钙化斑块对双源64层CT血管成像诊断颈动脉狭窄的影响

Effect of calcified plaques on diagnosis of carotid stenosis with dural source 64-slice CT angiography

目的评估钙化斑块对双源64层CT血管成像（CTA）诊断颈内动脉（ICA）狭窄的影响。方法筛选93例前循环缺血性脑血管病的患者，同时接受CTA与DSA检查。CTA采用双源64层CT进行扫描，运用多平面重建（MPR）、曲面重建（CPR）、最大密度投影（MIP）和容积显示（VR）技术进行重组和轴位像扩大测量狭窄血管和正常血管的直径。采用北美症状性颈动脉内膜切除试验（NASCET）的方法进行血管狭窄度的分级。根据CT值的大小确定钙化斑块，钙化斑块定义为CT值≥130Hu。CTA和DSA检查结果由两名高年资放射科医师和2名神经内科医师分别进行测量。结果经CTA和DSA检查的186支血管中，ICA狭窄的有117支，其中检测出钙化斑块的有49支，其CT值为130～461Hu；而非钙化斑块致狭窄的ICA有68支。当ICA狭窄率〉50％时，CTA对不伴钙化斑块狭窄血管的诊断敏感度为100％，特异度为94．3％，阳性预测值为94．3％，阴性预测值为100％，Kappa值为0．941；CTA对伴有钙化斑块狭窄血管的诊断敏感度为100％，特异度为87．1％，阳性预测值为82．6％，阴性预测值为100％，Kappa值为0．831。当血管狭窄率〉70％时，不伴钙化斑块CTA的敏感度为100％，特异度为96．0％，阳性预测值为90．0％，阴性预测值为100％，Kappa值为0．928；伴有钙化斑块CTA的敏感度为100％，特异度为92．7％，阳性预测值为72．7％，阴性预测值为100％，Kappa值为0．805。结论64层CTA对非钙化和钙化的ICA狭窄的诊断均具有很高的敏感性，但特异性在诊断钙化斑块时略低。

Objective To evaluate the effect of calcified plaques on the diagnosis of internal carotid artery （ICA） stenosis with dural source 64-slice CT angiography （CTA）. Methods Ninety-three patients with anterior circulation ischemia were selected, and they received CTA and digital subtraction angiography （ DSA ） simultaneously. CTA scan was performed with a Dural source 64-slice CT. Multiplanar reconstruction （MPR）, curved planar reformation （CPR）, maximum intensity projection （MIP）, and volume render （VR） were used for recombination and enlarged axial images were used for measuring the diameters of stenotic and normal vessels. Classification of the stenotic degree was defined according to the North American Symptomatic Carotid Endarterectomy Trial （NASCET） , and the size of calcified plaque was determined according to the CT values. Calcification of plaque was defined as the CT Hu value ≥ 130. The examination materials of CTA and DSA were measured by two senior radiologists and two neurologists separately. Results Of the 186 arteries examined by CTA and DSA, 117 had ICA stenosis, among them the calcified plaques were detected in 49 arteries, and their CT Hu values were 130 -461 ; and the noncaleified plaque caused ICA stenosis was seen in 68 arteries. When the stenosis rate of ICA was 〉 50%, the diagnostic sensitivity, specificity, positive predictive value, negative predicting value, and Kappa value of CTA in ICA stenosis with noncalcified plaque were 100% , 94. 3% , 94. 3% , 100% , and 94. 1% , respectively; While in ICA stenosis with calcified plaque, the above data were 100% ,87. 1% ,82. 6% ,100% , and 0. 831, respectively. When the stenosis was 〉 70%, the sensitivity, specificity, positive predictive value, negative predicting value and Kappa value of CTA in ICA stenosis with noncalcified plaque were 100%, 96. 0% , 90. 0% , 100% , and 0. 928, respectively; while in ICA stenosis with calcified plaque, the above data were 100% , 92.7% , 72.7% , 100% , and 0. 805, respectively. Conclusion The 64-slice CTA has very high sensitivity on the diagnosis of non-calcified and calcified ICA stenosis, but the specificity was slightly lower in the diagnosis of calcified plaque.