颅内动脉粥样硬化性狭窄患者斑块三维高分辨率磁共振成像强化特征与卒中发生时间的相关性研究

Correlation between three-dimensional high-resolution magnetic resonance imaging enhancement characteristics of plaque and time of symptom onset of stroke in patients with intracranial atherosclerotic stenosis

目的采用三维高分辨率磁共振成像(3D HR MRI)技术评估颅内动脉粥样硬化性狭窄患者责任斑块的强化特征,分析斑块强化特征与卒中发生时间的相关性.方法根据卒中发生至HR MRI检查的时间间隔,将2014年1月至2016年1月在扬州大学附属医院MRI室收集的61例脑梗死患者分为早期组(<4周,26例)、中期组(4-12周,20例)和晚期组(>12周,15例),行T1WI、T2WI、数字减影血管造影、液体衰减反转恢复序列、磁共振血管成像等常规头颅MRI检查,以及三维可变翻转角快速自旋回波(3D-SPACE)T1WI及增强3D-SPACE T1WI序列扫描,将3D-SPACE T1WI序列上斑块增强前、后信号强度进行对比,定性分析斑块的强化程度,定量计算斑块的强化率,分析斑块强化特征及其与卒中发生至HR MRI检查时间之间的关系.结果3D HR MRI上责任斑块表现为管壁月牙形偏心增厚或者环形增厚,T1WI上多为稍高信号,注入对比剂后呈不同程度的强化或者无强化.对纳入的61例脑梗死患者的斑块强化特点进行分析,结果显示:早期组26例斑块明显强化21例(80.8%),轻度强化4例(15.4%),无强化1例(3.8%),强化率为80.49%±18.64%;中期组20例斑块明显强化2例(10.0%),轻度强化14例(70.0%),无强化4例(20.0%),强化率为52.09%±18.17%;晚期组15例斑块轻度强化2例(2/15),无强化13例(13/15),强化率为12.16%±10.44%.统计学分析显示3组间强化程度及强化率差异有统计学意义(χ^2=22.834,P<0.01;F=78.403,P<0.01).进一步分析,早期组和中期组强化程度及强化率差异有统计学意义(χ^2=-4.177,P<0.01;t=5.179,P<0.01),中期组和晚期组强化程度及强化率差异有统计学意义(χ^2=-2.484,P<0.05;t′=8.189,P<0.01),早期组和晚期组强化程度及强化率差异有统计学意义(χ^2=-3.796,P<0.01;t′=15.044,P<0.01).卒中发生至HR MRI检查的时间与强化率呈显著负相关(r=-0.903,P<0.01).结论HR MRI增强扫描能清晰地显示颅内动脉粥样硬化斑块的强化,随着发病时间间隔的延长,颅内动脉粥样硬化斑块的强化逐渐减弱,为由强化程度判断斑块的易损性提供了依据,对缺血性脑卒中的二级预防具有重要的指导意义.

Objective To assess the enhancement characteristics of plaques in patients with intracranial atherosclerotic stenosis using three-dimensional high-resolution magnetic resonance imaging(3D HR MRI),and to analyze the correlation between the enhancement characteristics of plaques and the time from onset of stroke symptoms to MRI examination.Methods The enhancement characteristics of plaques were retrospectively analyzed in 61 patients with cerebral infarction who were scanned in MRI room of the Affiliated Hospital of Yangzhou University from January 2014 to January 2016.According to the elapsed time between symptom onset and MR examination,61 patients were classified into early stage group(<4 weeks,n=26),middle stage group(4-12 weeks,n=20)and late stage group(>12 weeks,n=15).All cases underwent three-dimensional sampling perfection with application optimized contrast using different angle evolutions(3D-SPACE)T1WI and enhanced 3D-SPACE T1WI sequence scans,as well as routine head MRI examinations.The signal intensities of plaques before and after enhancement scanning were compared on the 3D-SPACE T1WI sequence.The degrees of plaque enhancement were qualitatively analyzed,and the enhancement rates of plaques were quantitatively calculated.The correlation between the enhancement characteristics of plaques and time of symptom onset of stroke was analyzed.Results Sixty-one intracranial atherosclerotic plaques on the 3D HR MRI showed eccentric thickening or annular thickening of the vessel wall,and slightly higher signals on the T1WI.They showed different degrees of enhancement or no enhancement after enhancement scans.The characteristics of plaque enhancement in 61 patients with cerebral infarction were analyzed.The results showed that 26 plaques in the early stage group were obviously enhanced for 21 cases(80.8%),mildly enhanced for 4 cases(15.4%),no enhancement for 1 case(3.8%),and the enhancement rate was 80.49%±18.64%.Twenty plaques in the middle stage group were obviously enhanced for 2 cases(10.0%),mildly enhanced for 14 cases(70.0%),no enhancement for 4 cases(20.0%),and the enhancement rate was 52.09%±18.17%.Fifteen plaques in the late stage group were mildly enhanced for 2 cases(2/15),no enhancement for 13 cases(13/15),and the enhancement rate was 12.16%±10.44%.There were statistically significant differences in the degrees of plaque enhancement and plaque enhancement rates among the three groups(χ^2=22.834,P<0.01;F=78.403,P<0.01).Further analysis showed that there was a statistically significant difference in the degree of enhancement and enhancement rate of plaques between the early stage group and the middle stage group(χ^2=-4.177,P<0.01;t=5.179,P<0.01),and there was a statistically significant difference between the middle stage group and the late stage group(χ^2=-2.484,P<0.05;t′=8.189,P<0.01),and the difference between the early stage group and the late stage group was also statistically significant(χ^2=-3.796,P<0.01;t′=15.044,P<0.01).There was a significant negative correlation between the time from onset of stroke symptoms to MRI examination and the enhancement rate of plaques(r=-0.903,P<0.01).Conclusions Enhanced HR MRI scanning can clearly show the enhancement of intracranial atherosclerotic plaques.With the prolongation of the onset time interval,the enhancement of intracranial atherosclerotic plaques gradually weakens,which can assess the vulnerability of plaques and has important guiding significance for secondary prevention of ischemic stroke.