大脑中动脉粥样硬化责任斑块与非责任斑块的高分辨磁共振对比研究

Comparison between culprit plaques and non-culprit plaques in atherosclerotic disease of the middle cerebral artery by high-resolution MRI

目的探讨高分辨磁共振成像(HR-MRI)评估大脑中动脉(MCA)粥样硬化患者高危斑块的价值。方法选取88例症状性MCA粥样硬化患者(症状组)和23例无症状狭窄者(无症状组),行头颅TOF磁共振血管成像(MRA)、覆盖MCA的M1段的轴位T1WI、T2WI和对比剂增强T1WI(CE-T1),以及脑DWI。定量分析狭窄率、最小管腔面积、斑块负荷以及各序列中斑块的信号强度指数。结果症状组中,责任斑块88个,非责任斑块20个;无症状组非责任斑块23个。症状组责任病变的狭窄率和斑块负荷均明显高于无症状组非责任病变者(狭窄率:63.61%±24.13%vs 55.61%±24.83%,P=0.002;斑块负荷:86.24%±13.83%vs 75.40%±17.08%,P<0.0001);且责任病变的最小管腔面积明显低于非责任病变[(0.95±0.70)mm2 vs(2.22±0.65)mm2,P<0.0001]。责任斑块与非责任斑块间斑块的T2WI和T1WI信号强度指数差异均无统计学意义(P均>0.05),但责任斑块呈混杂信号者所占比例明显高于非责任斑块(P均<0.05),症状组责任病变的CE-T1信号强度指数也明显高于无症状组非责任斑块(1.66±0.59vs 1.37±0.62,P=0.0002)。结论与单纯应用狭窄率对MCA动脉粥样硬化患者进行评价相比,HR-MRI的MCA管壁成像能够提供更多有价值的信息。评价MCA粥样硬化责任斑块时除了狭窄率,还应结合斑块负荷、斑块信号和强化等形态学指标进行综合考虑。

Objective To explore the value of multi-contrast high-resolution magnetic resonance imaging（HR-MRI）in the evaluation of high risk atherosclerotic plaques of middle cerebral artery（MCA）.Methods Eighty-eight symptomatic patients with atherosclerotic MCA and 23 asymptomatic patients were enrolled.MRI acquisition included time of flight MR angiography（TOF MRA）,T1 WI,T2WI and contrast-enhanced T1WI（CE-T1WI）images covering the entire M1 segment of MCA,and DWI for the whole brain.The morphological quantitative indexes were analyzed,included luminal stenosis,minimum lumen area（MLA）,plaque burden（PB）and plaque signal ratio.Results In symptomatic group,88 plaques were culprit lesions and 20 contralateral plaques were asymptomatic lesions.For asymptomatic group,there were 23 asymptomatic plaques.Both luminal stenosis and PBs of culprit lesions were significantly higher than those of asymptomatic lesions（Stenosis：63.61%±24.13% vs 55.61%±24.83%,P=0.002;PB：86.24%±13.83% vs 75.40%±17.08%,P〈0.0001）.Accordingly,MLAs of culprit lesions were significantly lower than those of asymptomatic lesions（[0.95±0.70]mm^2 vs[2.22±0.65]mm^2,P〈0.0001）.There was no significant difference in term of signal ratio on the T2 WI and T1 WI between culprit and asymptomatic lesions（P〉0.05）,but heterogeneous signal plaques were more in culprit group（P〈0.05）.Moreover,the CE-T1 WI signal ratios of culprit lesions was significant higher than those of asymptomatic lesions（1.66±0.59 vs 1.37±0.62,P=0.0002）.Conclusion MCA plaque wall imaging of HR-MRI provides incremental information to luminal stenosis in the evaluation of atherosclerotic patient.Besides luminal stenosis,other morphology index including plaque burden,plaque signal intensity and contrast enhancement and so on,should be considered in an integrative way for the accurate identification of MCA culprit plaques.