Bartlett E S, Walters T D, Symons S P, Aviv R I, Fox A J
University of Toronto, Princess Margaret Hospital, Toronto, Ontario, Canada.
AJNR Am J Neuroradiol. 2008 Oct;29(9):1677-83. doi: 10.3174/ajnr.A1210. Epub 2008 Jul 24.
Previous studies quantifying moderate and severe carotid stenosis by direct millimeter measures on CT angiography (CTA) did not consider how prevalence and gender may influence classification cutoff values.
Three hundred nineteen carotid arteries were evaluated in consecutive patients with known or suspected carotid artery disease. Millimeter measures were obtained of the stenotic carotid bulb lumen and distal internal carotid artery (ICA). Interclass correlation coefficients (ICC) defined interobserver and intraobserver agreement. North American Symptomatic Carotid Endarterectomy Trial (NASCET)-style percent stenosis ratios were calculated per carotid artery and used in linear regression and receiver operating characteristic (ROC) curve analysis to define equivalent millimeter quantification and classification values. Likelihood ratios and prevalence-specific positive/negative predictive values (PPV/NPV) were calculated to determine the most appropriate millimeter cutoff values to classify stenosis.
Interobserver agreement was excellent for stenosis measures (0.90) and good for distal ICA measures (0.79). Gender-specific regression curves and ROC curves indicated that millimeter stenosis is an excellent tool to quantify and classify carotid stenosis. Assuming a 10% prevalence of severe stenosis, we found that the cutoff value maximizing NPV and PPV was 1.1 mm for both genders (female: PPV = 86.2, NPV = 97.7; male: PPV = 83.2, NPV = 95.9). Assuming a 40% prevalence of moderate stenosis, we found that the cutoff values differed between genders: female = 2.0 mm (PPV = 91.3, NPV = 91.5), male = 2.1 mm (PPV = 91.6, NPV = 92.4). Specific millimeter cutoffs will vary depending upon the clinical scenario, prevalence, and gender.
Direct millimeter stenosis measures are an excellent tool to classify moderate and severe carotid artery stenosis. Millimeter classification cutoff values that best approximate NASCET classifications vary depending on prevalence and gender.
既往通过CT血管造影（CTA）直接进行毫米测量来量化中度和重度颈动脉狭窄的研究未考虑患病率和性别可能如何影响分类临界值。
对连续的已知或疑似颈动脉疾病患者的319条颈动脉进行评估。获取狭窄的颈动脉球部管腔和颈内动脉（ICA）远端的毫米测量值。组内相关系数（ICC）定义了观察者间和观察者内的一致性。每条颈动脉均计算北美症状性颈动脉内膜切除术试验（NASCET）式的狭窄百分比，并用于线性回归和受试者工作特征（ROC）曲线分析，以确定等效的毫米量化和分类值。计算似然比以及患病率特异性阳性/阴性预测值（PPV/NPV），以确定用于分类狭窄的最合适毫米临界值。
观察者间对狭窄测量的一致性极佳（0.90），对ICA远端测量的一致性良好（0.79）。性别特异性回归曲线和ROC曲线表明，毫米狭窄是量化和分类颈动脉狭窄的极佳工具。假设重度狭窄的患病率为10%，我们发现使NPV和PPV最大化的临界值对两性均为1.1毫米（女性：PPV = 86.2，NPV = 97.7；男性：PPV = 83.2，NPV = 95.9）。假设中度狭窄的患病率为40%，我们发现临界值在两性之间有所不同：女性 = 2.0毫米（PPV = 91.3，NPV = 91.5），男性 = 2.1毫米（PPV = 91.6，NPV = 92.4）。具体的毫米临界值将因临床情况、患病率和性别而异。
直接的毫米狭窄测量是分类中度和重度颈动脉狭窄的极佳工具。最接近NASCET分类的毫米分类临界值因患病率和性别而异。
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