MSCTA三维重建及AVA血管分析评价颅外段颈内动脉狭窄
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摘要
目的
本研究的目的是分析MSCTA在评价颅外段颈内动脉粥样硬化性狭窄中的作用；并比较高级血管分析(AVA)软件、MIP和VR重建在颈动脉狭窄程度判定中的应用价值。
材料与方法
21例临床怀疑颈动脉狭窄病人(男18例、女3例，年龄38～90岁、平均68.9岁)的42支颈动脉分别行血管造影及MSCTA(GE Lightspeed Qx/I Extra 8排多层螺旋CT)检查。MSCTA扫描范围从主动脉弓至鞍背水平，扫描条件：管电压120 kV、管电流250～320mA，视野20cm，层厚21.25mm，螺距0.875，重建间隔1.25mm，用高压注射器经肘静脉注入非离子型造影剂，注射速度3.5ml/s，扫描延迟时间采用经验值(17～22s)。
在Advantage Workstation 4.1工作站利用AVA软件、MIP及透明化VR行双侧颈动脉重建，分析MSCTA总体图像质量及斑块钙化程度，以血管造影作为金标准，分析AVA、MIP、VR对颈内动脉狭窄程度的判定，并比较MSCTA与血管造影对斑块形态，是否存在斑块内溃疡与多节段性病变的显示能力。
计算血管造影、MIP、VR对于狭窄程度测量的观察者间的一致性；用Spearman等级相关分析AVA、MIP、VR与血管造影在狭窄程度测量中的相关性；判断三种重建方法与血管造影对于狭窄严重程度分级的符合程度(kappa值)；计算AVA、MIP、VR对重度以上(≥70％)程度狭窄检出的敏感性、特异性。均以P＜0.05作为有统计学差异。
结果
1．图像质量：21例42个血管中，MSCTA总体图像质量优秀28支；良好12支；一般2支；没有差质量图像。
2.斑块钙化:7支血管因为大的钙化遮盖，MIP图像上无法评价狭窄程
度及斑块形态，而其相应的VR图像上可以评价。
3.狭窄程度:血管造影、MIP、VR检测颈动脉狭窄程度的观察者间一致
性好(分别为k=0.89、k=0.85、k=0.93，p<0.05);AvA、MIP、vR与血管
造影间对于狭窄程度的测量均具有明显相关性(分别r二0 .956、r二0.963、r
二0.974，p<0.001);对于狭窄严重程度分级的符合程度，MIP及VR与血
管造影相比有很高的一致性(分别k=0.909、k二0.962，p<0.001)，AvA的
一致性为较好(k二0.780，p<0.001)，中度狭窄的血管在AVA、MIP、VR中
分别有4支、1支、l支被高估，三种方法均没有低估狭窄程度的情况，且均
可正确诊断2支闭塞血管;A VA、MIP、VR判断重度以上程度狭窄的敏感性
和特异性分别为100%，87.5%;100%， 96.3%;一00%，96.9%。
4.斑块形态:VR显示不规则斑块最多，能显示所有血管造影、MIP图
像显示为不规则斑块的血管。·
5.斑块内溃疡:VR观察到7支血管7个溃疡;MIP显示其中6个，另1
个由于钙化遮盖，MIP图像上未见显示;血管造影显示其中5个。
6.多段性病变:VR及MIP图像观察到11支血管同时伴颈总动脉管腔
轻度狭窄，血管造影图像显示其中7例。
结论
1.MSCTA三维重建操作简单，可无创性准确评价颈动脉粥样硬化性狭
窄，对斑块形态、斑块内溃疡和多段性病变的显示较血管造影更为全面。特
别是VR重建，由于克服了钙化对显示能力的影响，较MIP更有优势。
2.MSCTA三维重建在颈动脉粥样硬化狭窄程度的判定中，与血管造影
相比有明显相关性;对于狭窄严重程度分级，VR和MIP与血管造影符合程
度高，AvA因其计算方法与金标准不同，在实际应用中容易产生高估狭窄
的情况。
PURPOSE
To determine the usefulness of MSCTA for evaluation of extracranial internal carotid atherosclerosis.
MATERIALS AND METHODS
In 21 patients, 42 carotid arteries were examined with conventional angiog-raphy and MSCTA (GE Lightspeed Qx/I Extra). For CT angiography, the scanning coverage was from aortic arch to sella turcica. Helical scanning (120KV, 250 ~320Ma, 20cm field of view, 1. 25mm thickness, 1. 875 pitch, 1. 25mm reconstructional interval) was started 17 ~22s after injection of nonionic contrast medium at a rate of 3.5ml/s by using an auto - power injector.
Original CT data were transferred to workstation (Advantage Workstation 4. 1 ) for reconstruction and were displayed on advanced vessel analysis ( AVA) , volume rendered (VR) and maximum intensity projection (MIP) images. The quality of CT images and the degree of calcified plaques were evaluated. The ability of AVA, MIP and VR in assessment of the degree of severity of internal carotid arterial stenosis was compared with conventional angiograpy which is considered as a standard. The ability for demonstration of plague morphology, plague ulceration and tendom stenosis was also compared between MSCTA and conventional angiography.
The interobserver agreement on measurement of the percentage of stenosis on MIP and VR images and on conventional angiograms was calculated by using k values. The correlation between the three separated CT reconstructions and conventional angiography was evaluated by using Spearman rank correlation a-nalysis. We also estimated the agreement of stenosis severity categorization be-
tween three CT imaging techniques and conventional angiography by using k values. At last, the sensitivity and specificity of AVA, MIP and VR in detection of severe stenosis were evaluated. A P value less than 0.05 was considered statistically significant in all tests.
本研究的目的是分析MSCTA在评价颅外段颈内动脉粥样硬化性狭窄中的作用；并比较高级血管分析(AVA)软件、MIP和VR重建在颈动脉狭窄程度判定中的应用价值。
材料与方法
21例临床怀疑颈动脉狭窄病人(男18例、女3例，年龄38～90岁、平均68.9岁)的42支颈动脉分别行血管造影及MSCTA(GE Lightspeed Qx/I Extra 8排多层螺旋CT)检查。MSCTA扫描范围从主动脉弓至鞍背水平，扫描条件：管电压120 kV、管电流250～320mA，视野20cm，层厚21.25mm，螺距0.875，重建间隔1.25mm，用高压注射器经肘静脉注入非离子型造影剂，注射速度3.5ml/s，扫描延迟时间采用经验值(17～22s)。
在Advantage Workstation 4.1工作站利用AVA软件、MIP及透明化VR行双侧颈动脉重建，分析MSCTA总体图像质量及斑块钙化程度，以血管造影作为金标准，分析AVA、MIP、VR对颈内动脉狭窄程度的判定，并比较MSCTA与血管造影对斑块形态，是否存在斑块内溃疡与多节段性病变的显示能力。
计算血管造影、MIP、VR对于狭窄程度测量的观察者间的一致性；用Spearman等级相关分析AVA、MIP、VR与血管造影在狭窄程度测量中的相关性；判断三种重建方法与血管造影对于狭窄严重程度分级的符合程度(kappa值)；计算AVA、MIP、VR对重度以上(≥70％)程度狭窄检出的敏感性、特异性。均以P＜0.05作为有统计学差异。
结果
1．图像质量：21例42个血管中，MSCTA总体图像质量优秀28支；良好12支；一般2支；没有差质量图像。
2.斑块钙化:7支血管因为大的钙化遮盖，MIP图像上无法评价狭窄程
度及斑块形态，而其相应的VR图像上可以评价。
3.狭窄程度:血管造影、MIP、VR检测颈动脉狭窄程度的观察者间一致
性好(分别为k=0.89、k=0.85、k=0.93，p<0.05);AvA、MIP、vR与血管
造影间对于狭窄程度的测量均具有明显相关性(分别r二0 .956、r二0.963、r
二0.974，p<0.001);对于狭窄严重程度分级的符合程度，MIP及VR与血
管造影相比有很高的一致性(分别k=0.909、k二0.962，p<0.001)，AvA的
一致性为较好(k二0.780，p<0.001)，中度狭窄的血管在AVA、MIP、VR中
分别有4支、1支、l支被高估，三种方法均没有低估狭窄程度的情况，且均
可正确诊断2支闭塞血管;A VA、MIP、VR判断重度以上程度狭窄的敏感性
和特异性分别为100%，87.5%;100%， 96.3%;一00%，96.9%。
4.斑块形态:VR显示不规则斑块最多，能显示所有血管造影、MIP图
像显示为不规则斑块的血管。·
5.斑块内溃疡:VR观察到7支血管7个溃疡;MIP显示其中6个，另1
个由于钙化遮盖，MIP图像上未见显示;血管造影显示其中5个。
6.多段性病变:VR及MIP图像观察到11支血管同时伴颈总动脉管腔
轻度狭窄，血管造影图像显示其中7例。
结论
1.MSCTA三维重建操作简单，可无创性准确评价颈动脉粥样硬化性狭
窄，对斑块形态、斑块内溃疡和多段性病变的显示较血管造影更为全面。特
别是VR重建，由于克服了钙化对显示能力的影响，较MIP更有优势。
2.MSCTA三维重建在颈动脉粥样硬化狭窄程度的判定中，与血管造影
相比有明显相关性;对于狭窄严重程度分级，VR和MIP与血管造影符合程
度高，AvA因其计算方法与金标准不同，在实际应用中容易产生高估狭窄
的情况。
PURPOSE
To determine the usefulness of MSCTA for evaluation of extracranial internal carotid atherosclerosis.
MATERIALS AND METHODS
In 21 patients, 42 carotid arteries were examined with conventional angiog-raphy and MSCTA (GE Lightspeed Qx/I Extra). For CT angiography, the scanning coverage was from aortic arch to sella turcica. Helical scanning (120KV, 250 ~320Ma, 20cm field of view, 1. 25mm thickness, 1. 875 pitch, 1. 25mm reconstructional interval) was started 17 ~22s after injection of nonionic contrast medium at a rate of 3.5ml/s by using an auto - power injector.
Original CT data were transferred to workstation (Advantage Workstation 4. 1 ) for reconstruction and were displayed on advanced vessel analysis ( AVA) , volume rendered (VR) and maximum intensity projection (MIP) images. The quality of CT images and the degree of calcified plaques were evaluated. The ability of AVA, MIP and VR in assessment of the degree of severity of internal carotid arterial stenosis was compared with conventional angiograpy which is considered as a standard. The ability for demonstration of plague morphology, plague ulceration and tendom stenosis was also compared between MSCTA and conventional angiography.
The interobserver agreement on measurement of the percentage of stenosis on MIP and VR images and on conventional angiograms was calculated by using k values. The correlation between the three separated CT reconstructions and conventional angiography was evaluated by using Spearman rank correlation a-nalysis. We also estimated the agreement of stenosis severity categorization be-
tween three CT imaging techniques and conventional angiography by using k values. At last, the sensitivity and specificity of AVA, MIP and VR in detection of severe stenosis were evaluated. A P value less than 0.05 was considered statistically significant in all tests.
引文
1. Endarterectomy for Asymptomatic Carotid Artery Stenosis. Executive Committee for the Asymptomatie Carotid Atheroselerosis Study. JAMA 1995; 273: 1421-1428.
2．凌华威，潘自来，管永靖等。螺旋CT血管造影在颈动脉狭窄诊断中的临床应用。中国医学影像技术，1999；15(11)：850～852。
3．鲁晓燕，喻敏，桂秋萍等。颈动脉狭窄：影像学检查与手术对照分析。放射学实践，2002；17(6)：509～510。
4. Leclerc X, Godefroy O, Lucas C et al. Internal carotid arterial stenosis: CT angiography with volume rendering. Radiology 1999; 210: 673-682.
5. Leclerc X, Godefroy O, Pruvo JP, Leys D. Computed tomographic angiography for the evaluation of carotid artery stenosis. Stroke 1995; 26: 1577 1581.
6. Marcus CD, Ladam-Marcus VJ, Bigot JL, et al. Carotid Artery Stenosis: Evaluation at CT Angiography with the Volume-rendering Technique. Radiology, 1999; 211: 775～780.
7. Link J, Brossman J, Penselin V, Gluer CC, Heller M. Common carotid artery bifurcation: preliminary results of CT angiograph and colour coded duplex sonography compared with digita subtraction angiography. Am J Roentgenol 1997; 168: 361-365.
8. Troyer A, Saloner D, Pan XM, et al. Major carotid plaque surface irregularities correlate with neurologic symptom. J-Vase-Surg. 2002; 35: 741.
9. Hatsukami TS, Ferguson MS, Beach KW, et al. Carotid Plaque Morphology and Clinieal Events. Stroke. 1997; 28: 95-100.
10. Barnett HJ, Eliasziw M, Meldrum H. Plaque Morphology as a Risk Factor for stroke. JAMA 2000; 284(2): 177.
11. Streifler JY, Eliasziw M, Fox AJ, et al. Angiographic detection of carotid plaque ulceration. Comparison with surgical observations in a multicenter study. North American Symptomatic Carotid Endarterectomy Trial. Stroke 1994; 25: 1130 2.
12. Randoux B, Marro B, Koskas F, et al. Carotid Artery Stenosis: Prospective Comparison of CT, Three-dimensional Gadolinium-enhanced MR, and Conventional Angiography. Radiology 2001; 220: 179 185.
2．凌华威，潘自来，管永靖等。螺旋CT血管造影在颈动脉狭窄诊断中的临床应用。中国医学影像技术，1999；15(11)：850～852。
3．鲁晓燕，喻敏，桂秋萍等。颈动脉狭窄：影像学检查与手术对照分析。放射学实践，2002；17(6)：509～510。
4. Leclerc X, Godefroy O, Lucas C et al. Internal carotid arterial stenosis: CT angiography with volume rendering. Radiology 1999; 210: 673-682.
5. Leclerc X, Godefroy O, Pruvo JP, Leys D. Computed tomographic angiography for the evaluation of carotid artery stenosis. Stroke 1995; 26: 1577 1581.
6. Marcus CD, Ladam-Marcus VJ, Bigot JL, et al. Carotid Artery Stenosis: Evaluation at CT Angiography with the Volume-rendering Technique. Radiology, 1999; 211: 775～780.
7. Link J, Brossman J, Penselin V, Gluer CC, Heller M. Common carotid artery bifurcation: preliminary results of CT angiograph and colour coded duplex sonography compared with digita subtraction angiography. Am J Roentgenol 1997; 168: 361-365.
8. Troyer A, Saloner D, Pan XM, et al. Major carotid plaque surface irregularities correlate with neurologic symptom. J-Vase-Surg. 2002; 35: 741.
9. Hatsukami TS, Ferguson MS, Beach KW, et al. Carotid Plaque Morphology and Clinieal Events. Stroke. 1997; 28: 95-100.
10. Barnett HJ, Eliasziw M, Meldrum H. Plaque Morphology as a Risk Factor for stroke. JAMA 2000; 284(2): 177.
11. Streifler JY, Eliasziw M, Fox AJ, et al. Angiographic detection of carotid plaque ulceration. Comparison with surgical observations in a multicenter study. North American Symptomatic Carotid Endarterectomy Trial. Stroke 1994; 25: 1130 2.
12. Randoux B, Marro B, Koskas F, et al. Carotid Artery Stenosis: Prospective Comparison of CT, Three-dimensional Gadolinium-enhanced MR, and Conventional Angiography. Radiology 2001; 220: 179 185.