急慢性脑卒中及TIA相关的MCA斑块的磁共振形态学研究

目的运用高分辨磁共振(HR-MRI)管壁成像技术,以症状性大脑中动脉(middle cerebral artery,MCA)粥样硬化症患者为研究对象,定性和定量分析斑块的形态学特征,探索MCA斑块与卒中相关的高危HR-MRI特征。方法收集2013年4月~2014年5月之间在我院就诊的症状性MCA动脉粥样硬化症患者,利用3.0 T MR仪行头颅3D TOFMRA、双侧MCA的HR-MRI和全脑扩散加权成像(DWI),其中HR-MRI包括T_2WI、T_1WI、STIR和对比增强T_1WI。将患者分为陈旧性脑梗死组、短暂性脑缺血发作(TIA)组和急性脑梗死组。对hr MRI的定性分析是以同序列眼外肌信号为参考将斑块分为等、高、低及混杂信号四种类型;定量测量最小管径和斑块厚度,计算斑块负荷、管腔重塑率和斑块强化率。结果有141例患者纳入本研究,平均(53.6±10.1)岁,男96例(68.09%),其中陈旧性脑梗死组15例(10.64%),TIA组86例(60.99%),急性脑梗死组40例(28.37%)。根据HR-MRI,T_1WI、T_2WI和STIR序列中急性脑梗死组的混杂信号斑块的数量和比例均明显多于TIA组和陈旧性脑梗死组,差异均有统计学意义(P0.0001;P0.0001;P=0.0006)。定量分析发现,急性脑梗死组的最小管径明显小于TIA组和陈旧性脑梗死组(P0.0001);陈旧性和急性脑梗死组的斑块厚度显著大于TIA组(P=0.0003);急性脑梗死组的斑块负荷和管腔重塑率最大(P=0.0021;P=0.0846),且急性脑梗死组的斑块强化率的平均值也大于其他两组(P=0.0413)。结论利用HR-MRI管壁成像技术可实现对症状性MCA粥样硬化斑块的形态及信号进行无创性评估。急慢性脑卒中相关的MCA斑块在多序列HR-MRI中呈现不同的形态学特征。

MRI characteristics of atherosclerotic plaque in acute/chronic stroke and transient ischemic attack

Objective To evaluate the morphological characteristics and high risk features of symptomatic atherosclerotic plaque of middle cerebral artery (MCA) using high-resolution magnetic resonance imaging (hrMRI). Methods 141 patients with symptomatic atherosclerosis of MCA from April 2013 to May 2014 underwent 3D TOF-MRA,.hrMRI of bilateral MCA and whole brain diffusion weighted imaging (DWI) using a 3.0 T MR imaging system. According to the clinical symptoms and DWI findings , the patients were divided into chronic infarction,.transient ischemic attack (TIA),.and acute infarction groups..Using the signal intensity of extraocular muscle as reference, the plaques were qualitatively categorized as isointense,.hyperintense, hypointense or heterogeneous..The minimal diameter of stenotic lumen and thickness of plaque,.plaque burden,.remodeling ratio and contrast enhancement ratio were calculated. Results Of 141 patients, 96 men (mean age:53.6±10.1 years), were chronic infarction (15/96,.10.64%), TIA (86/96, 60.99%), and acute infarction (40/96, 28.37%). More heterogeneous plaques were significantly found in acute infarction than that of TIA and chronic infarction on T1WI(P<0.0001), T2WI (P<0.0001), and STIR (P=0.0006). The minimal diameters of stenotic lumen in acute infarction were significantly less than those in TIA and chronic infarction group (P<0.0001)..The plaque thickness in chronic and acute infarction was significantly greater than that in TIA (P=0.0003)..The plaque burden (P=0.0021), remodeling ratio (P=0.0846), and contrast enhancement ratio (P=0.0413) were significantly greater in acute infarction. Conclusion hrMRI shows more heterogeneous plaques, more severe stenosis, thinner plaques, larger plaque burden, higher remodeling ratio, and greater contrast enhancement ratio in acute MCA infarction. The MRI characteristics can aid prediction of symptomatic atherosclerotic plaques.