颈动脉粥样硬化斑块成分的磁共振成像

缺血性卒中与颈动脉粥样硬化密切相关.运用高分辨率3.0T磁共振成像检测颈动脉斑块的成分,包括纤维帽、脂质核心、出血和钙化等,有助于评估缺血性卒中的风险并指导治疗.文章就颈动脉粥样硬化斑块成分的磁共振成像研究现状进行了综述.     

颈动脉粥样硬化斑块成分与性别的相关性研究

目的探讨颈动脉粥样硬化患者斑块成分的性别差异。方法选取进行颈动脉3.0T MR高分辨扫描的颈动脉粥样硬化斑块患者154例,男性95例,女性59例,根据MR扫描结果,对斑块成分和性质进行分析,比较男、女性的斑块成分差异。结果男性斑块内富脂质坏死核(42.1%vs 20.0%,P=0.005)和薄或破裂纤维帽(59.7%vs39.5%,P=0.046)的发生率明显高于女性;女性斑块内钙化的发生率有高于男性的趋势(74.6%vs 65.3%,P=0.225),男性与女性斑块内出血发生率比较,差异无统计学意义(24.2%vs 22.0%,P=0.756)。结论颈动脉粥样硬化斑块患者中,男性不稳定斑块的发生率高于女性,这可能有助于解释脑卒中发病率的性别差异。     

光学相干断层扫描比较不稳定性和稳定性心绞痛患者粥样硬化斑块特征

目的 应用光学相干断层成像(OCT)技术比较不稳定性心绞痛(UAP)和稳定性心绞痛(SAP)患者冠状动脉粥样硬化斑块特征.方法 对临床诊断的23例UAP和24例SAP患者,在完成冠状动脉造影并确诊冠心病后进行OCT检查.根据OCT结果 回顾性比较分析UAP和SAP患者冠状动脉粥样硬化斑块特征,包括富含脂质斑块(≥2个象限的脂质斑块)、斑块纤维帽厚度、薄纤维帽粥样斑块(TCFA)、斑块破裂、钙化和血栓等.结果 47例患者中有44例成功进行OCT检查,包括22例UAP和22例SAP患者.UAP患者冠状动脉富含脂质斑块为91%(20/22),多于SAP患者的73%(16/22),但差异无统计学意义(P=0.741).UAP患者冠状动脉脂质斑块表面纤维帽厚度明显小于SAP患者[(69.5±34.7)μm比(141.1±68.5)μm,P=0.000],纤维帽侵蚀比例为59%(13/22),明显多于SAP患者的9%(2/22,P=0.000);TCFA[73%(16/22)比14%(3/22),P=0.000]和斑块破裂[50%(11/22)比9%(2/22),P=0.003]多于SAP患者.UAP患者冠状动脉斑块表而可见血栓形成多于SAP患者,但差异无统计学意义[27%(6/22)比9%(2/22),P=0.761].在斑块钙化方面,UAP与SAP患者之间差异无统计学意义.结论 OCT技术可清晰显示冠状动脉粥样斑块特征.与SAP患者比较,UAP患者冠状动脉粥样硬化斑块表现为纤维帽更薄、更多的纤维帽侵蚀、更多的破裂斑块和TCFA.     

老年高血压患者颈动脉易损斑块与近期缺血性脑卒中的相关性

目的应用高分辨率磁共振成像技术,探讨老年高血压患者颈动脉粥样硬化易损斑块发生与近期缺血性脑卒中之间的相关性。方法选择连续符合纳入标准的73例患者,分为有症状组44例和无症状组29例,双盲评价影像资料,分析2组斑块成分(斑块内出血、脂质坏死核、纤维帽较薄/破裂)及管腔狭窄程度与30d内发生缺血性脑卒中的相关性。结果与无症状组比较,有症状组患者纤维帽较薄/破裂发生率高,差异有统计学意义(P=0.001)。斑块纤维帽稳定性预测30d内临床症状稳定性的敏感性、特异性和准确率分别为79.5%、65.5%和74.0%,纤维帽较薄/破裂患者发生缺血性脑卒中的危险性是纤维帽完整较厚者的7.39倍,OR值7.39,95%CI:2.69²0.3(P<0.001)。2组斑块内出血、脂质坏死核及管腔狭窄程度比较,差异无统计学意义(P>0.05)。结论老年高血压患者颈动脉斑块纤维帽较薄/破裂与30d内发生缺血性脑卒中具有显著相关性,可以作为预测近期临床症状稳定性的影像学指标。     

老年颈动脉粥样硬化斑块患者磁共振检查结果与临床症状的相关性

目的探讨老年颈动脉粥样硬化斑块患者的磁共振成像(MRI)与临床症状的相关性。方法颈动脉粥样硬化斑块老年患者75例根据有无脑缺血症状分为症状组(观察组)和非症状组(对照组)。MRI检查比较两组管腔厚度、狭窄程度及斑块的成分。结果 MRI与彩色多普勒超声(CDFI)两者诊断颈动脉粥样硬化斑块结果具有高度一致性;观察组管腔狭窄程度、管壁平均厚度均大于对照组(P0.05);观察组斑块脂质核心、斑块出血、斑块纤维帽破溃的比例均大于对照组(P0.05);管壁平均厚度、纤维帽破溃是颈动脉粥样硬化斑块患者产生临床症状的独立危险因素(P0.05)。结论通过MRI对老年颈动脉粥样硬化患者的管壁情况和斑块成分进行分析,可以预测患者发生缺血性脑血管事件的可能性。     

高分辨磁共振成像评价颈动脉粥样硬化斑块成分

目的探讨高分辨MRI不同序列检查评价缺血性脑血管病患者颈动脉粥样硬化斑块成分的临床意义。方法选择64例缺血性脑血管病患者,其中短暂性脑缺血发作(TIA)患者18例,脑梗死患者46例。采用头颈联合线圈,行高分辨MRI检查,先后选用三维时间飞跃法、T_1WI、T_2WI和质子加权成像4种不同序列,分析斑块成分。结果 64例患者中,有完整厚纤维帽25例(39.1%)、完整薄纤维帽20例(31.2%)、破损纤维帽19例(29.7%),脂质池和坏死核心53例(82.8%),斑块内钙化44例(68.8%),斑块内出血31例(48.4%),斑块内纤维化33例(51.6%),脑梗死患者与TIA患者各类斑块成分所占比例比较,差异均无统计学意义(P>0.05)。结论高分辨MRI不同序列检查对颈动脉斑块的检测有助于分析斑块的成分特征,确定斑决的稳定性。     

颈动脉粥样硬化斑块炎性过程的无创影像学研究

目的应用高分辨率动态对比增强磁共振成像(DCE-MRI)和正电子发射断层显像(PET)比较不同斑块成分局部放射性活度标准化靶-本底比值(TBR)间的区别,评估颈动脉不稳定斑块炎性反应程度。方法选取颈动脉粥样硬化患者41例,分别行DCE-MRI、PET检查,共扫描1031层,将1031层扫描根据TBR分为2组,TBR≥1.25作为炎性反应组(247层),TBR<1.25作为无炎性反应组(784层)。以DCE-MRI的部分血浆容积(Vp)衡量斑块内新生血管容积,以PET的斑块TBR定义炎症量化巨噬细胞活性,分析TBR与Vp的相关性。结果炎性反应组男性、吸烟、LDL-C明显高于无炎性反应组,体质量指数、HDL-C明显低于无炎性反应组,差异有统计学意义(P<0.05,P<0.01)。TBR与Vp无相关性(r=0.029,P=0.680)。结论 DCE-MRI可以敏感的反应新生血管情况,PET可以显示斑块内炎性细胞反应情况,但尚不能证明新生血管与炎性细胞存在显著相关性。     

B超与高分辨MRI诊断颈动脉粥样硬化斑块的价值

目的 探讨B超与高分辨MRI在颈动脉粥样硬化斑块诊断中的效果.方法 分析该院收治的临床拟诊颈动脉粥样硬化患者32例,比较B超与高分辨MRI的诊断价值.结果 高分辨MRI检出斑块数明显高于B超(P＜0.05);斑块特征中纤维帽破裂、纤维帽形态、斑块内是否出血或血栓与是否发生临床事件具有显著相关性.结论 B超与高分辨MRI均能准确评估管腔狭窄,但是MRI能够准确分析斑块的成分、形态,有效评估斑块的稳定性.     

有症状颈动脉粥样硬化斑块的病理学研究现状

斑块的比较组织学研究证明,不稳定斑块的组织学特征是斑块表面溃疡形成。破裂、纤维帽变薄以及纤维帽被大量巨噬细胞和Ｔ细胞浸润。体外研究表明,巨噬细胞和Ｔ细胞释放的细胞因子和蛋白酶能破坏纤维帽胶原并使平滑肌细胞凋亡,从而促使斑块破裂。因此,颈动脉斑块表面的炎症细胞浸润可能是促使斑块破裂的关键因素,进而发生栓塞或颈动脉闭塞、进一步了解颈动脉粥样硬化中的细胞募集行为,有利于发现不稳定斑块并找到使斑块稳定的治疗方法。     

有症状颈动脉粥样硬化斑块的病理学研究现状

斑块的比较组织学研究证明，不稳定斑块的组织学特征是斑块表面溃疡形成、破裂、纤维帽变薄以及纤维帽被大量巨噬细胞和T细胞浸润。体外研究表明，巨噬细胞和T细胞释放的细胞因子和蛋白酶能破坏纤维帽胶原并使平滑肌细胞凋亡，从而促使斑块破裂。因此，颈动脉斑块表面的炎症细胞浸润可能是促使斑块破裂的关键因素，进而发生栓塞或颈动脉闭塞。进一步了解颈动脉粥样硬化中的细胞募集行为，有利于发现不稳定斑块并找到使斑块稳定的治疗方法。     

In vivo 18F-fluorodeoxyglucose positron emission tomography imaging provides a noninvasive measure of carotid plaque inflammation in patients.

OBJECTIVES: Given the importance of inflammation in atherosclerosis, we sought to determine if atherosclerotic plaque inflammation could be measured noninvasively in humans using positron emission tomography (PET). BACKGROUND: Earlier PET studies using fluorodeoxyglucose (FDG) demonstrated increased FDG uptake in atherosclerotic plaques. Here we tested the ability of FDG-PET to measure carotid plaque inflammation in patients who subsequently underwent carotid endarterectomy (CEA). METHODS: Seventeen patients with severe carotid stenoses underwent FDG-PET imaging 3 h after FDG administration (13 to 25 mCi), after which carotid plaque FDG uptake was determined as the ratio of plaque to blood activity (target to background ratio, TBR). Less than 1 month after imaging, subjects underwent CEA, after which carotid specimens were processed to identify macrophages (staining with anti-CD68 antibodies). RESULTS: There was a significant correlation between the PET signal from the carotid plaques and the macrophage staining from the corresponding histologic sections (r = 0.70; p < 0.0001). When mean FDG uptake (mean TBR) was compared with mean inflammation (mean percentage CD68 staining) for each of the 17 patients, the correlation was even stronger (r = 0.85; p < 0.0001). Fluorodeoxyglucose uptake did not correlate with plaque area, plaque thickness, or area of smooth muscle cell staining. CONCLUSIONS: We established that FDG-PET imaging can be used to assess the severity of inflammation in carotid plaques in patients. If subsequent natural history studies link increased FDG-PET activity in carotid arteries with clinical events, this noninvasive measure could be used to identify a subset of patients with carotid atherosclerosis in need of intensified medical therapy or carotid artery intervention to prevent stroke.     

影像学检查对缺血性脑血管病患者颈动脉粥样硬化斑块的研究

目的采用双源CT血管造影(CTA)和高分辨MRI,探讨缺血性脑血管病患者颈总动脉分叉处粥样硬化斑块的性质、成分和动脉管腔狭窄程度与缺血性脑血管病的关系。方法选择缺血性脑血管病患者40例,经颈部CTA检测出颈总动脉分叉处粥样硬化斑块并伴管腔狭窄,再接受MRI扫描;分析颈动脉粥样斑块的性质、成分及管腔狭窄程度。结果 40例患者中,CTA检出斑块61个,其中混合性斑块31个;钙化性斑块18个;软斑块12个。高血压30例,检出斑块49个;无高血压10例,检出斑块12个。MRI检出斑块61个,其中Ⅲ型14个;Ⅳ～Ⅴ型23个,Ⅵ型6个;Ⅶ型18个。斑块内溃疡6例;颈动脉粥样硬化斑块造成同侧急性脑梗死14例,双侧颈动脉斑块造成双侧脑梗死10例,一侧颈动脉检出粥样斑块而对侧发生脑梗死2例。结论缺血性脑血管病患者颈动脉粥样硬化斑块主要以混合性斑块为主,双侧好发;高血压患者斑块发生率高于无高血压患者;颈动脉粥样硬化斑块造成同侧脑梗死发生率较高。     

彩色超声心动图对颈动脉粥样硬化斑块的诊断价值

目的：探讨彩超对颈动脉粥样硬化斑块的诊断价值。方法：180例患有不同程度慢性病患者,按年龄分为三组：〈60岁组（39例）,60岁≤年龄〈70岁组（49例）,≥70岁（92例）,对各组患者进行颈动脉超声检查,观察斑块好发部位、超声特征并进行统计分析。结果：180例中有132例（73．3％）发现动脉粥样硬化斑块,其中硬斑、软斑、扁平斑、溃疡斑的发生率分别为42．1％,33．0％,21。0％,3．9％;有23例（17．4％）发现不同程度的动脉狭窄,随年龄的增长,颈动脉粥样硬化发生率（61．5％比67．3％比87．0％）及血管狭窄的发生率（5．1％比10．2％比17．4％）也随着明显增加（P均〈0．05）。斑块的发生部位依次为颈总动脉分叉处（46．2％）、颈总动脉主干（28．0％）、颈内动脉起始段（21．9％）、颈外动脉（3．9％）。结论：二维及彩色多普勒超声是准确、经济、有效的颈动脉无创性检查方法,能够早期发现颈动脉粥样硬化斑块及其硬化程度,有助于动脉粥样硬化的防治。     

Ossification in atherosclerotic carotid arteries

Summary Background. Heterotopic ossification as newly formed bone in extraosseous tissue is an uncommon finding in ahterosclerotic lesions. The exact mechanisms and development of bone formation in regard to late stage calcified atherosclerosis still remains under debate. Methods. We studied 400 autopsy carotid probes and 306 samples of atherosclerotic carotid endatherectomy. Radiographic analysis and classification of calcification was performed followed by light microscopy. In probes with detected ossifications further analysis using immunohistochemistry, scanning electron microscopy (SEM) and energy dispersive x-ray microanalysis (EDX) including calcium mapping was performed. Results. Ossification in ahterosclerotic carotid arteries was a finding in only a minority of samples (5%) and occurred at sites of large calcific deposits. Histomorphology of bone formation equaled skeletal bone showing osteoblastic cells, osteocytes included in osteoid matrix, bone marrow and osteolytic giant multinucleated cells. Closely related to newly formed bone zones of neovascularization were found. Development of ossification seemed to occur in five stages (lipidous plaque, fibrous cellular plaque, fibrous acellular plaque, calcified plaque and osteogenesis). The environment of sites of ossification was characterized by a varying texture of extracellular fibrous matrix, foam cells, smooth muscle cells, fibroblasts and calcified deposits. Conclusions. Heterotopic ossifications of atherosclerotic plaques seem to be a specific differentiation of fibrous plaques. Components of atherosclerotic lesions like vascular wall cells, neovessels and matrix structures seem to be involved in the process of transformation to mature bone tissue.     

The prevalence of inflammation in carotid atherosclerosis: analysis with fluorodeoxyglucose-positron emission tomography.

AIMS: There is increasing evidence that (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) imaging can be useful for non-invasive measurement of atherosclerotic plaque inflammation in humans. However, it is unknown how often atherosclerosis has inflammation in humans. Thus, we examined the prevalence of inflammation in documented carotid atherosclerosis using FDG-PET imaging. METHODS AND RESULTS: FDG-PET imaging was performed in 100 consecutive patients who underwent carotid artery ultrasonography (CA-US) for screening of carotid atherosclerosis. Carotid atherosclerosis was considered when patients had the plaque score >or=5 and/or the focal thickening of the maximum intima-media complex >or=2 mm (localized plaque) by CA-US. The inflammation of carotid atherosclerosis was quantified by measuring the standardized uptake value (SUV) of FDG of the carotid artery. Inflammation was defined as present if the SUV score was >or=1.60 (>or=1 x standard deviation above the average). FDG-PET imaging revealed inflammation in 12 of 41 (29%) patients having carotid atherosclerosis, whereas in 6 of 59 (10%) patients not having carotid atherosclerosis (P < 0.01). In patients with documented atherosclerosis by CA-US, body mass index, waist circumference, and the number of localized plaques were greater in a subset with inflammation than in a subset without. CONCLUSION: Inflammation was visualized by FDG-PET imaging in approximately 30% of patients with documented carotid atherosclerosis.     

老年患者股动脉和颈动脉及冠状动脉粥样硬化斑块稳定性的比较

目的　探讨股动脉、颈动脉、冠状动脉粥样硬化斑块的稳定性。方法　收集我院老年尸体解剖病例 15例 ,将所有病例的两侧股动脉、两侧颈动脉、左冠状动脉前降支进行连续取材 ,常规病理检查 ,部分节段行α 平滑肌肌动蛋白、CD6 8、bax染色。结果　股动脉粥样硬化斑块中的平滑肌细胞、巨噬细胞数量与颈动脉相近。与冠状动脉比较 ,股动脉粥样硬化斑块中的平滑肌细胞相对多 ,巨噬细胞相对少 ;bax在巨噬细胞的表达多 ,在平滑肌细胞的表达少。结论　平滑肌细胞、巨噬细胞数量的不同导致了 3种动脉粥样硬化斑块不同的稳定性。股动脉中的粥样硬化斑块较冠状动脉更稳定。     

Low thrombogenicity of calcified atherosclerotic plaques is associated with bone morphogenetic protein-2-dependent inhibition of tissue factor expression

Morphology of atherosclerotic plaque is a major determinant of plaque thrombogenicity. Calcified atherosclerotic lesions are less prone to thrombosis and contain less tissue factor (TF) than lipid-rich plaques. Although bone morphogenetic protein (BMP)-2 is a known mediator of vascular calcification, the role of BMP-2 in the regulation of plaque thrombogenicity has not been established. We hypothesized that the expression of BMP-2 within highly calcified atherosclerotic plaques inhibits TF expression and reduces thrombogenicity of calcified lesions. In the present study, we measured levels of TF and BMP-2 in human calcified and lipid-rich carotid plaques and studied the effects of BMP-2 on TF expression in human monocytes in vitro. Quantitative immunohistochemical analysis of endarterectomy specimens for TF and BMP-2 revealed that calcified plaques contained nearly three-times less TF antigen than lipid-rich ones. In contrast, calcified plaques expressed two-times more BMP-2 antigen than lipid-rich lesions. BMP-2 markedly decreased protein expression and surface redistribution of TF in activated human monocytes in vitro. BMP-2-mediated inhibition of TF expression in monocytes/macrophages could contribute to reduced thrombogenicity of calcified atherosclerotic plaques.     

Structure-dependent dynamic mechanical behavior of fibrous caps from human atherosclerotic plaques

BACKGROUND. Although thrombosis associated with a fissured atherosclerotic plaque is believed to be the most common cause of acute coronary syndromes, the underlying factors that trigger plaque rupture are currently unknown. However, the mechanical behavior of the plaque is probably of critical importance. METHODS AND RESULTS. To test the hypothesis that the mechanical properties of a plaque are dependent on its composition and, in particular, that the stiffness of fibrous caps changes within the range of frequencies carried by a physiological pressure wave, the stress-strain relation was studied in 27 fibrous caps and related to the underlying histological structure of the fibrous cap. Fibrous caps were obtained during 14 autopsies from the abdominal aorta and were classified by histological examination as cellular (n = 7), hypocellular (n = 9), or calcified (n = 11). Hypocellular fibrous caps were 1-2 times stiffer than cellular caps (p less than 0.005), and calcified caps were 4-5 times stiffer than cellular caps (p less than 0.005). All 27 fibrous caps demonstrated an increase in stiffness with increasing frequencies of stress ranging from 0.05 to 10 Hz; the increase in stiffness was similar in all three histological classes. CONCLUSIONS. We conclude that the stiffness of fibrous caps from human atherosclerotic plaques is related to the underlying histological structure and that the stiffness increases with frequency in the range of physiological heart rates. The protective benefit of beta-adrenergic receptor blocking agents in coronary artery disease may, in part, be related to the frequency dependence of atherosclerotic plaque stiffness.