3.0T高分辨MRI对症状性大脑中动脉狭窄的诊断价值

The value of 3.0T High-resolution magnetic resonance imaging in the diagnosis of symptomatic middle cerebral arterial stenosis

目的应用3.0T高分辨磁共振成像(High-resolution MRI,HRMRI)探讨:症状性大脑中动脉(MCA)狭窄的病因;症状性MCA粥样硬化狭窄患者责任血管与非责任血管斑块特点及管壁特征的区别。方法应用3.0T磁共振扫描仪对18例症状性MCA狭窄患者进行MCA管壁成像扫描,扫描系列包括T_1w-db space(平扫+增强)。结果符合图像质量要求的16例症状性MCA狭窄患者图像纳入统计分析,其中13例MCA为动脉粥样硬化,2例MCA为血管炎,1例MCA为动脉夹层;责任血管组上壁斑块、不规则斑块、强化斑块较非责任血管组常见(P分别为0.034、0.001、0.011),且责任血管组斑块强化更明显;在最大管腔狭窄处(MLN)处,与非责任血管组相比,责任血管组具有较大的管腔狭窄程度、斑块负荷(PB)、管壁面积(WA)、最大管壁厚度(MVT)(P分别为0.008、0.002、0.042、0.043),责任血管组具有较小的血管面积(VA)、管腔面积(LA),较大的重塑指数(RI)及平均管壁厚度(m VT),差异无统计学意义(P均>0.05);判断双侧MCA斑块特点(位置、规则性、强化类型、强化程度)的组间一致性较好(K分别为0.83、0.94、0.88、0.95,P均<0.001);测量管壁特征时组间信度良好,MLN处的血管面积VA、LA、WA、PB、RI、管腔狭窄程度、MVT、m VT的组间相关系数(ICC)分别为0.94、0.96、0.92、0.99、0.91、0.99、0.94、0.94(P均<0.001),参考管腔(REF)处的VA、LA的ICC分别为0.96、0.92(P均<0.001)。结论HRMRI可清晰显示MCA管壁、管腔,甄别动脉狭窄的病因,试验可重复性高;可根据不同管壁病理改变在HRMRI的表现特征鉴别动脉狭窄的病因:动脉粥样硬化斑块在HRMRI上表现为管壁偏心性增厚,增强扫描呈偏心性强化;血管炎在HRMRI上表现为管壁显著环形增厚,增强扫描呈环形强化;动脉夹层在HRMRI T_1WI像上为长条状高信号表现;责任血管的斑块特点、管壁特征不同于非责任血管,这有助于识别罪犯斑块、责任血管及评估斑块稳定性。

Objective Using 3.0T High-resolution magnetic resonance imaging （HRMRI） to investigate： causes of symptomatic middle cerebral artery （MCA） ; differences of plaque and vessel wall characteristics between culprit arteries and non-culprit arteries in patients with symptomatic MCA atherosclerotic stenosis. Method Eighteen patients with symp-tomatic MCA stenosis underwent middle cerebral arterial wall imaging. HRMRI scans included pre-contrast T2 w-db space and post-contrast T2 w-db space. Results Among 16 patients qualified for statistical analysis, 13 MCAs were atherosclero-sis, were vasculitis and 1 was arterial dissection. Compared with group of non-culprit artery,group of culprit artery had more plaques on superior wall,and more irregular and enhanced plaques （P was 0. 034 ,0. 001 and 0. 01l respectively） . At maximal lumen narrowing （ MLN） , group of culprit artery had larger lumen stenosis, plaque burden （ PB） , wall area （ WA） and maximal vessel thickness （ MVT） （ P was 0. 008、 0. 002、 0. 042 and 0. 043 respectively） ; group of culprit artery had smaller vessel area （VA） and lumen area （LA） ,greater remodeling index （RI ） and mean vessel thickness （mVT）,but no significant differences existed between two groups （ All P 〉 0. 05 ） . Inter-observer reproducibility was excellent for identif-ying plaque characteristics （location,regularity,enhanced type and degree） （ K was 0. 83 ,0. 94,0. 88 and 0. 95 respective-ly,all P〈0.001） ,and for measuring VA,LA,WA,PB,RI, lumen stenosis, MVT and mVT at MLN （Interclass correlation coefficient [ICC ] was 0.94、 0 .9 6、 0 .9 2、 0 .9 9、 0 .9 1、 0 .9 9、 0 .9 4、 0 .9 4 , all P 〈 0.001 ） and VA, LA at reference site （REF） （ ICC was 0. 96 ,0. 92 respectively,both P 〈0. 001） . Conclusion HRMRI helps to clearly visualize the lumen and vessel wall of MCA, and distinguish causes of arterial stenosis with high reproducibility. Different pathological manifesta-tions on HRMRI indicate underlying causes of arterial stenosis ： atherosclerotic plaques manifest as eccentric thickening of arterial wall with eccentric enhancement, vasculitis has concentric vessel thickening and enhancement, arterial dissection shows long-striped hyper-intensity on HRMRI T2 WI. The plaque and vessel wall characteristics differ between culprit arter-ies and non-culprit arteries,which help to identify culprit plaques and arteries,and evaluate plaque stability.