Myocardial Contrast Echocardiography: Texture Analysis for Identification of Nonperfused versus Perfused Myocardium

This study examined texture analysis for objective identification of nonperfused myocardial segments in myocardial contrast echocardiographic (MCE) images. Short-axis MCE images from six open chest pigs after coronary artery ligation were examined. Six of 26 features (low gray level run emphasis, high gray level run emphasis, sum mean, sum variance, coefficient of variance and diagonal variance) demonstrated a significant texture value difference (P < 0.01) between the nonperfused and perfused segments with minimal statistical distribution overlap between the two groups. This study demonstrates that texture features other than mean gray level can objectively distinguish nonperfused from perfused myocardium in MCE images and may thus augment the diagnostic accuracy of current analysis techniques.     

Tissue characterization with intra-arterial ultrasound: Special promise and problems

Although we are able to identify many tissue types based on the screen image in intravascular ultrasound, there is additional information in the ultrasound signal which could be of assistance in characterization and identification of tissue. Intravascular ultrasound has several special characteristics which affect tissue characterization. These include the high transducer frequency, small transducers, short and relatively uniform path to the tissue, and limited tissue types to identify. These characteristics influence the results obtained by absolute backscatter, local statistics, frequency dependent backscatter, and angle dependency of backscatter. These effects are both positive and negative, and in many cases can be observed in clinical imaging. Another area of tissue characterization which can be performed with ultrasound is measurement of arterial wall elasticity. This can be of importance in the evaluation of mechanisms of dilatation, and the potential for complications.     

Ultrasonic tissue characterization of normal and ischemic myocardium

Cardiac ultrasonic tissue characterization is designed to use the alterations in acoustic signals from the myocardium to differentiate normal from ischemic or infarcted tissue due to their characteristic backscatter attenuation. Various approaches such as use of a gray scale, color display, or quantitative image analysis have been used for tissue characterization, but all depend on subjective assessments and are not necessarily reproducible. The most promising method has been the use of "raw" radiofrequency signals and measure changes in the ultrasonic attenuation with an index of backscatter to distinguish normal from abnormal myocardium called "integrated backscatter" (IB). Various studies have demonstrated the changes in the ultrasonic backscatter with ischemia or infarction. In this review we summarize our experience with a research prototype instrument in tissue characterization and differentiation of normal, ischemic, infarcted, and post ischemic reperfused myocardium in anesthetized open chest dogs. Currently we are investigating the role of ultrasonic tissue characterization to estimate infarct size and plan to apply these observations to patients in order to detect viable myocardium and quantitate infarct size.     

冠状动脉粥样硬化斑块组织定征:血管内超声研究现状

传统血管内超声对斑块仅可定性为软斑块、纤维斑块和钙化斑块,利用射频数据尚可分析反射波或背向散射的频谱参数以确定斑块构成信息.虚拟组织学作为一种新的组织超声分析技术,在射频数据分析的基础上通过彩色编码以不同颜色来区分不同的斑块成分,绿色代表纤维组织,黄色代表纤维脂质,白色代表钙化组织,红色代表坏死组织.血管内超声弹性图是评价局部斑块弹性的新技术,该技术基于组织受压产生变形的弹性原理,可用以检出斑块并评价其破裂趋势或弹性物质构成.     

Incremental Value of Three-Dimensional Echocardiography Over Transesophageal Multiplane Two-Dimensional Echocardiography in Qualitative and Quantitative Assessment of Cardiac Masses and Defects

In the present study, we compared three-dimensionally (3-D) reconstructed images with multiplane two-dimensional (2-D) transesophageal echocardiographic (TEE) images in 17 patients with various cardiac masses and defects. To overcome the problem of making measurements from 3-D reconstructed images, we carefully "dissected" the 3-D dataset using paraplane and anyplane 2-D sections, which were then used to obtain the maximum sizes of the cardiac masses and defects. Of the 15 vegetations and 9 abscesses detected by 3-D TEE in 7 patients, only 8 (53%) vegetations and 4 (44%) abscesses were detected by multiplane 2-D TEE (P < 0.02). Also, the exact anatomical location, shape, geometry, and extent of various cardiac masses and defects were more clearly delineated by 3-D than 2-D TEE. The maximum dimensions of cardiac masses and defects were larger by 3-D than by 2-D TEE in 17 (89%) of the 19 lesions available for comparison (P < 0.002). In addition, 3-D TEE correlated more closely than 2-D TEE when compared to surgical measurements in three patients in whom they were available. Thus, it would appear that in several instances, the exact size of the cardiac lesion could only be assessed by analysis of the 3-D volumetric dataset. Out preliminary study has demonstrated the superiority of transesophageal 3-D reconstruction over multiplane 2-D TEE in both qualitative and quantitative assessment of various cardiac mass lesions and pathological defects.     

Pericardiocentesis Guided by Two-Dimensional Echocardiography

Echodirected pericardiocentesis has become the method of choice for the initial treatment of clinically significant pericardial effusions since it was introduced into the regular practice at the Mayo Medical Center in April 1980. Between April 1980 and January 1, 1994, 610 consecutive two-dimensional (2-D) echodirected pericardiocenteses were performed at the Mayo Clinic. There have been no deaths in the series of consecutive cases. In the first 500 consecutive cases examined in detail, there were five serious complications and 18 nonthreatening complications. Echodirected pericardiocentesis is a safe, humane, and cost-effective means of performing a pericardial tap. Excellent results have been obtained even with a large number of physician operators. This technique is well suited to the primary care setting. Physicians performing this procedure should be familiar with reading and performing 2-D echocardiography. Qualified physicians can be trained, fairly easily, to perform echodirected pericardiocentesis.     

Three-Dimensional Echocardiography for Quantitative Analysis of Left-Ventricular Aneurysm

Background: Quantitative analysis of left-ventricular (LV) aneurysms after myocardial infarction is prognostically relevant and assists in planning surgery. Three-dimensional (3D) echocardiography facilitates clear visualization of cardiac anatomy and accurate assessment of functional parameters. The aim of the present study was to determine the ability of 3D echocardiography to quantify LV aneurysms. Methods: Ten patients with a known LV-aneurysm after myocardial infarction underwent 3D echocardiography and cardiac magnetic resonance (CMR) imaging at 1.5 Tesla within 3 days. For 3D echocardiography, a multiplanar transesophageal examination was performed with full LV coverage and the 3D dataset was analyzed offline. The LV-aneurysm was defined by a wall thickness <5 mm. The following quantitative parameters were determined: left ventricular end-diastolic and end-systolic volumes, LV myocardial mass (LV-mass) and mass of the LV-aneurysm. LV ejection fraction and percentage of aneurysm mass (%-aneurysm) were calculated. Results: LV volumes and ejection fraction showed a strong correlation between 3D echocardiography and CMR (r = 0.94–0.97; P < 0.01). Importantly, the mass and percentage of mass of the LV-aneurysm demonstrated a high correlation as well (r = 0.94 and r = 0.86, respectively; P < 0.01). For all parameters, the calculated bias between both methods was found to be minimal (0.8–7.6%). Conclusions: Three-dimensional echocardiography proved to be a reliable tool for quantitative analysis of LV volumes, ejection fraction and aneurysm size in patients with prior myocardial infarction. In addition, 3D visualization of the complex cardiac anatomy in patients with LV-aneurysm may assist surgical procedure planning. (Echocardiography 2010;27:64-68)     

氟性主动脉硬化症二维超声心动图观察

将46例地方性氟中毒病人分四个年龄组进行超声心动图检查,与氟病区和非氟病区各46名健康人进行对照观察。初步探讨了地方性氟中毒二维超声心动图的改变情况。结果表明:(1)氟病组主动脉壁增厚100％,厚度7.5～9.8mm,增厚呈周围性,其厚度与年龄、病程不相关;(2)氟病组主动脉壁中度以上增强37例(79.8%),对照Ⅰ组中度以上增强4例(8.7%);(3)M超主动脉根部搏动幅度,氟病组小于对照组;(4)氟病组31～40、41～50岁组左室后壁厚度大于对照组,房室腔及其它项目无差异。本组结果提示:地方性氟中毒可致主动脉硬化症,从而明显提早并加重大动脉的硬化为钙化过程,提出了氟性主动脉硬化症。并就其病理生理机制进行了讨论。     

Evaluation of Hemodynamic Determinants of Quantitative Tissue Doppler Echocardiography in the Assessment of Left Ventricular Function

The aim of the present study was to determine whether quantitative tissue Doppler echocardiography has a role in the assessment of left ventricular hemodynamics. Thirty patients with suspected or known heart disease, but no wall motion abnormalities, took part in the study. Quantitative tissue Doppler echocardiography was performed using new software for digital analysis of the tissue Doppler signal. Average systolic subendocardial (S1), subepicardial (S2), and transmural (S3) wall velocity data were obtained from the inferoposterior wall and compared with the hemodynamics, including high fidelity pressure readings. S1 and S3 rates were found to be most reliable, being directly related to the peak rate of left ventricular pressure rise (dP/dt_peak) and inversely to systemic vascular resistance (SVR) and resistance index (SVRI). The best correlation was between S1, dP/dt_peak, and SVRI (multiple regression analysis: r = 0.76, P < 0.0001; simple regression analysis relating S1 to dP/dt_peak/SVRI: r = 0.77, SEE = 0.25, P < 0.0001). Thus, wall velocity indices as defined in this study have promise to become helpful in guiding the therapeutic modulation of inotropy and afterload in patients with heart failure.     

Comparison of Two-Dimensional Echocardiography and Pulsed Doppler Tissue Imaging during Dobutamine-Atropine Stress Testing to Detect Coronary Artery Disease

In order to compare the diagnostic accuracy of two-dimensional (2-D) echocardiography and pulsed Doppler tissue imaging (pDTI) during dobutamine-atropine stress testing (DAST) to detect significant coronary lesions, 41 patients underwent DAST (up to 40 microg/k/min of dobutamine with additional atropine during submaximal heart rate responses) and coronary angiography. Pulsed Doppler tissue sampling of territories corresponding to the left anterior descending (LAD), left circumflex (LCx), and right coronary arteries (RCAs) were performed in the apical four-chamber plus aorta and two-chamber apical views. The measurements were repeated at rest, at low dose (10 microg/k/min), and at peak stress. Pulsed DTI measurements included peak early systolic (Vs), peak early diastolic (Ve), and peak late diastolic (Va) velocities. Harmonic 2-D echocardiography was recorded at rest, low dose, peak stress, and recovery, and compared with pDTI assessment. Positive 2-D echocardiography was considered as infarction or ischemic response. The results were evaluated for the prediction of significant coronary stenosis (50% luminal narrowing). Feasibility of pDTI was 100%, 95%, and 98% for the LAD, the LCx, and RCA territories, respectively. At rest, Vs in territories supplied by arteries with coronary artery disease (CAD) (6.3 +/- 2.0 cm/sec) was not different from those without (6.6 +/- 2.1 cm/sec). Vs increased less in territories supplied by arteries with than without CAD (75 +/- 107% vs 102 +/- 69%, P = NS). Ve was lower in territories with CAD at rest (6.0 +/- 2.1 cm/sec vs 8.2 +/- 3.4 cm/sec, P < 0.0001) and low dose (7.2 +/- 2.1 cm/sec vs 8.8 +/- 3.6 cm/sec, P < 0.01), but similar at peak stress (7.6 +/- 3.5 cm/sec vs 8.1 +/- 3.3 cm/sec). Ve increase was similar in territories with (36 +/- 74%) than without CAD (15 +/- 6 4%). Va was similar at rest and low dose in territories with and without CAD (9.2 +/- 2.7 cm/sec vs 9.1 +/- 2.3 cm/sec and 10.9 +/- 3.1 vs 10.3 +/- 3.6 cm/sec, respectively), but lower at peak stress in territories with CAD (13.3 +/- 4.6 cm/sec vs 15.3 +/- 4.5 cm/sec, P = 0.05). The Va increase was lower in territories with CAD (43 +/- 37% vs 77 +/- 72%, P < 0.05). In a territory-based analysis, a failure to achieve Vs > or =10.5 cm/sec at peak stress in the LAD and LCx, and > or =10.0 cm/sec in the RCA territory, was found to be the more accurate limit to detect CAD in the corresponding arteries: sensitivity (95% confidence intervals): 63% (55-71), P = NS vs 2-D echocardiography: 59% (51-67); specificity 76% (68-84), P < 0.01 vs. 2-D echocardiography: 95% (89-100); and accuracy 69% (63-75), P = NS vs 2-D echocardiography: 76% (70-82). Thus, pDTI is feasible during DAST but not more accurate than 2-D echocardiography for the detection of significant CAD in a territory-based study.     

Quantitative Tissue Doppler Echocardiography: Physiological Nonuniformity of Left Ventricular Transmural Myocardial Wall-Motion Velocities and Gradients

Tissue Doppler echocardiography (TDE) is a new method by which transmural myocardial function can be studied noninvasively. In order to investigate physiology and reproducibility, 24 young, healthy volunteers were examined by M-mode TDE. Nonuniformity of transmural tissue layer velocities became apparent: Subendocardial and subepicardial velocities of the anteroseptal myocardial wall (AW) were 3.5 ± 0.7 and 1.3 ± 0.5 cm/sec (P < 0.0001 , t- test), whereas in the posterolateral wall (PW) values of 3.6 ± 0.6 and 1.2 ± 0.4 cm/sec (P < 0.0001 , t- test ), respectively, were revealed. The ratios, termed "myocardial velocity gradients" as a new indicator of left ventricular performance, were 3.1 ± 1.0 and 3.4 ± 1.1, respectively. AW and PW did not differ (N.S.). Tolerance borders did not overlap, and intraobserver variability did not reach intersubject variability (P < 0.0001, F-ratio test). TDE provides new and more sophisticated insights into left ventricular performance. It seems to be accurate and reliable and therefore worth introducing into the clinical arena.     

Quantitative assessment of short axis wall motion using myocardial strain rate imaging

Although left ventricular wall motion has been usually assessed with four-point scale (1 = normal; 2 = hypokinesis; 3 = akinesis; 4 = dyskinesis) based on the visual assessment, this method is only qualitative and subjective. Recently, a new echocardiographic system that enables calculation of myocardial strain rate based on tissue Doppler information has been developed. We investigated whether myocardial strain rate could quantify regional myocardial contraction in 17 patients with and without wall motion abnormalities including 6 patients undergoing dobutamine stress echocardiography. Left ventricular short-axis wall motion was assessed with standard two-dimensional echocardiography at basal, mid-ventricular, and apical levels. The same levels were imaged with tissue Doppler method to determine regional myocardial strain rate. Sixty-four segments were judged normokinesis, 53 segments hypokinesis, and 18 segments akinesis at rest; 16 segments were judged normokinesis and 6 segments hypokinesis at stress. No segments characterized dyskinesis. Strain rates of normokinetic, hypokinetic, and akinetic wall segments at rest were significantly different each other (-2.0 +/- 0.6 for normokinesis,-0.6 +/- 0.5 for hypokinesis,P < 0.0001 vs. normokinesis, and-0.008 +/- 0.3 for akinesis, P < 0.0001 vs. normokinesis and hypokinesis). Further, strain rates well reflected the change in wall motion induced by dobutamine challenge: strain rates in the 15 segments revealing augmented wall motion changed from -2.0 +/- 0.7 to -4.7 +/- 1.7 (1/sec) (P < 0.0001) and those in the 7 segments revealing deteriorated or unchanged wall motion changed from -2.1 +/- 1.0 to -1.7 +/- 0.8 (1/sec) (P < 0.05). In conclusion, strain rate agreed well with assessed wall motion. Strain rate imaging may be a new powerful tool to quantify regional wall contraction.     

Coarctation of the Aorta: Quantitative Analysis by Transesophageal Echocardiography

Transesophageal echocardiography and standard two-dimensional echocardiography were performed in 15 patients with suspected coarctation of the aorta. Aortic diameters and crosssectional areas were determined by means of TEE and compared with clinical findings and catheterization data. The isthmus of the aorta could be imaged in all patients using TEE, but in only seven patients using standard suprasternal echocardiography. Compared with controls, aortic diameters were narrowed in 9 of 15 patients, and cross-sectional areas were reduced in 13 of 15. There was a satisfactory correlation between TEE data and angiographic and hemodynamic data. TEE is a promising method of a diagnosing and quantifying coarctation of the aorta, and is more sensitive than conventional two-dimensional and Doppler echocardiography.     

Left Ventricular Apical Thin Point Viewed with Two-Dimensional Echocardiography

The aim of this study was to evaluate the usefulness of two-dimensional echocardiography in observing the left ventricular apical thin point (LVATP) and to view the change in thickness and width of the LVATP during the cardiac cycle. Transthoracic echocardiography was performed in 32 healthy adult volunteers to observe the LVATP in an apical three-chamber view. The width and thickness of the LVATP were measured at the end-diastole as well as at the end-systole. With two-dimensional echocardiography, the LVATP could be clearly shown. The width of the LVATP at the end-diastole and end-systole was 3.3 mm ± 1.4 mm versus 0.9 mm ± 0.4 mm, P < 0.001; the thickness of the LVATP at the end-diastole and end-systole was 1.7 mm ± 0.6 mm versus 1.8 mm ± 0.8 mm, P > 0.05. The LVATP can be viewed with two-dimensional echocardiography; the LVATP changes significantly in width during the cardiac cycle, whereas the thickness of the LVATP changes insignificantly.     

Pericardiocentesis Guided by Contrast Echocardiography

Although pericardiocentesis is a relatively safe procedure, there are some hazards, particularly when hemorrhagic fluid is aspirated. Having the opportunity to outline the space from which the fluid is withdrawn is of particular interest in this situation. A current technique of echocardiography with contrast enhancement involves injection of a few milliliters of agitated saline solution or reinjection of blood-stained fluid. Performing this procedure, we repeatedly observed a weak and inhomogeneous echo contrast; therefore, we evaluated the applicability of the ultrasound contrast medium SH U 454 (Echovist Schering, Berlin, Germany) for contrast enhancement in hemorrhagic pericardiocentesis. In all patients, pericardiocentesis was performed in a supine position by a subxiphoid approach. A Teflon catheter / needle unit attached to a syringe containing a few milliliters of contrast medium was introduced in the usual way. On the return of hemorrhagic fluid, 1–2 ml of Echovist was injected to provide contrast from the space from which it had been aspirated. We observed excellent contrast clearly outlining the pericardial space through the injection of 1–2 ml of contrast medium. No adverse or side effects were seen resulting from Echovist injection to the pericardial sac. In conclusion, contrast echocardiography appears to be a useful tool to secure the correct position of the needle during pericardiocentesis of hemorrhagic or loculated effusions. It is suggested that injection of Echovist should be considered whenever the contrast obtained by the conventional technique is poor and inconclusive.     

Detection of Early Cardiac Dysfunction in Patients with Beta Thalassemia by Tissue Doppler Echocardiography

Backgrounds: In this study we tried to evaluate the prognostic significance of several echocardiographic parameters on the occurrence of heart failure or arrhythmias in patients with beta thalassemia. Methods: We investigated possible differences in myocardial function between a population of 37 asymptomatic patients with beta thalassemia and 25 age‐matched healthy controls, all of whom underwent an echocardiographic study, including tissue Doppler imaging (TDI), moreover plasmatic levels of N‐terminal pro‐BNP (NT‐pro BNP) were measured in all patients. We followed the patients for 22 ± 8 months to evaluate adverse cardiac events. Results: Conventional echocardiographic parameters of left ventricle were comparable in both groups. Whereas TDI peak systolic velocity (Sm) and diastolic parameter (E/Em ratio) were significantly abnormal in patients with thalassemia. Moreover eleven adverse cardiac events were observed during follow‐up. Baseline systolic velocity (Sm) <7.9 cm/s was significantly associated with cardiac complications (P < 0.05). We also demonstrated that systolic velocity is inversely related to NT‐proBNP plasmatic levels (P < 0.001). Conclusions: Our study suggests that mitral annular systolic velocity <7.9 cm/s is associated to the onset of adverse cardiac events. (Echocardiography 2011;28:175‐180)