颈动脉不稳定性粥样硬化斑块的研究

颈动脉粥样硬化不稳定斑块是急性脑血管疾病的主要病理基础,本文主要介绍颈动脉斑块形成的病理机制,影响其稳定性的因素及目前对其检测和诊断方法.     

颈动脉粥样硬化斑块MR成像的研究

目的 探讨多对比加权的MRI序列对颈动脉粥样硬化斑块检出并定性分析的价值。方法 采用采用1．5T磁共振仪、多对比加权序列3D—TOF、FSEPDWI、FSE—DIRT．WI、FSE—DIRPDWI、FSE—DIRT2WI对24例动脉粥样硬化的患者的35个颈动脉斑块进行MRI成像．分析斑块信号特征。结果 35个粥粥样斑块中18个斑块在所有序列上信号单一均匀；17个斑块在一个或多个序列上信号混杂，其中9个斑块含有脂质核心信号；9个斑块含钙化信号；1个表现为血管腔内血栓形成管腔闭塞。10个斑块可见厚纤维帽信号；23个表现为薄纤维帽信号特征；2个斑块表面不光滑。结论 采用多对比加权的MRI序列可以检出颈动脉粥样硬化斑块．并在一定程度上可对其进行成分分析。     

颈动脉粥样硬化斑块CEUS研究进展

CEUS在临床应用日益普及,通过观察造影剂在组织内的灌注过程,实现对病灶的分析,在判断颈动脉粥样硬化斑块的稳定性和评估药物治疗效果方面的应用已较为成熟。目前,CEUS用于颈动脉斑块的靶向显影和治疗方面研究也在逐步开展。本文对CEUS在颈动脉粥样硬化斑块诊疗领域的应用现状及新技术、新进展进行综述。     

颈动脉斑块易损性的临床研究进展

脑卒中是人类三大死亡原因之一,以缺血性脑卒中为主,占总脑卒中的70%～75%,而动脉粥样硬化(atherosclerosis,AS)斑块破裂所致栓子是导致缺血性脑卒中主要原因,其形成不仅与斑块大小有关,而且与斑块易损性明显相关.近年来,颈动脉斑块易损性的研究越来越受到重视,如何准确评价斑块易损性是现代医学领域研究的热点之一.随着医学技术的发展,斑块易损性的研究越来越全面,现将颈动脉粥样硬化斑块易损性的临床研究进展综述如下.     

速度向量成像评价颈动脉粥样硬化斑块稳定性

目的通过测定等长握力试验前后颈动脉粥样硬化斑块超声力学参数变化,提取有效评价斑块稳定性指标,建立不稳定斑块超声评价新方法。方法采用高频超声经体表获取64例患者71个孤立性颈动脉粥样硬化斑块标准等长握力试验前后连续3个心动周期实时二维灰阶超声图像,导入二维速度向量成像工作站脱机分析。观察握力试验前后血管内膜运动速度向量大小、时相和方向变化及彩色M型二维和重建三维应变、应变率显像。测量握力试验前后斑块肩部、顶部及相同节段内膜对应点和无斑块参考段对应点血管内膜峰值应变和应变率及峰值差值,进行统计比较分析。结果颈动脉粥样硬化斑块处内膜二维速度向量图显示颈动脉内膜运动速度向量大小、方向和时相紊乱、不同步;握力前斑块顶部内膜峰值应变、应变率显著高于对应点内膜测值（P〈0.05）;握力前后斑块肩部内膜峰值应变、应变率显著高于斑块同一平面对应点内膜测值（P〈0.05）。握力前后斑块左肩部内膜峰值应变高于顶部测值（P〈0.05）,斑块内膜左肩部与顶部及顶部与右肩部的应变峰值差差异有统计学意义（P〈0.01）。结论颈动脉粥样硬化斑块段内膜运动的机械不同步和斑块两侧肩部与顶部间峰值应变和应变率差值的不对称性,有可能作为动脉粥样硬化不稳定斑块的初查和量化评价指标。     

颈动脉粥样硬化斑块的超声表现

目的 探讨颈动脉粥样硬化斑块的超声特点.方法 对1 500例健康查体者进行了颈动脉血管检查.结果 检出颈动脉粥样硬化斑块305例,其中局限性斑块型225例,占73.77%;弥漫性增厚型30例,占9.84%;混合型50例,占16.39%.结论 颈动脉超声检查是诊断、评估动脉壁病变的有效手段之一,在对颈动脉粥样硬化的预防、治疗评价中起着重要作用.     

磁共振增强对颈动脉粥样硬化斑块内纤维帽的诊断价值

目的:探讨MR增强扫描诊断CAS病变斑块纤维帽的价值。方法:对20例CAS病变患者行颈动脉MR高分辨扫描,检查序列包括(QIR)T1WI、(FSE)T2WI/PDWI、3D-TOF和增强,比较各序列纤维帽显示情况。结果:纤维帽在T1WI、PDWI的显示多在I级以下,纤维帽显示达到Ⅱ级以上的层面比例,T2WI高于3D-TOF,增强扫描也高于3D-TOF,差异具有统计学意义;纤维帽显示达到Ⅲ级的层面比例,增强扫描高于T2WI,差异具有统计学意义。结论:3D-TOF、T2WI适合纤维帽显示,增强扫描可以进一步提高MRI对纤维帽的显示效果。     

高血压病与颈动脉粥样硬化斑块的关系

目的：采用颈动脉彩色多普勒超声观察高血压患者颈动脉粥样硬化的变化,探讨颈动脉粥样硬化斑块与高血压病的关系。方法：超声检测１４２例高血压患者的双侧颈动脉,高血压病可分为如下三组：①单纯高血压组（ＥＨ）;②高血压伴心肌梗塞组（ＥＨＭ）;③高血压伴缺血性脑卒中组（ＥＨＳ）。检测结果并与５１名健康者作对比。结果：高血压病患者的斑块检出率、斑块面积、斑块指数和斑块积分均明显高于对照组,以伴心肌梗塞和缺血性脑     

缺血性脑卒中患者颈动脉粥样硬化斑块危险因素的分析

目的 探讨缺血性脑卒中颈动脉粥样硬化斑块形成的危险因素。方法 将148例缺血性脑卒中患者，经颈动脉彩超检查分为有斑块组80例和无斑块组68例。分别检测颈动脉内膜一中层厚度（IMT）、血糖、血压、血脂、纤维蛋白原、C-反应蛋白、胰岛素样生长因子-1，先进行单因素比较，然后进行非条件logistic多元回归分析。结果 斑块组年龄、颈动脉IMT、总胆同醇、低密度脂蛋白、纤维蛋白原、C-反应蛋白水平及高血压、糖尿病比例高于无斑块组（P≤0．05）：logistic多元回归分析表明，C反应蛋白（OR=3．546，P=0．035）、纤维蛋白原（OR=1．074，P=-0．012）是颈动脉粥样硬化斑块形成的最危险因素。结论 在缺血性脑卒中，颈动脉IMT增厚可反应颈动脉硬化程度；高龄、高血压、高血糖、高脂血症、纤维蛋白原增高、C-反应蛋白增高可能是颈动脉粥样硬化斑块形成的危险因素；C-反应蛋白、纤维蛋白原在颈动脉粥样硬化斑块的发生发展中起了重要作用。     

High-resolution intravascular magnetic resonance quantification of atherosclerotic plaque at 3T

Background

The thickness of fibrous caps (FCT) of atherosclerotic lesions is a critical factor affecting plaque vulnerability to rupture. This study tests whether 3 Tesla high-resolution intravascular cardiovascular magnetic resonance (CMR) employing tiny loopless detectors can identify lesions and accurately measure FCT in human arterial specimens, and whether such an approach is feasible in vivo using animal models.

Methods

Receive-only 2.2 mm and 0.8 mm diameter intravascular loopless CMR detectors were fabricated for a clinical 3 Tesla MR scanner, and the absolute signal-to-noise ratio determined. The detectors were applied in a two-step protocol comprised of CMR angiography to identify atherosclerotic lesions, followed by high-resolution CMR to characterize FCT, lesion size, and/or vessel wall thickness. The protocol was applied in fresh human iliac and carotid artery specimens in a human-equivalent saline bath. Mean FCT measured by 80 μm intravascular CMR was compared with histology of the same sections. In vivo studies compared aortic wall thickness and plaque size in healthy and hyperlipidemic rabbit models, with post-mortem histology.

Results

Histology confirmed plaques in human specimens, with calcifications appearing as signal voids. Mean FCT agreed with histological measurements within 13% on average (correlation coefficient, R = 0.98; Bland-Altman analysis, -1.3 ± 68.9 μm). In vivo aortic wall and plaque size measured by 80 μm intravascular CMR agreed with histology.

Conclusion

Intravascular 3T CMR with loopless detectors can both locate atherosclerotic lesions, and accurately measure FCT at high-resolution in a strategy that appears feasible in vivo. The approach shows promise for quantifying vulnerable plaque for evaluating experimental therapies.     

同型半胱氨酸联合颈动脉斑块检测用于早期诊断缺血性脑卒中的临床研究

目的 探讨同型半胱氨酸（Hcy）联合颈动脉斑块在早期缺血性脑卒中患者中的表现特征,以便为早期诊断提供依据.方法 早期缺血性脑卒中患者78例列入研究组,同期体检健康者80例列入对照组,两组患者均行Hcy和颈动脉斑块临床检测,并进行记录对比.结果 研究组患者Hcy浓度明显高于对照组,颈动脉内膜中层厚度明显厚于对照组,颈动脉斑块患病率明显高于对照组,差异有统计学意义（P〈0.05）.结论 Hcy浓度提高、存在颈动脉斑块和颈动脉内膜中层厚度增厚可作为临床早期诊断缺血性脑卒中的指标之一,可早期发现脑动脉血管状况不良的患者,并做好预防,减少临床脑梗死的发病,降低致残致死率.     

MRI评估颈动脉粥样硬化斑块成分、类型及其与临床症状的相关性

目的：应用3.0 T MRI评估颈动脉粥样硬化斑块内成分,并据此对斑块进行分型;探讨斑块成分、类型与临床发生缺血性脑血管事件的相关性,评价应用高场强MR对斑块进行早期诊断的预警作用。方法对108例经超声检查发现颈动脉粥样硬化斑块的患者施行颈动脉斑块的MRI检查。颈动脉MR检查使用Philips或GE 3.0 T MR扫描仪,线圈选用颈动脉专用8通道表面线圈,扫描序列包括3D TOF、T1WI、T2WI、PDWI、MP-RAGE及CE-T1WI。FOV 14 cm,TOF及MP-RAGE序列扫描层厚2 mm,间隔-1 mm,余各序列扫描层厚2 mm,间隔0。对颈动脉分叉前后管腔的狭窄程度、斑块的成分（有无出血、钙化、疏松间质）、纤维帽的状况（厚、薄、破溃）等情况做出判断,依据颈动脉粥样硬化斑块MRI分型标准对每支血管的斑块进行分型。将入组血管按照颈动脉供血区相应脑缺血性症状的有无分为有症状组及无症状组两组,用独立t检验比较两组血管在狭窄程度上的差异;用卡方检验评估两组血管斑块内出现出血、钙化、疏松间质及纤维帽破溃的情况差异,判断斑块类型与临床症状的相关性;用Logistic回归分析狭窄程度、纤维帽破溃、斑块内出血、钙化及疏松间质对临床症状的影响度强弱。结果108例患者中,共发现有斑块血管198支：有症状组血管共计64支;无症状组血管共有134支,其中3支血管因MRI检查前已施行支架置入术不予入组,故无症状组血管共计131支。两组血管在管腔狭窄程度、纤维帽的完整性和斑块是否有出血方面均有统计学差异（P＜0.01或P＜0.05）,而在斑块钙化、疏松间质的出现率上则无统计学差异（P＞0.05）。在有症状组血管中,斑块类型比较密集,Ⅵ型斑块所占比例最大（71.8%）,而在无症状组,Ⅵ型与Ⅳ～Ⅴ型均较多（分别为44.7%和30.4%）;将两组中斑块类型粗略分为Ⅵ型与非Ⅵ型斑块,显示Ⅵ型斑块所占比例在有症状组更显著（P＜0.01）。在血管狭窄度、纤维帽破溃、斑块有出血、钙化及疏松间质这5个因素中,纤维帽是否有破溃与临床症状的关联程度最大,其次为管腔狭窄度的高低,而斑块内出血及疏松间质的有无对临床症状影响较弱,斑块内钙化则与临床症状的发生无关。结论有症状组与无症状组颈动脉斑块的MRI形态学特征具有明显差异;斑块内成分的差异与临床症状的出现有明显相关性,其与临床脑缺血性事件发生的相对危险度依次为：斑块破溃、管腔狭窄程度提升、斑块内存在疏松间质、斑块内有出血、斑块钙化;在斑块分型上,Ⅵ型代表了临床所谓的易损斑块,间接反映出斑块表面纤维帽破溃和斑块出血与临床症状关系密切。提示通过MRI检查分析斑块内成分来预测临床缺血性脑血管事件的发生是可行的,将能为临床采取相应治疗措施预防卒中发生提供可靠信息。     

颈动脉粥样硬化斑块生长部位与血管内膜及血流动力学的相关性研究

目前研究显示,动脉粥样硬化的形成与诸多因素有关,在斑块生成过程中,有一定的不均衡性,动脉粥样斑块发展在颈动脉两侧数量不均衡,以及两侧颈动脉斑块生长不对称等问题.这种不均衡性表现在一侧有斑块,另一侧不一定有斑块.通过检测斑块生长部位及血流动力学指标,探讨颈动脉粥样硬化斑块生长部位与血管内膜及血流动力学指标的关系,从而为动脉粥样硬化的早期预防和治疗提供客观的依据.     

颈动脉粥样斑块应变及应变率分布的初步探讨

目的 探讨超声检测颈动脉粥样硬化斑块应变及应变率的可行性，颈动脉粥样硬化斑块应变及应变率的分布情况。方法 选取26例冠心病患者的35处颈动脉斑块，运用组织速度成像(TVI)和Q-analysis软件测量斑块不同部位的位移、斑块应变及应变率的峰值，对同一处斑块分别在不同参数条件下测量斑块应变及应变率峰值。结果 斑块应变和应变率测量值在不同参数条件下差异无显著性意义；不同部位的斑块应变、应变率差异具有显著性意义；急性心肌梗死、陈旧性心肌梗死和心绞痛3组患者颈动脉斑块的受力情况存在差异。斑块肩部和纤维帽表面是应变最集中的部位，并且沿径向方向，从斑块表面至基底部，应变及应变率呈减小趋势。结论 TVI技术可以用于颈动脉斑块应变及应变率的分析。不同类型的斑块肩部及不同部位应变及应变率存在差异。     

孤立性颈动脉粥样硬化斑块内膜长轴切面力学状态的初步超声研究

目的 超声评价孤立性颈动脉粥样硬化斑块长轴切面上中下游内膜位点力学状态.方法 经体表获取标准等长握力试验前后46例患者48个孤立性颈动脉粥样硬化斑块最大厚度长轴切面超声图像,观察颈动脉粥样硬化斑块长轴切面上中下游内膜运动速度向量变化,测取颈动脉粥样硬化斑块血管内膜分析位点应变峰值及应变峰值绝对差值.结果 二维速度向量图显示颈动脉粥样硬化斑块处内膜运动速度向量大小、方向紊乱不同步;等长握力试验前后斑块上下游内膜位点测值高端与测值低端应变峰值差异有统计学意义(P=0.000),斑块上下游内膜位点测值高端与中游内膜位点应变峰值绝对差值和斑块上下游位点间应变峰值绝对差值差异有统计学意义(P＜0.017).结论 孤立性颈动脉粥样硬化斑块长轴切面上中下游血管内膜机械运动速度向量变化方向具有不一致性,斑块内膜不同位点间应变峰值存在不一致并能够应用超声速度向量技术定性和定量评价.     

Scan-rescan reproducibility of quantitative assessment of inflammatory carotid atherosclerotic plaque using dynamic contrast-enhanced 3T CMR in a multi-center study

Background

The aim of this study is to investigate the inter-scan reproducibility of kinetic parameters in atherosclerotic plaque using dynamic contrast-enhanced (DCE) cardiovascular magnetic resonance (CMR) in a multi-center setting at 3T.

Methods

Carotid arteries of 51 subjects from 15 sites were scanned twice within two weeks on 3T scanners using a previously described DCE-CMR protocol. Imaging data with protocol compliance and sufficient image quality were analyzed to generate kinetic parameters of vessel wall, expressed as transfer constant (K^trans) and plasma volume (v_p). The inter-scan reproducibility was evaluated using intra-class correlation coefficient (ICC) and coefficient of variation (CV). Power analysis was carried out to provide sample size estimations for future prospective study.

Results

Ten (19.6%) subjects were found to suffer from protocol violation, and another 6 (11.8%) had poor image quality (n = 6) in at least one scan. In the 35 (68.6%) subjects with complete data, the ICCs of K^trans and v_p were 0.65 and 0.28, respectively. The CVs were 25% and 62%, respectively. The ICC and CV for v_p improved to 0.73 and 28% in larger lesions with analyzed area larger than 25 mm². Power analysis based on the measured CV showed that 50 subjects per arm are sufficient to detect a 20% difference in change of K^trans over time between treatment arms with 80% power without consideration of the dropout rate.

Conclusion

The result of this study indicates that quantitative measurement from DCE-CMR is feasible to detect changes with a relatively modest sample size in a prospective multi-center study despite the limitations. The relative high dropout rate suggested the critical needs for intensive operator training, optimized imaging protocol, and strict quality control in future studies.     

Validation of 3D ultrasound vessel wall volume: an imaging phenotype of carotid atherosclerosis

Carotid atherosclerotic lesions are a major cause of stroke and the identification and quantification of such lesions in patients is important for the development of a better understanding of atherogenesis in high risk populations and for the design of studies to assess treatment efficacy. Our objective was to develop and validate a new three-dimensional ultrasound (3DUS) measurement or phenotype of carotid atherosclerosis, vessel wall volume (VWV), which is a three-dimensional measurement of vessel wall thickness and plaque within the carotid arteries measured in 3DUS images. To assess both intraobserver and interscan variability, 3DUS images were acquired from the right and left carotid arteries of ten subjects with carotid atherosclerosis scanned twice within a period of 2 wk. For both VWV and total plaque volume (TPV), an expert observer performed five measurement trials of all images acquired at baseline scan and 2-wk rescan with a 5-d period between measurement trials for images. Images were re-randomized for each measurement trial and both TPV and VWV were measured by observers who were blinded to subject identification for each time-point measurement. Coefficients of variation (COV) and intraclass correlation coefficients (ICC), for VWV measurements indicated higher intraobserver (scan COV = 4.6% ICC = 0.95, rescan COV = 3.4%, ICC = 0.96) and interscan reproducibility (COV = 5.7%, ICC = 0.85) than TPV measurements (intraobserver variability scan COV = 22.7% ICC = 0.85, rescan COV = 21.1% ICC = 0.88 and interscan variability, COV = 31.1%, ICC = 0.83), although absolute variances for both phenotypes were very similar (VWV = 90 mm3, TPV = 80 mm3).     

急性缺血性脑卒中患者血浆Lp-PLA2水平与颈动脉硬化斑块稳定性及神经功能缺损程度的关系

目的探讨血浆脂蛋白相关磷脂酶A2（Lp—PLA2）水平与急性缺血性脑卒中患者颈动脉粥样硬化斑块稳定性及神经功能缺损程度的关系。方法将106例急性缺血性脑卒中患者根据颈动脉彩超检查分为不稳定斑块组（44例）、稳定型斑块组（38例）和无斑块组（24例）,以40名健康体检者作为正常对照组,采用酶联免疫吸附试验（ELISA）测定血浆Lp—PLA2水平。所有患者按美国国立卫生研究所中风量表（NIHSS评分）进行神经功能缺损程度评估。结果急性缺血性脑卒中患者Lp—PLA2水平明显高于正常对照组（Z=-6．995,P〈0．05）;无斑块组、稳定型斑块组和不稳定斑块组Lp—PLA2水平依次升高,且无斑块组与有斑块组比较差异有统计学意义（Z=-5．670,P〈0．05）,稳定型斑块组和不稳定斑块组比较差异有统计学意义（Z=-6．185,P〈0．05）。受试者工作特征（ROC）曲线显示Lp—PLA2评估急性缺血性脑卒中患者斑块稳定性的最佳截断值为137．00μg/L,灵敏度为81．8％,特异性为95．1％。神经功能缺损程度随Lp．PLA2水平的增加呈递增趋势,差异有统计学意义（x^2=74．233,P〈0．05）。血浆Lp—PLA2水平与NIHSS评分呈明显正相关（0=0．861,P〈0．05）。结论急性缺血性脑卒中患者Lp—PLA2水平与颈动脉粥样硬化斑块稳定性和神经功能缺损程度有关,血浆Lp—PLA2水平可预测斑块稳定性,同时对急性缺血性脑卒中患者的病情监测有重要价值。