Hwang Chi-Shin, Shau Wen-Yi, Tegeler Charles H
Department of Neurology, Chung-Hsiao Municipal Hospital, 87 Tung-Teh Road, Taipei, Taiwan.
J Neuroimaging. 2002 Apr;12(2):124-30. doi: 10.1111/j.1552-6569.2002.tb00108.x.
Duplex scanning is an accepted method for noninvasive evaluation of carotid stenosis. However, the ultrasound criteria used for the detection of threshold stenoses vary widely between laboratories, and quality assurance measures to allow adjustment of criteria are often lacking. This study was completed using receiver operating characteristic (ROC) analysis to determine Doppler velocity criteria for threshold carotid stenoses, compared to an accepted standard, and to demonstrate methods to allow adjustment of criteria.
The study cohort included 134 patients who had carotid endarterectomy. Ultrasound and arteriographic data were collected for both the operated and nonoperated sides. Each carotid artery was treated as an independent case in the final analysis. Angiograms were used as the gold standard in ROC analysis to determine the Doppler velocity criteria for the detection of different threshold stenoses.
The ROC analysis results showed that for the detection of 70% stenosis, the best Doppler systolic criterion was 200 cm/s (sensitivity 93.6%, specificity 71.7%, area under the curve [AUC] 87.6%), the best diastolic criterion was 65 cm/s (sensitivity 85.1%, specificity 74.6%, AUC 84.3%), and the best criterion of carotid ratio (CR) (internal carotid artery systolic velocity/common carotid artery systolic velocity) was 3.0 (sensitivity 78.7%, specificity 75.4%, AUC 81.3%). For 50% stenosis, the best systolic criterion was 140 cm/s (sensitivity 90.3%, specificity 95.2%, AUC 97.0%), the best diastolic criterion was 60 cm/s (sensitivity 98.6%, specificity 77.8%, AUC 92.1%), and the best criterion of CR was 2.5 (sensitivity 93.1%, specificity 72.0%, AUC 89.0%).
This study showed that duplex scanning is able to detect threshold carotid stenoses. For the best performance, each laboratory should have its own criteria; however, the criteria provided here could be a helpful reference to those laboratories that have not yet established their own criteria. Most important, this study provides an example of how to evaluate the performance criteria, how to modify them, how such changes can affect performance, and how performance can be modified depending on the goals of the laboratory.
双功扫描是用于无创评估颈动脉狭窄的一种公认方法。然而，不同实验室用于检测临界狭窄的超声标准差异很大，而且往往缺乏用于调整标准的质量保证措施。本研究采用受试者操作特征（ROC）分析来确定临界颈动脉狭窄的多普勒速度标准，并与公认标准进行比较，同时展示调整标准的方法。
研究队列包括134例行颈动脉内膜切除术的患者。收集手术侧和非手术侧的超声及血管造影数据。在最终分析中，每条颈动脉被视为一个独立病例。血管造影用作ROC分析中的金标准，以确定检测不同临界狭窄的多普勒速度标准。
ROC分析结果显示，对于检测70%的狭窄，最佳的多普勒收缩期标准为200 cm/s（敏感性93.6%，特异性71.7%，曲线下面积[AUC] 87.6%），最佳的舒张期标准为65 cm/s（敏感性85.1%，特异性74.6%，AUC 84.3%），最佳的颈动脉比值（CR）（颈内动脉收缩期速度/颈总动脉收缩期速度）标准为3.0（敏感性78.7%，特异性75.4%，AUC 81.3%）。对于50%的狭窄，最佳的收缩期标准为140 cm/s（敏感性90.3%，特异性95.2%，AUC 97.0%），最佳的舒张期标准为60 cm/s（敏感性98.6%，特异性77.8%，AUC 92.1%），最佳的CR标准为2.5（敏感性93.1%，特异性72.0%，AUC 89.0%）。
本研究表明双功扫描能够检测临界颈动脉狭窄。为达到最佳性能，每个实验室应有自己的标准；然而，这里提供的标准可能对尚未建立自己标准的实验室有帮助。最重要的是，本研究提供了一个如何评估性能标准、如何修改它们、这些变化如何影响性能以及如何根据实验室目标修改性能的示例。
