冠状动脉粥样硬化血管影像学进展

大多数威胁生命的冠状动脉(冠脉)粥样硬化的不良后果是由冠脉斑块破裂和急性血栓形成引起的。随着影像学技术的进展,现在的成像方式能够提供高风险斑块的特征,预测不良心血管事件的发生,改善药物治疗策略和结果。本文主要讨论可识别高风险斑块的影像学技术,包括计算机断层扫描(CT)、磁共振成像(MRI)、虚拟组织学血管内超声(VH-IVUS)、近红外光谱学(NIRS)和冠脉血管镜,及其对未来不良心血管事件的预测作用,并总结这些成像技术的优势与局限性。     

OCT-IVUS一体成像的多模态血管腔内成像技术的应用与进展

作为冠状动脉介入诊疗中最主要的两种血管腔内影像学技术,光学相干断层成像(OCT)和血管内超声(IVUS)已在临床应用数十年。OCT具有更高的分辨率,能更好地对比斑块成分,IVUS能够穿透血液,具有更深的成像深度,两种影像学技术已成为心血管介入医生不可或缺的辅助手段。但两种影像学技术也各有不足,OCT成像穿透深度有限,IVUS的空间分辨率较弱。单一的OCT或IVUS很难完全提供血管及斑块内部完整的解剖学信息。利用二者的互补性,将OCT与IVUS成像导管集成到同一成像导管中,实现二者的多模态血管内成像,则可以为介入医生提供更加理想的斑块与血管壁的组织学和形态学信息。     

血管内超声和光学相干断层成像对冠状动脉粥样硬化斑块的诊治价值

冠状动脉性心脏病(CHD)亦称缺血性心脏病,其发病率和死亡率长期居世界首位。冠状动脉造影术(CAG)仍是目前诊断CHD的金标准,并广泛应用于CHD的诊疗中,但CAG的分辨率较低,对冠状动脉病变的内膜、外膜和详细病理变化的观察不够精确。血管内超声(IVUS)和光学相干断层成像(OCT)是两种分辨率较高的血管内成像技术,对CHD的诊断和介入治疗起到了很好的补充作用,目前临床上应用也日趋广泛。本文从IVUS和OCT识别冠状动脉粥样硬化斑块、指导和评价经皮冠状动脉介入术的研究现状进行综述。     

虚拟组织学成像血管内超声在冠心病研究中的应用

虚拟组织学成像血管内超声(VH-IVUS)是一种比较新的血管内超声后处理技术,可以实时重建斑块分类的组织图像,对斑块进行更准确的分辨,具有广泛的临床应用价值.本文就VH-IVUS在冠心病研究中的应用作一综述.     

血管内影像技术的新进展

近年来血管内影像技术,特别是血管内超声领域的研究进展,主要包括:(1)对易损斑块认识的不断深入和检测率的逐步提高;(2)更有效地指导冠状动脉介入治疗,特别是指导药物洗脱支架的置入和随访。多种新型血管内影像技术日趋成熟,包括虚拟组织学血管内超声、整合背向散射血管内超声、光学相干断层成像术、近红外光谱仪、血管镜及血管内磁共振与传统的灰阶血管内超声一起,推动着血管内影像技术进入崭新的阶段。     

腔内影像学和功能学面临的挑战

正冠状动脉腔内影像学近些年来取得了长足进步。冠状动脉造影术一直是评估冠状动脉疾病的最常用方法,但是只能显示血管直径狭窄程度,并不能提供血管壁结构和成分的信息以及全面反映狭窄的功能意义。以血管内超声(IVUS)和光学相干断层成像(OCT)为代表的冠状动脉腔内影像学技术的应用,能够深入认识血管壁结构、斑块成分     

超微血管成像技术对颈动脉斑块新生血管的诊断价值

目的:分析和探讨超微血管成像技术(SMI)对颈动脉斑块新生血管的诊断价值。方法:回顾性分析我院所收治的50例有症状的缺血性脑血管病患者的临床资料,患者分别接受SMI以及常规超声检查,分别记录两种方法的诊断结果,并进行比较。结果:经SMI诊断后,共发现斑块105个,其中低回声斑块62个,混合回声斑块(低回声为主)43个,显示血流信号的斑块有42个,其中34个斑块内发现微小信号,阳性诊断率为32.38%。常规超声检查共发现斑块75个,其中低回声斑块40个,混合回声斑块(低回声为主)35个;在4个斑块内发现微小信号,阳性诊断率为5.33%。与常规超声检查比较,SMI对斑块微小信号的阳性诊断率(5.33%比32.38%)显著升高,P0.01。结论:超微血流成像技术比常规超声检查对颈动脉斑块新生血管有更高的诊断率,值得推广和应用。     

有关血管内超声对易损斑块评估研究的进展

易损斑块（VP）已被广泛认为是引起急性冠状动脉综合征（ACS）和心脏猝死的主要原因。近年来，侵入性或非侵入性血管内超声成像技术已经成为检测VP的主要手段之一。本文就血管内超声对易损斑块评估的优缺点进行以下综述。     

颈动脉粥样硬化斑块与缺血性脑血管病的相关性

目的通过超声造影成像技术的新生血管增强程度评价颈动脉粥样硬化斑块与缺血性脑血管疾病之间的关系。方法将有颈动脉斑块病变的患者分为两组,一组为缺血症状组(63例),另一组为无缺血症状组(27例),对患者颈动脉硬化斑块进行超声造影检查,重点观察颈动脉硬化斑块内新生血管的血流灌注情况,比较有脑缺血症状患者组与无脑缺血症状患者组的颈动脉斑块内新生血管密度及造影增强程度的组间差异。结果有脑缺血症状患者组斑块的造影后增强强度(EI)及ratio值(误差比率值)明显高于无临床症状患者组(P0.05)。结论超声造影可显示斑块内新生毛细血管的再生情况,可以依据斑块内造影剂增强强度预测缺血性脑血管病发生风险的有效指标。     

光学相干断层成像技术在肺动脉疾病中应用一例

光学相干断层成像技术(optical coherence tomography,OCT)是目前为止分辨率最高的血管内成像技术,是继血管内超声(intravascular ultrasound,IVUS)技术之后的义一重大进步[1].OCT的图像逼真,分辨率高达10μm,比IVUS分辨率高10倍,接近观察到纽织水平,故被称作"体内的组织学显微镜"[1].目前已成为冠心病介入诊治中精准判断斑块成分、评价易损斑块,识别红白血栓、指导支架置入,评价支置入的即刻效果和随访观察的重要手段[1].     

动脉粥样硬化易损斑块的动物模型和检测技术

动脉粥样硬化易损斑块破裂、血栓形成是急性冠状动脉综合征的发病机制已成为共识。由于缺乏理想的易损斑块的动物模型,对斑块破裂前的血清学及影像学特征研究较少,尚缺乏能够早期识别易损斑块及预防斑块破裂的最佳方法。本实验室已成功构建家兔和Apo E-/-小鼠的易损斑块模型。易损斑块的检测技术主要包括非侵入性及侵入性的影像学检测及功能学检测技术。对易损斑块的早期准确识别以便及时干预具有十分重要的临床意义。     

Clinical applications of optical coherence tomography

Rupture of vulnerable plaque (VP) is responsible for most coronary events. Optical coherence tomography (OCT) is a high-resolution imaging method that allows excellent characterization of atherosclerotic plaque. While this technique is limited by the need to interrupt blood flow and a shallow depth of penetration, its resolution is an order of magnitude greater than possible with intravascular ultrasound (IVUS), and it has demonstrated better sensitivity and specificity for accurately determining plaque composition. Early in vitro and in vivo experiences have affirmed the excellent quality of these images making it an attractive technology for the analysis of VP. Its high resolution likely renders it the best imaging modality currently available for the evaluation of proper stent deployment and of intracoronary pathology in the setting of percutaneous coronary interventions (PCI). Our institution is currently involved in a multicenter trial to evaluate the effectiveness of OCT when compared to IVUS in this setting. Ongoing technological improvements aim to permit rapid scanning which should alleviate its current major limitation of needing to scan in a blood-free space. OCT is a promising new technology in the evaluation of atherosclerotic plaque and coronary microstructure.     

Usefulness of high-frequency vascular ultrasound imaging and serum inflammatory markers to predict plaque rupture in patients with stable and unstable angina pectoris

It remains unclear what kind of morphologic and biochemical features best predict plaque rupture in patients with angina pectoris (AP). This study aimed to investigate whether combined high-frequency vascular ultrasound imaging and measurements of serum inflammatory biomarkers can predict coronary plaque ruptures in patients with AP. The study population consisted of 20 patients with stable AP and 40 patients with unstable AP. High-frequency vascular ultrasound imaging was performed in the 2 groups to measure intima-media thickness, the plaque acoustic density of the common carotid arteries, and the flow-mediated dilation of the brachial arteries. Serum lipid profile and inflammatory biomarkers were measured in all patients. Using intravascular ultrasound, a list of coronary imaging parameters was obtained. A multivariate logistic regression model was applied to calculate the odds ratio of each parameter to predict coronary plaque ruptures detected by intravascular ultrasound. Of 139 coronary artery plaques identified by intravascular ultrasound, 48 plaques (9 in stable AP and 39 in unstable AP) developed ruptures. Among measured parameters, the values of carotid intima-media thickness, coronary external elastic membrane area, plaque area, plaque burden, plaque eccentric index and remodeling index, serum high-sensitivity C-reactive protein, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 were significantly higher in unstable AP than in stable AP (p <0.05 to 0.01). Of these parameters, carotid intima-media thickness, serum high-sensitivity C-reactive protein, and the coronary remodeling index were found to be significant predictors of coronary plaque rupture, with odds ratios of 9.51 (95% confidence interval 1.29 to 21.81), 3.02 (95% confidence interval 1.01 to 7.65), and 0.01 (95% confidence interval 0.00 to 0.34), respectively. In conclusion, combined high-frequency ultrasound imaging of coronary and carotid arteries and measurements of serum inflammatory markers are able to predict coronary plaque ruptures in patients with AP.     

In vitro analysis of coronary atheromatous lesions by intravascular ultrasound; reproducibility and histological correlation of lesion morphology.

AIM: To determine the reproducibility and histological correlation of qualitative intravascular ultrasound imaging of atheromatous coronary arteries using the recently proposed European Society of Cardiology classification of plaque composition in conditions approximating the clinical setting. METHODS: Atheromatous lesions (n=21), identified from 30 post-mortem human coronary arteries, were imaged using intravascular ultrasound in a pulsatile flow system which simulates coronary flow. Fifty sites (21 x minimum lumen area and 29 x distal reference sites) were selected independently by two observers from continuous video recordings. Atheromatous plaque was classified as echodense, echolucent, heterogeneous or calcified by each observer and by one observer on separate occasions. Arterial specimens were histologically sectioned at these sites and similarly analysed by a third observer blinded to the intravascular ultrasound appearances. RESULTS: Overall inter- and intra-observer reproducibility for plaque-type (Kappa 0.87[0.80-0.94] and 0.89[0. 85-0.93 respectively]) and focal calcification (0.78[0.74-0.82] and 0.88[0.84-0.92]) was high. Differences in site selection significantly influenced reproducibility particularly at reference sites. Agreement for overall plaque type between intravascular ultrasound and histology occurred in 89% of sites (Kappa 0.73[0.69-0. 77]). Specificity and positive predictive values for individual plaque types were greater than 90%. CONCLUSION: Using modern intravascular ultrasound technology in an in vitro system which approximates the clinical setting the proposed ESC classification of plaque composition by intravascular ultrasound is reproducible and correlates well with histology. It should therefore perform reliably in diagnostic intravascular ultrasound examinations and in the guidance of percutaneous coronary interventions.     

Assessment of coronary plaque with optical coherence tomography and high-frequency ultrasound

This study compares the ability of intravascular optical coherence tomography (OCT) and high-frequency intravascular ultrasound (IVUS) to image highly stenotic human coronary arteries in vitro. Current imaging modalities have insufficient resolution to perform risk stratification based on coronary plaque morphology. OCT is a new technology capable of imaging at a resolution of 5 to 20 microm, which has demonstrated the potential for coronary arterial imaging in prior experiments. Human postmortem coronary arteries with severely stenotic segments were imaged with catheter-based OCT and IVUS. The OCT system had an axial resolution of 20 microm and a transverse resolution of 30 microm. OCT was able to penetrate and image near-occlusive coronary plaques. Compared with IVUS, these OCT images demonstrated superior delineation of vessel layers and lack of ring-down artifact, leading to clearer visualization of the vessel plaque and intima. Histology confirmed the accuracy and high contrast of vessel layer boundaries seen on OCT images. Thus, catheter-based OCT systems are able to image near-occlusive coronary plaques with higher resolution than that of IVUS.     

Diagnostic accuracy of optical coherence tomography and intravascular ultrasound for the detection and characterization of atherosclerotic plaque composition in ex-vivo coronary specimens: a comparison with histology

BACKGROUND: Both intravascular ultrasound and optical coherence tomography have been purported to accurately detect and characterize coronary atherosclerotic plaque composition. The aim of our study was to directly compare the reproducibility and diagnostic accuracy of optical coherence tomography and intravascular ultrasound for the detection and characterization of coronary plaque composition ex vivo as compared with histology. METHODS AND RESULTS: Intravascular ultrasound (20 MHz) and optical coherence tomography imaging was performed in eight heart specimens using motorized pullback. Standard histology using hematoxylin-eosin and van Gieson staining was performed on 4 mum thick slices. Each slice was divided into quadrants and accurately matched cross-sections were analyzed for the presence of fibrous, lipid-rich, and calcified coronary plaque using standard definitions for both intravascular ultrasound and optical coherence tomography and correlated with histology. After exclusion of 145/468 quadrants, we analyzed the remaining 323 quadrants with excellent image quality in each procedure. Optical coherence tomography demonstrated a sensitivity and specificity of 91/88% for normal wall, 64/88% for fibrous plaque, 77/94% for lipid-rich plaque, and 67/97% for calcified plaque as compared with histology. Intravascular ultrasound demonstrated a sensitivity and specificity of 55/79% for normal wall, 63/59% for fibrous plaque, 10/96% for lipid-rich plaque, and 76/98% for calcified plaque. Both intravascular ultrasound and optical coherence tomography demonstrated excellent intraobserver and interobserver agreement (optical coherence tomography: kappa=0.90, kappa=0.82; intravascular ultrasound: kappa=0.87, kappa=0.86). CONCLUSION: Optical coherence tomography is superior to intravascular ultrasound for the detection and characterization of coronary atherosclerotic plaque composition, specifically for the differentiation of noncalcified, lipid-rich, or fibrous plaque.     

双源CT双能量冠状动脉斑块成像的初步应用

目的探讨双源CT双能量成像技术进行冠状动脉斑块成像的可行性。方法 40例病人行双能量CT冠状动脉斑块成像。结果 40例受检者均能得到冠状动脉成像的单能数据及双能量数据,其中10例行DSA者,CTA与DSA所见一致。其中3例行IVUS检查,共5处斑块,其中4处斑块双能图像与IVUS所见一致。结论单次对比增强双能量CT心脏成像,可同时获得优良的冠状动脉和冠状动脉斑块成像,并降低了射线剂量。     

Intravascular ultrasound predictors of restenosis after percutaneous transcatheter coronary revascularization

Objectives. This study sought to evaluate preintervention and postintervention intravascular ultrasound studies for potential predictors of angiographic restenosis and to use ultrasound predictors of restenosis to enhance our understanding of the pathophysiology of the restenosis disease process.

Background. Restenosis remains the major limitation of percutaneous transcatheter coronary revascularization. Although its mechanisms remain incompletely understood, numerous studies have identified some of the clinical, anatomic and procedural risk factors for restenosis. Intravascular ultrasound imaging of target lesions before and after catheter-based treatmetn consistently demonstrates more target lesion calcium, more extensive reference segment atherosclerosis, smaller final lumen dimensions, significant residual plaque burden and a greater degree of tissue trauma than is evident by angiography.

Methods. Intravascular ultrasound studies were performed in 360 nonstented native coronary artery lesions (final diameter stenosis 18 ± 11%) in 351 patients for whom follow-up angiographic data were available 6.4 ± 3.6 months later. Hospital charts were reviewed, and qualitative and quantitative coronary angiographic and intravascular ultrasound analyses were performed by independent core laboratories. Four dependent angiographic end points were tested: restenosis as a binary definition (50% diameter stenosis at follow-up) was the primary end point; follow-up diameter stenosis, late lumen loss and follow-up minimal lumen diameter were the secondary end points.

Results. Reference vessel size, the preintervention quantitative coronary angiographic assessment of lesion severity and the postintervention intravascular ultrasound cross-sectional measurements predicted the late angiographic results. In particular, the intravascular ultrasound postintervention cross-sectional narrowing (plaque plus media cross-sectional area divided by external elastic membrane cross-sectional area) predicted the primary end point (restenosi) and two of the three secondary end points (follow-up diameter stenosis and late lumen loss) and was therefore the most consistent predictor of restenosis.

Conclusions. Intravascular ultrasound variables are more powerful and consistent predictors of angiographic restenosis than currently accepted clinical or angiographic risk factors.     

Impact of plaque burden in the left main coronary artery determined by intravascular ultrasound on cardiovascular events in a Japanese population undergoing percutaneous coronary intervention

The left main coronary artery (LMCA) is a particularly important target of atherosclerotic plaque accumulation. The aim of this study was to investigate the connection between subclinical plaque burden in the LMCA measured by intravascular ultrasound and future cardiovascular events. Two hundred eighteen consecutive patients underwent percutaneous coronary intervention for the left anterior descending coronary artery or the left circumflex coronary artery under intravascular ultrasound guidance. Plaque burden in the LMCA was analyzed for these patients, and major adverse cardiac events were also evaluated. Data were analyzed by grouping the patients into tertiles according to plaque burden values; tertile 1, <32% area stenosis; tertile 2, 32% to 45% area stenosis; and tertile 3, >45% area stenosis. During a 3-year follow-up period (average 16.1 months), 12% of tertile 1, 18% of tertile 2, and 40% of tertile 3 experienced major adverse cardiac events, mostly due to repeat revascularization (p <0.001). On Cox multivariate analysis, plaque burden in the LMCA (per percentage) detected by intravascular ultrasound remained an independent significant predictor of major adverse cardiac events (hazard ratio 1.04, 95% confidence interval 1.02 to 1.07) and future revascularization (hazard ratio 1.05, 95% confidence interval 1.02 to 1.07) (p <0.001). In conclusion, plaque burden in the LMCA is useful as an indicator of coronary atherosclerosis and may be a significant predictor of cardiovascular events, especially revascularization.