颈动脉粥样硬化斑块二维超声特征与斑块标本结构一致性的研究

目的探讨颈动脉粥样硬化斑块术前二维超声基本形态及内部回声特征与颈动脉内膜剥脱术（CEA）后斑块大体标本高倍相机影像结构的一致性,以二维超声方法评估斑块易损性的特征。 方法连续纳入2014年1月至2015年5月因颈动脉狭窄70%~99%收入首都医科大学宣武医院行颈动脉内膜剥脱术治疗、术前颈动脉超声纵、横切面动脉粥样硬化斑块成像清晰的患者160例,根据二维超声斑块形态特征分为规则型（32例）与不规则型（128例）,其中溃疡型斑块91例,与CEA术后即刻斑块的外观形态结构进行比较;根据二维超声回声特征分为均质等回声斑块组（64例）、低至无回声斑块组（44例）、不均质强回声斑块组（52例）,分别与CEA术后即刻斑块的纵断解剖切面高倍相机成像显示内部结构特征进行对比。将超声回声均质的斑块（108例）按CEA术后斑块内部结构特征进行分类为均质性非粥样物质（64例）、粥样物质（10例）、新鲜出血（10例）及陈旧性出血坏死（5例）,测量不同性质斑块在二维超声图像上的平均灰阶中值（GSM）并进行比较。 结果160例颈动脉粥样硬化患者超声显示斑块形态与术中标本检查结果：（1）二维超声显示斑块形态与大体标本斑块形态特征的准确率93.1%（149/160）,对不规则斑块诊断的敏感度为95.3%,特异度83.9%;对溃疡性斑块诊断的敏感度84.8%,特异度88.5%,两种类型斑块的总准确率86.2%（138/160）。（2）二维超声回声特征为均质等回声斑块64例,标本内解剖结构显示为结构均匀一致非粥样物质者占95.3%（61/64）;低至无回声斑块44例,标本内结构显示为粥样物质和斑块内新鲜出血占86.3%（38/44）。术中标本显示为非粥样物质成分的斑块GSM值平均为55±19,显著高于粥样物质斑块39±11（P<0.001）和新鲜出血性斑块29±10（P<0.001）,而新鲜出血性斑块平均GSM值低于粥样物质性斑块。（3）不均质强回声斑块52例,二维超声特点为基底部钙化的斑块17例,CEA术中标本为斑块基底部钙化伴内部粥样物质8例,伴陈旧性出血坏死9例;中低回声混杂微小钙化（强回声）特征斑块29例,术中斑块大体标本均呈陈旧性出血与坏死组织相间。 结论二维超声对不规则型与溃疡型斑块的检出准确率高,回声特征的观察与斑块结构特征具有较高的一致性,GSM值的测量能弥补超声医师在二维超声影像上对低灰阶图像识别的困难,可在超声检测中进一步推广应用。     

实时三维超声测定颈动脉斑块体积的临床价值

目的 应用实时三维超声(RT-3DU)与CT血管造影(CTA)检测颈动脉斑块体积,评价RT-3DU在颈动脉斑块体积测定方面的临床应用价值.方法 对25例患者的32个颈动脉斑块分别进行RT-3DU和CTA检查.RT-3DU采用Qlab软件3DQ插件进行斑块半自动体积测定;CTA采用64层螺旋CT扫描仪和血管分析软件进行斑块体积测定.结果 RT-3DU测得斑块体积为(583.09±215.66)mm~3;CTA测定斑块体积为(602.84±182.45)mm~3.两组间测定值差异无统计学意义(P>0.05),呈显著正相关(r=0.885,P<0.01);随斑块体积增大,两组测定值间差异逐渐减小(r=-0.35,P<0.01);RT-3DU和CTA两种技术测定斑块体积时,观测者间重复性高,分别为2.6%和3.0%.结论 RT-3DU可准确测定颈动脉斑块体积,有重要的临床应用价值.     

Parametric analysis of carotid plaque using a clinical ultrasound imaging system

We evaluated quantitative ultrasonic methods for assessment of carotid plaque content. In vitro measurements of fixed, carotid plaque specimens obtained by surgical endarterectomy were performed using a clinical Philips HDI 5000 imaging system connected to a radiofrequency (RF) signal-acquisition system. We acquired RF signals and grey-scale images from carotid specimens (n = 17) and a tissue-mimicking reference phantom. Imaged plaque sections were then classified according to histology. Parametric images were constructed from the integrated backscatter (IBS), and the midband, slope and intercept values of a straight-line fit to the apparent backscatter transfer function. Analysis was performed on 82 regions-of-interest (ROIs). The IBS values for collagen, lipid and hemorrhage plaques were 5.8 +/- 5.4, 3.9 +/- 3.7, 2.8 +/- 2.2 dB, respectively. Midband and IBS parameter images exhibited good agreement in morphology with histology, whereas the slope and intercept parameter images were noisy. Mean IBS, midband, and grey-scale values of complex plaques were found to be statistically different (p < 0.05) from lipid, hemorrhage and fibrolipid plaques. The bias and limits of agreement (1.3 +/- 4.9 dB) between the grey-scale and IBS methods, however, indicated that the two methods were not interchangeable. Results indicate necessary improvements, such as reduction of large measurement variances and identification of robust parameters, that will permit multiparametric characterization of carotid plaque under in vivo conditions.     

Advanced Ultrasound Evaluation of Vulnerable Carotid Artery Plaque: Can a Combined Two-dimensional and Three-dimensional Plaque Imaging Analysis Identify Significant Plaque Characteristics Responsible for Strokes? A Case Series Study

ObjectivesImaging carotid plaque morphology with the use of ultrasound (US) may improve stroke risk management by identifying alterations in atheroma at increased risk for cerebrovascular events. Limited reports on advanced US plaque imaging have identified the potential for evaluation and risk stratification of vulnerable carotid plaques. The purpose of this series was to evaluate the usefulness of integrating an advanced US plaque imaging method to characterize atheromas and to measure the agreement with multidetector row computed tomography (CT) and radiographic pathology.MethodsThree patients with known high-grade symptomatic carotid artery disease confirmed on CT and scheduled for endarterectomy were recruited for this study. Before surgery, we prospectively assessed carotid arteries for high-risk morphological characteristics using our advanced US plaque imaging mechanism. The plaque characteristics considered included the presence of ulceration, internal lipid or hemorrhagic core(s), calcification(s), and/or thin/dense fibrous plaque caps. US plaque features were correlated with previous CT imaging and postendartertectomy histologic studies.ResultsThere was substantial agreement in the detection of morphologic characteristics. Our advanced US method yielded 100% sensitivity, specificity, and accuracy in the identification of ulceration, lipid/hemorrhagic core(s) and calcification(s), leading over CT. In the identification of a thin/dense fibrous plaque cap, CT yielded 0% sensitivity versus 33% on US.ConclusionsAdvanced US plaque imaging to further identify significant plaque abnormalities responsible for strokes can reliably identify vulnerable plaque characteristics on both two-dimensional and three-dimensional US. Our results suggest that the type of abnormality identified with our advanced US imaging method surpassed information gathered on CT. Our advanced imaging protocol shows potential for early noninvasive prediction of plaque vulnerability, thus improving preventive management of atherosclerosis.     

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。     

3.0TMRI对颈动脉粥样硬化斑块成分分析及分型的研究

目的：探讨3.0 T高分辨磁共振成像对颈动脉粥样硬化斑块内部成分检出及斑块稳定性判定的价值。材料与方法33例颈动脉粥样硬化斑块患者行MRI检查,扫描序列包括三维时间飞跃法(3D-TOF)成像、双翻转T1加权成像、T2加权成像、质子密度(PD)加权成像及增强颈部血管成像,研究、分析斑块内成分及其分型。结果33例患者中共检出颈动脉粥样硬化斑块63个,分型如下：Ⅰ-Ⅱ型占12.7%,Ⅲ型占27%,Ⅳ-Ⅴ型占19%,Ⅵ型占31.8%,Ⅷ型占9.5%,各型斑块在颈动脉3个部位的分布差异无统计学意义(Fisher确切概率P=0.106);所有检出的颈动脉斑块中稳定斑块共31个,不稳定斑块共32个,二者在是否出现脂质核心(LRNC)、出血(IPH)、血栓形成及纤维帽(FC)破裂方面均有统计学差异(P＜0.05),而钙化出现率无统计学差异(P＞0.05)。结论3.0 T高分辨率MRI能识别、区分颈动脉粥样斑块内成分,能鉴别稳定斑块和不稳定斑块,为临床选择治疗方案及疗效评价提供指导。     

Atherosclerotic plaque at the carotid artery bifurcation. Correlation of ultrasonographic imaging with morphology

Morphologic characteristics of atherosclerotic plaque at the carotid artery bifurcation were compared to the appearance of the plaque on real-time B-mode ultrasonography. Mural plaques propagating along the wall of the carotid sinus had a 72% frequency of recent organizing hemorrhage. Nodular plaques causing local narrowing of the vessel had only a 23% incidence of organizing hemorrhage. This difference was significant (P less than 0.01). The presence of recent organizing hemorrhage in mural plaques may account for the increased frequency of symptoms previously observed to occur ipsilateral to mural plaques compared to nodular plaques.     

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。     

Acoustic Radiation Force Impulse Imaging for Noninvasive Characterization of Carotid Artery Atherosclerotic Plaques: A Feasibility Study

Atherosclerotic disease in the carotid artery is a risk factor for stroke. The susceptibility of atherosclerotic plaque to rupture, however, is challenging to determine by any imaging method. In this study, acoustic radiation force impulse (ARFI) imaging is applied to atherosclerotic disease in the carotid artery to determine the feasibility of using ARFI to noninvasively characterize carotid plaques. ARFI imaging is a useful method for characterizing the local mechanical properties of tissue and is complementary to B-mode imaging. ARFI imaging can readily distinguish between stiff and soft regions of tissue. High-resolution images of both homogeneous and heterogeneous plaques were observed. Homogeneous plaques were indistinguishable in stiffness from vascular tissue. However, they showed thicknesses much greater than normal vascular tissue. In heterogeneous plaques, large and small soft regions were observed, with the smallest observed soft region having a diameter of 0.5 mm. A stiff cap was observed covering the large soft tissue region, with the cap thickness ranging from 0.7–1.3 mm. (E-mail: jeremy.dahl@duke.edu)     

In vitro Model Test and Preliminary Clinical Application of a New Method of Ultrasonographic Imaging: Vascular Enhancement Technology

Vascular enhancement technology (VET) is a new form of ultrasonographic technology that can optimize images by enhancing the B-mode display with information derived from power Doppler. We designed an in vitro model to evaluate the accuracy and application method of VET and to apply this technology preliminarily in vivo in the vascular periphery. An in vitro model was designed with a flow pump system to simulate blood flow in soft tissue and the intracranial vasculature. Modeling vessels were imaged by traditional B mode, color Doppler flow imaging and VET. The diameter of the various silicon tubes was measured to verify the accuracy of VET. For in vivo application, 15 normal subjects and 26 patients suspected of having carotid artery plaques and cerebrovascular disease were examined using these three image modes. The imaging effects were observed and compared. VET imaging could clarify the lumens of the modeling vessels and reduce artifacts. The caliber of three sizes of silicon tubing was also measured accurately by VET. Of 15 normal subjects, sound artifacts in large vessels were inhibited and the intermedia membrane was clearly displayed by VET. The boundaries of carotid plaques were manifested by VET with well-defined edges. Three cases of hypoechoic soft plaque on the anterior wall missed in B-mode imaging were detected by VET. Intracranial scanning with VET identified cerebral vascular disease, including cerebral stenosis, arteriovenous malformations and aneurysms. The size and shape of the focus displayed by VET coincided with that observed using digital subtraction arteriography. VET is helpful in improving detection of the boundary of vessels and visualization of the microvasculature. (E-mail: duanyy@fmmu.edu.cn)     

Quantification of Carotid Plaque Histology Using iPlaque Software

The iPlaque software package can use integrated backscatter (IB) values of carotid plaque to extract information on tissue composition. The aim of this study was to evaluate the association between the plaque histologic classification and IB values evaluated by iPlaque. In 49 patients undergoing carotid endarterectomy, IB values of whole carotid plaque were measured using iPlaque from the long-axis ultrasonographic image. Histologic findings of resected plaques were defined using the classification of the American Heart Association. The average IB values were statistically compared with the classification. Plaque samples from 49 patients were categorized into V, VI and VII, (13, 32 and 4 cases, respectively). Both the average and standard deviation of the IB values in each plaque sample significantly differed among the three classifications (p = 0.001). The IB of carotid plaque obtained by iPlaque analysis was associated with its histologic characteristics.     

Development and validation of an in vivo analysis tool to identify changes in carotid plaque tissue types in serial 3-D ultrasound scans

We have developed a three-dimensional (3-D) B-mode acquisition system suitable for imaging carotid plaques in vivo. A texture classification system using 157 statistical and textural algorithms, previously developed in our laboratory and shown to predict the contents of in vitro carotid plaques, was applied to in vivo 3-D image sets obtained from patients with both symptomatic and asymptomatic carotid artery plaques. Delineation of plaque boundaries is more difficult using in vivo images than in vitro images of excised plaques embedded in agar. This study has examined inter- and intraobserver variability studies to assess the degree of selectivity of the plaque region-of-interest (ROI) and assess the degree of repeatability for potential use in comparing serial scans. An interobserver limit of agreement of +/-12.9% and an intraobserver limit of repeatability of <2% were obtained. These results show that the plaque ROI selection is subjective, but is repeatable within acceptable limits.     

3.0T MRI可评估缺血性脑卒中患者颈动脉粥样硬化的斑块成分

目的 探究3.0 T MRI在缺血性脑卒中颈动脉粥样硬化斑块成分检查中的临床应用。方法 选择我院及上海交通大学附属第六人民医院2020年6月～2021年4月收治的62例因颈动脉粥样硬化所致的缺血性脑卒中患者作为研究对象。采用3.0 T MRI对所有患者颈动脉血管狭窄处的斑块成分及不同类型斑块的信号特征进行观察、分析,对比稳定斑块、不稳定斑块组成成分的差异。结果 共发现颈动脉粥样硬化斑块119个,斑块分型：Ⅰ～Ⅱ型11个（9.24%）,Ⅲ型31个（26.05%）,Ⅳ～Ⅴ型24个（20.17%）,Ⅵ型37个（31.09%）,Ⅶ型16个（13.45%）。所有斑块在MRI上均表现为环形或偏心性管壁增厚,且部分伴有局部新月形或半月形信号突入管腔,不同成分斑块在MRI上的表现各有所不同。所有检出的颈动脉斑块中稳定斑块共计62个,不稳定斑块57个。稳定斑块和不稳定斑块出现钙化的差异无统计学意义（P>0.05）,不稳定斑块出现脂质核心、出血、血栓形成以及纤维帽破裂的比例高于稳定斑块,差异有统计学意义（P<0.05）。结论 3.0 T MRI能够对缺血性脑卒中患者的颈动脉粥样硬化斑块内部成分...     

彩色多普勒超声诊断颈动脉狭窄205例分析

目的探讨颈动脉狭窄的彩色多普勒超声声像特征。方法对205例颈动脉狭窄患者行颈动脉超声检查,观察斑块的部位、形态、大小及回声特征,计算管腔狭窄程度及血流指数。结果 205例颈动脉狭窄患者,二维超声发现300支颈动脉IMT增厚,200支伴有斑块形成,彩色多普勒超声发现所有颈动脉狭窄患者收缩期及舒张末期流速均显著性增高。结论彩色多普勒超声能准确地判定颈动脉狭窄程度及狭窄位置,可作为颈动脉管壁病变的一种优良检查手段,为临床提供可靠诊断依据,也能作为治疗后随访手段。     

缺血性卒中合并2型糖尿病患者的颈动脉斑块的研究

目的:研究缺血性卒中合并2型糖尿病(type 2 diabetes mellitus,T2DM)患者的颈动脉斑块的临床特点和影响因素。方法:将2013年7月—12月收治的185例缺血性卒中患者分为T2DM组(n=72)及非T2DM组(n=113),用超声检查颈动脉斑块,其中22例患者行颈动脉CT血管造影(computed tomographic arteriography,CTA)检查;分析糖、脂代谢相关指标与颈动脉斑块大小的相关性。结果:T2DM组颈动脉斑块的发生率、性质、大小及颈动脉内中膜厚度(intima-media thickness,IMT)与非T2DM组比较差异有统计学意义(P0.05)。影响颈动脉斑块大小的主要因素为是否患T2DM、餐后2 h血糖(2 h postprandial blood glucose,2 h PBG)、稳态模型胰岛素抵抗指数(homeostatic model assessment for insulin resistance,HOMA-IR)、空腹血糖(fasting blood glucose,FBG)、低密度脂蛋白胆固醇(low density lipoprotein-cholesterol,LDL-C),P0.05。超声和CTA对22例患者颈动脉管腔的狭窄程度的检查结果差异有统计学意义(P0.05)。结论:缺血性卒中患者颈动脉斑块的大小与是否患T2DM、2 h PBG、HOMA-IR、FBG和LDL-C相关,合并T2DM时颈动脉斑块发生率升高,易损斑块比例升高。超声检查可作为颈动脉斑块筛查的首选方法,CTA更易于显示斑块的性质及管腔的狭窄程度。     

螺旋CT在新生儿肾上腺出血诊断中的应用——附18例报告

目的：总结新生儿肾上腺出血（NAH）的螺旋CT表现,探讨螺旋CT对NAH的诊断价值。方法：回顾性分析18例NAH患儿的螺旋CT平扫及增强扫描结果。结果：18例患儿CT平扫均显示肾上腺区单发圆形、椭圆形或不规则肿块,均单侧发生。肿块位于右侧15例,左侧3例,大小10mm×8mm～41mm×50mm。肿块呈均匀低密度占位3例,高低密度混杂占位4例,均匀高密度占位1例,囊性占位10例。肿块边缘清晰,光滑。18例患儿CT增强扫描均未见肿块内容物强化,可见边缘强化5例,受压的肾上腺强化7例。随访7d～3个月CT复查示肿块体积较前明显缩小、密度降低4例,随访3个月时CT示血肿消失1例,余14例于10d-1年行B超复查,结果示肿块完全消失10例,肿块范围明显缩小4例。结论：螺旋CT平扫对诊断NAH有重要价值,结合CT增强扫描有助于与肿瘤等鉴别,影像学随访有助于NAH的确诊。     

Shear-Wave Elastography Enables Identification of Unstable Carotid Plaque

Shear-wave elastography (SWE) is a novel ultrasound technique for quantifying tissue elasticity. The aim of this study was to identify differences in atherosclerotic plaque elasticity measured using SWE among individuals with symptomatic, asymptomatic progressive and asymptomatic stable carotid plaques. Consecutive patients from the Atherosclerotic Plaque Characteristics Associated with a Progression Rate of the Plaque and a Risk of Stroke in Patients with the Carotid Bifurcation Plaque Study were screened for this research. Neurosonography examination of carotid arteries was performed to identify plaque stenosis of ≥50% using B-mode ultrasound and SWE imaging to measure the mean, maximal and minimal elasticity. The set consisted of 97 participants—74 with asymptomatic stable stenosis, 12 with asymptomatic progressive stenosis and 11 with symptomatic stenosis. The mean elasticity in the asymptomatic stable plaque group was significantly higher than in the asymptomatic progressive (52.2 vs. 30.4 kPa; p < 0.001) and symptomatic (52.2 vs. 36.4 kPa; p = 0.033) plaque groups. No significant differences were found between asymptomatic progressive and symptomatic (p > 0.1) plaque groups. Asymptomatic stable, asymptomatic progressive and symptomatic plaques did not differ in echogenicity, calcifications, homogeneity, occurrence of ulcerated surface, or intra-plaque hemorrhage (p > 0.05 in all cases). SWE was a helpful modality for differentiating between stable and unstable atherosclerotic plaques in carotid arteries.     

Non-invasive Vascular Radial/Circumferential Strain Imaging and Wall Shear Rate Estimation Using Video Images of Diagnostic Ultrasound

The aim of this work was to develop a convenient method for radial/circumferential strain imaging and shear rate estimation that could be used as a supplement to the current routine screening for carotid atherosclerosis using video images of diagnostic ultrasound. A reflection model-based correction for gray-scale non-uniform distribution was applied to B-mode video images before strain estimation to improve the accuracy of radial/circumferential strain imaging when applied to vessel transverse cross sections. The incremental and cumulative radial/circumferential strain images can then be calculated based on the displacement field between consecutive B-mode images. Finally, the transverse Doppler spectra acquired at different depths along the vessel diameter were used to construct the spatially matched instantaneous wall shear values in a cardiac cycle. Vessel phantom simulation results revealed that the signal-to-noise ratio and contrast-to-noise ratio of the radial and circumferential strain images were increased by 2.8 and 5.9 dB and by 2.3 and 4.4 dB, respectively, after non-uniform correction. Preliminary results for 17 patients indicated that the accuracy of radial/circumferential strain images was improved in the lateral direction after non-uniform correction. The peak-to-peak value of incremental strain and the maximum cumulative strain for calcified plaques are evidently lower than those for other plaque types, and the echolucent plaques had higher values, on average, than the mixed plaques. Moreover, low oscillating wall shear rate values, found near the plaque and stenosis regions, are closely related to plaque formation. In conclusion, the method described can provide additional valuable results as a supplement to the current routine ultrasound examination for carotid atherosclerosis and, therefore, has significant potential as a feasible screening method for atherosclerosis diagnosis in the future.     

Development of integrated backscatter intravascular ultrasound for tissue characterization of coronary plaques

Tissue characterization of plaques of coronary arteries is important to clarify the process of acute coronary syndrome and prevent it. The purpose of this study is to develop an online integrated backscatter intravascular ultrasound (IB-IVUS) system and validate the diagnostic accuracy for the characterization of coronary plaques. A personal computer equipped with custom software was connected to an IVUS imaging system. Images were acquired from 242 segments of 46 coronary arteries from 25 cadavers obtained at autopsy. In the training study, a total of 724 regions-of-interests on color-coded maps were compared with histologic images. In the validation study, a total of 192 cross-sections of coronary arteries were evaluated. Receiver operating characteristic curve analysis showed that the cut-off points of -49 dB (area under curve = 0.98) and -29 dB (area under curve = 0.99) were the most reliable predictors of lipid pools, fibrosis and calcification. In the validation study, the analysis using IB values classified fibrous, lipid-rich and fibrocalcific plaque components with a high accuracy of 93%, 90% and 96%, respectively. The overall agreement between histologic and IB-IVUS diagnoses (n = 175) was high (Cohen's kappa = 0.81). The IB-IVUS system provides high diagnostic accuracy for analysis of tissue characteristics of coronary plaques.