Three-Dimensional Cardiac Strain Imaging in Healthy Children Using RF-Data

In this study, a new radio-frequency (RF)-based, three-dimensional (3-D) strain imaging technique is introduced and applied to 3-D full volume ultrasound data of the heart of healthy children. Continuing advances in performance of transducers for 3-D ultrasound imaging have boosted research on 3-D strain imaging. In general, speckle tracking techniques are used for strain imaging. RF-based strain imaging has the potential to yield better performance than speckle- based methods because of the availability of phase information but such a system output is commercially not available. Furthermore, the relatively low frame rate of 3-D ultrasound data has limited broad application of RF-based cardiac strain imaging. In this study, the previously reported two-dimensional (2-D) strain methodology was extended to the third dimension. Three-dimensional RF-data were acquired in 13 healthy children, in the age range of 6-15 years, at a relatively low frame rate of 38-51 Hz. A 3-D, free-shape, coarse-to-fine displacement and strain estimation algorithm was applied to the RF-data. The heart was segmented using 3-D ellipsoid fitting. Strain was estimated in the radial (R), circumferential (C) and longitudinal directions (L). Our preliminary results reveal the applicability of the 3-D strain estimation technique on full volume 3-D RF-data. The technique enabled 3-D strain imaging of all three strain components. The average strains for all children were in the lateral wall R = 37 ± 10% (infero-lateral) and R = 32% ± 10% (antero-lateral), C = −9% ± 4% (antero-lateral) and C = −9% ± 4% (infero-lateral), L = −18% ± 6 % (antero-lateral) and L = −15% ± 4% (infero-lateral). In the septum, strains were found to be R = 24% ± 10% (antero-septal) and R = 13% ± 5% (infero-septal), C = −13% ± 5% (antero-septal) and −13% ± 5% (infero-septal) and L = −13% ± 3% (antero-septal) and L = −16% ± 5% (infero-septal). Strain in the anterior and inferior walls seemed underestimated, probably caused by the low (in-plane) resolution and poor image quality. The field-of-view as well as image quality were not always sufficient to image the entire left ventricle. It is concluded that 3-D strain imaging using RF-data is feasible, but validation with other modalities and with conventional 3-D speckle tracking techniques will be necessary.     

Worsening Left Ventricular Apical Peak Strain Early After Right Ventricular Pacing

We aimed to determine the effect of short-term right ventricle pacing (RV) on left ventricle (LV) mechanics using speckle tracking analysis. Conventional echocardiography and two-dimensional strain imaging was studied in 38 patients, mean age 81.6 ± 7.0, that had undergone pacemaker placement and were greater than 90% ventricularly paced. Mean duration of 24 months of RV pacing resulted in a significant decline in: LV apical diastolic rotational velocities (−59.0 ± −38.9 °/s to −28.0 ± −11.5 °/s, p 0.02), peak strain in the LV apical septal wall (−15.6 ± 8.5 to −13.5 ± 7.6, p 0.02), peak strain in LV apical lateral wall (−13.4 ± 8.9 to −11.4 ± 7.3, p 0.02). Thus, with only 24 months of RV pacing, there was a significant decline in peak strain of the LV apex and in apical diastolic rotational velocity that could account for eventual decline in left ventricular function.     

Regional Left Ventricular Myocardial Shortening in Normotensive Patients Late after Aortic Coarctation Repair - Normal or Impaired?

Despite successful repair of aortic coarctation (AoC), changes in the left ventricular (LV) regional myocardial function are reported. The aims of this study were (i) to determine LV regional longitudinal deformation in patients who underwent a repair of AoC, who were normotensive and who had normal LV global function; and (ii) to establish a potential correlation between the degree of residual narrowing in the descending aorta and the extent of LV regional deformation. We studied 22 normotensive patients aged 19–58 y (mean 32.6; SD±11.3). Maximal strain, ε (%), as well as peak systolic and early and late diastolic strain rates (SRs; s⁻¹), were obtained on the basis of speckle tracking. The data were compared with those obtained from sex and age-matched controls. Regional SRs were significantly reduced for the LV anterior wall during systole and early diastole –1.1 vs. –1.39; 1.41 vs. 1.86 s⁻¹, respectively; p<0.05. Transaortic maximal and mean gradients across the coarctation site correlated with ε and systolic SR obtained from the midsegment of the LV anterior wall. Despite a successful repair, absence of systemic hypertension and normal global LV function, regional deformation properties of the anterior LV wall were impaired. The degree of longitudinal impairment in this anatomical region correlated with the extent of residual narrowing. (E-mail: miroslaw.kowalski@ikard.pl)     

What is the Primary Source of Discordance in Strain Measurement Between Vendors: Imaging or Analysis?

Strain imaging quantifies myocardial deformation in both overt and subclinical myocardial diseases. Strain values have been shown to vary between vendors. The aim of this study was to investigate whether this variation reflects differences of image characteristics or analysis software. We enrolled 45 patients (age 54 ± 14 years, 26 males) who underwent two echocardiograms on the same day with two different commercially available ultrasound systems. Three apical views were analyzed by two vendor-specific and two digital imaging and communications in medicine (DICOM)-based software packages. The results were compared in two ways; comparison of global longitudinal strain (GLS) by nine different combinations of ultrasound systems and strain software, and comparison of strains by wall, view and global levels. Comparison of GLS between two vendor-specific software packages yielded poor correlation (ρ = 0.35). The use of the same software on the images from different vendors was concordant (ρ = 0.74 and 0.64; bias = 0.0 and −0.5). There were no significant differences in correlation coefficients among the comparisons with DICOM-based software. There was no significant difference in correlation coefficients among three views (4CV vs. 3CV, p = 0.44; 4CV vs. 2CV, p = 0.47). Comparison of walls showed the septum to have the best correlation (ρ = 0.73), and the posterior wall (ρ = 0.31; p = 0.005 vs. septum) had the worst. Use of the same software to measure strain in images from different vendors minimizes the variation of GLS. Post-processing is the most important determinant in inter-vendor variation, with differences in acquisition having a small effect. These findings should be examined and confirmed with other combinations of ultrasound machines and deformation software.     

正常人心肌应变及应变率定量分析

目的 定量研究我国成年人心肌应变及应变率的正常值范围、心肌各节段之间的差异，以及与年龄和性别的关系。方法 应用GE Vivid 7超声仪及Q-analyze软件对50例健康者左右心室心肌各节段进行应变和应变率定量分析。结果 左室基底段、中间段和心尖段的应变和应变率依次递减，基底段最大，心尖段最小。左室基底段室间隔、前壁、后壁、下壁和侧壁的应变和应变率差异无显著性意义。右室中间段的应变和应变率最大，右室基底段的应变大于左室，右室中间段和心尖段的应变和应变率测量值均明显大于左室，性别和年龄对左右心室肌应变和应变率的影响不大。结论 应变或应变率成像能够定量分析局部心肌的变形，为临床评价心功能提供了又一有效工具。     

速度向量成像技术评价右心室长轴收缩功能的实验研究

目的 探讨速度向量成像(VVI)对右心室功能检测的可行性及准确性.方法 采集7只实验犬在3种不同心肌收缩功能状态下的右室长轴VVI图像,同步记录右室收缩期最大压力上升速率(dp/dt_(max)),分别测量右室游离壁和室间隔基底段、中间段、心尖段收缩期峰值速度(V)、峰值应变(S)和峰值应变率(SR),并与右心导管检查测定的右室dp/dt_(max)作相关分析.结果 应用多巴酚丁胺后右室应变和应变率明显增加.在酒石酸美托洛尔作用下右室各节段S、SR明显减低.相关分析表明:右室的平均S、SR与dp/dt_(max)有明显的相关性(r=0.79,0.75;P<0.01),右室游离壁基底段的S和SR与dp/dt_(max)的相关性高于其他节段(r=0.83,0.78;P<0.01).结论 VVI可定量估测右室长轴收缩功能,右室游离壁基底段收缩期S、SR是无创性估测右室长轴收缩功能的良好指标.     

斑点追踪成像评价冠心病患者左心室舒张期形变及解旋运动

目的 观察应用斑点追踪成像(STI)技术评价冠心病患者左心室舒张期形变及解旋运动的价值.方法 随机选择临床拟诊为冠心病患者117例,根据冠状动脉造影或冠状动脉CTA结果分成心肌梗死组(60例)、心肌缺血组(31例)及对照组(26例).常规测量二尖瓣口舒张期血流速度(E、A)及二尖瓣后瓣环的运动速度(E'、A'),计算E/E'.运用STI技术测量左心室舒张期各方向应变率、解旋率.结果 与心肌缺血组、对照组相比,心肌梗死组E/E'增大,纵向、径向、圆周方向舒张早期及晚期应变率、解旋率减低(P＜0.001);与对照组比较,心肌缺血组仅解旋率、舒张早期纵向应变率、舒张早期与晚期圆周方向应变率减低,差异均有统计学意义(P均＜0.05).结论 STI技术能有效评价冠心病患者左心室舒张期各方向的形变及解旋运动;与常规超声参数相比较,左心室舒张期径向、圆周方向应变率及解旋率能更早地反映心肌缺血患者左心室舒张功能的减低.     

Layer-Specific Radiofrequency Ultrasound-Based Strain Analysis in a Porcine Model of Ischemic Cardiomyopathy Validated by a Geometric Model

Local layer-specific myocardial deformation after myocardial infarction (MI) has not been studied extensively although the sub-endocardium is more vulnerable to ischemia and interstitial fibrosis deposition. Radiofrequency (RF) ultrasound-based analysis could provide superior layer-specific radial strain estimation compared with clinically available deformation imaging techniques. In this study, we used RF-based myocardial deformation measurements to investigate layer-specific differences between healthy and damaged myocardium in a porcine model of chronic MI. RF data were acquired epicardially in healthy (n = 21) and infarcted (n = 5) regions of a porcine chronic MI model 12 wk post-MI. Radial and longitudinal strains were estimated in the sub-endocardial, mid-wall and sub-epicardial layers of the left ventricle. Collagen content was quantified in three layers of healthy and infarcted regions in five pigs. An analytical geometric model of the left ventricle was used to theoretically underpin the radial deformation estimated in different myocardial layers. Means ± standard errors of the peak radial and longitudinal strain estimates of the sub-endocardial, mid-wall and sub-epicardial layers of the healthy and infarcted tissue were: 82.7 ± 5.2% versus 39.9 ± 10.8% (p = 0.002), 63.6 ± 3.3% versus 38.8 ± 7.7% (p = 0.004) and 34.3 ± 3.0% versus 35.1 ± 5.2% (p = 0.9), respectively. The radial strain gradient between the sub-endocardium and the sub-epicardium had decreased 12 wk after MI, and histologic examination revealed the greatest increases in collagen in the sub-endocardial and mid-wall layers. Comparable normal peak radial strain values were found by geometric modeling when input values were derived from the in vivo measurements and literature. In conclusion, the estimated strain values are realistic and indicate that sub-endocardial radial strain in healthy tissue can amount to 80%. This high value can be explained by the cardiac geometry, as was illustrated by geometric modeling. After MI, strain values were decreased and collagen content was increased in the sub-endocardial and mid-wall layers. Layer-specific peak radial strain can be assessed by RF strain estimation and clearly differs between healthy and infarcted tissue. Although the relationship between tissue stiffness and tissue strain is not strictly local, this novel technique provides a valuable way to assess layer-specific regional cardiac function in a variety of myocardial diseases.     

速度向量成像估测正常儿童心室长轴心肌节段功能的研究

目的 通过速度向量成像（VVI）探索正常儿童左右心室长轴各节段运动的变化规律。方法采集44名健康儿童心尖四腔切面,Syngo Workplace软件测定各节段的速度、应变、应变率和位移,分析VVI参数与年龄之间的关系。结果 ①正常儿童左右心室的速度、应变、应变率和位移从基底段到心尖段依次降低。右室游离壁的速度、位移、应变和应变率明显高于左室游离壁和室间隔的相应节段（P〈0．05）。②左室游离壁基底段和中间段的速度与年龄具有较好的相关性（r=0．436,P〈0．01;r=0．464,P〈0．01）;右室游离壁的各节段速度与年龄无相关性（P〉0．05）。③左右室的游离壁基底段的应变与年龄具有较好的相关性（r=0．478,P〈0．Ol;r：0．497,P〈0．01）;右室游离璧中间段的应变率与年龄有较好的相关性（r=0．520,P〈0．01）。结论应变和应变率受到年龄的影响,因此在估测局部心肌节段功能时应考虑到该影响。     

The Cardiac State Diagram as a Novel Approach for the Evaluation of Pre- and Post-ejection Phases of the Cardiac Cycle in Asphyxiated Fetal Lambs

The aim of this study was to investigate myocardial wall motion using echocardiography and color-coded tissue velocity imaging and to generate a cardiac state diagram for evaluation of the duration of the pre- and post-ejection phases in asphyxiated fetal lambs. Six near-term lambs were partly exteriorized and brought to cardiac arrest through asphyxia. Echocardiography measurements were recorded simultaneously with arterial blood sampling for lactate and blood gases. All fetal lambs exhibited prolongation of the pre- and post-ejection phases at the time when the most pronounced changes in lactate concentration and pH occurred. The mean change in duration of the pre- and post-ejection phases for all fetal lambs was 36 ± 7 ms (p < 0.002) and 77 ± 17 ms (p < 0.019), respectively, and the percentage change was 50% (p < 0.001) and 38% (p < 0.049), respectively. As asphyxia progressed in fetal lambs, the duration of the pre- and post-ejection phases increased. The cardiac state diagram has the potential to be a comprehensible tool for detecting fetal asphyxia.     

Bidirectional Ultrasound Elastographic Imaging Framework for Non-invasive Assessment of the Non-linear Behavior of a Physiologically Pressurized Artery

Studies of non-destructive bidirectional ultrasound assessment of non-linear mechanical behavior of the artery are scarce in the literature. We hereby propose derivation of a strain–shear modulus relationship as a new graphical diagnostic index using an ultrasound elastographic imaging framework, which encompasses our in-house bidirectional vascular guided wave imaging (VGWI) and ultrasound strain imaging (USI). This framework is used to assess arterial non-linearity in two orthogonal (i.e., longitudinal and circumferential) directions in the absence of non-invasive pressure measurement. Bidirectional VGWI estimates longitudinal (μ_L) and transverse (μ_T) shear moduli, whereas USI estimates radial strain (?_r). Vessel-mimicking phantoms (with and without longitudinal pre-stretch) and in vitro porcine aortas under static and/or dynamic physiologic intraluminal pressure loads were examined. ?_r was found to be a suitable alternative to intraluminal pressure for representation of cyclic loading on the artery wall. Results revealed that μ_T values of all samples examined increased non-linearly with ε_r magnitude and more drastically than μ_L, whereas μ_L values of only the pre-stretched phantoms and aortas increased with ?_r magnitude. As a new graphical representation of arterial non-linearity and function, strain–shear modulus loops derived by the proposed framework over two consecutive dynamic loading cycles differentiated sample pre-conditions and corroborated direction-dependent non-linear mechanical behaviors of the aorta with high estimation repeatability.     

Age- and gender-related normal left ventricular deformation assessed by cardiovascular magnetic resonance feature tracking

Background

Assessment of left (LV) ventricular function is one of the most important tasks of cardiovascular magnetic resonance (CMR). Impairment of LV deformation is a strong predictor of cardiovascular outcome in various cardiac diseases like ischemic heart disease or cardiomyopathies. The aim of the study was to provide reference values for myocardial deformation derived from the CMR feature tracking imaging (FTI) algorithm in a reference population of healthy volunteers.

Methods

FTI was applied to standard short axis and 2-, 3- and 4-chamber views of vector-ECG gated CMR cine SSFP sequences of 150 strictly selected healthy volunteers (75 male/female) of three age tertiles (mean age 45.8yrs). Global peak and mean radial, circumferential and longitudinal endo- and myocardial systolic strain values as well as early diastolic strain rates were measured using FTI within a standard protocol on a 1.5T whole body MR scanner.

Results

Global peak systolic values were 36.3 ± 8.7% for radial, −27.2 ± 4.0% for endocardial circumferential, −21.3 ± 3.3% for myocardial circumferential, −23.4 ± 3.4% for endocardial longitudinal and −21.6 ± 3.2% for myocardial longitudinal strain. Global peak values were -2.1 ± 0.5s⁻¹ for radial, 2.1 ± 0.6s⁻¹ for circumferential endocardial, 1.7 ± 0.5s⁻¹ for circumferential myocardial, 1.8 (1.5-2.2)s⁻¹ for longitudinal endocardial, 1.6 (1.4-2.0)s⁻¹ for longitudinal myocardial early diastolic strain rates. Men showed a higher radial strain than women whereas the circumferential and longitudinal strains were lower resulting in less negative values. Circumferential and longitudinal strain rates were significantly higher in female subjects. Radial strain increased significantly with age whereas the diastolic function measured by the radial, circumferential and longitudinal strain rates showed a decrease.The coefficients of variation determined in ten further subjects, who underwent two CMR examinations within 12 days, were −4.8% for circumferential and −4.5% for longitudinal endocardial mean strains.

Conclusions

Myocardial deformation analysis using FTI is a novel technique and robust when applied to standard cine CMR images providing the possibility of a reliable, objective quantification of global LV deformation. Since strain values and strain rates differed partly between genders as well as between age groups, the application of specific reference values as provided by this study is recommendable.     

应变及应变率成像评价酒精性心肌病右心室纵向心肌局部舒缩功能的价值

目的探讨应变及应变率成像技术评价酒精性心肌病（ACM）右心室纵向心肌局部舒缩功能的价值。方法酒精性心肌病患者30例（AcM组）和健康志愿者30例（正常对照组）,分别检测两组常规超声参数、应变及应变率参数。应变及应变率参数通过心尖四腔切面右心室游离壁3个节段的应变及应变率曲线获取,并测量每一曲线上的收缩期和舒张期峰值。收缩期参数包括：右心室游离壁基底段、中间段和心尖段收缩期应变峰值（S）、收缩期应变率峰值（SRs）;舒张期参数包括：舒张早期应变率峰值（SRe）和舒张晚期应变率峰值（SRa）。结果ACM组右心室前后径较正常对照组显著增厚,差异有统计学意义（P〈0．05）,但右心室射血分数略微减低,差异无统计学意义。ACM组右心室游离壁基底段、中间段和心尖段s、SRs、SRe和SRa与对照组比较均显著减低,差异均有统计学意义（P〈0．05）。结论应变及应变率成像可作为评价ACM右心室纵向心肌局部舒缩功能的一种无创的、有效的新方法。     

二维应变与组织多普勒评价心肌应变的对比研究

目的评价新的超声软件二维应变（2DS）在定量心肌应变与应变率中的价值。 方法采集18例正常人与15例前壁心肌梗死（心梗）患者心尖二腔长轴二维灰阶与组织多普勒（TVI）动态图，用2DS与TVI2种方法分别测量各节段心肌长轴峰值收缩速度（Vs）、峰值收缩应变（S）及应变率（Sr）并做对比；采集乳头肌水平短轴二维灰阶动态图，应用2DS测量各节段心肌径向Vs、S、Sr，对比正常与梗死节段心肌测值。 结果2DS所测正常与心梗患者的长轴Vs、S及Sr均与TVI测值无差异（P〉0．05）；2DS所测左室乳头肌水平各段心肌的径向Vs、S及Sr在正常组无差异（P〉0．05），而心梗组的梗死节段测值明显低于非梗死节段（P〈0．01），并明显低于正常组相应节段（P〈0．01）。 结论2DS可准确定量节段心肌运动速度、应变与应变率，可通过测量心肌长轴与径向的上述参数用于评价心肌功能。     

Longitudinal two-dimensional strain rate imaging: a potential approach to predict the response to cardiac resynchronization therapy

The purpose of our study was to test the usefulness of speckle-tracking two-dimensional echocardiography (in particular longitudinal strain and strain rate) in predicting the response to cardiac resynchronization therapy. The standard approach has been tissue Doppler-based echocardiographic imaging (TDI) has initially showed promising results in small clinical trials. However, recent larger, prospective randomized clinical trials (PROSPECT, ReTHINK) showed that TDI is inadequate to predict response from CRT in patients with heart failure. Altogether, these data suggest the need to identify alternative echocardiographic parameters to predict the response to CRT. We included 53 patients suffering from heart failure, who received CRT. TDI and two-dimensional speckle tracking imaging in addition to standard echocardiography were performed prior to CRT. The standard deviation of time to peak longitudinal strain in 12 LV segments (Tstrain-SD) and the standard deviation of time to the end of longitudinal systolic strain rate in six basal LV segments (Tsr-SD) were calculated. Standard echocardiography was performed 6 months after CRT. Patients were classified as echocardiographic responders if the LV end-systolic volume was reduced >15% compared with baseline volumes. No significant difference was seen in baseline Ts-SD, and Tstrain-SD between non-responders and responders. However, the Tsr-SD was much higher in responders than non-responders (95.9 ± 33.0% vs. 64.8 ± 39.6%, P < 0.05), and it showed a sensitivity of 73% and specificity of 65% for the defined echocardiographic response using a cutoff value of 70.7 ms. Our study demonstrates that longitudinal two-dimensional strain rate imaging is a promising potential echocardiographic parameter to predict benefit from CRT in patients with heart failure. This hypothesis needs to be further tested in prospective randomized clinical trials.     

Can natural strain and strain rate quantify regional myocardial deformation? A study in healthy subjects

Strain rate (SR) and strain (epsilon) have been proposed as new ultrasound (US) indices for quantifying regional wall deformation, and can be measured from color Doppler myocardial data by determining the local spatial velocity gradient. The aim of this study was to define normal regional SR/epsilon values for both radial and longitudinal myocardial deformation. SR/epsilon profiles were obtained from 40 healthy volunteers. For radial deformation, posterior left ventricular (LV) wall SR/epsilon were calculated. For longitudinal, they were determined for basal, mid- and apical segments of the 1. septum; 2. lateral, 3. posterior and 4. anterior LV walls and for the 5. right ventricular (RV) lateral wall. SR/epsilon values describing radial deformation were higher than the corresponding SR/epsilon values obtained for longitudinal deformation. Longitudinal SR/epsilon were homogeneous throughout the septum and all LV walls. This was in contrast to the normal base-apex velocity gradient. The RV segmental SR/epsilon values were higher than those obtained from the corresponding LV wall and inhomogeneous (higher in the apical segments). SR/epsilon imaging appears to be a robust technique for quantifying regional myocardial deformation.     

速度向量成像技术对正常人颈总动脉管壁形变特征的初步研究

目的 应用速度向量成像（VVI） 技术初步研究正常人颈总动脉管壁形变特征.方法 超声采集并动态存储47 例正常人颈总动脉长轴及短轴二维灰阶图像.应用VVI技术观察颈总动脉管壁纵向和周向应变及应变率曲线,以同步记录心电图为时相对照,测量颈总动脉管壁收缩期纵向和周向峰值应变及应变率.结果 正常人颈总动脉后壁近心点、中点及远心点间的收缩期纵向峰值应变及峰值应变率差异无统计学意义（P〉0.05）;正常人颈总动脉短轴管壁各节段间收缩期周向峰值应变及应变率差异无统计学意义（P〉0.05）.结论 正常人颈总动脉管壁收缩期纵向峰值应变及应变率沿颈总动脉后壁长轴分布基本均匀,收缩期周向峰值应变及应变率在颈总动脉管壁短轴方向分布亦基本均匀.     

速度向量成像技术检测胎儿心肌节段功能的临床研究

目的 探讨速度向量成像技术检测正常胎儿左室心肌节段功能的临床应用价值.方法 应用Sequoia 512彩色多普勒超声诊断系统,在四腔心观采集151例孕18～40周的正常胎儿超声图像,用心肌速度向量软件分析左室后间隔和侧壁心肌长轴方向收缩期和舒张期峰值速度、应变及应变率.结果 各组基底段至心尖段心肌速度逐渐减低(P＜0.01),各节段心肌应变和应变率差异无统计学意义(P＞0.05).收缩期和舒张期峰值速度随孕周的增加而增大(P＜0.01),而应变、应变率随孕周增加差异无统计学意义(P＞0.05).结论 速度向量成像技术不受声束角度、胎方位、胎心率的影响,能够无创客观地定量评价胎儿左室长轴心肌节段舒缩功能,为临床检测胎儿心脏节段功能提供了又一有效方法 .     

Experimental assessment of a new research tool for the estimation of two-dimensional myocardial strain

One-dimensional strain imaging has been shown to be angle dependent. To address this problem, a new methodology, 2D-strain, has become available. The aim of this study was to validate this methodology in an in vivo set-up against sonomicrometry. In five open chest sheep, ultrasound gray-scale images were acquired of the inferolateral wall from two different angles. The longitudinal and radial strain components were simultaneously extracted using the novel 2D-strain methodology. The extracted values were compared with sonomicrometry using Bland-Altman statistics and correlation coefficients. A good agreement was found for the longitudinal strain component, while, for the radial strain estimates, the accuracy was less. 2D-strain is a fast and accurate tool to assess longitudinal strain from apical views. Further improvements are needed for the method to be sufficiently accurate in estimating the deformation perpendicular or close to perpendicular to the ultrasound beam.     

应变率成像对正常青年人左室心肌舒缩变形的定量研究

目的应用应变率成像(SRI)技术检测正常青年人左室壁应变率,分析正常左室心肌舒缩变形特点。方法应用SRI对31例正常青年人左室前间隔与后壁径向、各室壁节段纵向收缩期、舒张早期和房缩期应变率SRs、SRe及SRA进行测定分析。结果左室径向SRs、SRe及SRA基本表现为后壁显著大于前间隔,后壁的SRs、SRe从基底向心尖依次递减,SRA各水平之间无显著性差异。各室壁纵向SRs、SRe及SRA不同水平之间基本无显著性差异,即心肌应变率(SR)呈较均衡分布;基底部不同室壁之间SRs、SRe有显著性差异,室间隔最小,余水平各室壁SRs、SRe无显著性差异;各室壁的SRA仅中段有统计学差异,后、下壁低于其它室壁。结论SRI能够定量分析局部室壁径向与纵向舒缩变形,是一种临床无创评价局部心肌功能的新方法。