兔颈动脉粥样硬化模型:MRI表现及组织病理学特征

制作兔颈动脉粥样硬化模型,利用MRI显示病变的进展,组织病理学显示病变的类型。利用气囊式导管损伤颈总动脉内皮后予以高脂饮食制作23例兔右侧颈总动脉     

颈动脉粥样硬化斑块MRI成像

动脉粥样硬化是威胁人类健康的一类严重疾病,脑缺血性卒中与颈动脉粥样硬化密切相关。本文回顾MRI成像技术在颈动脉粥样硬化斑块检测中的应用。     

老年人离体颈动脉管壁MRI表现与病理对照研究

目的 通过与病理对照,探讨3.0T高分辨率MRI检测老年人离体颈动脉血管壁结构特征及对动脉粥样硬化病变形态学和定量分析的能力。方法 对9对（18根）老年人的离体颈动脉标本,在3.0 T MR仪上采用特制小孔径线圈行高分辨率T1WI、T2WI脂肪抑制扫描,测量血管截面的最大内膜厚度、管腔面积、内膜面积和中膜面积,并根据美国心脏病协会(AHA)动脉粥样斑块病理分型及MRI分型标准进行分型,进行病理与影像的Pearson和Spearman相关分析以及一致性Kappa检验。结果 以T2WI脂肪抑制序列显示的颈动脉管腔面积、中膜面积和内膜面积的病理组织学相关性较高[T2WI与病理测量分别为(27.53±6.77) mm2和(25.83 ±6.69)mm2,r2 ＝0.91,P2 ＝0.024;(12.31 ±3.31)mm2和( 12.28±3.71) mm2,r2 ＝0.70,P2 ＝0.020;中位数12.29 mm2（范围1.12～33.18 mm2）和11.62 mm2（范围0.89～32.84 mm2）,r2 ＝0.74,P2 ＝0.016];颈动脉粥样硬化MRI分型与AHA病理分型结果具有较好的一致性（Kappa值＝0.74,95％可信区间为0.67～0.80）。结论 3.0T高分辨率多序列MRI能清晰显示离体颈动脉血管壁的形态特征和细微结构并允许进行量化评估,尤其是T2WI脂肪抑制序列具有对动脉粥样硬化病变准确定位和分型的能力。     

3.0T高分辨MRI对颈动脉斑块分型的研究

目的：探讨在3．0T上运用高分辨多序列MRI对颈动脉斑块进行定性、分型的能力。材料和方法：53例经超声筛选的颈动脉斑块病人，包括近期脑卒中者27例，在3．0TMR仪上行多序列（3D—TOF、T1W、T2W和PDW）扫描，参照修改的AHA动脉粥样硬化MRI分型标准，对颈总动脉、颈内动脉和分叉部的斑块进行定性和分型，计算症状侧颈动脉斑块的发病率和比数比，以评估各型斑块发生脑卒中的危险度。计数资料行卡方检验或Fisher切概率检验，P〈0．05有统计学意义；比数比的显著性检验用Mantel—Haenszel法，并计算95％可信区间。结果：①270个部位中，Ⅰ-Ⅱ型占32．2％，Ⅲ型占45．9％，Ⅳ-Ⅴ型占14．4％，Ⅵ型占3．0％，Ⅶ型占4．5％，各型斑块在颈动脉3个部位的分布差异有统计学意义（Fisher确切概率P：0．00596）；②Ⅳ-Ⅴ型、Ⅵ型斑块在症状侧颈动脉的发病率和比数比高于其他类型，Ⅵ型斑块比数比为16．42。结论：在3．0TMR上应用高分辨多序列技术对进展期的斑块具有准确定位及初步分型的能力，Ⅳ-Ⅴ型和Ⅵ型斑块显示了较强的脑卒中发生趋势，尤其是Ⅵ型斑块。     

Atherosclerosis of the carotid artery: Evaluation by magnetic resonance angiography

Carotid artery atherosclerotic plaques (APs) can lead to brain ischemia, an event shown to correlate with both the degree of stenosis and the composition of the AP. Currently, accurate estimates of stenosis can be obtained by either x-ray angiography or three-dimensional time of-flight (TOF) magnetic resonance angiography (MRA). Our purpose was to determine whether three-dimensional TOF MRA images could also provide information on plaque location, morphology, and composition. Seven pre-endarterectomy patients underwent three-dimensional TOF MRA. After endarterectomy, plaque histology was evaluated. Three-dimensional TOF MRA images contained sufficient soft tissue contrast to differentiate the plaques from the surrounding tissues in all cases. Estimation of plaque morphology had 80% correlation with histology. Finally, intraplaque hemorrhage and calcification were depicted as regions of moderately high and very low intensity, respectively. These preliminary results suggest that three-dimensional TOF MRA may be useful in studying the development and progression of carotid atherosclerosis.     

颈动脉斑块内出血的高分辨力MRI研究进展

颈动脉斑块内出血是颈动脉粥样硬化斑块不稳定的重要表现之一,其可以引起斑块扩大及破裂,是发生缺血性脑卒中的重要危险因素之一。诊断斑块内出血的影像方法主要包括MRI、CT及超声,高分辨力MRI技术具有无创、空间分辨力高、多对比成像等特点,是目前检测斑块内出血最有效的影像方法,其主要包括2D和3D序列,其中近年来发展的部分3D序列进一步提高了空间分辨力及诊断敏感性和特异性。就颈动脉斑块内出血的高分辨力MRI的研究进展予以综述。     

MRI与DSA对颈动脉狭窄和粥样硬化斑块评估能力的比较

目的 探讨MRI与DSA对颈动脉粥样硬化患者血管狭窄及粥样硬化斑块病变特点评估能力的差异.方法 46例缺血性脑血管疾病患者,超声发现颈动脉粥样硬化斑块后分别行颈动脉MRI及DSA检查.颈动脉MR检查序列包括三维时间飞跃法(3D TOF)、T1WI、T2WI、质子密度加权成像( PDWI)及增强T1WI;颈动脉DSA检查分别摄取颈动脉的正位像和侧位像.观察颈动脉分叉处管腔的狭窄程度和斑块的病变特征,包括纤维帽的状况、斑块内出血和钙化.计算Kappa值分析MRI和DSA对血管狭窄程度判断结果的一致性;应用配对卡方检验检测两种方法对溃疡斑块的检出差异.结果 89支血管的MR图像质量均满足诊断要求.MRI显示血管狭窄程度的M(范围)为50％(16％～78％),DSA显示为47％(7％～73％),二者具有很好的一致性(Kappa值为0.882,P＜0.01).MRI发现34支血管具有斑块纤维帽破溃,DSA发现10支血管具有溃疡斑块(x2=20.346,P＜0.01).此外,MRI发现37支血管有斑块内出血,71支血管有斑块内钙化,而DSA均不能显示.结论 MRI可以准确判断颈动脉的狭窄程度,在显示溃疡斑块、斑块内出血以及钙化方面较DSA更具优势.     

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和管壁高分辨MR检查,MR检查序列包括3DTOF、DIR T1WI、T2WI、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、T1WI、PDWI、T2WI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。     

破裂与非破裂颈动脉粥样硬化斑块周围血流动力学的MRI分析

目的 分析颈内动脉起始部粥样硬化斑块周围血流动力学改变,探讨可能导致纤维帽破裂的流体力学因素.方法 前瞻性纳入19例颈内动脉起始部粥样硬化病变患者,进行颈动脉MRI.观察斑块形态结构,并据此将斑块分为纤维帽完整组和纤维帽破裂组.利用颈动脉MR增强血管成像原始图像进行血流动力学分析,计算颈动脉分叉部血管管壁切应力(WSS)、静态压、血管狭窄率等数据,两组之间比较采用两独立样本的Mann-Whitney U检验和t检验.结果 19例颈内动脉起始部斑块中,纤维帽完整组8例、斑块纤维帽破裂11例.纤维帽完整组最大管壁切应力、平均管壁切应力、最小静态压及平均静态压对应的中位数(上下四分位数范围)分别为42.92(27.13～68.19)、32.04(21.21～55.68)、-1 717.36(-3 433.61～-721.10)、-1 341.64(-2 868.00～-612.86)Pa,纤维帽破裂组对应的数据分别为67.18(60.46～139.51)、55.76(40.41～124.57)、-3884.02(-18767.39～-2886.33)、-3065.92(-16064.18～-1 915.09)Pa,两组间差异有统计学意义(U值分别为18.00、18.00、17.00、18.00,P值均＜0.05).斑块纤维帽完整组和纤维帽破裂组颈内动脉狭窄率分别为(47.13±13.50)％、(62.91±11.96)％,两组之间比较差异有统计学意义(t=2.69,P=0.02).结论 破裂与非破裂颈动脉粥样硬化斑块间的血流动力学存在差异,可能会对斑块破裂造成影响.     

颈动脉粥样硬化与股动脉粥样硬化的比较

目的:比较颈动脉粥样硬化与股动脉粥样硬化的异同点。方法:将205名受试者分为正常组(n=85)和冠心病组(n=120),进行颈动脉和股动脉超声检查,并对年龄、体重指数、血压、吸烟史、血脂、血糖、颈动脉内膜中层厚度(IMT)、股动脉IMT及冠心病家族史、男性性别进行单因素分析和Logistic分析。结果:①股动脉IMT及血管弹性指标较颈动脉呈增高趋势;②冠心病组颈动脉斑块发生率显著高于股动脉斑块发生率;③多因素分析表明年龄、血糖、家族史、颈动脉IMT是冠心病的危险因素。结论:股动脉与颈动脉在血管IMT、血管僵硬度、动脉斑块发生率存在差异;颈动脉IMT是冠心病的高危因素。     

颈动脉球囊扩张再狭窄动物模型的建立

目的　探索再狭窄的发病机制进行干预研究 ,建立颈动脉再狭窄家兔动物模型。方法　取颈部正中切口 ,无菌暴露兔右颈动脉 ;在颈内动脉 (ICA)起始部及颈总动脉 (CCA)近心侧距动脉分叉2cm处用动脉夹临时夹闭 ;自颈外动脉 (ECA)远端结扎并由结扎近心侧穿刺进入导丝、球囊导管 ,撤除CCA动脉夹进行球囊扩张血管成形术 (PTA)。于PTA后不同时间进行组织学及形态学分析 (左侧颈总动脉作正常对照组 )。结果　PTA后早期CCA主要病理改变是血栓形成 ,中晚期为血管平滑肌细胞(VSMC)由中层移行之内膜并失控增殖伴有基质增多 ;第 15天管腔出现明显狭窄 (P <0 .0 1)内膜增厚(P <0 .0 1)。结论　家兔颈总动脉PTA模型模拟了临床过程 ,成功率高 ,为PTA之动脉阶段局部用药或转基因治疗实验首选模型     

动态增强MRI技术评价动脉粥样斑块的实验研究

目的 利用动态增强MRI探讨动脉粥样斑块Gd-DTPA强化的特点和强化机制.方法 12只新西兰大白兔,通过高脂饮食联合内膜剥脱术在腹主动脉建立斑块模型.术后10～16周行动态增强MRI扫描.以71 s为间隔获得35帧TtWI,并在第3次扫描开始的同时静脉注射Gd-DTPA.扫描结束后12 h内取动脉斑块行HE和CD31免疫组织化学染色,计数新生血管.在MRI上测量斑块的时间-信号强度曲线,计算曲线的描述性参数,和新生血管计数进行Pearson相关性分析.以组织病理检查结果为参照,分析斑块强化特点.结果 静脉注射Gd-DTPA后,动脉斑块明显强化,呈现"快进慢出"的特点.斑块内部强化程度不均匀,纤维成分强化较强,脂质和炎细胞聚集灶强化较弱.新生血管计数(117.7±93.3)和时间-信号强度曲线得到的峰值(1.05±0.30)、初始斜率(0.82±0.28)和7 min曲线下面积(4.97±1.67)有显著正相关,相关系数r分别为:0.553(P＜0.01)、0.468(P＜0.05)、0.554(P＜0.01).结论 动脉粥样硬化斑块呈"快进慢出"的强化特点.新生血管生成、内膜通透性增加及细胞外基质增多可能是斑块被Gd-DTPA强化的原因.DEC-MRI定量分析斑块新生血管密度有一定的可行性.     

Asymptomatic postendarterectomy dissection of the internal carotid artery detected incidentally on MRI

A patient who had recently undergone carotid endarterectomy was found to have internal carotid artery dissection on an MRI examination. This is a supposedly rare complication of this frequently performed operation. Since most patients with dissection of the ICA (from whatever cause) are symptomatic when the diagnosis is made, its incidental detection in an asymptomatic patient suggests that this complication may be commoner than generally recognised. We review the ways in which carotid dissection may occur during endarterectomy and the differential diagnosis of the MRI appearances.     

Persistent hypoglossal artery: MRI, MRA and digital subtraction angiography

We present the MRI, MRA and digital subtraction angiography (DSA) findings in a persistent hypoglossal artery found incidentally in a patient with cutaneous and intracranial haemangiomata. Received: 20 September 2000/Accepted: 21 November 2000     

Magnetic resonance imaging of carotid artery abnormalities in patients with sphenoid sinusitis

Sphenoid sinusitis is unusual in children, but when it occurs, it can lead to serious intracranial complications. We show the value of MRI in demonstrating intracranial abnormalities due to sphenoid sinus infection, particularly those involving the internal carotid arteries and cavernous sinuses. We reviewed our imaging experience of sphenoid sinusitis and found four patients with ICA narrowing who had undergone MR evaluation including conventional and diffusion imaging. MR angiography was also performed in three patients to determine the extent of ICA narrowing. Narrowing of ICA was found in the cavernous segment in all patients and in the supraclinoid segment in three. Cerebral infarction was found in two patients. In one patient the cavernous sinus showed hyperintensity on diffusion-weighted images and hypointensity on apparent diffusion coefficient map, suggesting reduced diffusion. Although infrequent in children, sphenoid sinus infection should be considered as a possible cause of intracranial infection, particularly in teenagers. Early recognition of cavernous sinus involvement and ICA narrowing may lead to prompt treatment and hence a more favorable outcome.     

Atherosclerotic plaque features and distribution in bilateral carotid arteries of asymptomatic elderly population: A 3D multicontrast MR vessel wall imaging study

PurposeThis study sought to investigate the characteristics of morphology, compositions and distribution of carotid atherosclerotic plaques in asymptomatic elderly population using three dimensional (3D) multicontrast magnetic resonance vessel wall imaging.Materials and methods146 asymptomatic elderly subjects (≥ 60 years) were recruited and underwent 3D multicontrast MR vessel wall imaging for bilateral carotid arteries on a 3.0T MR scanner. The presence of carotid atherosclerotic plaque was determined and the stenosis was measured. The characteristics of plaque morphology and compositions were evaluated and compared among distal internal carotid artery (D-ICA), proximal-ICA (P-ICA), carotid bulb (CB), distal common carotid artery (D-CCA) and proximal-CCA (P-CCA).ResultsOf all recruited 140 subjects (72.1 ± 5.7 years, 63 males), 87 (62.1%) had carotid plaques, 17 (12.1%) had high-risk plaques and 51 (36.4%) had multiple plaques. Of all 280 carotid arteries, only 16 (5.7%) had luminal stenosis (21.1% ± 11.4%). Among carotid arteries without luminal stenosis, the prevalence of plaque and high-risk plaques was 43.2% and 8.3%, respectively. Carotid plaques were mostly found in CB segment (33.9%), followed by P-ICA (13.6%), P-CCA (11.1%), D-CCA (4.6%) and D-ICA (3.6%). Age was independently associated with presence of multiple carotid plaques (odds ratio, 1.835; 95% confidence interval, 1.196–2.815; P = 0.005).ConclusionCarotid artery atherosclerotic plaques are prevalent and a substantial number of high-risk plaques can be found in the asymptomatic elderly subjects. Longitudinal studies are warranted to investigate the risk of having ischemic stroke for asymptomatic elderly individuals with carotid artery high risk plaques.     

Evaluation of carotid stenosis with axial high-resolution black-blood MR imaging

High-resolution axial black-blood MR imaging (BB MRI) has been shown to be able to characterise carotid plaque morphology. The aim of this study was to explore the accuracy of this technique in quantifying the severity of carotid stenosis. A prospective study of 54 patients with symptomatic carotid disease was conducted, comparing BB MRI to the gold standard, conventional digital subtraction X-ray angiography (DSA). The BB MRI sequence was a fast-spin echo acquisition (TE=42 ms, ETL=24, field of view = 100×100 mm, slice thickness = 3.0 mm) at 1.5 T using a custom-built phased-array coil. Linear measurements of luminal and outer carotid wall diameter were made directly from the axial BB MRI slices by three independent blinded readers and stenosis was calculated according to European Carotid Surgery Trial (ECST) criteria. There was good agreement between BB MRI and DSA (intraclass correlation = 0.83). Inter-observer agreement was good (average kappa = 0.77). BB MRI was accurate for detection of severe stenosis (80%) with sensitivity and specificity of 87 and 81%, respectively. Eight cases of DSA-defined moderate stenosis were overestimated as severe by BB MRI and this may be related to non-circular lumens. Axial imaging with BB MRI could potentially be used to provide useful information about severity of carotid stenosis.     

In vitro characterization of atherosclerotic carotid plaque with multidetector computed tomography and histopathological correlation

This in vitro study evaluated the performance of 16-slice multidetector computed tomography (MDCT) in the assessment of carotid plaque components, with histology as the gold standard. Twenty-one specimens (n=21) were scanned and reconstructed after optimization of the protocol. Three corresponding MDCT images and histologic sections were selected from each specimen. The Hounsfield values (HV) of the major plaque components (calcifications, fibrous tissue and lipid) were assessed. Plaque areas (mm²) assessed with MDCT were compared with the results from histologic analysis. A value of 140 kVp and an intermediate reconstruction algorithm was the optimal protocol. In 15 out of 21 specimens it was possible to match MDCT images with histology. The HV of calcifications, fibrous tissue and lipid were 45±21, 79±20 and 960±491 HU (P<0.001), respectively. Plaque areas were compared in 27 matched levels. The calcified and lipid areas on MDCT and histology correlate well (R²=0.83 and R²=0.68, respectively). The mean difference in lipid area was 0.1 mm² (95% CI=–2.1–2.3 mm²). This in vitro study showed that MDCT is capable of characterizing and quantifying the lipid rich portion of the atherosclerotic plaque.     

运用3.0T MR高分辨多序列技术对颈动脉斑块分型的研究

目的:探讨3.0T MRI高分辨多序列成像对颈动脉斑块的定位和分型能力.方法:31例经超声筛选的颈动脉斑块患者,在3.0T磁共振仪上,采用相控阵颈部线圈和心电门控,行3D-TOF、T1WI、T2WI和PDWI横断面扫描,在颈总动脉、分叉部及颈内动脉3个部位,对斑块进行初步定性和分型.结果:25例共150个血管断面中,Ⅰ～Ⅱ型占34%,Ⅲ型占44.7%,Ⅳ～Ⅴ型占14%,Ⅵ型占3.3%,Ⅶ型占4.0%;Ⅶ型的钙化斑块均被CT所证实.不同类型斑块在颈动脉各部位的分布上差异无显著性意义(P=0.112).Ⅵ型病例近期均有同侧大脑半球颈动脉供血区缺血事件发生.结论:在3.0T MR上应用高分辨多序列技术能清晰显示颈动脉血管壁的细微结构和斑块的形态特征,对进展期斑块具有准确定位和初步分型能力,可作为一项无创性评价颈动脉粥样斑块的理想方法.     

Tissue characterisation of atherosclerotic carotid plaques by MRI

Carotid artery plaques with intraplaque haemorrhage or atheromatous debris have been found to be associated with an increased risk of embolic stroke. Other methods have failed to detect plaque morphology, and it is not clear whether MRI allows differentiation between prognostically and therapeutically relevant plaque types. We examined 17 carotid bifurcation plaques which had been removed in toto by MRI. For quantifying MR signal intensities (I) the contrast-to-noise ratio (CNR) was used: (I_Tissue-I_Ref)/SD_Ref, with normal saline (0.9%) as reference (Ref) and the standard deviation (SD) of the noise. Measurements were correlated with the histopathological appearance of simple plaques, consisting of fibrous intimal thickening, lipid deposits and/or atheromatous tissue with cholesterol crystals, largely calcified plaques, and complicated plaques, containing recent intramural haemorrhage or friable atheromatous debris. Significantly different mean CNR could be measured in the three plaque types on T1- and T2-weighted sequences (p<0.00001) and using the FLASH pulse sequence with a flip angle of 15° (p<0.001). With the T1-weighted sequence simple plaques showed a CNR of 4.4±2.3, calcified plaques –4.8±2.5 and complicated plaques 15.1±4.3. Using this technique, each single plaque could be correctly classified, an unalterable prerequisite for a clinical application. To date, motion artefacts due to patient movement or insufficiently triggerable vessel pulsation in combination with relative long acquisition times (6–7 min) have limited in vivo investigations. If these problems could be overcome, MRI might become a valuable technique for studying carotid plaque morphology.