Harmonic imaging in fetal echocardiography.

Noncontrast harmonic imaging (HI) has been shown to improve image quality in adults with poor acoustic windows. The utility of fetal echocardiography may be limited by suboptimal acoustic windows, and the use of HI in fetal echocardiography has not previously been defined. The purpose of this study was to compare the quality of fundamental imaging (FI) and HI in fetal echocardiography. Sixty-two fetal echocardiograms, including 44 (71%) with limited acoustic windows, were performed with the use of FI and HI. Image quality and visualization of the ventricles, valves, and the aortic and ductal arches were evaluated and compared between FI and HI. Mean HI scores were higher than mean FI scores for all the structures evaluated. Compared with FI, HI improved the image quality and visualization of cardiac structures in this group of fetuses with predominantly suboptimal acoustic windows. Harmonic imaging is a useful adjunct to FI in echocardiography, and the benefits of HI extend to cardiac imaging in the fetus.     

Does second harmonic imaging improve left ventricular endocardial border identification at higher heart rates during dobutamine stress echocardiography?

BACKGROUND: The increased heart rate during dobutamine stress echocardiography (DSE) may impair endocardial border visualization. Second harmonic imaging (SHI) enhances left ventricular (LV) border visualization compared with conventional fundamental imaging (FI) at rest. However, its role during DSE is not well established yet. OBJECTIVE: Our objective was to compare the additional value of SHI to FI for the LV endocardial border visualization during various stages of DSE. METHODS: Eighty patients underwent DSE. Imaging was performed with both FI and SHI at rest and at low-and peak-dose dobutamine infusion. Endocardial border visualization was assessed by using a 16-segment/3-point score (0 = well visualized; 1 = poorly visualized; 2 = not visualized). RESULTS: Heart rate increased from rest (70 +/- 13 bpm) to low-dose dobutamine (77 +/- 17, P <.01) and showed further increase at peak dose (129 +/- 16, P <.001 versus low dose). There was a higher prevalence of segments with an invisible LV endocardial border with FI compared with SHI at rest (9.4% versus 6.2%, P <.0001), at low dose (10.8% versus 6.3%, P <.0001), and at peak dose (15.0% versus 8.2%, P <.0001). There was an increase in the number of segments with an invisible border from rest to peak stress by FI (P =.0001), whereas the difference was less significant for SHI (P =.07). CONCLUSION: Second harmonic imaging improves visualization of the LV endocardial border compared with FI during DSE. The advantage of SHI over FI is more marked at higher heart rates than at rest.     

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.     

Measurement of left ventricular volumes by 3-dimensional echocardiography with tissue harmonic imaging: a comparison with magnetic resonance imaging.

We hypothesized that tissue harmonic imaging (THI) in comparison with fundamental imaging (FI) would improve endocardial border detection, and therefore in combination with 3-dimensional echocardiography (3D echo), it would be a precise method for left ventricular (LV) volume measurement. Ten healthy subjects and 18 consecutive patients with dilated hearts underwent estimation of LV volumes by magnetic resonance imaging (MRI) and transthoracic 3D echo with THI and FI. In patients, the agreement between MRI and 3D echo was closer with THI in comparison with FI for assessment of LV volumes. Thus the mean +/- 2 SD of differences between MRI and 3D echo with THI versus FI, respectively, was -6.4 +/- 40.0 mL versus -17.4 +/- 57.6 mL (P <.01) for the end-diastolic volume (EDV), and 0.0 +/- 26.6 mL versus -8.1 +/- 35.6 mL (P <.01) for the end-systolic volume (ESV). In patients, THI in comparison with FI approximately halved observer variation on EDV and ESV. In healthy subjects, only ESV showed significantly reduced observer variation by THI. In conclusion, because THI demonstrated a clinically relevant reduction in observer variation and a closer agreement to the MRI technique in patients with dilated hearts, it should replace FI in LV volume measurements.     

Rapid freehand scanning three-dimensional echocardiography: accurate measurement of left ventricular volumes and ejection fraction compared with quantitative gated scintigraphy.

This study was performed to assess clinical feasibility of rapid freehand scanning 3-dimensional echocardiography (3DE) for measuring left ventricular (LV) end-diastolic and -systolic volumes and ejection fraction using quantitative gated myocardial perfusion single photon emission computed tomography as the reference standard. We performed transthoracic 2-dimensional echocardiography and magnetic freehand 3DE using a harmonic imaging system in 15 patients. Data sets (3DE) were collected by slowly tilting the probe (fan-like scanning) in the apical position. The 3DE data were recorded in 10 to 20 seconds, and the analysis was performed within 2 minutes after transferring the raw digital ultrasound data from the scanner. For LV end-diastolic and -systolic volume measurements, there was a high correlation and good agreement (LV end-diastolic volume, r = 0.94, P <.0001, standard error of the estimates = 21.6 mL, bias = 6.7 mL; LV end-systolic volume, r = 0.96, P <.0001, standard error of the estimates = 14.8 mL, bias = 3.9 mL) between gated single photon emission computed tomography and 3DE. There was an overall underestimation of volumes with greater limits of agreement by 2-dimensional echocardiography. For LV ejection fraction, regression and agreement analysis also demonstrated high precision and accuracy (y = 0.82x + 5.1, r = 0.93, P <.001, standard error of the estimates = 7.6%, bias = 4.0%) by 3DE compared with 2-dimensional echocardiography. Rapid 3DE using a magnetic-field system provides precise and accurate measurements of LV volumes and ejection fraction in human beings     

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。     

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。     

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.     

Harmonic imaging for endocardial visualization and myocardial contrast echocardiography during transesophageal echocardiography.

BACKGROUND: Although harmonic imaging (HI) improves endocardial visualization and is necessary for myocardial perfusion imaging, it has yet to be implemented in transesophageal echocardiography. Our goal was to determine whether HI implemented in a prototype transesophageal echocardiography probe improved endocardial visualization and allowed perfusion imaging. METHODS: In 23 patients, fundamental and harmonic images were obtained in the transgastric short-axis (TSAX) and midesophageal 4-chamber views, and reviewed for endocardial visualization by 3 readers blinded to imaging mode. In 14 additional patients, perfusion imaging was performed in the TSAX view during contrast infusion. RESULTS: HI improved overall endocardial visualization, most noticeably in the anterior and lateral segments (P <.004) in the TSAX view, and in the lateral segments (P <.01) in the midesophageal 4-chamber view. The salvage rate was 8.3% in the TSAX view and 12.6% in the midesophageal 4-chamber view. Myocardial perfusion was consistently confirmed in the inferior (86%), posterior (100%), and lateral (79%) segments, but rarely in the septal (21%), anteroseptal (0%), and anterior (14%) segments. CONCLUSION: Use of HI with transesophageal echocardiography improves endorcardial visualization and allows partial assessment of myocardial perfusion.     

Is there a role for intravenous transpulmonary contrast imaging in pediatric stress echocardiography?

OBJECTIVE: Intravenous transpulmonary contrast echocardiography plays a significant role in the enhancement of endocardial border delineation during stress echocardiography in the adult population. The current study was conducted to evaluate the feasibility of intravenous transpulmonary contrast in pediatric patients and to compare the quality of endocardial visualization by harmonic 2-dimensional (2D) imaging alone with harmonic 2D echocardiography with contrast imaging. METHODS: Twenty-two children, age 9.3 +/- 3.9 underwent dobutamine (19 patients) or exercise (3 patients) stress echocardiography. None had intracardiac shunting. Each patient underwent both harmonic 2D imaging alone and harmonic 2D imaging with contrast administration at peak stress. Oxygen saturation, heart rate, and blood pressure were monitored. Endocardial delineation was evaluated by qualitative grading of 22 endomyocardial regional segments in each patient. Contrast images were graded by an echocardiographer who was blinded to the scores previously assigned to harmonic 2D echocardiography images. RESULTS: There were no changes in saturation, heart rate, or blood pressure during or after contrast administration. Use of contrast significantly improved endocardial visualization in 11 of 22 segments (P <.05), particularly lateral, apical, and anterior left ventricular wall segments. CONCLUSION: Intravenous intrapulmonary administration is feasible and has no obvious adverse effects in a small pediatric patient group. Contrast echocardiography improves endocardial border delineation over harmonic imaging in pediatric stress echocardiography.     

Altered left ventricular contraction pattern during right ventricular pacing: assessment using real-time three-dimensional echocardiography

Background: Chronic right ventricular apical (RVA) pacing has been associated with increased risk of heart failure and adverse outcome. The acute effects of RVA pacing on three‐dimensional (3D) ventricular function and mechanical dyssynchrony are not well known. We performed a real‐time 3D echocardiographic (RT3DE) study to assess global and regional left ventricular function during RVA pacing. Methods: Twenty‐six patients with implanted cardiac devices and normal intrinsic atrioventricular conduction were included in the study. RT3DE was performed during intrinsic sinus rhythm and during RVA pacing. Quantification of global and regional left ventricular function was performed offline by time‐volume analysis of 16 myocardial segments. Time to reach minimum regional volume was calculated for each segment as a percentage of the cardiac cycle. The systolic dyssynchrony index (SDI) was defined as the standard deviation of these time periods. Longitudinal function was assessed by time‐volume analysis of apical, midventricular, and basal segments. Results: During RVA pacing, a reversed apical‐to‐basal longitudinal contraction sequence was observed in 58% of all patients. RVA pacing was associated with increased left ventricular (LV) dyssynchrony (SDI increase from 4.4 ± 2.2% to 6.3 ± 2.4%, P = 0.001) and reduced LV ejection fraction (decrease from 53 ± 13% to 47 ± 14%, P = 0.05). Conclusion: RT3DE assessment of LV function provides evidence that pacing from the RVA results in acute alterations in LV contraction sequence and increased LV dyssynchrony. Further studies are warranted to assess the potential of RT3DE to identify patients who might be at increased risk of pacing‐induced heart failure or who might benefit from alternate‐site or multisite pacing. (PACE 2011; 76–81)     

Echocardiographic imaging of technically difficult patients in the intensive care unit: use of optison in combination with fundamental and harmonic imaging.

Previous studies of intravenous contrast agents have excluded patients in the intensive care unit. These patients remain among the most technically difficult to image with ultrasound. We studied the effect of different imaging modalities with and without intravenous contrast (Optison) on endocardial border visualization during echocardiography. Fifty patients in the intensive care unit (32 men, 24 on mechanical ventilator, 10 with chest bandages; mean age, 59 years; mean weight, 91.7 kg; mean height, 67.6 inches) were considered to have technically difficult images when the endocardium could not be visualized in at least 2 of the 6 segments in either apical view. Each patient was studied with the use of fundamental (F), harmonic (H), fundamental + Optison (F + O), and H + O techniques, with standard long-axis, short-axis, and apical 4- and 2-chamber views. Intravenous Optison (0.5 to 1.5 mL) was given before F + O and H + O imaging. There were no contrast-related side effects noted. All images were stored digitally in a quad-screen format. For each set of images, segments (n = 22) were given an endocardial border visualization score of 0 if not visualized, 1 if visualized in either systole or diastole, and 2 if visualized in both. There was stepwise improvement in endocardial border visualization, with mean endocardial border visualization score of 1.09 +/- 0.83 (F), 1.33 +/- 0.81 (H), 1.64 +/- 0.62 (F + O), and 1.90 +/- 0.35 (H + O). There was a statistically significant difference between each group (P <.001). The incremental benefit of Optison was greater with harmonic imaging than with fundamental (P <.001). The use of Optison is safe and effective in the intensive care unit. In combination with harmonic imaging, contrast provides maximal endocardial border delineation during echocardiographic imaging of technically difficult patients in the intensive care unit.     

Harmonic imaging improves estimation of left ventricular mass

OBJECTIVES: To assess the effect of tissue harmonic imaging (THI) on assessment of left ventricular mass index (LVMI) measurements by M-mode trans-thoracic echocardiography, when compared with magnetic resonance imaging (MRI). METHODS: 20 hypertensive male subjects were studied. LVMI was measured in all subjects by both gradient-echo MRI (Lscelsint Prestige 1.9 T) and by transthoracic echocardiography (ATL HDI 5000). M-mode echocardiography recordings were taken for each patient, two with fundamental imaging (FI) and two using THI in a randomised order and the images unlabelled. Recordings were analysed off-line, by a blinded observer. LVMI by MRI was calculated using Simpson's rule on serial short axis slices of 8 mm thickness. Data are expressed as mean +/- SD. RESULTS: There was a difference in LVMI measurements between FI and THI (LVMI) (79 +/- 20 vs. 93 +/- 25 g2; p < 0.001). A lower mean difference was obtained by THI, compared to FI, when compared with MRI (2 +/- 15 vs. -32 +/- 22 g2; p < 0.001) suggesting that FI underestimates LVMI. Inter-observer variability was similar between THI and FI (4.5 +/- 15 vs. 6.4 +/- 15 g2; p = 0.46). CONCLUSION: In hypertensive males, M-mode echo derived from FI underestimated LVMI. These results imply that widely accepted reference ranges for LVMI using FI are not applicable when THI is used.     

经胸三维超声心动图评价左室收缩功能方法的初步研究

目的　探讨采用磁场定位系统经胸三维超声心动图(3DE)测定左室收缩功能的方法及可行性。方法　健康志愿者17例。利用磁场发射及接收装置通过手动控制探头在心尖区扇形扫描进行三维数据采集。每例受检者均分别采集60、30及10幅图像（3D60、3D30、3D10）各自进行三维重建。同时记录采集时间。采用圆盘总和法（disksummation）测定左室舒张末期容积（LVEDV）和左室收缩末期容积（LVESV）,得出每搏输出量（SV）及左室射血分数（LVEF）。同时用常规二维Simpson法测量LVEF。结果　①3D10重建后的左室短轴图像不完整,左室壁有不规则中断,心腔内结构难以评价。3D60及3D30重建后的左室短轴图像完整,内膜、二尖瓣及瓣下结构清晰可辨。②二维超声心动图(2DE)测得LVEF为0.62±0.06,与3D60及3D30的测值显著相关（r值分别为0.87,0.83,P<0.001）。③3D60测定的EDV,ESV,SV及EF分别为（88.11±18.08）ml、（38.01±9.23）ml、（50.09±13.30）ml和0.57±0.07;3D30测定的EDV,ESV,SV及EF分别为（87.51±15.58）ml、（37.18±9.62）ml、（50.33±11.48）ml和0.58±0.08;二者间各项测值差异无显著性意义（P均>0.1）,且显著相关（r值分别为0.94,0.88,0.88,0.87,P均<0.001）。④3D60的采集时间为（152.55±53.27）s,3D30的采集时间为（72.82±17.16）s,比3D60的时间节省48％。结论　磁场定位系统扇形扫描经胸3DE测定正常人左室收缩功能是准确可行的。采集30幅图像与采集60幅图像得到的左室收缩功能指标无显著差异,前者可缩短约一半的检查时间,更加迅速方便,有利于临床应用。     

Three-dimensional echocardiography with tissue harmonic imaging shows excellent reproducibility in assessment of left ventricular volumes.

We studied the reproducibility of repeated measurements of left ventricular (LV) volumes by 2-dimensional (biplane method of disks) and 3-dimensional echocardiography (coaxial scanning) with tissue harmonic imaging. Ten healthy subjects underwent estimation of LV volumes by transthoracic echocardiography twice within 1 week by 2 different operators to investigate interexamination and operator variance. In addition, the analysis of LV volume was done manually by 2 observers to assess both interobserver and intraobserver variances. With 3D echocardiography, observer variation had the greatest impact on variance. Operator variability showed important contributions to total variance with the use of 2D echocardiography. The reproducibility of 3D echocardiography and tissue harmonic imaging is excellent and comparable to magnetic resonance imaging techniques; 3D echocardiography therefore should provide a powerful tool for noninvasive LV volume estimation.     

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.)     

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。     

Rapid full volume data acquisition by real-time 3-dimensional echocardiography for assessment of left ventricular indexes in children: a validation study compared with magnetic resonance imaging.

OBJECTIVE: We sought to assess the feasibility, accuracy, and reproducibility of a rapid full volume acquisition strategy using real-time (RT) 3-dimensional (3D) echocardiography (3DE) for measurement of left ventricular (LV) volumes, mass, stroke volume (SV), and ejection fraction (EF) in children. METHODS: A total of 19 healthy children (mean 10.6 +/- 2.8 years, 11 male and 9 female) were prospectively enrolled in this study. RT 3DE was performed using an ultrasound system to acquire full volume 3D dataset from the apical window with electrocardiographic triggering in 8 s/dataset. The images were processed offline using software. The LV endocardial and epicardial borders were traced manually to derive LV end-systolic volume, end-diastolic volume, mass, SV, and EF. Magnetic resonance imaging (MRI) studies were performed on a 1.5-T scanner using a breath hold 2-dimensional cine-FIESTA (fast imaging employing steady-state acquisition) sequence. RESULTS: All RT 3DE and MRI data were acquired successfully for analysis. Measurements of LV end-systolic volume, end-diastolic volume, mass, SV, and EF by RT 3DE correlated well by Pearson regression ( r = 0.86-0.97, P < .001) and agreed well by Bland-Altman analysis with MRI. The interobserver and intraobserver variability of RT 3DE measurements were less than 5%. CONCLUSIONS: This prospective study demonstrated that RT 3DE measurements of LV end-systolic volume, end-diastolic volume, mass, SV, and EF in children using rapid full volume acquisition strategy are feasible, accurate, and reproducible and are comparable with MRI measurements.     

Semiautomatic detection of left ventricular contours in contrast-enhanced echocardiographic images: Comparison with magnetic resonance imaging.

The aim of this study was to evaluate the accuracy of a semiautomatic contour detection method for left ventricular (LV) volume calculation in contrast-enhanced echocardiographic images. In 26 patients, LV volumes were automatically measured by magnetic resonance imaging and second harmonic echocardiography after intravenous Levovist administration. LV cavity edges were manually drawn and semiautomatically outlined using the active contour algorithm, improved by a nonlinear anisotropic filter; LV volumes were calculated by the modified Simpson's rule. Manual and semiautomatic analysis of echocardiographic images lasted 45 +/- 6 and 20 +/- 8 seconds, respectively. Contrast echocardiography volumes were smaller than those by magnetic resonance imaging (mean difference: 16 mL for manual and 18 mL for automatic analysis). LV volumes by echocardiography closely related with those by magnetic resonance imaging using both manual (r = 0.955) and semiautomatic (r = 0.945) analysis; the correlation was closer for end-systolic than for end-diastolic volumes. In conclusion, this method provides a fast measure of LV volumes in contrast-enhanced images while reducing operator dependency.     

Enhanced detection of left atrial spontaneous echo contrast by transthoracic harmonic imaging in mitral stenosis.

BACKGROUND: Spontaneous echo contrast (SEC) of the left atrium is associated with increased risk of thromboembolism in patients with mitral stenosis (MS). The determination of the presence and severity of left atrial (LA) SEC is of prognostic importance in these patients. Harmonic imaging (HI), a novel echocardiographic technique that differs from conventional fundamental imaging (FI) in that it involves transmitting ultrasound at one frequency and receiving at twice the transmitted frequency, produces better endocardial border definition and myocardial opacification. However, there are no data about its value for the detection of LA SEC. The purpose of this study was to investigate the utility of transthoracic noncontrast tissue HI in the detection of LA SEC in patients with MS. METHODS: Seventy-four consecutive patients with MS (49 women, mean age 51 years) underwent standard transthoracic echocardiography (TTE) in both HI and FI modes and transesophageal echocardiography (TEE) to determine the presence and severity of LA SEC. Left atrial SEC was graded by TEE as either mild (only seen at high gain) or severe (visible in the entire left atrium at normal gain control of the equipment). The control group comprised 30 patients randomly selected from patients who did not have LA SEC at the TEE examination. RESULTS: Atrial fibrillation was found in 46 patients (62.2%). The mean mitral valve area and mean mitral gradient were 1.0+/-0.3 cm(2) and 8.2+/-4.1 mm Hg, respectively. Nine patients (12.2%) had episodes of systemic embolism; 8 had stroke, and 1 had peripheral embolism. Left atrial thrombus was found in 11 patients (14.9%) by TEE. Left atrial SEC was present in all but one patient by TEE (mild in 35 patients, severe in 38). Fundamental imaging with TTE, however, revealed LA SEC in only 5 (6.8%) of the 73 patients. In contrast, with HI, LA SEC could be detected in 63 (86.3%) patients. In the detection of severe LA SEC, the sensitivities of FI and HI were 13.2% (5/38) and 100% (38/38), respectively. Left atrial SEC was not observed in control subjects by either FI or HI. CONCLUSIONS: Transthoracic HI significantly enhances the detection of LA SEC in patients with MS.