颈动脉斑块脂质和纤维成份高分辨MRI表现及其病理基础

High-resolution MR imaging used for fibrous and lipid components of carotid atheromatous plaques in vivo

目的:应用3.0T MR高分辨成像(HRMR)在体显示颈动脉粥样斑块,探讨斑块脂质成分和纤维成分的HRMR表现及其病理基础。方法:经彩超检查证实的症状性颈动脉狭窄37例,均行管壁高分辨MRI检查,检查序列包括3D TOF、DIR T1WI、T2WI及PDWI。其中22例检查前1周内行CTA检查,9例检查后1周内行颈动脉内膜剥脱术,5例接受颈动脉支架置入术。根据颈动脉内膜剥脱术斑块所在的颈动脉部位,将获得的病理标本与MRI图像逐层对照,研究斑块纤维成分和纤维帽、脂质成分和脂质坏死池的MRI表现,探讨MRI表现的病理基础。结果:37例共发现52支颈动脉存在斑块,斑块钙化21支(40.4%)、无钙化斑块31支(59.6%);31支软斑块中,纤维成分为主者8支(15.6%),有明显脂质核心斑块23支(44.2%);其中,伴斑块出血5支(10%)、脂质坏死核心3支(6%),纤维帽撕裂(溃疡或纤维帽撕裂)3支(6%)。相对于胸锁乳突肌,斑块脂质成分在TOF图像上呈等信号,T1WI呈等信号或稍高信号,PDWI多呈等信号或略高信号、少数呈低信号,T2WI上呈等信号或低信号;脂质坏死池在TOF、T1WI、PDWI和T2WI上均呈高信号;纤维帽和纤维成分的信号相仿,在TOF图像上呈等信号或低信号,T1WI上呈高信号或略高信号,PDWI呈稍高或等信号,T2WI上呈稍高信号。硬斑块纤维帽厚度(1.1±0.4)mm,软斑块纤维帽厚度(0.7±0.3)mm。硬斑块和软斑块的纤维帽厚度差异有统计学意义(P<0.001)。结论:多序列高分辨MRI可以显示斑块脂质成分、纤维成分和纤维帽,并对斑块脂质和纤维帽进行初步的定量,为在体分析斑块的结构提供评价指标,为斑块风险性评价提供参考。

Objective：To explore MR findings of the fibrous and lipid components of carotid atheromatous plaques in vivo with high-resolution magnetic resonance imaging.Methods：37 patients with carotid atheromatous plaques revealed by color doppler ultrasound underwent high-resolution MR scanning using the protocol of time-of-flight MR angiography,DIR T1WI,PDWI and T2WI sequences.The total vessel wall area,the fibrous and lipid components and fibrous cap of carotid atheromatous plaques were determined by two observers,9 carotid endarterectomy specimens were acquired and the corresponding regions fibrous and lipid components of the pathologic specimens were compared with MRI findings.Results：52 carotid plaques were found in 37 patients,calcification was present in 40.4%（21/52）,lipid core was present in 44.2%（23/52）,lipid necrotic core in 6%（3/52）,intraplaque hemorrhage was present in 10%（5/52）,fibrous cap rupture（ulceration or fibrous cap rupture） was present in 6%（3/52）.The lipid components manifested isointensity on TOF,isointensity or slight hyperintensity on T1WI and PDWI,isointensity or hypointensity on T2WI.However,the lipid necrotic core presented hyperintensity on four sequences;the fibrous components manifested isointensity or hypointensity on TOF,hyperintensity or slight hyperintensity on T1WI,isointensity or slight hyperintensity on PDWI,slight hyperintensity on T2WI.The mean fibrous cap thickness of calcified plaque was（1.1±0.4）mm,the mean fibrous cap thickness of non-calcified plaque was（0.7±0.3）mm,there was statistical significance between them.Conclusion：High resolution MRI can manifest plaque fibrous components,lipid components and the fibrous cap.