颈动脉粥样斑块3T MR高分辨成像和MRA诊断

目的:应用3.0T MR高分辨管壁成像和MR血管造影在体显示颈动脉粥样斑块,探讨MR对颈动脉斑块的诊断价值.方法:经彩超检查证实的症状性颈动脉狭窄37例,所有病例行管腔MRA扣管壁高分辨MR检查,MR检查序列包括3D TOF、DIR T1 WI、T2 WI、PDWI和MRA.其中,17例检查前1周内行CT血管造影检查,9例患者检查后1周内行颈动脉内膜剥脱术.根据颈动脉内膜剥脱术手术部位,将获得的病理标本与MR图像逐层对照,研究斑块脂质成分、纤维成分和纤维帽、斑块钙化、出血和脂质坏死池等MR表现,探讨斑块变性的MR表现及其病理基础.结果:37个病例共发现52条颈动脉分叉处斑块,其中,管腔轻度狭窄24条(46.1％),中度狭窄19条(36.5％),重度狭窄7条(13.5％),闭塞2条(3.9％).斑块钙化21条(40.4％)、无钙化斑块31条(59.6％);31条软斑块中纤维成分为主斑块8条(15.6％),有明显脂质核心斑块23条(44.2％);其中,伴斑块出血5条(10％)、脂质坏死核心3条(6％),纤维帽撕裂(溃疡或纤维帽撕裂)3条(6％).相对于胸锁乳突肌,脂质坏死池在TOF、T1 WI、PDWI、T2Wl均呈显著高信号,钙化在各序列均呈低信号.斑块内出血的信号与出血的时间有关,新鲜出血各序列表现为点、结节或片状高信号,亚急性出血或者陈旧出血的信号与出血时间长短有关.结论:颈动脉MRA和管壁高分辨成像是评估颈动脉斑块风险性的有效手段,无创性MRA可以显示颈动脉斑块的狭窄程度;管壁高分辨成像可以直接显示斑块纤维帽、斑块内结构和成分,预测斑块脱落的风险性.

Evaluation of carotid artery atheromatous plaques by using MR angiography and high-resolution MRI

Objective： To assess the diagnostic value of MR in carotid atheromatous plaques with MR angiography and high-resolution MRL Methods：Thirty-seven patients with carotid atheromatous plaques revealed by color Doppler ultra- sound underwent high-resolution MR scanning using the protocol of time-of-flight MR angiography,DIR T1WI,PDWI and T2 WI sequences. 17 of them underwent CT angiography in a week, 9 of them underwent carotid endarterectomy. According to characteristics of the pathological specimens from carotid endarterectomy, the findings of MRI were compared step by step. The components of the plaques were analyzed and compared, such as lipid, fiber and fiber cap, patches, calcification, bleeding and lipid pool. The performance and plaques degeneration on MR pathological basis were discussed. Results： MRI found fifty-two carotid plaques in 37 patients,the induced slight, medium, high degree of stenosis and occlusions of carotid artery were 46.1% （24/52） ,36.5%（19/52） ,13.5% （7/52） and 3.9% （2/52） ,respectively. Calcification was found in 21/ 52 plaques （40.4%）, soft plaque in 59.6% （31/52）. Of the 31 soft plaque,MRI identified fibrous plaque in 15.6% （8/52） and lipid core in 44.2% （23/52）. Of the 23 lipid plaque,MRI detected lipid necrotic core in 6% （3/52）, intraplaque hemor- rhage in 10% （5/52） and fibrous cap rupture in 6% （3/52）. On four MR sequences images,the lipid necrotic core presen- ted hyperintensity,the calcification manifested hypointensity, the intraplaque hemorrhage might present hyperintensity, hy- pointensity or isointensity, respectively. The signal intensity of hemorrhage on MRI was related to the time of hemorrhage. Conclusion. MR angiography in combination with high resolution MRI was considered to be valuable tools in evaluating the risk of atheroselerostic plaques. The degree of stenosis could be found by MR angiography. The fibrous cap, calcification, lipid necrotic core and the intraplaque hemorrhage of carotid plaques could be evaluated by high resolution MRI.