The relative contributions of myocardial wall thickness and ischemia to ultrasonic myocardial integrated backscatter during experimental ischemia

The purpose of this study was to assess the empirical relationship between myocardial integrated backscatter (IB) and myocardial wall thickness (WT) in normal myocardium. A second object was to estimate the additional contribution to acute ischemic integrated backscatter levels given this relationship. Myocardial IB measurements and simultaneous myocardial WT measurements were made in 16 open-chested pigs with intact coronary circulation (normal myocardium) and 10 min after the flow in the left anterior descending coronary artery had been reduced to 20% of its baseline value (ischemic myocardium). Measurements were made 50 times during one cardiac cycle and averaged over 10 cardiac cycles. IB and WT measurements were normalized with respect to the nonischemic end-diastolic values. The relationship between IB and WT in normal myocardium was estimated in every individual pig by simple linear regression. Estimates of IB during ischemia were calculated on the basis of this relationship and the ischemic WT measurements. Differences of the estimator and the actual measurement made during ischemia depict the actual contribution of the state of acute ischemia, without the influence of WT. The slope of the relationship between IB and WT during normal myocardial contraction ranged from -0.16 to 0.03 dB/% (mean = -0.036 dB/%, SD = 0.06 dB/%). The additional contribution of ischemia ranged from -3.84 to 5.56 dB (mean = 0.31 dB, SD = 2.72 dB). It was concluded that the average contribution of ischemia to IB measurements is insignificant if the IB dependency on WT is removed from the data and that the higher level of ischemic IB measurements can be explained by the decrease in wall thickness during ischemia and not by the ischemia itself.     

Ultrasonic analysis of anthracycline-induced myocardial damage using cyclic variation of integrated backscatter.

To test the feasibility of integrated backscatter (IB) for detecting anthracycline cardiotoxicity, we performed conventional echocardiography and IB analysis. For interindividual comparison, 32 patients with non-Hodgkin's lymphoma and 14 control subjects were selected. Of the patients, 10 had been treated with doxorubicin doses of 400 mg/m(2) (high dose). In intraindividual comparison, 8 patients were examined before doxorubicin therapy and at a dose of 100 mg/m(2) and 8 were examined before and at a 300-mg/m(2) dose. Cyclic variation of IB (CV-IB) was obtained at the left ventricular posterior wall, using a modified, commercially available system in M-mode format. In interindividual comparison, CV-IB in high- and moderate-dose groups was smaller. In intraindividual comparison, CV-IB decreased after treatment with 300 mg/m(2) of doxorubicin. CV-IB was affected in some patients treated with a moderate dose of doxorubicin. IB analysis may be helpful for detecting early anthracycline cardiotoxicity.     

Ultrasonic tissue characterization with integrated backscatter during inotropic stimulation

Ultrasonic tissue characterization with integrated backscatter is an objective method to quantitatively define the physical state of the myocardium. To determine if backscatter imaging during inotropic stimulation could be used objectively to determine the myocardial viability and ischemia in patients with ischemic heart disease, the backscatter changes were examined in 23 patients with myocardial infarction during dobutamine stress two-dimensional (2-D) echocardiography. Coronary angiography was performed within 1 to 2 days after the stress test. The results of this study demonstrated that changes in backscatter variability correlated significantly with the wall motion changes in stress echocardiography during dobutamine infusion (p < 0.0001). In addition, it was shown that the backscatter changes were significantly different in various types of myocardial tissue. In 23 healthy control segments, the ultrasonic backscatter variability was preserved and unchanged during inotropic stimulation (p = NS). In 15 viable infarct zones, restoration or an increase in backscatter variability during low-dose dobutamine infusion was noted, this being lost when ischemia developing during high-dose dobutamine infusion (p < 0.01). In 9 nonviable infarct zones, the phase-weighted variation was usually ≤ 0 and did not change significantly during inotropic stimulation, regardless of the patency of the infarct-related arteries. In 15 remote ischemic myocardial zones, the backscatter variability was preserved at the baseline level, did not change during low-dose dobutamine infusion, but decreased significantly during high-dose dobutamine stress (p < 0.01). In conclusion, dobutamine stress tissue characterization could offer an objective approach for the detection of myocardial viability and ischemia, and might be a useful adjunct to the conventional stress echocardiography.     

Robustness of integrated backscatter for myocardial tissue characterization

Integrated backscatter (IB) has been used for ultrasonic tissue characterization. To assess the potential variables in IB measurements, we performed both theoretical simulations and in vitro phantom measurements. First, we simulated data in which the scatterer position randomly was varied. IB values for the resulting images were calculated. Second, RF data from a tissue-mimicking phantom were acquired. Third, an adapted imaging approach, based on phase insensitivity, was evaluated. For both the simulations and phantom measurements, IB showed a standard deviation of +/-20%. These large deviations can be explained by variations in interference of signals and are not related to the state of the tissue. Small deviations in position of the scatterers resulted in important variations in IB. They must be taken into account and may limit the use of IB in cardiological applications. An improvement potentially can be obtained using phase insensitivity in new ultrasound processing schemes.     

Effect of preload reduction on sonographic myocardial integrated backscatter

PURPOSE: Sonographic myocardial tissue characterization with integrated backscatter (IBS) is affected by both structural and functional properties of the myocardium. The aim of the present study was to investigate the effect of preload reduction by hemodialysis (HD) on IBS measurements. METHODS: Fifty-two patients on maintenance HD underwent echocardiography before and after a routine HD session. Measurements included the variation of IBS during the cardiac cycle (CV-IBS) and calibrated IBS (cal-IBS). RESULTS: After HD, there were significant reductions in left ventricular end-diastolic and end-systolic dimensions and left atrial diameter. There was a reduction in stroke volume and LV ejection fraction consistent with a reduction in preload. Furthermore, CV-IBS was significantly lower after HD (7.9 +/- 2.2 versus 6.9 +/- 1.8 dB, 7.0 +/- 2.1 versus 6.2 +/- 1.9 dB, and 9.0 +/- 2.6 versus 8.1 +/- 2.0 dB [p < 0.01], respectively, in the left anterior, lateral, and inferior wall of the ventricle). Cal-IBS remained unchanged after dialysis compared with baseline. CV-IBS and ultrafiltration volume were significantly correlated. CONCLUSION: HD leads to a decrease in CV-IBS that appears to be preload-dependent. This finding is in concordance with diminished left ventricular performance during HD.     

A relationship between ultrasonic integrated backscatter and myocardial contractile function.

We have shown previously that the physiologic, mechanical cardiac cycle is associated with a parallel, cardiac cycle-dependent variation of integrated backscatter (IB). However, the mechanisms responsible are not known. The mathematical and physiological considerations explored in the present study suggest that the relationship between backscatter and myocardial contractile function reflects cyclic alterations in myofibrillar elastic parameters, with the juxtaposition of intracellular and extracellular elastic elements that have different intrinsic acoustic impedances providing an appropriately sized scattering interface at the cellular level. Cardiac cycle-dependent changes in the degree of local acoustic impedance mismatch therefore may elicit concomitant changes in backscatter. Because acoustic impedance is determined partly by elastic modulus, changes in local elastic moduli resulting from the non-Hookian behavior of myocardial elastic elements exposed to stretch may alter the extent of impedance mismatch. When cardiac cell mechanical behavior is represented by a three-component Maxwell-type model of muscle mechanics, the systolic decrease in IB that we have observed experimentally is predicted. Our prior observations of regional intramural differences in IB and the dependence of IB on global contractile function are accounted for as well. When the model is tested experimentally by assessing its ability to predict the regional and global behavior of backscatter in response to passive left ventricular distention, good concordance is observed.     

全心尖切面心肌背向散射积分参数评价心肌缺血

目的探讨全心尖切面心肌背向散射积分参数评价心肌缺血的可靠性。方法分析22例冠心病(CAD)患者和18例冠状动脉定量造影(QCA)正常患者的全心尖切面心肌所测左室16个节段背向散射积分参数，分别比较cAD组中室壁运动异常节段心肌、室壁运动正常节段心肌及对照组心肌的CVIB、CVIB％及AII％值。结果CAD组中室壁运动异常节段心肌CVIB、CVIB％值均显著低于后二者，而AII％值则显著高于后二者。结论全心尖切面所测左室16个节段背向散射积分参数能够敏感、客观并比较全面地反映心肌缺血情况。     

全心尖切面心肌背向散射积分参数评价心肌缺血

目的探讨全心尖切面心肌背向散射积分参数评价心肌缺血的可靠性.方法分析22例冠心病(CAD)患者和18例冠状动脉定量造影(QCA)正常患者的全心尖切面心肌所测左室16个节段背向散射积分参数,分别比较CAD组中室壁运动异常节段心肌、室壁运动正常节段心肌及对照组心肌的CVIB、CVIB%及AII%值.结果 CAD组中室壁运动异常节段心肌CVIB、CVIB%值均显著低于后二者,而AII%值则显著高于后二者.结论全心尖切面所测左室16个节段背向散射积分参数能够敏感、客观并比较全面地反映心肌缺血情况.     

多巴酚丁胺负荷超声心动图与背向散射积分对陈旧性心肌梗死患者心肌存活性的研究

目的：探讨小剂量多巴酚丁胺负荷超声心动图与背向散射技术评估陈旧性心肌梗死患者的心肌存活性。方法：分别测量28例心肌梗死患者在不同负荷阶段时(注药剂量分别为0，5，10，20μg.kg^-1.min^-1)，胸骨旁左心室乳头肌水平短轴观的4个节段(前室间隔、前壁、后壁和下壁)的背向散射积分周期变异(CVIB)和标化背向散射积分周期变异(CVIB％)，并在冠状动脉重建术后随访常规超声心动图。结果：非心肌梗死组及非存活心肌组的CVIB和CVIB％在小剂量多巴酚丁胺负荷过程中无显著变化，而存活心肌组CVIB和CVIB％均在5—10μg.kg^-1.min^-1时增加并保持较高水平至负荷终点。结论：陈旧性心肌梗死患者的心肌背向散射积分参数在小剂量多巴酚丁胺负荷状态下呈现出有意义的改变，两种方法的结合可用于定量检测存活心肌。     

超声背向散射积分评估肝脏肿瘤的消融治疗疗效

目的探讨超声背向散射积分(IBS)在肝癌射频或微波消融治疗疗效评价中的应用价值。方法43个肝脏肿瘤病灶,在微波或射频消融治疗前后,分别测定肿瘤及消融区的IBS值,比较治疗前后的IBS值变化,并以增强CT/MRI检查作为对照。结果肿瘤消融后IBS值明显大于消融前,与增强CT/MRI确定的范围有良好的相关性。结论通过观察IBS值的变化,超声背向散射积分为肝脏肿瘤消融治疗疗效评估提供了一种无创的量化检查方法。     

高血压左心室重构心肌背向散射积分的定量分析

目的：探讨不同左心室构型心肌背向散射参数变化评价高血压病的价值。方法：根据左心室质量指数和相对室壁厚度将原发性高血压患者146例分成4组，左心室正常组（组1），向心性重构组（组2），向心性肥厚组（组3）和离心性肥厚组（组4），正常对照组32人，测量和分析各组室间隔（IVS）及后壁（PW）心肌背向散射积分（IBS），校正IBS（IBS％），IBS周期变化（CVIB）及跨壁梯度（TGIB），结果：IBS％，IVS及PW部位，以组3为最高，其次为组2，组4，组1最小（P＜0．01），CVIB：IVS及PW以组3最低，其次为组4，组2，组1最大（P＜0．05），左心室后壁组3和组2内存在TGIB（P＜0．05），结论：高血压向心性肥厚组背向散射参数变化与临床观察到的该组患者各种风险最高的结论相一致。应用背向散射积分技术可以定量评价高血压心肌病变严重程度。     

心肌收缩力对心肌背向散射积分及其周期性变化幅度的影响

目的　观察犬在正常状态和心肌收缩力发生变化时心肌背向散射积分平均值 (AII)及其随心动周期变化幅度 (CVIB)的改变 ,探讨AII及CVIB的变化规律。方法　选用成年杂种犬 7只 ,麻醉后分别在静脉注射多巴酚丁胺和心得安前后获取室间隔基底部及左室后壁心肌组织的心肌背向散射积分 (IBS)变化曲线图 ,同时测出AII和CVIB。结果　在静脉注射多巴酚丁胺和心得安前后 ,室间隔基底部和左室后壁心肌AII均无明显改变 (P >0 .0 5 ) ;静脉注射多巴酚丁胺后 ,其CVIB比用药前明显升高 (室间隔基底部 :9.5± 0 .6vs 6.8± 0 .3 ,P <0 .0 0 1;左室后壁 :10 .9± 0 .7vs 8.5± 0 .3 ,P <0 .0 0 1) ;静脉注射心得安后 ,其CVIB比用药前明显降低 (室间隔基底部 :5 .2±0 .3vs 7.1± 0 .2 ,P <0 .0 0 1;左室后壁 :6.3± 0 .6vs 8.6± 0 .3 ,P <0 .0 0 1)。结论　AII和CVIB的变化有着不同的组织学和生理学基础。心肌收缩力的改变并不影响AII ,却能使CVIB发生明显变化。当心肌收缩力增强时 ,CVIB明显升高 ;当心肌收缩力减弱时 ,CVIB明显降低。CVIB值的变化与心肌收缩力有关     

心肌背向散射积分参数评价存活心肌的临床研究

目的探讨心肌背向散射积分参数评估缺血后存活心肌的临床价值.方法应用二维超声心动图(2-DE)及背向散射联机分析技术,观测31例陈旧性前间壁心肌梗死患者血管重建术前后前间隔心肌节段运动状态、标化背向散射积分(%AII)、背向散射周期变异幅度(CVIB).结果血管重建术后,62个心肌节段中,45个节段有存活心肌,17个节段无存活心肌.与术前比较,术后45个有存活心肌节段的%AII明显降低(1.6±0.3vs2.3±0.5,P＜0.01),CVIB明显增高(7.2±1.1vs3.4±1.2,P＜0.01).术后有存活心肌节段的%AII及CVIB与无存活心肌节段差异存在显著性意义(均P＜0.05).结论IBS两个参数,即%AII和CVIB,可以区分存活心肌和非存活心肌,能检测梗死区存活心肌.     

背向散射积分对心肌梗死患者心室血液状态的定量分析

目的探讨背向散射积分(IBS)技术定量评价心肌梗死患者心室血液状态的价值及其与血栓形成的关系.方法采用超声IBS技术检测29例正常人(A组)及76例心肌梗死患者,分为心肌梗死组(B组,32例)、心肌梗死合并室壁瘤组(C组,23例)、心肌梗死合并左心室血栓组(D组,21例)的左心室、右心室血液IBS值及心尖部心包IBS值,并计算左心室及右心室的血液IBS值与心尖部心包IBS的比值,即心室血液的校正IBS(IBS%),并进行组间比较.结果心肌梗死时左心室血液IBS%值较正常组增高(P＜0.05),且B、C及D组IBS%值呈逐渐增高趋势.以左心室血液IBS%＞23判断有无左心室血栓的敏感性、特异性、准确性分别为71.4%、89.3%、85.7%.结论IBS技术可以评价心肌梗死患者心室的血液状态,有可能成为早期预测心脏血栓形成的检测方法.     

陈旧性心肌梗死患者心肌背向散射积分参数的临床研究

目的　探讨心肌背向散射积分 (IBS)参数评估陈旧性心肌梗死患者心肌病变的价值及其与局部心肌收缩功能的关系。方法　应用背向散射联机分析及彩色室壁运动技术 ,观测 2 1例陈旧性前间壁心肌梗死患者及 2 7例正常人前间隔标化平均背向散射积分 ( %AII)、背向散射积分周期变异幅度 (CVIB)、室壁增厚率(WT % )及心内膜位移速度 (Vsem)。结果　与正常人相比 ,心肌梗死患者的 %AII明显增加 ( 2 .3± 0 .3vs 1.6±0 .2 ,P <0 .0 1) ,CVIB明显减低 ( 3 .5± 1.6vs 7.9± 1.3 ,P <0 .0 1)。CVIB与反映局部心肌收缩功能的两个指标 (WT %及Vsem )均呈高度相关 (r分别为 0 .77和 0 .81,均P <0 .0 1) ,%AII与WT %及Vsem呈一定程度相关 (r分别为 -0 .5 5和 -0 .64 ,均P <0 .0 1)。结论　 %AII和CVIB可以区分正常心肌和梗死区心肌 ,并能反映局部心肌收缩功能 ,具有评估心肌存活性的潜力。     

Cardiac cycle-dependent variation of integrated backscatter is not distorted by abnormal myocardial wall motion in human subjects with paradoxical septal motion

To define the dependence of cardiac cycle-dependent variation of integrated backscatter on regional myocardial wall motion, 8 children mean age 10.6 +/- 1.3 y with congenital cardiac lesions associated with paradoxical septal motion were studied (study group). Six healthy children mean age 9.0 +/- 0.3 y with no history of cardiac disease served as controls (control group). Subjects in the study group had paradoxical septal motion but normal septal wall thickening detected by conventional two-dimensional and M-mode echocardiography. The control group had normal septal motion evident by conventional echocardiographic criteria. The percentage of systolic septal thickening was 46 +/- 4.5% and 42 +/- 5.9% in the study and control groups (p = NS). Cyclic variation was measured in parasternal long-axis views from several septal sites in each subject. Mean values of the magnitude of cyclic variation from independent septal sites were averaged to yield a regional average value for each subject. The average regional magnitude of cyclic variation was 8.3 +/- 1.0 dB and 5.7 +/- 0.4 dB in the study and control groups (p = NS). The results indicate that the measurement of cyclic variation of integrated backscatter is not distorted by altered regional wall motion, and that it reflects intrinsic contractile function.     

心肌梗死患者背向散射积分变化及临床意义

目的 探讨背向散射积分技术(IBS)定量评价心肌存活和左心室重构的临床应用。方法 记录18例健康志愿者和36例接受经皮冠脉支架置入术的初发急性心肌梗死患者的心尖左心室长轴、心尖四腔和两腔观超声背向散射图像，对比观察正常对照组与心肌梗死患者术后1周内、1个月及3个月时不同室壁节段心肌IBS值及其周期变异幅度(CVIB)的动态变化，并分析其与患者左心室形态及心功能改变之间的关系。结果 无左心室重构的A组，再灌注后1周内梗死与非梗死节段的IBS与正常组差异无显著性意义，梗死节段的CVIB较正常组明显减低；1个月及3个月时，CVIB随心功能恢复而逐渐改善。发生左心室重构的B组，再灌注后1周内梗死节段的IBS较正常组明显增高，梗死与非梗死节段的CVIB均显著减低；1个月及3个月时梗死与非梗死节段IBS均逐渐增高，而CVIB仅非梗死节段恢复。结论 心肌梗死患者的心肌背向散射积分参数与正常对照组明显不同，可作为评价心肌活性、预测左心室重构和心功能恢复程度的客观指标。     

IBS参数及SRI技术综合评价表阿霉素复合化疗药物早期心肌毒性

目的：探讨背向散射积分技术（Integrated backscatter,IBS）及应变率显像技术（Strain rate imaging,SRI）综合评价蒽环类抗肿瘤药表阿霉素（EPI）早期心肌毒性价值。方法：应用Philips iE33型超声诊断仪及其配置的背向散射联机分析软件和应变率成像软件测定30例接受EPI化疗的肿瘤患者于化疗前、达到表阿霉素累积剂量分别为100mg/m2、200mg/m2、300mg/m2 24小时后进行心肌背射参数、组织多普勒应变率成像测定：心肌背向散射积分均值（IBS）、心肌校正的背向散射积分均值（IBS%）、背向散射积分的心动周期变化幅度（CVIB）、背向散射积分周期变异率（CVIB%）和心尖四腔观后间隔应变ε及应变率（Strain rate,SR）。30例组织病理确诊为不同部位肿瘤的患者,准备行表阿霉素为主的化疗。结果：EPI化疗前后心肌IBS均呈周期性变化,但EPI化疗组变化幅度明显减低;EPI化疗组心肌IBS%较对照组明显增高（P<0.05）,CVIB和CVIB%则较对照组明显减低（P<0.05,P<0.01）;与化疗前相比较,当表阿霉素累积剂量200mg/m2时就观察到明显左室收缩功能损害：SR明显下降（1.82±0.57/s vs 1.45±0.44/s）且与SR值呈正相关,而应变ε无明显变化（21.45±5.43% vs 21.15±8.18%）;随后当表阿霉素累积剂量在300mg/m2时,左室舒张功能出现明显改变：二尖瓣舒张早晚期血流速度比值E/A明显下降（1.16±0.36 vs 0.93±0.24）与SR无明显相关,左室射血分数（LVEF）用药前及在整个化疗过程中（累积剂量100~300mg/m2内）均值有所下降,但始终在正常范围内且差异无显著意义。结论：IBS参数测定及SRI技术从结构和功能上可早期（累积剂量为200mg/m2）综合评价EPI心脏毒性,IBS参数的变化不仅反映表阿霉素复合化疗患者的心肌病理改变,还可间接反映局部心肌收缩功能改变。     

扩张型心肌病心肌组织超声背向散射积分特性的临床研究

目的 应用心肌组织超声背向散射积分(IBS)技术研究扩张型心肌病患者的声学特性及临床意义。方法 采用HPSONOS 5500彩色多普勒超声诊断仪配备声学密度定量(AD)分析软件,对比检测20例扩张型心肌病患者和20例正常人胸骨旁长轴观室间隔基底段及后壁、乳头肌水平短轴观中段室间隔及后壁的背向散射信号,获得IBS平均值、IB最大值及CVIB(周期变异率)及曲线形态。其中病例组5例进行复检。结果 扩张型心肌病组各节段的IBS校正平均值、IBS校正最大值均显著高于正常组(P<0.05),CVIB值则低于正常组(P<0.05),曲线形态多数呈不规则类型。5例复检患者中2例随临床症状改善而心肌IBS值较前有所降低、CVIB值有所增高。结论 扩张型心肌病患者的心肌IBS值升高、CVIB值减低、曲线形态异常,提示该病患者心肌间质纤维化增多,心肌收缩力呈某种程度丧失。心肌IBS值与心肌收缩力相关联,经治疗心功能改善者心肌IBS值有所降低、CVIB值有所增高。提示此类患者心肌间质纤维化较轻。     

超声背向散射积分对急性心肌梗死早期诊断的临床研究

目的 研究心肌组织背向散射积分（IBS）及IBS心动周期变化幅度（CVIB）用于临床早期诊断急性心肌梗死的价值。方法 选30例正常人,15例急性心肌梗死患者（24h以内）、15例旧性心肌梗死患者（心肌梗死在3个月以上）,应用HPB5500型超声诊断仪,在胸骨旁左室乳头肌短轴切面,分别测量左心室前间隔,前壁、侧壁,后壁,下壁和后间壁心肌组织的IBS,并将其与心包IBS的比值作为心肌IBS的校正值（IBS％）;舒张末期与收缩末期的IBD差值即CVIB,并将其与心包IBS的比值作为心肌CVIB的校正值（CVIB％）。同时作心电图的比较对照。结果 15例急性心肌梗死患者心肌梗死部位及正常人（21．4vs8．1,21．4vs7,2,均P＜0．001）,而CVIB明显小于非梗死部位及正常人（6．5vs10．16．5vs7．5,均P＜0．001）。与心电图变化一致。陈旧性心肌梗死部位的IBS明显高于急性心肌醒梗死部位（25．6vs2.4,P＜0．05）,CVIB则明显低于急性心肌梗死部位（3．9vs6．5,P＜0．05）。结论 IBS对临床上诊断急性心肌梗死有很高的特异性和敏感性,并可判断病变心肌的范围和功能状况,可作为早期诊断急性心肌梗死的可靠指标。