Harmonic imaging with Levovist for transthoracic echocardiographic reconstruction of left ventricle in patients with post-ischemic left ventricular dysfunction and suboptimal acoustic windows.

BACKGROUND: Attempts to perform transthoracic 3-dimensional echocardiography (3DE) are often encumbered by poor definition of chamber borders in adult patients who have technically suboptimal acoustic windows. METHODS: To assess whether harmonic imaging (HI) and contrast agents can facilitate transthoracic 3DE assessment of the left ventricle, we used fundamental imaging (FI), HI alone, and HI coupled with the echo-enhancing contrast agent Levovist in 15 consecutive patients with post-ischemic left ventricular (LV) dysfunction and technically difficult windows. Dynamic 3DE image data sets were obtained at 5-degree angles (36 slices) from a transthoracic apical view. From these data a total of 240 myocardial segments were analyzed with the use of dynamic short-axis paraplane slices at basal, middle, and apical LV levels (standard 16 segment model). For border definition, each segment was scored in random sequence on the following scale by 2 independent investigators: 0 = not seen, 1 = suboptimal visualization, and 2 = well defined. RESULTS: Our results showed a significant increase in the number of well-visualized segments when harmonic mode combined with Levovist injection was compared with FI and HI alone. CONCLUSION: Harmonic imaging alone improves LV assessment by 3DE when compared with FI. Contrast imaging in which Levovist is added to HI further improves the capability of transthoracic tomographic 3DE in the visualization of LV myocardial segments. This could allow 3DE by transthoracic windows to be used more widely in adults for the evaluation of LV volume and function.     

Three-dimensional (3D) echocardiographic analysis of congenital heart disease in the fetus: comparison with cross-sectional (2D) fetal echocardiography.

OBJECTIVE: We attempted to assess the ability of Doppler-gated three-dimensional (3D) fetal echocardiography to reconstruct and display specific cardiac structures in fetuses with cardiac anomalies and to determine whether any advantage is offered by 3D sonographic cardiac examination over conventional fetal echocardiography. DESIGN: After 2D fetal echocardiographic examination, 3D cardiac data were collected prospectively in 22 fetuses with various congenital heart defects. Their ages ranged from 19 to 35 weeks' gestation. Basic echocardiographic key views of the venoatrial, atrioventricular and ventriculoarterial connections were derived from volume data sets and selected for 3D reconstruction and analysis. Comparisons were made with 2D echocardiographic imaging of the fetal hearts and the diagnostic image quality of visualized structural details was evaluated. RESULTS: The underlying cardiac malformation was well or satisfactorily visualized in 20 fetuses using 2D imaging. Gated 3D volume data sets enabled diagnostically acceptable visualization of all affected cardiac structures in 7 of 22 fetuses. High-quality 3D reconstruction of the site and spatial orientation of ventricular septal defects was obtained in 9 of 13 patients. Two-dimensional imaging remained the principal diagnostic modality in all cases with additional structural detail being obtained by 3D imaging in only two fetuses. CONCLUSIONS: Three-dimensional imaging of fetal heart disease is feasible for a wide range of lesions, and may provide additional information of clinical value in a small number of cases when compared with 2D imaging.     

The role of echocardiography in diagnosing space-occupying lesions of the heart

In contrast to primary cardiac tumors, which are less frequent and mostly benign in nature, the majority of intracardiac tumors are metastatic lesions. Cardiac ultrasound has evolved enormously since its emergence in the 1950s and is presently the modality of choice for imaging space-occupying lesions of the heart; it provides high quality, real-time images that are extremely valuable in the evaluation of cardiac masses. Although transthoracic echocardiography is an excellent initial diagnostic technique to evaluate and diagnose cardiac masses, transesophageal echocardiography provides superior image resolution and better visualization of cardiac masses in patients with suboptimal transthoracic echocardiography studies. Computed tomography and magnetic resonance imaging are additional tools used for cardiac imaging and may provide useful information in addition to that obtained by echocardiography, especially when the images obtained by the latter are suboptimal.     

Three-dimensional fetal echocardiography: gated versus nongated techniques.

The purpose of this study was to compare gated with nongated three-dimensional fetal echocardiography in terms of the ability to demonstrate fetal cardiac anatomy. We examined nine fetuses in utero using conventional two-dimensional sonographic imaging equipment, an electromagnetic position sensor, and a computer-graphics workstation. Free-hand sweeps were performed through the fetal heart and great vessels in either transverse or sagittal orientations with respect to the fetal heart. Seven transverse and five sagittal sweeps were selected for reconstruction and analysis. Cardiac gating was performed by using a temporal Fourier transform to determine the fundamental frequency of cardiac motion. Two-dimensional data from each sweep were reprojected to a series of volume data sets. Each series was then condensed to a single volume, so that each two-dimensional sweep could be compared with its respective gated and nongated volume data sets. The two-dimensional data were reviewed utilizing a display with forward and backward cineloop capability. The gated and nongated volume data sets were displayed interactively as a series of three orthogonal planes, with the ability of the observer to control the location of each image plane within the volume. The gated data were animated with variable display frame rates. Conventional two-dimensional imaging provided a fairly complete evaluation of the fetal heart when scanning included the four-chamber view with a sweep across the outflow tracts. Nongated three-dimensional fetal echocardiography allowed visualization of some structures and views not demonstrated with two-dimensional ultrasonography. Gated three-dimensional fetal echocardiography provided significantly better visualization and comprehension of cardiac anatomy than nongated three-dimensional fetal echocardiography. The superiority of gated over nongated three-dimensional fetal echocardiography appears to come from both improved image quality and the anatomic clues that derive from the ability to view cardiac motion.     

Real-time three-dimensional fetal echocardiography--optimal imaging windows

A total of 15 fetuses were scanned using 2-D array volumetric ultrasound (US). Acquired cardiac data were converted for rendering dynamic 3-D surface views and reformatting cross-sectional views. The image usefulness was compared between the data obtained from subcostal/subxiphoid and other imaging windows; the former are usually free of acoustic shadowing. Of 60 data sets recorded, 12 (20%) were acquired through subcostal windows in 6 (40%) patients. Subcostal windows were unavailable from the remaining patients due to unfavourable fetal positions. Of the 12 sets, 6 (50%) provided the dynamic 3-D and/or cross-sectional views of either the entire fetal heart or a great portion of it for sufficient assessments of its major structures and their spatial relationships. Of 48 data sets from other windows, only 9 (19%) provided such 3-D and/or cross-sectional views; the lower rate being due to acoustic shadowing. Real-time 3-D US is a convenient method for volumetric data acquisition. Through subcostal windows, useful information about the spatial relationships between major cardiac structures can be acquired. However, to offer detailed information, considerable improvement in imaging quality is needed.     

Real-time 3-dimensional fetal echocardiography with an instantaneous volume-rendered display: early description and pictorial essay.

OBJECTIVE: Random fetal motion, rapid fetal heart rates, and cumbersome processing algorithms have limited reconstructive approaches to 3-dimensional fetal cardiac imaging. Given the recent development of real-time, instantaneous volume-rendered sonographic displays of volume data, we sought to apply this technology to fetal cardiac imaging. METHODS: We obtained 1 to 6 volume data sets on each of 30 fetal hearts referred for formal fetal echocardiography. Each volume data set was acquired over 2 to 8 seconds and stored on the system's hard drive. Rendered images were subsequently processed to optimize translucency, smoothing, and orientation and cropped to reveal "surgeon's eye views" of clinically relevant anatomic structures. Qualitative comparison was made with conventional fetal echocardiography for each subject. RESULTS: Volume-rendered displays identified all major abnormalities but failed to identify small ventricular septal defects in 2 patients. Important planes and views not visualized during the actual scans were generated with minimal processing of rendered image displays. Volume-rendered displays tended to have slightly inferior image quality compared with conventional 2-dimensional images. CONCLUSIONS: Real-time 3-dimensional echocardiography with instantaneous volume-rendered displays of the fetal heart represents a new approach to fetal cardiac imaging with tremendous clinical potential.     

Fetal iGRASP cine CMR assisting in prenatal diagnosis of complicated cardiac malformation with impact on delivery planning

Limited visualization of the fetal heart and vessels by fetal ultrasound due to suboptimal fetal position, patient habitus and skeletal calcification may lead to missed diagnosis, overdiagnosis and parental uncertainty. Counselling and delivery planning may in those cases also be tentative. The recent fetal cardiac magnetic resonance (CMR) reconstruction method utilizing tiny golden‐angle iGRASP (iterative Golden‐angle RAdial Sparse Parallel MRI) allows for cine imaging of the fetal heart for use in clinical practice. This case describes an unbalanced common atrioventricular canal where limited ultrasound image quality and visibility of the aortic arch precluded confirming or ruling out presence of a ventricular septal defect. Need of prostaglandins or neonatal intervention was thus uncertain. Cardiovascular magnetic resonance imaging confirmed ultrasound findings and added value by ruling out a significant ventricular septal defect and diagnosing arch hypoplasia. This confirmed the need of patient relocation for delivery at a paediatric cardiothoracic surgery centre and prostaglandins could be initiated before the standard postnatal ultrasound. The applied CMR method can thus improve diagnosis of complicated fetal cardiac malformation and has direct clinical impact.     

Three-dimensional (3-D) ultrasonography for obtaining the four and five-chamber view: comparison with cross-sectional (2-D) fetal sonographic screening.

OBJECTIVES: To assess the ability of Doppler-gated 3-D fetal echocardiography to reconstruct and display specific cardiac structures routinely visualized during antenatal ultrasound in a population at low risk for cardiac anomalies. To determine whether any advantage is offered by 3-D sonographic cardiac examination over conventional sonographic fetal screening techniques. DESIGN: After routine two-dimensional sonographic examination, 3-D cardiac data were collected prospectively in 30 fetuses with gestational ages between 19 and 23 weeks from a low risk patient population. Basic echocardiographic key views were derived from 3-D data and selected for reconstruction and analysis. Four- and five-chamber views were rated and only those views judged to be well visualized were considered as positive results. RESULTS: The four- and five-chamber views were well visualized in all but one fetus using conventional 2-D imaging. Gated 3-D volume data sets enabled visualization of these structures in only 19 of 30 fetuses but provided additional structural depth and allowed a dynamic 3-D perspective of valvar morphology and ventricular wall motion. The right ventricular outflow tract was available from the 3-D volumes in 16 subjects. CONCLUSIONS: Considering the versatility of gated 3-D fetal cardiac imaging we believe that it may soon become an important component of fetal screening thus helping to retrieve standard cardiac cross sections when 2-D imaging is limited by lack of sonographer experience or sonographic windows. Diagnostically acceptable echocardiographic views were obtained more consistently with 2-D ultrasound than with 3-D volume data.     

自然组织谐波成像临床应用的研究

目的：研究自然组织谐波对心内膜显示能力和心内结构清晰度的影响。方法： 采用自然组织谐波成像对６７ 例不同患者经胸二维成像进行对比分析。结果：成像理想的２０ 例患者在自然组织谐波和基波成像条件下其心内膜清晰度和心脏结构显示能力无明显差别。４７例成像困难的患者,自然组织谐波成像能明显提高心内膜显示能力,改善心脏结构清晰度,以心尖切面左室外侧壁和前壁心内膜显示能力提高较明显,尤其心尖四腔心切面图像质量改善最佳。结论： 自然组织谐波成像可提高心内膜显示能力和心脏组织结构清晰度, 但并非适用于任何人。     

Tissue harmonic imaging in the diagnosis of small hepatocellular carcinoma: Usefulness for detecting posterior acoustic enhancement

We attempted to evaluate the usefulness of ultrasonic tissue harmonic imaging (HI) in the diagnosis of small hepatocellular carcinoma (HCC) and compare its effectiveness with that of conventional fundamental imaging (FI) prospectively. Nine patients with 16 nodules of HCC measuring less than 20 mm in diameter were evaluated with both FI and HI. The boundaries of 14 nodules were more clearly visualized on HI than on FI. Posterior acoustic enhancement, which is diagnostic of HCC, was not detected on FI, although it was detected in 5 nodules on HI (p<0.05); however, one nodule located in a section of the liver that was 8 cm below the abdominal wall was visualized only by FI. We conclude that HI is more useful than FI in the diagnosis of small HCC nodules, although HI has minor limitations of the applicable location.     

实时空间复合成像技术在胎儿超声心动图中的应用研究

目的 对比观察实时空间复合成像与组织谐波成像技术对胎儿超声心动图图像质量的影响。方法 使用ATL-5000超声仪,探头频率为2～5MHz,在实时复合成像和谐波成像条件下对50例20～24周胎儿进行超声心动图检查,探查四腔心切面,DICOM格式保存图像后进行图像质量的评分并分析其差异。结果 所有50例胎儿超声心动图应用实时复合成像技术后不同程度减少了伪像,实时复合成像图像质量评分高于组织谐波成像评分（P〈0．001）。结论 实时复合成像技术明显改善了胎儿超声心动图的图像质量,在胎儿心动图检查中有重要的应用价值。     

组织谐频成像与基频成像在心脏声像图中的对比观察

目的:探讨组织谐频成像（THI）与常规基频成像（FI）的对比观察，研究THI改善声像图质量，增强图像的显现力。方法：对150例（标准受检100例、透声差受检50例）心脏（正常或异常）进行观察，分析两种检查的图像质量。结果：FI成像标准受检图像显示优良率81％，透声差受检图像显示优良率64％。THI成像标准受检图像显示优良率91％，透声差受检图像显示优良率88％。结论：无论标准受检或透声差受检THI的图像质量均较FI的图像质量明显改善，可提高诊断的准确性。     

组织谐波显像和CK技术结合在冠心病应用的研究

目的　彩色室壁运动技术（Ｃｏｌｏｒ Ｋｉｎｅｓｉｓ ＣＫ） 的应用受二维图像质量影响。组织谐波显像（ｔｉｓｓｕｅ ｈａｒｍｏｎｉｃｉｍａｇｅ ＴＨＩ）能改善声窗不佳者二维图像质量。本文拟观察ＴＨＩ对ＣＫ 评价室壁运动的影响。方法　非选择性冠心病患者２１ 名,分别在基波（ＦＩ） 和谐波（ＨＩ）下采集二维和收缩末ＣＫ 图像,比较两种显像方式下心内膜显示、二维和ＣＫ 图像质量以及ＣＫ 评价室壁运动的准确性。结果　ＨＩ下心内膜显示改善,二维和ＣＫ 图像质量提高,ＣＫ图像采集成功率由ＦＩ的８４－８ ％ 增加到９５－８ ％ ,评价室壁运动的准确性由６８－４ ％ 增加到８８－７％ 。结论　ＴＨＩ和ＣＫ技术的结合提高了ＣＫ 技术的临床适用性。     

Multi-View 3-D Fusion Echocardiography: Enhancing Clinical Feasibility with a Novel Processing Technique

A novel system for fusing 3-D echocardiography data sets from complementary acoustic windows was evaluated in 12 healthy volunteers and 12 patients with heart failure. We hypothesized that 3-D fusion would enable 3-D echocardiography in patients with limited acoustic windows. At least nine 3-D data sets were recorded, while three infrared cameras tracked the position and orientation of the transducer and chest respiratory movements. Corresponding 2-D planes of the fused 3-D data sets and of single-view 3-D data sets were assessed for image quality and compared with measurements of left ventricular function obtained with contrast 2-D echocardiography. The signal-to-noise ratio in accurately fused 3-D echocardiography recordings improved by 55% in systole (p < 0.001) and 47% in diastole (p < 0.00001) compared with the apical single-view recordings. The 3-D data sets acquired during short breath holds were successfully fused in 11 of 12 patients. The improvement in endocardial border definition (from 11.7 ± 6.0 to 24.0 ± 3.3, p < 0.01) enabled quantitative assessment of left ventricular function in 10 patients, with no significant difference in ejection fraction compared with contrast 2-D echocardiography. In patients with heart failure and limited acoustic windows, the novel fusion protocol provides 3-D data sets suitable for quantitative analysis of left ventricular function.     

Imaging techniques in cardiac electrophysiology

Modern cardiac electrophysiology procedures include catheter-based arrhythmia ablation and transvenous device implantation, which are highly dependent on accurate, real-time cardiac imaging. With the realization that anatomic structures are critical to successful electrophysiologic procedures, accurately defining a patient's cardiac anatomy has become more important. Fluoroscopy allows for 2D imaging of cardiac structures in real-time, and is used to guide catheter and lead placement, but does not allow for visualization of soft tissues. Intracardiac echocardiography allows for both direct visualization of anatomic structures within the heart and real-time imaging during catheter placement. Despite advances in intracardiac echocardiography catheters that allow for larger windows, the ability to accurately delineate anatomic structures depends on the patient's anatomy and operator experience. Neither of these techniques allows for electrical mapping of the heart; however, both anatomic and electrical intracardiac mapping can be achieved with advanced mapping systems. These systems allow for real-time catheter localization, help elucidate cardiac anatomy, evaluate electrical activation during arrhythmias and guide catheter placement for deliverance of radiofrequency current. More recently, 3D cardiac computed tomography has been used to accurately define intracardiac anatomy; however, catheter tracking and electrical mapping cannot be performed by computed tomography. Mapping systems are now being merged with computed tomography images to produce an accurate anatomic and electrical map of the heart to guide catheter ablations. The objective of this paper is to describe the current imaging and mapping techniques used in electrophysiologic procedures.     

Imaging techniques in cardiac electrophysiology

Modern cardiac electrophysiology procedures include catheter-based arrhythmia ablation and transvenous device implantation, which are highly dependent on accurate, real-time cardiac imaging. With the realization that anatomic structures are critical to successful electrophysiologic procedures, accurately defining a patient’s cardiac anatomy has become more important. Fluoroscopy allows for 2D imaging of cardiac structures in real-time, and is used to guide catheter and lead placement, but does not allow for visualization of soft tissues. Intracardiac echocardiography allows for both direct visualization of anatomic structures within the heart and real-time imaging during catheter placement. Despite advances in intracardiac echocardiography catheters that allow for larger windows, the ability to accurately delineate anatomic structures depends on the patient’s anatomy and operator experience. Neither of these techniques allows for electrical mapping of the heart; however, both anatomic and electrical intracardiac mapping can be achieved with advanced mapping systems. These systems allow for real-time catheter localization, help elucidate cardiac anatomy, evaluate electrical activation during arrhythmias and guide catheter placement for deliverance of radiofrequency current. More recently, 3D cardiac computed tomography has been used to accurately define intracardiac anatomy; however, catheter tracking and electrical mapping cannot be performed by computed tomography. Mapping systems are now being merged with computed tomography images to produce an accurate anatomic and electrical map of the heart to guide catheter ablations. The objective of this paper is to describe the current imaging and mapping techniques used in electrophysiologic procedures.     

M-mode magnetic resonance imaging: a new modality for assessing cardiac function

Summary. Magnetic resonance imaging (MRI) studies of the heart have been used for some years, but there are few tools available to quantify cardiac motion. A method has been developed that creates an M-mode MRI image, analogous to the one used in echocardiography, to display motion along a line as a function of time. The M-mode image is created from MRI images acquired with an ordinary gradient echo cine sequence. In a cinematographic display of the images, a cursor line can be positioned in order to determine the orientation of the measurement. A resampling algorithm then calculates the appearance of the M-mode image along the cursor line. The MRI method has been compared to echocardiographic M-mode in a phantom study and by measuring mitral and tricuspid annulus motion in 20 normal subjects. The phantom study showed no significant differences between MRI and echocardiographic M-mode measurements (difference mm). The annulus motion exhibits a similar pattern using both methods and the measured amplitudes are in close agreement. M-mode MRI provides similar information to echocardiography, but the cursor line can be placed arbitrarily within the image plane and the method is thus not limited to certain acoustic windows. This makes M-mode MRI a promising technique for assessing cardiac motion.     

Quantification of Left Ventricular Size and Function Using Contrast-Enhanced Real-Time 3D Imaging with Power Modulation: Comparison with Cardiac MRI

In patients with optimal images, real-time 3-D echocardiography (RT3DE) allows accurate evaluation of left ventricular (LV) volumes and ejection fraction (EF). However, in patients with poor acoustic windows, lower correlations were reported despite the use of contrast. We hypothesized that power modulation (PM) RT3DE imaging that uses low mechanical indices and provides uniform LV opacification could overcome this problem. Accordingly, we sought to: (i) Test the feasibility of quantification of LV volumes and EF from contrast-enhanced (CE) PM RT3DE images, (ii) validate this technique against cardiac magnetic resonance (CMR) reference and (iii) test its clinical value by quantifying the improvement in accuracy and reproducibility. We studied 20 patients who underwent CMR, harmonic nonenhanced RT3DE and CE PM RT3DE imaging on the same day. All images were analyzed to obtain end-systolic and end-diastolic LV volumes (EDV, ESV) and calculate EF. To determine the reproducibility of each RT3DE technique, imaging was repeated in the same setting by a second sonographer. In addition, patients were divided according to the quality of their RT3DE images into two groups, for which agreement with CMR and reproducibility were calculated separately. CE PM RT3DE imaging improved the accuracy of EDV, ESV and EF measurements in patients with poor acoustic windows without significantly affecting those in patients with optimal images. In addition, CE PM RT3DE imaging improved the reproducibility of the measurements, as reflected by a twofold decrease in intermeasurement variability. Importantly, the variability in CE PM RT3DE–derived volumes and EF was under 10%, irrespective of image quality. This methodology may become the new standard for LV size and function, which will be particularly important in patients with poor acoustic windows or contraindications to CMR.     

自然组织谐波显像的临床应用价值

目的：研究超声心动图检查中自然组织谐波显像（NTHI）改善图像质量是否有程度的差异。方法：经胸用基波显像（FI）及NTHI对比分析成像条件不同的80例二维超声心动图的胸骨旁左室长轴切面（LAX）、心尖两腔切面（AP2）和心尖四腔切面（AP4）及22个不同节段的内膜可视度（EV）及心内结构清晰度。内膜EV根据内膜不可见、可见、清晰分为1、2、3分。结果：NTHI能明显提高总的及不同切面的EV,所有22个节段EV也明显改善,但改善程度以AP2、AP4及其基底段、中段最佳;图像质量差的比图像质量好的心内结构改善更明显。但NTHI示心内结构稍显增厚,彩色血流显像不丰富。结论：支持NTHI能显著改善超声心动图二维图像,但不同节段、不同切面及成像条件不同的患者改善程度不同,因使心内结构稍显增厚,判断是否有病理改变时应注意。     

High-frame-rate tissue harmonic imaging enhances anatomic M-mode sections of the left ventricle in short-axis view.

BACKGROUND: High-frame-rate echocardiography (HFRE) and tissue harmonic imaging (THI) may improve image quality, thereby enabling anatomic M-mode sections of left ventricular (LV) wall segments to be visualized in various planes in the short-axis view. OBJECTIVES: The goals of this study were to compare image quality between HFRE and conventional-frame-rate echocardiography (CFRE) and between fundamental imaging (FI) and THI, and to obtain anatomic M-mode values of basal short-axis LV segments from healthy subjects for use in the evaluation of abnormal segments in patients with myocardial infarction (MI). METHODS AND RESULTS: The study included 28 healthy subjects and 15 patients with MI who underwent 2-dimensional echocardiography with an ultrasonographic system equipped with THI and anatomic M-mode. Left ventricular image cineloops at the basal short-axis view that were obtained with 3 combinations of imaging techniques (FI + CFRE, FI + HFRE, and THI + HFRE) were digitized and displayed side-by-side in random order for comparison by blinded readers. M-mode sections were done in 3 planes: anteroseptal-posterior, inferoseptal-lateral, and anterior-inferior basal segments. The THI + HFRE combination showed the best image quality with significant reduction in noise artifacts, resulting in a good signal-to-noise ratio and good tractability of all LV segments by anatomic M-mode. In healthy subjects, significant intersegmental differences existed in the diastolic and systolic thicknesses and in the percent systolic thickening of LV segments. In patients with MI, LV systolic thickening was significantly decreased in abnormal segments. No significant differences were noted in ejection fraction and fractional shortening among the 3 anatomic M-mode planes. CONCLUSION: High-frame-rate tissue harmonic imaging improved image quality, thereby allowing reproducible anatomic M-mode measurements in various planes in the short-axis view and providing a convenient objective evaluation of global and regional LV function.