磁共振成像技术识别兔腹主动脉易损斑块的实验研究

目的探讨磁共振成像(MRI)识别动脉粥样斑块性质的价值。方法制作兔腹主动脉易损斑块模型,对兔腹主动脉分别采用MRI扫描,血管内超声(IVUS)检查和病理学检查。结果成功建立兔腹主动脉易损斑块模型。MR图像T_1WI、T_2WI、PDWI序列中易损斑块呈高信号,FSE-PDWZ脂肪抑制信号消失,SE T_1WI增强扫描可见斑块略有强化;稳定斑块的影像学表现为斑块厚度增大,以等信号居多,增强扫描后斑块强化明显;与病理切片结果符合率较高,与IVUS的结果相近。结论MRI可以检测兔腹主动脉粥样斑块并进行定性分析。     

血管内超声评价兔腹主动脉易损斑块模型

目的应用血管内超声（IVUS）评价兔腹主动脉易损斑块（VP）模型建立情况。方法10只雄性新西兰大白兔高脂喂养4周后,经球囊扩张损伤腹主动脉,再高脂喂养8周后行IVUS检查。结果IVUS结果显示8只兔子有6只成功建立了vP模型。结论球囊扩张＋高脂饮食方法可成功建立兔腹主动脉vP模型,IVUS是评价斑块情况的简便方法。     

核磁共振成像对兔腹主动脉易损斑块的诊断价值

目的探讨核磁共振成像(MRI)对兔腹主动脉易损斑块(VP)的诊断价值。方法 20只雄性新西兰大白兔给以球囊拉伤腹主动脉+高脂饮食8周,建立兔腹主动脉VP模型。15只兔成功建立VP模型后分别进行MRI扫描和病理组织学检查。结果与病理切片相对应的90组MRI图像,发现斑块52处,其中VP36处,纤维性斑块16处;与病理组织学比较,MRI识别兔动脉粥样硬化易损斑块的敏感性和特异性分别为83.8%和90.6%。结论 MRI对识别兔腹主动脉易损斑块有较好的价值。     

兔动脉粥样硬化易损斑块早期预警指标的回归性研究

目的 通过对动脉粥样硬化易损斑块破裂前各项检测指标的回归分析,明确预测易损斑块破裂的最佳指标.方法 40只雄性新西兰纯种兔用球囊损伤腹主动脉+高脂喂养10周,于8周末分为p53基因组(20只)和LacZ基因组(20只),在腹主动脉斑块形成处分别转染携带人野生型p53基因或LacZ基因的重组腺病毒载体,2周后分别给予中国斑点蝰蛇毒(CRVV)和组胺药物触发斑块破裂.应用酶联免疫吸附法(ELISA)检测斑块破裂前血清中的高敏C反应蛋白(hs-CRP)、可溶性细胞间黏附分子-1(sICAM-1)和可溶性血管细胞间黏附分子(sVCAM-1)的变化,免疫比浊法测定血浆中纤维蛋白原的水平,联合应用体表超声心动图、血管内超声(IVUS)显像仪和声学密度定量(AD)技术检测易损斑块破裂前的各项影像学指标及声学密度强度,利用logistic回归分析判断以上各项检测指标与易损斑块破裂的关系.结果两组实验兔在药物触发后有21只兔共34处发生斑块破裂及血栓形成.p53基因组(存活19只)斑块破裂率89.5%(17/19),与LacZ基因组(存活18只)斑块破裂率22.2%(4/18)比较,差异有统计学意义(P＜0.01).药物触发前,斑块破裂组(n=21)hs-CRP水平、体表血管超声测值(腹主动脉内膜中层厚度、峰值速度)、AD值、IVUS测值明显高于斑块未破裂组(n=16),logistic回归分析显示IVUS测值斑块偏心指数(EI)、斑块面积(PA)和血清学sVCAM-1的OR值分别为26.917、19.301和1.339(均P＜0.05),校正的AD值AⅡ-c%的OR值为0.458(P＜0.05).结论 IVUS测值E1、PA、血清学指标sVCAM-1以及AD值是预测斑块易损性的重要指标.

Abstract：

Objective To detect the optimal predictors of vulnerable atherosclerotic plaques. Methods Forty New Zealand white rabbits underwent balloon-induced abdominal aortic wall injury and were fed a high cholesterol and saturated fat diet containing 1% cholesterol for 8 weeks. Rabbits were then randomly divided into two groups: group A ( n = 20, the aortic segments rich in plaques were incubated transluminally with recombinant adenovirus carrying p53 ) and group B [n = 20, incubated transluminally with β galactosidase (LacZ) genes]. Two weeks later, rabbits underwent pharmacological triggering with injection of Chinese Russell's viper venom (CRVV) and histamine. Before pharmacologically triggering,concentrations of hs-CRP, sVCAM-1 and sICAM-1 were measured by means of Enzyme-linkedimmunosorbent assay (ELISA). Fibrinogen was analyzed by nephelometer. Ultrasound imaging, accuracy densitometry (AD) examination and intravascular ultrasound (IVUS) were performed to analyze the in vivo features of vulnerable plaques. Logistic regression was used to detect the predictors for vulnerable plaques. Results The ratio d plaque rupture after pharmacological triggering was significantly higher in group A (89.5% ,17/19) than in group B (22.2%,4/18). Serum hs-CRP level was significantly higher in plaque rupture group than in non-rupture group before pharmacological triggering (P ＜ 0. 05 ). In the meantime, parameters derived from ultrasound imaging [intima-media thickness (IMT) and peak velocity (VP), values of accuracy densitometry], measurements of IVUS [external elastic membrance area (EEMA),plaque area(PA), plaque burden (PB), eccentric index (EI) and remodeling index(RI)]were significantly larger in plaque rupture group than in non-rupture group. Logistic regression showed that EI(OR=26.917),PA(OR=19.301), sVCAM-1(OR=1.339)and AⅡ-c%(OR=0.458)were independent predictors for plaque rupture(all P＜0.05).Conclusion The major predictors of vulnerable plaques were eccentric index (EI) and plaque area(PA), sVCAM-1 and AⅡ-c% in this model.     

血管内超声检验兔动脉粥样硬化斑块的研究

目的建立兔动脉粥样硬化模型,通过血管内超声（intravascularultrasound,IVUS）检查粥样硬化斑块．评价IVUS在粥样硬化斑块诊断的临床价值。方法选取20只健康的新西兰大白兔,按简单随机化方法分为两组,每组10只。一组单纯喂养高脂饲料;另一组除喂养高脂饲料外,4周时行腹主动脉内膜损伤术。12周后行IVUS检查,标记斑块远端、近端图像。观察病变处内中膜厚度．并通过病理检查评价IVUS效果。通过病理切片．生物病理图像分析系统处理,分别测量两组兔斑块厚度,并与IVUS结果相比较．同时比较不同方法观察到的斑块性质。结果高脂饲料加内膜损伤组（8只）12周时斑块厚度明显高于纯高脂组（8只）,差异有统计学意义[（521．286±124．732）μm vs.（240．029±73．528）μm,P〈0．05]。IVUS显示所有兔子（16只）的斑块厚度为（412．7±165．8）μm,病理为（360．2±98．1）μm,两者比较差异无统计学意义（P〉0．05）;对于斑块性质的判断,两者比较差异也无统计学意义（P〉0．05）。结论采用动脉内膜损伤加高脂饮食的方式来制作动脉粥样硬化斑块的模型是可行的、实用的。IVUS对血管斑块性质的界定及厚度的测量结果可靠。     

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。     

兔动脉粥样硬化易损斑块早期预警指标的回归性研究

Objective To detect the optimal predictors of vulnerable atherosclerotic plaques. Methods Forty New Zealand white rabbits underwent balloon-induced abdominal aortic wall injury and were fed a high cholesterol and saturated fat diet containing 1% cholesterol for 8 weeks. Rabbits were then randomly divided into two groups: group A ( n = 20, the aortic segments rich in plaques were incubated transluminally with recombinant adenovirus carrying p53 ) and group B [n = 20, incubated transluminally with β galactosidase (LacZ) genes]. Two weeks later, rabbits underwent pharmacological triggering with injection of Chinese Russell's viper venom (CRVV) and histamine. Before pharmacologically triggering,concentrations of hs-CRP, sVCAM-1 and sICAM-1 were measured by means of Enzyme-linkedimmunosorbent assay (ELISA). Fibrinogen was analyzed by nephelometer. Ultrasound imaging, accuracy densitometry (AD) examination and intravascular ultrasound (IVUS) were performed to analyze the in vivo features of vulnerable plaques. Logistic regression was used to detect the predictors for vulnerable plaques. Results The ratio d plaque rupture after pharmacological triggering was significantly higher in group A (89.5% ,17/19) than in group B (22.2%,4/18). Serum hs-CRP level was significantly higher in plaque rupture group than in non-rupture group before pharmacological triggering (P ＜ 0. 05 ). In the meantime, parameters derived from ultrasound imaging [intima-media thickness (IMT) and peak velocity (VP), values of accuracy densitometry], measurements of IVUS [external elastic membrance area (EEMA),plaque area(PA), plaque burden (PB), eccentric index (EI) and remodeling index(RI)]were significantly larger in plaque rupture group than in non-rupture group. Logistic regression showed that EI(OR=26.917),PA(OR=19.301), sVCAM-1(OR=1.339)and AⅡ-c%(OR=0.458)were independent predictors for plaque rupture(all P＜0.05).Conclusion The major predictors of vulnerable plaques were eccentric index (EI) and plaque area(PA), sVCAM-1 and AⅡ-c% in this model.     

兔动脉粥样硬化易损斑块早期预警指标的回归性研究

Objective To detect the optimal predictors of vulnerable atherosclerotic plaques. Methods Forty New Zealand white rabbits underwent balloon-induced abdominal aortic wall injury and were fed a high cholesterol and saturated fat diet containing 1% cholesterol for 8 weeks. Rabbits were then randomly divided into two groups: group A ( n = 20, the aortic segments rich in plaques were incubated transluminally with recombinant adenovirus carrying p53 ) and group B [n = 20, incubated transluminally with β galactosidase (LacZ) genes]. Two weeks later, rabbits underwent pharmacological triggering with injection of Chinese Russell's viper venom (CRVV) and histamine. Before pharmacologically triggering,concentrations of hs-CRP, sVCAM-1 and sICAM-1 were measured by means of Enzyme-linkedimmunosorbent assay (ELISA). Fibrinogen was analyzed by nephelometer. Ultrasound imaging, accuracy densitometry (AD) examination and intravascular ultrasound (IVUS) were performed to analyze the in vivo features of vulnerable plaques. Logistic regression was used to detect the predictors for vulnerable plaques. Results The ratio d plaque rupture after pharmacological triggering was significantly higher in group A (89.5% ,17/19) than in group B (22.2%,4/18). Serum hs-CRP level was significantly higher in plaque rupture group than in non-rupture group before pharmacological triggering (P ＜ 0. 05 ). In the meantime, parameters derived from ultrasound imaging [intima-media thickness (IMT) and peak velocity (VP), values of accuracy densitometry], measurements of IVUS [external elastic membrance area (EEMA),plaque area(PA), plaque burden (PB), eccentric index (EI) and remodeling index(RI)]were significantly larger in plaque rupture group than in non-rupture group. Logistic regression showed that EI(OR=26.917),PA(OR=19.301), sVCAM-1(OR=1.339)and AⅡ-c%(OR=0.458)were independent predictors for plaque rupture(all P＜0.05).Conclusion The major predictors of vulnerable plaques were eccentric index (EI) and plaque area(PA), sVCAM-1 and AⅡ-c% in this model.     

血管内膜表面温度差对识别兔腹主动脉易损斑块的价值

目的 评价血管内膜表面温度差在判定兔腹主动脉易损斑块中的价值.方法 雄性新西兰大白兔20只,给予球囊拉伤腹主动脉加高脂饮食喂养16周,建立兔腹主动脉易损斑块模型.存活的大白兔通过中国斑点蝰蛇毒和组胺触发,诱发斑块破裂以及血栓形成.行兔腹主动脉斑块和周围组织的表面温度差测定.结果 16只实验兔顺利完成模型建立,在这些模型上共发现斑块24处.共进行54次斑块表面温度测量.14只兔有17处光学显微镜下观察切片符合易损斑块的特征,共进行了37次表面温度测量;6只有7处符合纤维性斑块特征,进行了17次表面温度测量;4处为非斑块区,共进行9次测量.易损斑块的表面温度差水平为0.94±0.25℃,而纤维斑块的水平为0.15±0.14℃,非斑块区的水平为0.10±0.08℃.易损斑块的表面温度差较纤维斑块和非斑块区明显增高,有统计学差异(P＜0.01).血管内膜表面温度差大于0.3℃识别兔动脉粥样硬化易损斑块的敏感性和特异性分别为86.5％和85.2％.结论 血管内膜表面温度差的测定有助于识别易损斑块.     

普伐他汀对兔腹主动脉易损斑块内细胞凋亡影响的研究

目的 探讨普伐他汀对兔动脉粥样硬化易损斑块内细胞凋亡的影响.方法 新西兰大白兔30只,随机分为三组,均通过动脉内膜损伤术加高脂饮食形成动脉粥样硬化斑块.术后一组给予高脂饮食（对照组）,另一组给予高脂饮食加普伐他汀（普伐他汀1组,P1组）,第三组术后2个月内给予高脂饮食,第3个月起加普伐他汀（普伐他汀2组,P2组）,三组均通过超声检测斑块形成情况,测量内中膜厚度（IMT）.饲养4个月后处死兔子,取易损斑块,通过TUNEL法检测斑块细胞凋亡情况.结果 兔腹主动脉IMT逐渐增厚,术后1个月后普伐他汀组明显小于高脂饮食组（P＜0.01）;细胞凋亡在高脂饮食组中的表达,集中在脂核区和纤维帽区,明显高于其他两区（P＜0.01,P＜0.01）;普伐他汀组凋亡细胞主要在脂核区,明显大于其他三区（P＜0.01）;两组比较细胞凋亡在纤维帽区,普伐他汀2组明显小于高脂饮食组（P＜0.01）.结论 IMT与动脉粥样硬化程度高度相关,普伐他汀能通过减少纤维帽区的细胞凋亡而稳定斑块.     

Interventional applications of intravascular ultrasound imaging: initial experience and future perspectives

Intravascular ultrasound imaging offers the potential to provide more detailed information about vessel and lesion morphology and physiology than is currently available from angiography. The greatest impact of intravascular ultrasound upon clinical decisions may be in the area of cardiac and vascular interventions. To evaluate the utility of intravascular ultrasound, we prospectively studied 45 patients, 11 of whom underwent interventional procedures. Intravascular ultrasound imaging was performed before and after interventions using a 20 MHz, mechanically rotating transducer on either 6.5 Fr or 8.0 Fr catheter systems. Interventions included seven peripheral vessel balloon angioplasties (Femoral artery-two, Renal artery-two, Arteriovenous fistula-two, Aortic coarctation-one), two Femoral artery rotational atherectomies, and two balloon valvuloplasties (Pulmonic valve-1, Mitral valve-1). Intravascular ultrasound and digital angiography provided similar information about vessel size. However, morphological information about the vessel wall, plaque composition, plaque topography, luminal thrombus, and vessel dissections was better appreciated by intravascular ultrasound. Intravascular ultrasound was determined to have provided unique and clinically useful information in 10/11 (91%) interventions. These preliminary data illustrate the potential value of intravascular ultrasound for the evaluation of the vascular system and in particular its value in interventional procedures.     

Comparison of unenhanced magnetic resonance imaging and ultrasound in detecting very small hepatocellular carcinoma

BACKGROUNDIn hepatocellular carcinoma (HCC), detection and treatment prior to growth beyond 2 cm are important as a larger tumor size is more frequently associated with microvascular invasion and/or satellites. In the surveillance of very small HCC nodules (≤ 2 cm in maximum diameter, Barcelona clinical stage 0), we demonstrated that the tumor markers alpha-fetoprotein and PIVKA-Ⅱ are not so useful. Therefore, we must survey with imaging modalities. The superiority of magnetic resonance imaging (MRI) over ultrasound (US) to detect HCC was confirmed in many studies. Although enhanced MRI is now performed to accurately diagnose HCC, in conventional clinical practice for HCC surveillance in liver diseases, unenhanced MRI is widely performed throughout the world. While, MRI has made marked improvements in recent years.AIMTo make a comparison of unenhanced MRI and US in detecting very small HCC that was examined in the last ten years in patients in whom MRI and US examinations were performed nearly simultaneously.METHODSIn 394 patients with very small HCC nodules, those who underwent MRI and US at nearly the same time (on the same day whenever possible or at least within 14 days of one another) at the first diagnosis of HCC were selected. The detection rate of HCC with unenhanced MRI was investigated and compared with that of unenhanced US.RESULTSThe sensitivity of unenhanced MRI for detecting very small HCC was 95.1% (97/102, 95% confidence interval: 90.9-99.3) and that of unenhanced US was 69.6% (71/102, 95% confidence interval: 60.7-78.5). The sensitivity of unenhanced MRI for detecting very small HCC was significantly higher than that of unenhanced US (P < 0.001). Regarding the location of HCC in the liver in patients in whom detection by US was unsuccessful, S_7-8 was identified in 51.7%.CONCLUSIONCurrently, unenhanced MRI is a very useful tool for the surveillance of very small HCC in conventional clinical follow-up practice.     

New approach in diagnosis of bile duct disease with ultrasound and magnetic resonance imaging

Abstract Advances in technology have made possible the clinical application of magnetic resonance cholangiography, endoscopic, intra-operative and laparoscopic ultrasound in the study of the biliary tree, in addition to conventional magnetic resonance imaging and transabdominal ultrasound. The role of the conventional, as well as the newer techniques, in the diagnosis of bile duct disease and the limitations and pros and cons of each technique, will be the subject of the present discussion.     

Assessment of aortic regurgitation severity by magnetic resonance imaging of the thoracic aorta

A new method of assessing the severity of aortic regurgitationseverity by magnetic resonance imaging has been developed. Twogroups were studied: 20 controls (age=58 ± 19 years)without valvular aortic disease, and 24 patients (age=62 ±13 years) with chronic aortic insufficiency evaluated by magneticresonance and aortic root cineangiography within 1 week of eachother. A magnetic resonance sequence (TR=35 mslTE=12 mslflipangle=20°/magnet=1.5 T) was acquired in a plane containingthe thoracic aorta. A transverse saturation band 30 mm widewas positioned 30–40 mm above the aortic valve. Aorticinsufficiency was graded, the importance of end-diastolic retrogrademovement in the saturation band in the descending aorta wasnoted. Magnetic resonance was also compared to Doppler echocardiographyin 20 patients. In the controls, we found that retrograde blood flow was absent(18/20) or mild (2/20). In contrast, the presence of markedretrograde movement in a saturation band across the thoracicaorta was always associated with severe aortic regurgitation(angiographic grade III or IV). This rapid method (imaging time less than 20 min) can be appliedin most patients with aortic regurgitation and is likely tobe helpful when echocardiography is not possible or gives inconclusiveresults.     

Plaque characterization of atherosclerotic coronary arteries by intravascular ultrasound

Intravascular ultrasound provides cross-sectional images of arteries and enables accurate delineation of lumen dimensions and wall structure. Moreover, ultrasound characterization of atherosclerotic plaque subtypes may have important implications in determining the natural history and the clinical outcome of patients with coronary artery disease. The reliability of intravascular ultrasound to differentiate plaque morphology subtypes was studied in 60 coronary segments excised from 33 coronary arteries obtained from 17 patients at necropsy. Ultrasound was performed with a 25-MHz transducer mounted on the distal end of a rigid probe that was rotated manually inside the lumen artery. Plane film radiography was also performed to establish the presence of calcific deposits. A total of 82 histologic transverse sections corresponding to 82 ultrasound imaging sites were studied from the 60 coronary segments. Of the first 54 images, 36 were fibrous plaques and yielded dense homogenous echo reflections, 6 had discrete areas of lipid that were less echogenic and 12 had calcific deposits that cast echo-free shadows beyond areas of intense echo reflections. The predictive accuracy of evaluating plaque composition in the remaining 28 ultrasound imaging sites was 96%. Thus, anatomical structure of coronary arteries and composition of atherosclerotic lesions can be assessed accurately with intravascular ultrasound and may have potential for better understanding of the atherosclerotic process and provide guidance to interventional procedures.     

Quantitative evaluation of carotid atherosclerotic plaques by magnetic resonance imaging

In order to study human atherosclerotic plaque burden and composition in vivo, an imaging technique is needed that can directly measure volume and characterize the cross-sectional morphologic components of the atherosclerotic arterial wall. High-resolution magnetic resonance imaging (MRI), which is noninvasive and nonirradiative, has been described as one promising modality to achieve these purposes. MRI allows direct visualization of the diseased vessel wall and is capable of characterizing the morphology of individual atherosclerotic carotid plaques.