measured in the carotid plaque images of 1121 patients with asymptomatic carotid stenosis 50% to 99% in relation to the bulb (Asymptomatic Carotid Stenosis and Risk of Stroke study); the patients were followed for up to 8 years.
The JBA had a linear association with future stroke rate. The area under the receiver-operating characteristic curve was 0.816. Using Kaplan-Meier curves, the mean annual stroke rate was 0.4% in 706 patients with a JBA <4 mm(2), 1.4% in 171 patients with a JBA 4 to 8 mm(2), 3.2% in 46 patients with a JBA 8 to 10 mm(2), and 5% in 198 patients with a JBA >10 mm(2) (P < .001). In a Cox model with ipsilateral ischemic events (amaurosis fugax, transient ischemic attack [TIA], or stroke) as the dependent variable, the JBA (<4 mm(2), 4-8 mm(2), >8 mm(2)) was still significant after adjusting for other plaque features known to be associated with increased risk, including stenosis, grayscale median, presence of discrete white areas without acoustic shadowing indicating neovascularization, plaque area, and history of contralateral TIA or stroke. Plaque area and grayscale median were not significant. Using the significant variables (stenosis, discrete white areas without acoustic shadowing, JBA, and history of contralateral TIA or stroke), this model predicted the annual risk of stroke for each patient (range, 0.1%-10.0%). The average annual stroke risk was <1% in 734 patients, 1% to 1.9% in 94 patients, 2% to 3.9% in 134 patients, 4% to 5.9% in 125 patients, and 6% to 10% in 34 patients.
The size of a JBA is linearly related to the risk of stroke and can be used in risk stratification models. These findings need to be confirmed in future prospective studies or in the medical arm of randomized controlled studies in the presence of optimal medical therapy. In the meantime, the JBA may be used to select asymptomatic patients at high stroke risk for carotid endarterectomy and spare patients at low risk from an unnecessary operation.
验证假设，即颈动脉粥样硬化斑块超声图像中管腔旁的暗（低回声）区（JBA）大小可预测同侧缺血性卒中的发生。
JBA 定义为管腔旁无可见回声帽的灰度值<25 的像素区域，在图像归一化后。在 1121 例无症状颈动脉狭窄 50%至 99%的患者中，对颈动脉斑块图像进行 JBA 测量（无症状颈动脉狭窄和卒中风险研究）；对患者进行长达 8 年的随访。
JBA 与未来卒中发生率呈线性相关。受试者工作特征曲线下面积为 0.816。Kaplan-Meier 曲线显示，706 例 JBA<4mm²的患者平均年卒中发生率为 0.4%，171 例 JBA 4-8mm²的患者为 1.4%，46 例 JBA 8-10mm²的患者为 3.2%，198 例 JBA>10mm²的患者为 5%（P<0.001）。在以同侧缺血事件（一过性黑矇、短暂性脑缺血发作[TIA]或卒中）为因变量的 Cox 模型中，调整其他已知与风险增加相关的斑块特征（狭窄、灰度中位数、存在无声影的离散白色区域提示新生血管形成、斑块面积和对侧 TIA 或卒中史）后，JBA（<4mm²、4-8mm²、>8mm²）仍有意义。斑块面积和灰度中位数无统计学意义。使用有意义的变量（狭窄、无声影的离散白色区域、JBA 和对侧 TIA 或卒中史），该模型预测了每位患者的年度卒中风险（范围 0.1%-10.0%）。734 例患者的平均年卒中风险<1%，94 例患者的 1%至 1.9%，134 例患者的 2%至 3.9%，125 例患者的 4%至 5.9%，34 例患者的 6%至 10%。
JBA 的大小与卒中风险呈线性相关，可用于风险分层模型。这些发现需要在未来的前瞻性研究或最佳药物治疗存在的随机对照研究的医疗臂中得到证实。在此期间，JBA 可用于选择高卒中风险的无症状患者进行颈动脉内膜切除术，并避免低风险患者接受不必要的手术。
