声学造影在心血管系统疾病中的应用及进展

经胸超声心动图(transthoracic echocardiography, TTE)是目前筛查和诊断心血管系统疾病最常用且最简便的影像学检查,近年来取得了较快发展。但由于对透声较差的患者,不能很好地识别心内膜边缘,会严重影响对节段性室壁运动异常检测的准确性,心脏声学造影(contrast echocardiography, CE)是超声心动图与声学造影相结合的一种心血管成像技术,通过外周静脉注射造影剂来增强心腔和血管腔的显像,改善对心肌与心腔界面的显示,还可以直接显示心肌灌注,在临床上的应用日益增多。它主要包括两大类:心腔造影技术和心肌造影技术,在此基础上又衍生出多种诊疗技术。如今CE技术已在临床上得到较多的应用,为诊断心血管疾病提供了有力的帮助。     

心肌声学造影在冠心病诊断中的研究进展

心肌造影超声心动图 (Myocardial ContrastEchocardiography,MCE)在评价心肌血流灌注中的运用成为一项十分热门的研究课题。MCE是指将含有微气泡的造影剂直接经冠状动脉或外周静脉注入 ,当微泡通过心肌微血管床时 ,应用二维或多普勒超声技术增强含血心肌的超声心动图显像 ,观察心肌血流灌注、冠脉血流储备。本文就近年来心肌声学造影在冠心病诊断方面的研究作一综述。1　声学造影剂的研究声学造影剂是 MCE的决定性因素之一。早年造影剂所产生的微泡直径大、不均匀、易破裂 ,无法通过肺循环进入左心室。故这项技术主要用于右心显影 ,认…     

心肌声学造影与第二谐波成象技术实验研究新进展

心肌声学造影评价心肌血流灌注和功能，方法简便易行，但尚有一定的局限性。国外新近推出的第二谐波成象可明显增强心腔及心肌血管超声造影剂的显影效果，两者联合作用，在评价冠脉解剖、生理功能及心肌灌注方面，有广阔的应用前景。     

经静脉途径注射自制声振白蛋白左心声学造影的实验研究

观察了经犬股静脉注入自制声振白蛋白左心显影效果．结果：本研究造影剂微泡直径４．２±２．４μｍ，浓度１６５±０６９×１０８／ｍｌ．经股静脉注射该造影剂共１０次，均见右室显影．５～８个心动周期后，左左室相继显影（显影率１００％）．持续约１１～３０个心动周期后左室造影作用消失．结论：声振５％人体白蛋白微泡直径小于红细胞，经犬股静脉注射后可实现满意的左室腔声学显影．如能应用到临床，将为超声心动图在冠心病室壁运动、心功能准确定量等方面提供帮助．     

实时造影匹配成像技术诊断肝血管瘤

二维图像是目前诊断肝血管瘤的主要依据,但有时难以与恶性病变相鉴别.编码相应反转技术(CPI)是一种低MI的造影模式,在低MI状态下,组织谐波信号被减到最小,保留造影剂的宽带谐波信号可极大地增加造影剂信号与周围组织信号的对比,从而获得不同时期所观察区域造影剂灌注图像,从而大大提高造影成像的分辨率及敏感性.TAD(Tru造影剂检测技术)造影过程中可双幅显示图像,在观察位置较特殊或较小的病灶时可更好的锁定目标,减少靶目标丢失的可能性.本研究应用新型超声造影剂声诺维结合CPI成像技术对肝血管瘤的血流灌注和清除进行动态实时观察,旨在了解不同肝血管瘤造影剂灌注时相、回声变化规律,探讨肝血管瘤的增强模式.     

心肌声学造影的进展

心肌声学造影 (Myocardial ContrastEchocardiography,MCE)是通过注射声学造影剂的方法使之灌注到冠脉微血管结构中 ,从而使含血心肌的超声心动图显像增强 ,近年来 ,心肌声学造影已取得突破性进展 ,新一代声学造影剂的发现及超声显像技术的发展使经静脉注射声学造影剂导致心肌显像成为可能。心肌声学造影不仅能直接反映冠脉微循环状况、确定急性心肌梗塞的危险区、评价心肌存活性及冠脉血流储备 ,而且还可以用于标靶特定组织及局部药物或基因的转导。1　心肌声学造影剂196 8年 Gramiak和 Shah[1] 首次报道了经心腔注射生理盐水后经超声…     

全氟显左心声学造影的临床应用

目的:探讨全氟显左心声学造影临床应用的可行性。方法:在50例患者中,经外周静脉弹丸式注射全氟显,进行左心声学造影检查,观察造影剂注射前后左心室显影等级、心内膜边界增强效果和心肌显影情况。结果:50例患者中只有1例患者左室充盈等级为2~3级,其余49例患者左室充盈等级均为3级。造影前50例患者中共有155个节段心内膜显示不清,造影后该155个节段的内膜边界显示清晰,内膜边界增强率为100%。50例患者左室壁心肌组织均获得了满意的显影效果。结论:临床经外周静脉弹丸式注射全氟显行左心声学造影,取得了满意的效果。     

心肌声学造影对急性心肌梗死患者经皮冠脉介入术后心肌微循环的影响

目的探讨心肌声学造影对急性心肌梗死(AMI)患者经皮冠脉介入术(PCI)后TIMI血流达Ⅲ级者心肌微循环的影响。方法采用Sequoia512型超声心动仪,应用二次谐波成像和高机械指数超声发射,对30例AMI患者PCI术后进行经静脉声诺维心肌声学造影显像和超声检查。结果共210个节段与梗死相关动脉再灌注有关,灌注正常即心肌造影计分(MCS)1分146段,灌注不良MCS 0.5分53段,无灌注MCS 0分11段。运动正常节段中MCS 1分者明显高于运动异常节段(P<0.05)。根据声学造影记分指数(CSI)将患者分为A组22例(CSI>0.8),B组8例(CSI≤0.8)。A组射血分数(EF)显著大于B组(P<0.05)。结论TIMIⅢ级血流并非再灌注成功的金标准。心肌微循环与心室收缩功能有一定相关性,微循环良好的患者EF值大于微循环较差者。经静脉声诺维心肌声学造影是一种安全无创的检测手段,是反映心肌微循环灌注的有效方法。     

用心肌声学造影评价择期经皮冠状动脉介入治疗改善心肌梗死患者心肌组织灌注的效果

目的应用选择性心肌声学造影(MCE)评价择期经皮冠状动脉(冠脉)介入治疗(PCI)改善心肌梗死患者心肌组织灌注的临床疗效。方法选择24例前壁心肌梗死患者,发病到择期PCI的时间为6±2(3~12)周,于PCI前选择性冠脉内注射声诺维(Sonovue),利用对比脉冲序列成像技术(CPS)进行心肌声学造影(MCE)检查;冠脉开通后30 min再次行MCE检查,采用CUSQ软件进行脱机图像分析,计算心肌微血管血流量、最大造影剂充盈缺损面积和缺血心肌改善指数,评价心肌组织灌注效果。随访患者心脏功能及PCI术后30 d的主要心脏事件(MACE)。结果(1)24例患者的“罪犯”血管完全开通,TIMI血流3级;(2)冠脉内注入造影剂即刻能够获得清晰心肌显影,所有患者均获得较满意左心室及心肌显影效果。MCE显示,24例于PCI术前“罪犯”左前降支血管对应心脏节段节段性充盈减低或无造影剂充盈,PCI术后30 min 92%(22/24)的患者心脏节段充盈较术前显著改善,局部血流量值较术前提高;(3)24例患者PCI术后72 h左心室射血分数(EF值)较术前增加(52%±10%比62%±6%,P<0.05),住院期间无MACE发生。本研究中2例PCI术后心肌灌注不良患者,分别于术后1个月出现心力衰竭(心功能Ⅲ级),1例术后2周出现劳累性心绞痛,均经药物治疗稳定。结论选择性MCE技术是一项简便、安全的评价冠脉介入术心肌组织灌注的有效方法;未行再灌注治疗的心肌梗死患者应尽早行择期PCI术,挽救梗死区的缺血心肌,改善左心室功能。     

心肌灌注断层显像对急性心肌梗死再灌注的研究

目的：通过心肌灌注断层显像研究急性心肌梗死（ＡＭＩ）患者经尿激酶及经皮冠状动脉腔内成形术（ＰＴＣＡ）治疗前后梗死范围的变化。方法：用９９ｍ锝甲氧基异丁基异腈心肌灌注断层显像测定３６例ＡＭＩ患者心肌再灌注前后的心肌梗死面积。结果：再灌注组和无再灌注组首次心肌显像心肌缺损面积无显著性差异（Ｐ＞０．０５）；再灌注组再次显像心肌缺损面积明显小于首次显像（１７．５±２．８％和３１．９±４．５％，Ｐ＜０．０５）；无再灌注组再次显像心肌缺损面积与首次显像无明显差异（２９．６±４．７％和３２．４±５．１％，Ｐ＞０．０５）；预后不良组（ｎ＝６）心肌缺损面积明显高于预后较好组（３４．６±５．１％和２１．４±３．６％，Ｐ＜０．０５）。结论：心肌灌注断层显像可作为ＡＭＩ再灌注疗效评价较准确的手段。     

Contrast echocardiography: clinical applications and future prospects

BACKGROUND: Contrast echocardiography has been used as a clinical method for more than 20 years. Using conventional ultrasound techniques the clinical use of contrast was limited. Now the development of "contrast specific" imaging modalities has increased the indications for contrast echocardiography. CONTRAST AGENTS: For clinical use two classes of contrast agents are available: 1. "right heart" contrast media (Echovist, agitated solutions), which do not cross the pulmonary vascular bed following intravenous injection and which can be used with conventional (fundamental) imaging methods, 2. "left heart" contrast media (Levovist, Optison, SonoVue) which need "contrast specific" imaging modalities for optimal use. INDICATIONS: Despite of the developments in Doppler methods and transesophageal echocardiography "right heart" contrast media still are needed in some patients with atrial and pulmonary shunts, complex congenital heart disease, noisy Doppler recordings of tricuspid regurgitation. For "left heart" contrast media improvement of endocardial border definition is the most important indication, which has been validated in a series of well performed studies. Therefore contrast enhanced recordings are recommended in the clinical echo laboratory when unenhanced recordings are suboptimal. Coronary flow reserve of the LAD can be measured using contrast enhanced Doppler echocardiography. All contrast specific imaging modalities provide assessment of myocardial perfusion. The previously used imaging modalities (Harmonic B mode, Pulse Inversion and Harmonic Power Doppler) did not provide sufficient myocardial contrast signals using real-time imaging. Although intermittent imaging resulted in good myocardial opacification, this modality did not gain wider clinical acceptance. NEW TECHNOLOGIES: Using new contrast specific imaging technologies like Power Pulse Inversion, Power Modulation and Coherent Imaging myocardial perfusion can be evaluated in "real-time". Thus simultaneous assessment of left ventricular wall motion and myocardial perfusion became a reality and facilitated the data acquisition. New ultrasound contrast media like SonoVue can be used for all imaging modalities. Recent studies have demonstrated that the information derived from myocardial contrast echocardiography provides clinically relevant information on top of the findings obtained from conventional left ventricular wall motion analysis.     

Intravenous contrast echocardiography

Intravenous contrast echocardiography has become possible in Japan because of the release of the commercially available contrast agent, Levovist. Intravenous administration of Levovist satisfactorily stains the left ventricular cavity, which makes it possible to clearly delineate the endocardial border. Clear delineation of the endocardial border provides easy and accurate measurement of left ventricular dimension and wall thickness, and wall motion abnormalities can be easily and accurately judged, too. Another benefit of intravenous contrast echocardiography is the assessment of myocardial perfusion. Our preliminary experimental and clinical experiences showed the possibility of myocardial staining with intravenous contrast echocardiography. Impressive myocardial staining is obtainable with the combined use of intermittent and contrast harmonic power Doppler imaging. In order to obtain reproducible and clear myocardial contrast images, we have to pay attention to how to inject contrast and settings of ultrasound equipment, i.e., mechanical index, gain setting, depth of focus point, and pulse repetition frequency, artifacts. In the near future, a lot of issues should be standardized to make it possible to compare myocardial contrast echo studies.     

Comparison of native and contrast-enhanced harmonic echocardiography for visualization of left ventricular endocardial border

Our study was designed to compare the utility of fundamental and second harmonic imaging (SH) for visualization of the left ventricular (LV) endocardial border. SH is a new imaging modality using nonlinear acoustic response, which may provide better endocardial border delineation. Standard apical views were studied in 42 patients using fundamental frequency (FF), SH without contrast (1.6- to 1.8-MHz and 2.1- to 2.5-MHz transmission frequencies), and SH after an intravenous injection of 2.5 g of Levovist. The quality of endocardial delineation in 16 standard segments was scored from 0 to 2. The endocardial visualization index was calculated as a mean of the scores. SH with and without contrast significantly improved LV endocardial border detection (endocardial visualization index 1.25+/-0.53, 1.64+/-0.67, 1.55+/-0.69, and 1.73+/-0.28 for fundamental, lower, and higher frequency harmonic and contrast-harmonic mode, respectively, p <0.005). Improvement was found in all LV segments. The number of invisible segments decreased from 142 (FF) to 54, 112, and 61 (in lower, higher, and contrast SH mode, respectively, p <0.001). Endocardial delineation in the apical segments using SH was optimal after contrast injection. In the basal LV area, contrast-enhanced images were less informative because of signal attenuation. Thus, SH significantly improves visualization of the LV endocardial border. Contrast enhancement with Levovist improves imaging of the apical segments but has no additional advantage in the basal segments. SH emerges as first-line modality for studies of LV function.     

Improvement in Endocardial Border Delineation Using Tissue Harmonic Imaging

Background and Methods: For years, tissue has been assumed to be a linear medium in diagnostic ultrasound applications; thus, no backscattered signals in the second harmonic band are expected in harmonic imaging without the injection of a contrast agent. However, it has been shown that a useful tissue image is formed even without a contrast agent. The aim of this study was to evaluate whether this tissue harmonic image provided improved visualization of endocardial borders. Fifty-six adult patients with various heart diseases were investigated using conventional two-dimensional echocardiography and tissue harmonic imaging. In 30 of these patients, the left ventricular endocardial borders were well defined in the standard parasternal and apical views using conventional two-dimensional echocardiography. In the remaining 26 patients, delineation of endocardial borders was not possible in at least two segments. The equipment used was an ATL HDI-3000 diagnostic system equipped with harmonic imaging. Results: In all 56 patients, the myocardium and valves could be imaged with tissue harmonic imaging. Harmonic recordings were sharper and contained fewer clutter artifacts than conventional recordings. Most striking was the enhancement of left ventricular endocardial borders. In the 26 patients with incomplete delineation of left ventricular endocardial borders, wall motion could be evaluated in 290 of 312 (93%) segments with tissue harmonic imaging compared with only 168 of 312 (54%) segments with conventional echocardiography (P < 0.001). Conclusions: Tissue harmonic imaging improves image quality and can be used to enhance the definition of left ventricular endocardial borders. These findings can be explained by the nonlinear propagation of ultrasound within the tissue, which results in distortion of the transmitted signal and, thus, harmonic generation.     

Use of harmonic echocardiographic contrast imaging and intravenous bolus of Levovist for evaluation of the left ventricle

Harmonic imaging is a new imaging modality using nonlinear acoustic response, which is particularly sensitive for the particles of contrast agents. Our study was designed to compare the potential of harmonic echocardiographic imaging of the left ventricle using a contrast agent, Levovist to improve the detection of endocardium in patients with suboptimal image quality. 40 patients were studied using standard transthoracic apical views of the left ventricle patients using fundamental frequency and second harmonic frequency after and intravenous injection of 2.5 g Levovist. The quality of endocardial delineation in 16 standard segments was scored from 0 to 2. Endocardial visualization index was calculated as a mean of the scores to express overall diagnostic quality. Harmonic imaging with contrast significantly improved left ventricular endocardial border detection (endocardial visualization index at baseline 1.24 +/- 0.41, with contrast 1.63 +/- 0.38; p < 0.001). The improvement was qualitatively observed in all parts of the left ventricle: in apex (2.4 +/- 0.8), in the middle part (2.5 +/- 0.9) and slightly less in the basal part (2.1 +/- 1.1) as scored on a 0-3 scale. The number of invisible segments decreased from 124 (fundamental) to 50 in contrast harmonic mode. The persistence of the contrast enhancement, prolonged in harmonic as compared to fundamental imaging (284 +/- 136s vs 117 +/- 87s; p < 0.001) enabled convenient recording of all necessary views. Harmonic imaging after an intravenous injection of Levovist significantly improves the visualization of left ventricular endocardial border. Prolonged contrast effect after a single bolus enhances the pertinence of the method in clinical practice.     

Multicenter evaluation of SonoVue for improved endocardial border delineation

OBJECTIVES: Two multicenter studies were conducted to evaluate the safety and efficacy of SonoVue as a contrast agent for enhanced left ventricular endocardial border delineation (LVEBD), and to compare the efficacy of SonoVue and Albunex in adult patients with a suboptimal, nonenhanced echocardiogram. BACKGROUND: The use of contrast to enhance echocardiographic assessment of LVEBD is well-established. SonoVue is a new microbubble contrast agent that contains sulfur hexafluoride. METHODS: Patients were randomized to receive four injections of SonoVue (0.5, 1, 2, and 4 ml), or two injections of Albunex and two injections of hand-agitated saline (0.08 and 0.22 ml/kg). Echocardiographic images were evaluated at the study centers and by four blinded, offsite reviewers for degree of left ventricle opacification (LVO), duration of contrast enhancement, and LVEBD. RESULTS: LVO scores were significantly higher for all doses of SonoVue. Patients with complete LVO ranged from 34%-87% for SonoVue and from 0%-16% for Albunex. The mean duration of useful contrast effect ranged from 0.8-4.1 minutes for SonoVue and < 15 seconds for Albunex. Mean increases in LVEBD scores ranged from 3.8-18.2 for SonoVue and 0.1-4.3 for Albunex. SonoVue (cumulative 7.5 ml dose) was well-tolerated, with a safety profile similar to that observed in the control group. CONCLUSIONS: SonoVue is superior to Albunex for improving visualization of endocardial borders in patients with suboptimal noncontrast echocardiograms. Optimal increases in LVEBD, LVO, and duration of useful contrast effect were observed at the 2.0 ml dose of SonoVue.     

The clinical applications of contrast echocardiography.

Ultrasound contrast agents are approved for opacification of the heart chambers and to improve endocardial border definition. The myocardial contrast enhancement is also very useful for assessing thickening of the myocardium and myocardial perfusion. Several multicentre and numerous single-centre trials have demonstrated the usefulness of contrast echocardiography in clinical practice. Contrast echocardiography is probably one of the best validated echocardiographic techniques. Improved accuracy of contrast-enhanced images is not restricted to patients with a poor baseline image quality. Even with an optimal baseline image quality the borders are not as well defined as after LV opacification. Usage of contrast can improve image alignment and helps to avoid off-axis scanning. Contrast studies are particularly useful when a precise measurement of LV function is needed: 1. To decide about the need of implantable cardioverter-defibrillators (ICDs), cardiac resynchronization therapy (CRT), 2. Follow-up of patients with moderate valvular disease and decision for surgical treatment, 3. Selection and monitoring of patients undergoing chemotherapy with cardiotoxic drugs, 4. Assessment of LV function in patients in intensive care and coronary care units. Optimal endocardial border delineation is crucial and often can be achieved only by ultrasound contrast: 1. Assessment of LV thrombi and masses, 2. Left ventricular non-compaction/apical hypertrophy, 3. Right ventricular dysplasia, right ventricular thrombus, 4. Stress echocardiography and regional wall motion assessment. Future echocardiography will be more 3D and more quantitative than current echocardiography. And contrast echocardiography has already proven its value for both applications.     

Clinical Experience with SonoVue in Myocardial Perfusion Imaging

Ultrasound-enhancing agents have the potential to evaluate myocardial perfusion, adding a new dimension to echocardiography. This article summarizes the clinical studies involving SonoVue, a new intravenous ultrasound contrast agent, in assessing myocardial perfusion. Safe and well tolerated, SonoVue coupled with echocardiography has the capability to identify perfusion abnormalities, as confirmed by scintigraphic imaging. While the optimal modalities for ultrasound perfusion assessment are not yet determined, numerous technical advances have been introduced: continuous infusion or slow intravenous administration of the agent, harmonic intermittent imaging, pulse inversion, background subtraction, color coding, and others. SonoVue is a promising new agent in the booming field of myocardial contrast echocardiography.