联机声学密度定量与心肌原始射频信号强度的相关性

目的：验证商用超声诊断仪所测定的心肌背向散射信号强度的可靠性。方法：60只中国本兔随机分为2组，每组30只，测定经胸测量其收缩末期和舒张末期的心肌背向散射积分，开胸分别向冠状动脉内注入高钾或高钙溶液使心脏停搏于舒张期或收缩期。分别用商用超声诊断仪和专用的声学射频信号检测仪测定其回波强度。结果：离体心脏心肌背向散射积分收缩期和舒张期的测值均和活体心脏无显著差异，收缩期和舒张期之间则有显著的差别，舒张期明显高于收缩期；离体心脏的心肌射频信号强度收缩期和舒张期之间也存在着这种差异。结论：联机声学密度定量分析系统所测信号强度准确反映心肌的声学特性。     

不同程度缺血心肌超声背向散射参数变化的实验研究

目的：探讨不同程度缺血心肌背向散射特性变化的规律。方法：用杂种犬20条建立不同程度心肌缺血的动物模型,测定心肌超声背向散射参数。结果：不同程度心肌缺血时心肌背向散射积分及周期变化幅度和两者的跨壁梯度均有显著的差别。结论：心肌超声背向散射参数可以作为判断心肌缺血程度的重要指标。     

背向散射积分技术评价PTCA术前后左室肌回声与收缩功能

目的：用超声背向散射积分(IBS)评价经皮冠状动脉成形术(PTCA)前后左室肌回声及收缩功能变化。方法：对33例择期行PTCA 支架术的冠心病患者用HP 5500型超声诊断仪，于PTCA术前及术后3天、1～3个月对胸骨旁乳头肌短轴切面的前间壁、下壁、后壁、侧壁行二维超声心动图(2DE)检测各节段的室壁运动情况、声学密度一背向散射积分(AD-IBS)检测心肌背向散射积分平均值及其标化值，心肌整层及心内外膜下心肌层的周期变化幅度并计算跨壁梯度指数。结果：左室存活心肌背向散射积分参数值于术后3天就有了改善，与术前相比有统计学意义；术后1～3个月检测，左室存活心肌回声及收缩功能均有明显改善。结论：PTCA能够有效地挽救存活心肌，背向散射积分技术能够为早期检测存活心肌及早期评价或预测PTCA疗效提供敏感指标。     

轻度缺血心肌的超声背向散射特性

超声背向散射积分是一项新的超声组织定征技术，为探讨该技术在冠心病研究方面的意义，本研究应用背向散射积分联机分析技术观测了１０例犬轻度缺血心肌不同时间点的散射特性。结果显示，同基础状态相比，在狭窄即刻缺血区域心肌的背向散射积分周期变异即开始减低，其中心内膜下心肌背向散射积分周期变异明显减低（Ｐ＜０．０５）；背向散射积分在狭窄即刻有增高趋势，但尚无统计学差异。再灌注后这些变化迅速恢复。散射特性的变化主要由心内膜下心肌散射特性的变化所致，心外膜下心肌的散射特性无明显变化。室壁增厚率在实验过程中无明显变化。结果说明超声背向散射积分联机分析简便、准确、可定量反映心肌病理结构和功能的细微改变，比室壁运动观察更客观、更敏感，可望为冠心病的早期诊断提供一个新方法     

背向散射积分、组织多普勒与核素扫描对心肌缺血和存活的相关性临床研究

目的:进一步探讨组织多普勒和组织定征技术临床应用的可行性。方法:12例超声发现节段性室壁运动失常患者分别进行多巴酚丁胺负荷超声心动图、超声组织多普勒、背向散射积分及核素扫描检查。结果:有收缩储备节段背向散射积分曲线形态评分较无收缩储备节段明显降低,背向散射积分周期变异幅度(CVIB)、T波顶点时心内膜运动速度(Vendo)、心肌中部心动周期中最大运动速度(TVC)、收缩期心肌运动速度峰值跨壁梯度(MVGm+)及放射性核素摄取率均较无收缩储备节段显著增高,有收缩储备节段背向散射积分平均值(AII)与无收缩储备节段的差别无显著性。心肌收缩期运动指标与CVIB正相关,与AII负相关。放射性核素摄取率与TVC、Vendo、MVGm+正相关,与AII负相关,与CVIB相关呈临界状态。结论:背向散射积分和组织多普勒指标在判断心肌缺血与存活的临床应用方面有很大潜力。     

心肌组织背向散射积分及回声强度与心肌纤维走行的关系

目的　探讨心肌组织超声背向散射积分及回声强度与心肌纤维走行的关系。方法　 16只犬 ,随机分为 2组 ,静脉注射高钾、高钙溶液 ,使心脏分别停搏于舒张、收缩状态 ,取胸骨旁乳头肌短轴观方位左心室前壁心肌立方体组织块 ,分别从该组织块垂直矢状切面、垂直冠状切面及侧冠状切面采集超声射频、视频图像 ,用HP5 5 0 0型超声诊断仪声学密度定量 (AD)技术和“DFY型超声图像定量分析诊断仪” ,获得感兴趣区超声背向散射积分 (IBS)及回声强度 (EI)值 ,切取相应位置心肌组织行光镜观察。结果　收缩、舒张状态侧冠状切面心肌中层与垂直矢状切面及垂直冠状切面心肌中层比较 ,其IBS、EI值的差异均具有显著性意义 (均P <0 .0 5 )。病理检查结果可见与胸骨旁乳头肌短轴观相对应切片心肌中层为环行肌纤维纵截面 ;与之相垂直面切片心肌中层为环行肌纤维横截面。中层心肌走行方向在垂直矢状切面、垂直冠状切面与入射声波垂直 ,在侧冠状切面与之平行。结论　心肌组织IBS、EI值与心肌纤维走行方向密切相关。超声束与心肌纤维垂直时IBS、EI值最大 ,平行时最小 ,均表现为各向异性     

超声组织定征对犬顿抑心肌的实验研究

目的 探讨超声背向散射积分组织技术检测顿抑心肌的价值。方法 HP5500型彩超仪及S8探头,各项设置在试验中保持一致,杂种犬19种,麻醉后开胸,结扎冠状动脉左前降支近端,15min后再灌注,检测基础状态、结扎15min、再灌注后 心肌的平均背向散射积分值、背向散射积分周期变化幅度、室壁增厚率的变化。结果 结扎15min后,平均背向散射积分值增加,周期变化幅度次之,室壁增厚率的恢复最慢,结论 超声背向散射积分值增加,周期变化幅度减小或消失。心肌的增厚率明显降低,再灌注后,上述各项指标逐渐恢复,平均背向散射积分值恢复最快,周期变化幅度次之,室壁增厚率的恢复最慢。结论 超声背向散射组织定征技术能早期、快速、准确地检测顿抑心肌。     

儿童扩张型心肌病的心肌超声背向散射参数研究

目的研究儿童扩张型心肌病心肌超声背向散射参数特点。方法采用超声背向散射积分技术,对20例扩张型心肌病（DCM）患儿及20例健康儿童,于左室长轴观采集室问隔中部及左室后壁心肌背向散射积分数据,包括校正平均背向散射积分（AⅡ％）和背向散射积分周期变化幅度（CVIB）。同时采集常规M型超声参数,并于心腔四腔观及五腔观,行脉冲多勒超声检查获得二尖瓣口和左室流出道血流图,计算左室Ri指数。结果与对照组比较,DCM组左室舒张末内径、收缩末内径、Tei指数、左室后壁AⅡ％增大（P〈0．01）,室间隔、左室后壁CVIB减低（P〈0．01）,背向散射积分曲线形态异常。DCM患儿心肌背向散射参数与左室Tei指数之间无相关性（P〉0．05）。结论扩张型心肌病儿童心肌背向散射参数变化特征：AⅡ％升高、CVIB下降、IBS曲线形态异常;左室Ri指数明显增高,心脏整体功能下降。     

背向散射积分超声组织定征识别存活心肌的实验

目的探讨背向散射积分检测技术识别存活心肌的敏感性和准确性。方法应用商品化的背向散射积分联机分析处理系统检测活体开胸犬重度缺血、晕厥和梗死心肌模型的标化背向散射积分（ＩＢＳ）、标化背向散射积分周期变异（ＣＶＩＢ）及室壁增厚率。结果重度缺血心肌ＩＢＳ明显增高,ＣＶＩＢ明显减低。再灌注后ＣＶＩＢ的恢复幅度高于室壁增厚率。晕厥心肌的ＩＢＳ和ＣＶＩＢ基本正常,但室壁增厚率明显减低。梗死心肌的ＩＢＳ明显增高,ＣＶＩＢ消失或呈反相,再灌注后无改善。结论背向散射积分超声组织定征能敏感反映不同程度缺血心肌的散射特性变化,为无创判定心肌存活性和评价心肌功能提供了一个新的技术手段     

超声心动图肾移植术后心脏变化的分析

目的：进一步确定尿毒症患肾移植术后对心脏结构及心功能的影响，以及声学自动边缘检测技术（AQi）、组织声学密度度量技术（AD）在本病的诊断价值。方法：对6例患进行术前和术后的对比，观察内容：血压、血生化指标，心脏结构、收缩与舒张功能，不同部位的AD指标－背向散射积分（IBS）。结果：多数指标都有改善。以左室后壁（LVPW），主动脉内径（AORD）、舒张期、收缩期左室心肌重量指数（LVMdI、LVMsI)，左室后壁的背向散射积分舒末与收末强度差（PPLL）等较为明显。结论：肾移植术后对心脏结构及心功能指标都有改善。     

Quantification of the myocardial velocity gradient and myocardial wall thickening velocity in healthy children: a new indicator of regional myocardial wall motion.

Doppler tissue imaging allows the measurement of tissue motion velocity in real time. However, tissue velocities are affected by translational motion and by the angle of Doppler interrogation. The myocardial velocity gradient and myocardial wall thickening velocity, determined by color Doppler tissue imaging, can be used to evaluate regional wall thickening and thinning motion independent of translational motion. To determine the control values for myocardial velocity gradient and myocardial wall thickening velocity for the interventricular septum and posterior wall, we studied 120 healthy children (mean age: 7.8 +/- 5.0 years). Peak values of myocardial velocity gradient and myocardial wall thickening velocity at each cardiac phase were measured: systole, early diastole, and atrial contraction. The peak values of myocardial velocity gradient and myocardial wall thickening velocity were higher in the posterior wall than those in the interventricular septum, suggesting that thickening and thinning are more dynamic in the posterior wall. Linear regression analysis demonstrated that absolute values of myocardial velocity gradient at systole, early diastole, and atrial contraction, and wall thickening velocity at atrial contraction decreased with body surface area (BSA). On the other hand, absolute values of myocardial wall thickening velocity at systole and early diastole increased with BSA, and myocardial wall thickening velocity at early diastole in interventricular septum did not change. Myocardial velocity gradient at systole and early diastole, and myocardial wall thickening velocity at systole were strongly related to BSA. In contrast, myocardial velocity gradient and myocardial wall thickening velocity at atrial contraction strongly correlated with time interval between 2 consecutive QRS complexes. Because myocardial wall thickening velocity at early diastole in the interventricular septum did not correlate with BSA or time interval between 2 consecutive QRS complexes, it might evaluate diastolic function of interventricular septum independent of body size or heart rate.     

Potential relationships among myocardial stiffness, the measured level of myocardial backscatter ("image brightness"), and the magnitude of the systematic variation of backscatter (cyclic variation) over the heart cycle.

BACKGROUND: In a number of recently published studies comparing measurements from patients with those from control subjects, a decreased magnitude of the systematic variation of backscattered energy over the heart cycle (cyclic variation) is accompanied by an increased level of overall myocardial backscatter (calibrated myocardial image brightness) when measured at a specific phase of the heart cycle (eg, end systole or end diastole). The goal of this study was to investigate whether this observation is consistent with predictions based on a model of the mechanisms of cyclic variation incorporating changes in relative intracellular and extracellular acoustic impedance over the heart cycle. METHODS: A previously described 3-component Maxwell-type model of muscle mechanics representing cardiac cell mechanical behavior was utilized to predict the systematic variation in the relative acoustic impedance differences between intracellular and extracellular elastic properties over the heart cycle and hence the observed magnitude of cyclic variation and overall myocardial scattering level. Predictions were obtained for a series of specific values of relative intracellular and extracellular acoustic impedance. RESULTS: Results indicate that the predicted magnitude of cyclic variation can be directly related to the overall myocardial backscatter level. For example, specific changes in the acoustic impedance (stiffness properties) of the extracellular matrix without any change in the intracellular acoustic impedance result in predicted values of -43.5 dB, -38.5 dB, and -33.5 dB for end-diastolic myocardial backscatter levels with corresponding values of 5.0 dB, 2.5 dB, and 1.3 dB for the predicted magnitude of cyclic variation, respectively. CONCLUSION: This study suggests that observed decreases in the magnitude of cyclic variation with concomitant increases in the measured overall myocardial backscatter level are consistent with predictions from a model based on the relative acoustic impedance differences between intracellular and extracellular elastic properties over the heart cycle. These results suggest that ultrasonic backscatter measurements may provide a noninvasive approach for assessing some relationships among myocardial stiffness, degree of fibrosis, and contractile performance.     

压力对心腔内造影剂微气泡后向散射强度的影响

目的与方法：本研究应用声学密度法在体外搏动心脏模型中定量分析压力对声振白蛋白微气泡后向散射强度的影响,并观察正常人体心腔内双氧水微气泡后向散射强度在心动周期中的变化规律。结果：Ａｌｂｕｎｅｘ声振白蛋白微气泡在心腔内压力的作用下,其大小可发生可逆性变化,而这种变化可相应地引起后向散射强度可逆的周期性变化。舒张末期和收缩末期后向散射强度之差与造影剂浓度无关,而与收缩末期压力高低密切相关。在初步的人体研究中,我们也观察到了同样的心腔内造影剂后向散射强度的变化规律。结论：有可能通过应用声学密度法观察心腔内造影剂微气泡后向散射强度变化、无创性估计心腔内压力。     

Noncompressibility of myocardium during systole with freehand three-dimensional echocardiography

BACKGROUND: Measures of ventricular performance, such as the ejection fraction, assume that myocardium is noncompressible and does not change volume significantly from end diastole to end systole. Although this principle is widely accepted as true, little data exist in the literature to support it. Freehand 3-dimensional (3D) echocardiography has previously been shown to be highly accurate for measurement of myocardial mass and volume. Therefore, we hypothesized that it has sufficient accuracy to test the validity of this assumption. We measured myocardial volume at end diastole and end systole in 2 groups of subjects with hypertrophy. METHODS: Forty-one healthy young adult athletes and 17 adult patients with hypertension, hypertrophy, normal ejection fraction, and heart failure symptoms underwent examination with freehand 3D echocardiography. Endocardial and epicardial surfaces at end diastole and end systole were reconstructed, and their volumes were computed. From these surface volumes, myocardial volume at end diastole and end systole and epicardial stroke volume and endocardial stroke volume were calculated. These volumes were compared with the 2 sample paired t test. RESULTS: Myocardial volume was constant from diastole to systole (174.7 +/- 45.3 mL versus 174.6 +/- 45.8 mL; P = not significant), and endocardial and epicardial stroke volumes were identical (76.0 +/- 17.4 mL versus 76.0 +/- 17.1 mL; P = not significant). The average absolute difference between the end-diastolic and end-systolic myocardial volumes was 1.9 mL, or less than 1.1% of end-diastolic volume. CONCLUSION: Myocardial volume measured with freehand 3D echocardiography does not change significantly during systole. Myocardial volume may be considered noncompressible for purposes of measurement of ventricular function with freehand 3D echocardiography. Comparison of end-diastolic and end-systolic myocardial volumes may be used for quality assurance in performing 3D reconstructions.     

血流对组织背向散射强度的影响

目的　探讨心脏灌注压、血液浓度和血流速度对组织背向散射强度的影响。方法　以 0～ 2 0 0mmHg 的压力用全血和代血浆分别灌注 40只中国本兔的离体心脏 ,测定心肌背向散射积分值。检测 3 0例正常人左右颈总动脉和颈内静脉腔内的背向散射积分 ,并与血流速度进行相关分析。结果　全血和代血浆灌注离体心脏 ,心肌背向散射积分的测值均随着灌注压的升高而逐渐增大 ,在较低压力阶段 (0～ 60mmHg)心肌背向散射积分随灌注压升高而明显增大 ,但在较高的压力阶段增高的趋势逐渐减小。在各种不同的压力下 ,用全血灌注时心肌背向散射积分均高于用代血浆灌注时的测值。颈总动脉和颈内静脉血流的平均背向散射积分相近[(9.5± 1.8)dBvs (9.9± 1.5 )dB ,P =0 .3 5 ] ,和血流速度无关 (相关系数为 0 .0 71)。结论　血液浓度和灌注压对心肌的背向散射积分值有一定的影响 ,但血流速度对组织背向散射强度无明显的影响。     

Anisotropy of apparent backscatter in the short-axis view of mouse hearts

The goals of this investigation were to measure the anisotropy of backscattered ultrasound observed in the short-axis view of mouse hearts in systole and diastole and to compare these measurements with predictions from a computer simulation. Measurements of midmyocardial apparent backscatter were obtained from analyses of the hearts of seven wild-type mice using a clinical imaging system utilizing a linear array with a nominal center frequency of 13 MHz. A computer model simulating the short-axis view was implemented based on previous measurements of the angle of insonification dependence of myocardial backscatter and attenuation. Results demonstrate that the measured backscatter was largest for those myocardial regions corresponding to approximately perpendicular insonification relative to the myofibers and the smallest for regions of approximately parallel insonification, with the minimum to maximum values of apparent backscatter differing by approximately 10 dB. The measured anisotropy of backscatter was similar for end-systole and end-diastole and was in good agreement with the predicted anisotropy obtained from the computer simulations. (E-mail: mrh@wuphys.wustl.edu)     

Cyclic variation in ultrasonic myocardial integrated backscatter is due to phasic changes in the number of patent myocardial microvessels.

OBJECTIVE: We tested the hypothesis that the cyclic variation in ultrasonic myocardial integrated backscatter (IBS) is due to cardiac contraction-induced changes in the number of patent myocardial microvessels. METHODS: We performed experiments in open-chest dogs in which we increased the number of patent myocardial microvessels without changing cardiac contraction. We achieved this either by direct intracoronary administration of adenosine (group 1; n = 10) or by producing a noncritical coronary stenosis (group 2; n = 7). RESULTS: At baseline, IBS was lowest in systole and highest in diastole. This cyclic variation in IBS was closely associated with the phasic changes in myocardial blood volume that were measured with myocardial contrast echocardiography. During adenosine administration, the diastolic IBS increased from -18.8 +/- 6.5 to -17.5 +/- 6.1 dB (P = .002), with an associated increase in the difference between the systolic and diastolic IBS from 3.8 +/- 1.1 to 4.6 +/- 1.0 dB (P = .009). After a noncritical stenosis was produced, diastolic IBS also increased from -26.6 +/- 8.3 to -25.2 +/- 7.3 dB (P = .001), with an associated increase in the difference between the systolic and diastolic IBS from 3.7 +/- 1.2 to 5.0 +/- 1.0 dB (P = .02). No change in IBS was noted in the bed that did not receive adenosine or the bed that had a stenosis. CONCLUSIONS: The variation in IBS during the cardiac cycle is closely associated with the phasic changes in myocardial blood volume seen during cardiac contraction. When the number of patent myocardial arterioles is increased via adenosine or placement of a noncritical stenosis, diastolic IBS increases with a concomitant increase in IBS cyclic variation. These results may have important clinical applications for the noninvasive diagnosis of noncritical coronary stenosis at rest.     

CK技术判断顿抑心肌程度的实验研究

目的：本研究旨在评价彩色室壁动力分析（ＣｏｌｏｒＫｉｎｅｓｉｓ，简称ＣＫ）技术判断顿抑心肌程度的价值。建立８条犬心肌顿抑模型，根据冠状动脉结扎时间的不同将其分为两组。超声检查结果与核素心肌灌注显像和病理检查比较。发现（１）比较心肌顿抑节段３０和６０分钟时收缩期和舒张期心内膜ＣＫ彩色宽度，并分别与非缺血心肌节段心内膜ＣＫ宽度比较，差别均有显著性意义（ｐ均＜００１）。（２）比较冠状动脉结扎３０和６０分钟ＳＰＥＣＴ收缩和舒张期缺血心肌区内放射性计数与峰计数的比值，并分别与３０和６０分钟心肌顿抑节段收缩期和舒张期心内膜ＣＫ色带宽度进行比较，发现其高度相关（ｐ均＝０００１）。本研究表明ＣＫ的色带宽度可以反映短暂心肌缺血再灌注后心肌顿抑的程度，心肌缺血的时间越长心肌顿抑的程度越重，可能为预测心肌顿抑的持续时间提供依据     

Alterations in ultrasonic backscatter during intra-aortic balloon counterpulsation support in patients with acute myocardial infarction

Alterations of ultrasonic backscatter parameters have been evident in humans with myocardial infarction or ischemia. The backscatter variability could be restored in ischemic or stunned myocardium after reperfusion. The aims of this study were to determinate changes in regional myocardial ultrasonic backscatter during intra-aortic balloon counterpulsation (IABP) support in patients with acute myocardial infarction (AMI), and to evaluate whether backscatter imaging could be a functional guide of IABP support. A total of 9 patients with AMI were investigated during IABP support with a two-dimensional (2-D) ultrasonic backscatter imaging approach for parasternal short-axis view. Coronary angiography was performed in 6 of the 9 patients. A total of 21 vessel territories were studied in different modes of IABP support: 1:1, 1:2 and standby. Restoration of cyclic variation of backscatter after IABP support was demonstrated in 10 vessel territories. Failure of restoration of cyclic variation of backscatter after IABP support was noted in 6 vessel territories with severe coronary lesions (total or nearly total occlusion) or scar tissue. No changes of the ultrasonic backscatter were found in nonischemic vessel territories with patent coronary arteries or TIMI III coronary flow. In addition, the wall motion score did not change significantly with different IABP support. These results suggest that IABP could restore the cyclic variation of backscatter in ischemic myocardium. Myocardial anisotropy may play an influential role in the alterations of ultrasonic backscatter. We propose that ultrasonic backscatter could be a noninvasively functional guide of IABP use in patients with AMI.     

Mean Myocardial Velocity Mapping in Quantifying Regional Myocardial Contractile Reserve in Patients with Impaired Left Ventricular Systolic Function: Doppler Myocardial Imaging Study

The aim of this study was to use Doppler myocardial imaging–derived mean myocardial velocity (MMV) at baseline and during low-dose dobutamine stress echocardiography (DSE) to quantify regional contractile reserve of the left ventricle (LV). Sixteen patients (mean age 59 ± 7 years) with coronary artery disease and regional left ventricular wall motion abnormalities were studied. During each increment of Dobutamine infusion, 6 2-dimensional transthoracic apical images were acquired in standard gray-scale and Doppler myocardial imaging modes at 30° steps over 180°. For the analysis, the LV was divided into 18 segments. For each segment, both wall motion score and MMV obtained in systole and both early and late diastole were measured at baseline and at each stage of DSE. In viable segments by wall motion score, MMV increased during DSE in systole and in early and late diastole. In contrast, in nonviable segments, MMV did not change during DSE. Mean myocardial velocity mapping is a promising new approach to quantify regional myocardial contractile reserve of the LV. (J Am Soc Echocardiogr 2000;13:96-107.)