Speckle Tracking Technique Research Articles

Analysis of Rayleigh-Lamb Modes in Soft-solids with Application to Surface Wave Elastography

The goal of Surface Wave Elastography (SE) techniques is to estimate the shear elasticity of the sample by measuring the surface wave speed. In SE the thickness of the sample is often assumed to be infinite, in this way, the surface wave speed is directly linked to the sample's shear elasticity. However for many applications this assumption is not true. In this work, we study experimentally the Rayleigh-Lamb modes in soft solids of finite thickness to explore the optimal conditions for SWE. Experiments were carried out in three tissue mimicking phantoms of different thicknesses (10mm, 20mm and 60mm) and same shear elasticity. The surface waves were generated at the surface of the phantom using piston attached to a mechanical vibrator. The central frequency of the excitation was varied between 60Hz to 160Hz. One component of the displacement field generated by the piston was measured at the surface and in the bulk of the sample trough a standard speckle tracking technique using a 256 element, 7.5MHz central frequency linear array and an ultrasound ultrafast electronics. Finally, by measuring the phase velocity at each excitation frequency, velocity dispersion curves were obtained for each phantom. The results show that instead of a Rayleigh wave, zero order symmetric (S0) and antisymmetric (A0) Lamb modes are excited with this type of source. Moreover, in this study we show that due to the near field effects of the source, which are appreciable only in soft solids at low frequencies, both Lamb modes are separable in time and space. We show that while the Ao mode dominates close the source, the S0 mode dominates far away.

A Novel Speckle Tracking Technique for Investigating Regional Motion of the Carotid Wall: Spatio-temporal Variation in Distension Associates with Presence of Calcified Plaque

Arterial calcification may lead to regional variation in distension imposing stresses on the arterial wall that predispose to plaque rupture. The objective of this study was to use a novel speckle tracking method to investigate regional motion of the carotid wall and to determine whether this relates to subclinical disease. Measurements were obtained on 256 subjects from the Twins UK cohort (mean ± SD age 62 ± 10.2 years). The left carotid was imaged for an assessment of plaque and calcification. Speckle-tracking was then used to measure regional circumferential strain of the left common carotid in 6 separate 60° segments of the circumference of the arterial wall in a plaque free plane of the common carotid approximately 1 cm proximal to the bifurcation. Regional variation in circumferential strain around the circumference of the arterial wall was characterized by the standard deviation of circumferential strain and that of the time from onset of systole to peak circumferential strain in each segment. Spatio-temporal variation in circumferential strain characterized by variation in the time to peak circumferential strain was associated with age and presence of calcified plaque (regression coefficients 0.73 units/year and 14.2 increase for presence of calcified plaque, each P<0.001) independent of other confounding factors and of other measures of arterial wall damage such as carotid intima-media thickening, carotid distensibility and carotid-femoral pulse wave velocity. Arterial ageing and calcification are associated with spatio-temporal variation in distension of the carotid artery.

Abstract 12717: Improvement of Longitudinal Function is Closely Related to Reverse Remodeling in Cardiac Resynchronization Therapy

Introduction: Response to cardiac resynchronization therapy (CRT) is often defined as reverse remodeling as a reduction in left ventricular (LV) end systolic volume (ESV). How myocardial mechanics are affected by biventricular pacing is not fully clarified. We tested the hypothesis that longitudinal and circumferential function are affected differently by biventricular pacing. Methods: Echocardiography (two dimensional) was performed before and 6 months after CRT implantation in heart failure patients with LV ejection fraction (EF) ≤ 35% and QRS ≥ 120 ms. LV function was assessed by EF and by global longitudinal (GLS) and global circumferential (GCS) strain from 16 LV segments by speckle tracking technique. CRT responders were defined as patients with reverse remodeling with a reduction in ESV ≥ 15% at 6 months. Results: We included 138 heart failure patients (65±10 years, 22% women, NYHA functional class 2.8±0.4, 48% ischemic cardiomyopathy). In the total population, GLS did not change (-8.5±3.9% to -8.9±4.7%, p=0.31) after 6 months with biventricular pacing, while GCS (-11.3±3.3% to -14.2±4.5%, p&lt;0.001) and EF (27±9% to 36±12%, p&lt;0.001) improved. Analyzing CRT responders (62%) and non-responders separately, GLS improved in responders (-8.4±3.8% to -9.5±3.8%, p=0.02) but not in non-responders (-8.7±4.1% to -7.9±4.5%, p=0.30) (Figure). GCS improved in both groups (-11.3±3.0% to -15.0±4.3%, p&lt;0.001 and -11.4±3.8% to 13.0±4.7%, p=0.01). ΔGLS was a predictor of CRT response (OR 0.84 (0.75-0.95), p=0.009) and of ΔESV (1.62 (0.45-2.79), p=0.007) independently of ΔGCS. Conclusions: Biventricular pacing by CRT generally induced less changes in GLS than in GCS and EF. Importantly, GLS improved only in CRT responders with reverse remodeling. We suggest that reverse remodeling is more dependent on improved longitudinal function than circumferential function.

Tissue Doppler imaging optical flow (TDIOF): a combined B-mode and tissue Doppler approach for cardiac motion estimation in echocardiographic images.

The quantitative analysis of cardiac motion from echocardiographic images helps clinicians in the diagnosis and therapy of patients suffering from heart disease. Quantitative analysis is usually based on tissue Doppler imaging (TDI) or speckle tracking. These methods are based on two techniques which to a large degree are independent: the Doppler phenomenon and image sequence processing. Herein, to increase the accuracy of the speckle tracking technique and to cope with the angle dependence of TDI, a combined approach dubbed tissue Doppler imaging optical flow (TDIOF) is proposed. TDIOF is formulated based on the combination of B-mode and Doppler energy terms minimized using algebraic equations and is validated on simulated images, and in vivo data. It was observed that the additional Doppler term is able to increase the accuracy of speckle tracking, compared to two popular motion estimation and speckle tracking techniques (Horn-Schunck and block matching methods). This observation was more pronounced when noise was present. The magnitude and angular error for TDIOF applied to simulated images, when comparing estimated motion with ground-truth motion, were 15% and 9.2°/frame, respectively. As an additional validation, echocardiography-derived strains were compared to tagged MRI-derived myocardial strains in the same subjects. The correlation coefficient (r) between the TDIOF-derived radial strains and tagged MRI-derived radial strains value was 0.83 (P < 0.001). The correlation coefficient ( r) for the TDIOF-derived circumferential strains compared to the tagged MRI-derived circumferential strains was 0.86 (P < 0.001). The comparison of TDIOF-derived and block matching speckle tracking and Horn-Schunck optical flow strain values using student t-test demonstrated superiority of TDIOF (95% confidence interval, P < 0.001).

Can serum tenascin-c be used as a marker of inflammation in patients with dilated cardiomyopathy?

Tenascin-C (TN-C), an extracellular matrix glycoprotein, is specifically expressed at high levels during embryonic development, but not in the adult heart. TN-C reappears at sites of inflammatory tissue remodeling or wound healing under various pathologic conditions, such as acute myocardial infarction, acute myocarditis,and some cases of cardiomyopathy. Therefore, the expression of TN-C might be useful for detecting the clinical characteristics of, and ventricular remodeling in, dilated cardiomyopathy (DCM). To evaluate the role of TN-C as a sensitive marker for active inflammation in children with newly onset DCM This case controlled study included 24 patients aged from 6 to 72 months with a mean age 45.19 ± 11.03 compared to 20 age and sex matched healthy children. The subjects were divided into 3 groups. Group 1: included twelve patients with acute onset DCM, (less than 6 months duration) ,Group 2: included twelve patients with established chronic DCM, (more than 6 months duration) and Group 3: twenty (20) healthy age and sex matched children served as control group: all studied patients were subjected to full medical history ,thorough clinical examination. Serum Tenascin-C , chest X-ray and echocardiography using conventional parameters as M-mode, 2D, CW Doppler and 2D speckle tracking technique. The 2D Speckle Tracking data showed that the patients group had lower Global peak Strain Longitudinal Apical long axis( G SL ap lax), G peak SL apical 4 chamber(a4c), G peak SL apical 2 chamber(a2c) and G peak SL average with highly statistical significant difference using T -test. Moreover the global echocariographic assessment showed that acute cases had lower G peak SL ap lax, G peak SL ap4c, G peak SL a2c, G peak SL avg, than the chronic cases with a highly statistically significant difference ( P < 0.001). These data confirm furthermore the global affection of the acute DCM cases than the chronic cases.Our study showed highly significant statistical elevation of serum Tenascin-c among DCM patients than in controls ( P value <0.001). It also showed that acute cases had statistically significant higher serum levels of Tenascin-c than chronic cases ( P value <0.001). This indicates that serum Tenascin-C level is elevated in cases of acute dilated cardiomyopathy and is decreased significantly in chronic DCM. And showed that circulating tenascin-C is generally associated with the severity of left ventricular dysfunction. Serum-Tenascin Level was significantly increased in patients with idiopathic dilated cardiomyopathies. This increase was noted in acute and chronic cases, with significant difference between both being higher in the acute cases, and associated with the severity of heart failure and the LV dysfunction as detected by 2D speckle tracking echocardiography.

Left Atrium: Still a Neglected Chamber?

It is widely recognized that an effective cardiovascular system is based upon both a good ventricular-vascular interplay and a good ventricular-atrial interaction in all the phases of cardiac cycle. Moreover, left atrial dysfunction has been identified to be contributory in several common cardiovascular conditions, such as heart failure, atrial fibrillation and valvular heart disease; for instance, a good anatomical and functional assessment of this cardiac chamber is mandatory. For this purpose a multimodality imaging approach – including two-dimensional and three-dimensional echocardiography, speckle tracking technique, cardiac computed tomography (CT) and cardiac magnetic resonance (CMR) – is the most suitable one to achieve the best functional and anatomical evaluation of this cardiac chamber.

Biaxial mechanical testing of posterior sclera using high-resolution ultrasound speckle tracking for strain measurements

This study aimed to characterize the mechanical responses of the sclera, the white outer coat of the eye, under equal-biaxial loading with unrestricted shear. An ultrasound speckle tracking technique was used to measure tissue deformation through sample thickness, expanding the capabilities of surface strain techniques. Eight porcine scleral samples were tested within 72h postmortem. High resolution ultrasound scans of scleral cross-sections along the two loading axes were acquired at 25 consecutive biaxial load levels. An additional repeat of the biaxial loading cycle was performed to measure a third normal strain emulating a strain gage rosette for calculating the in-plane shear. The repeatability of the strain measurements during identical biaxial ramps was evaluated. A correlation-based ultrasound speckle tracking algorithm was used to compute the displacement field and determine the distributive strains in the sample cross-sections. A Fung type constitutive model including a shear term was used to determine the material constants of each individual specimen by fitting the model parameters to the experimental stress–strain data. A non-linear stress–strain response was observed in all samples. The meridian direction had significantly larger strains than that of the circumferential direction during equal-biaxial loadings (P's<0.05). The stiffness along the two directions was also significantly different (P=0.02) but highly correlated (R2=0.8). These results showed that the mechanical properties of the porcine sclera were nonlinear and anisotropic under biaxial loading. This work has also demonstrated the feasibility of using ultrasound speckle tracking for strain measurements during mechanical testing.

Improving the accuracy and stability of the speckle tracking technique in processing images obtained in echocardiographic examinations

Tracking techniques are widely used in the processing of images in ultrasound cardiological examinations. One of the applications of this method consists in the automatic delineation of the internal and external borders of the cardiac chambers for all frames of the source video. However, owing to significant deformations of the image, which are often observed in practice, a loss of tracking can occur. We propose a new technique to improve the accuracy and stability of the classical speckle tracking algorithm taking into account the special features of the video picture of the ultrasound examination of the heart. The method is based on an assessment of the nature of the movement of regions of the heart wall using the obtained images, prediction of the position of the speckle in the next frame, and using this information to calculate the weighted function of mutual correlation used to determine the exact position of a speckle. Testing of the proposed method on the actual clinical results of echocardiographic examinations has demonstrated its high stability and accuracy, which is sufficient for practical application in ultrasound diagnostics.

Impact of pre-excitation syndrome on left ventricular systolic function and cardiac synchronization assessed by tissue Doppler imaging and speckle tracking techniques

Background The pathogenic mechanism for the development of left ventricular (LV) dysfunction in patients with asymptomatic pre-excitation syndrome has not yet been fully elucidated. We sought to assess the impact of pre-excitation on LV systolic function and whether the use of tissue Doppler imaging (TDI) and speckle tracking is more helpful in detection of the LV dyssynchrony than conventional echo parameters in these patients. Methods This observational case control study was carried out on adults with manifest pre-excitation syndromes. A detailed echocardiographic assessment was performed including TDI and speckle tracking examination. Results Our study patients were divided into two groups, group 1: with lateral accessory pathways (AP) (23 patients aged 31.65 ± 6.5 years), group 2: with septal AP (25 patients, 34.84 ± 10.8 years). Echocardiography showed a lower ejection fraction (EF) in group 2 than in group 1 (0.60 ± 0.07% in group 1 vs. 0.50 ± 0.08% in group 2, p = 0.000). The radial strain dyssynchrony index was higher in group 2 than in group 1 (58.78 ± 33.47 vs. 139.52 ± 21.14 ms; p < 0.0001) with a significant negative correlation with EF (r = −0.8, p = 0.000). Dyssynchrony detection was higher using speckle tracking technique than M mode/Doppler methods (p = 0.006). Conclusion Patients with pre-excitation syndrome may have depressed LV function unrelated to tachyarrhythmia, especially if the AP has a septal location. This dysfunction may be associated with the LV dyssynchronus contraction caused by pre-excitation. The use of TDI and speckle tracking echocardiographic techniques may be associated with an increase in the identification of manifest pre-excitation patients with significant LV dyssynchrony.

Alteration in the global and regional myocardial strain patterns in patients with inferior ST-elevation myocardial infarction prior to and after percutaneous coronary intervention

This study was designed to investigate the alteration on regional and global strains of left and right ventricle (LV, RV) in patients with inferior wall ST-elevation myocardial infarction (MI). Patients were examined prior to and 7 days after percutaneous coronary intervention (PCI) using speckle-tracking techniques. Fifty-nine patients (36 males and 23 females) and 60 healthy controls (40 males and 20 females) were enrolled in this study. LV strains were measured from three deformations including radial, longitudinal, and circumferential. RV strains were measured only from the longitudinal. Three types of LV global strains were significantly lower in patients than in controls, and LV global longitudinal and circumferential strains were moderately improved by PCI. The LV regional strains reduced significantly in most of the segments (87%) after inferior wall MI and over half of them (60%) were improved by PCI. The RV global longitudinal strains were significantly lower in patients than in controls, and they were moderately improved by PCI. In conclusion, the regional and global strains of LV and RV were reduced in patients with inferior wall MI, and PCI most markedly improved the global strains and regional strains of the infarct and adjacent myocardium in the apical and middle levels.

Global longitudinal strain at baseline is a marker of ventricular arrhythmias in patients with cardiac resynchronization therapy

Purpose: Pre-implant predictors of ventricular arrhythmia (VA) are not fully investigated in patients receiving cardiac resynchronization therapy (CRT). A sensitive marker of VA in these patients will be valuable for correct choice of CRT type, with or without a cardioverter defibrillator (CRT-D). We aimed to explore if assessment of left ventricular (LV) function by speckle tracking strain echocardiography could predict VA in heart failure patients eligible for CRT. Methods: We investigated heart failure patients with left bundle branch block treated with CRT. Echocardiography was performed before CRT-implantation and after 6 months (CRT turned on). Systolic myocardial function was assessed as LV ejection fraction (EF) by Simpson biplane method and global longitudinal strain (GLS) using speckle tracking technique. VA was defined as non-sustained ventricular tachycardia or appropriate anti-tachycardia pacing or shock during 2 years follow-up from CRT-implantation. Results: We included 73 heart failure patients (NYHA class 2.8±0.4, EF 28±9%), 44% with ischemic and 56% with non-ischemic dilated cardiomyopathy. VA was documented in 19 patients (26%). LV function by GLS was lower in patients with VA compared to those without VA during 2 years follow-up, both at baseline (-6.3±4 vs. -8.8±4%, p=0.03) and at 6 months (-5.9±6 vs. -9.7±5%, p=0.01). EF was not a marker of VA during 2 years follow-up, neither at baseline (26±10 vs. 29±9%, p=0.26) nor at 6 months (36±8 vs. 41±12%, p=0.18). Conclusions: In our study LV function by GLS was a marker of subsequent VA in heart failure patients receiving CRT, while EF was not. Our results suggest that EF measurement alone is not adequate for risk prediction of VA. Assessment of GLS might be considered as part of decision making for correct choice of CRT.

Negative effects of trastuzumab adjuvant chemotherapy on cardiac mechanics. role of specific myocardial layers

Background: Trastuzumab (TZB), an anti HER-2 receptor monoclonal antibody, has been shown to be very effective in patients with breast cancer overexpressing HER-2. It has a mild cardiac toxicity, which may increase when administered in combination with anthracyclines. Anthracycline treatment showed to induce a myocardial overexpression of HER-2 receptors. Myocardial deformation indexes associated with Speckle Tracking (ST) myocardial imaging have shown to be very sensitive identifying left ventricular (LV) dysfunction in this setting. The aim of the study is to assess the effect of TZB therapy on specific myocardial layers after anthracycline treatment. Patients and methods: The study was designed to assess TZB-induced cardiac damage by ST technique in patients with HER-2 positive breast cancer treated with TZB sequentially after Epirubicin treatment. Inclusion criteria: 18–70 yo, histologically confirmed HER-2 positive breast cancer, candidates for TZB-based regimen; LVEF ≥55%; ECOG PS score 0-2, no history of cardiac disease. The following assessments were carried out at baseline, after Epirubucin treatment, at each TZB treatment and every 3 months during 1 year follow-up: ECOG PS score, conventional echocardiography and 2D/3D ST parameters (circumferential and longitudinal S and SR, LV torsion) Results: At Dec 2012, 38 patients (mean ± SD age 51±10 yo) have been enrolled. A significant reduction of the longitudinal peak of SR (0.71±0.16 s-1 vs 0.81±0.14 s-1; p<0.05) was found after Epi treatment, while a significant increase of circumferential function (1.03±0.31 s-1 vs 0.71±0.13 s-1; p<0.01) was evidenced. From the third dose of TZB a maked reduction of the circumferential function (0.69±0.18 s-1 vs 1.03±0.31 s-1; p<0.01) and of LV rotation (15.26±5.38 vs 22.88±6.41; p<0.001) was found, while no further reduction in the longitudinal function was determined. Conclusions: The aim of the study was that to ascertain the amount, timing and type of the pre-clinical cardiac dysfunction induced by TZB when administered after anthracyclines. We evidenced that after anthracyclines longitudinal function is impaired while a compensatory increase of LV circumferential function and of LV torsion is present. After TZB we showed mostly a toxicity of mid and sub epicardial fibres, responsible mainly for the circumferential function and of the torsion of the left ventricle. These effects could be related to the higher toxicity of TZB on the hyperactive myocardial fibres after Epi treatment. Follow up data will show if this mid and sub epicardial myocardial impairment will persist over time.

Non invasive and real time evaluation of mice aortic stiffness by ultrafast ultrasound imaging: a new tool for evaluation of preclinical vascular disease models

Background: Mice models of arterial disease are critical for a better understanding of vascular diseases. Pulse wave velocity (PWV) is widely used as an index of arterial stiffness. Indeed, its evaluation has been reported through invasive measurement by the ratio of distance between 2 arterial cannula tips divided by transit time or non-invasively by MRI which requires a long acquisition time. Our goal was to evaluate the capacity of a new ultrasound ultrafast imaging technique, at high frame rate (up to 5 kHz) to determine non-invasively, in real-time, the abdominal aortic PWV at different levels of blood pressure. Methods: Littermates BalbC wild type mice (n=6) were used with comparable ages (303±95days) and weights (27±3g). Invasive arterial blood pressure (BP) catheter allowed to measure acute pressor responses to increasing doses of phenylephrine (PE) (0.01–700 μg/kg) infused via a venous catheter in anesthetized mice with pentobarbital sodique (60mg/kg/ip). The abdominal aorta was imaged using a conventional linear ultrasonic probe (15MHz, 256 elements) connected to a unique ultrafast scanner (SuperSonic Imagine, France) acquiring at 5400 frames/s which allows to visualize aortic PWV. Tissue velocities of the arterial walls were computed off line and analyzed by speckle tracking technique to provide the pulse wave velocity. Results are mean±SD. Results: We identified 2 PWVs one at the ECG-peak-R-wave, at the time of aortic diastolic blood pressure (PWV-DBP) and one at the ECG-end-T-wave at the time of aortic systolic blood pressure (PWV-SBP). Heart Rate was 415±50bpm. These 2 PWVs were forward waves running along the arterial wall. The mean difference between PWV-DBP and PWV-SBP was 2.3±1.4 m/s. A linear relationship between PWV and BP was observed for the 2 PWVs ranging from 2.5 and 10.0 m/s for a pressure range of 55 to 265 mmHg. Interestingly this linear relation of aortic BP was similar in diastole and in systole with respective slope of 0.037±0.008m/s/mmHg and 0.035±0.010m/s/mmHg, with a good fit: r2= 0.90 and 0.83 respectively. Conclusion: We demonstrated the capability of new ultrafast ultrasound scanner to visualize and calculate non invasively in real time mice aortic PWV at different times of cardiac cycle despite very high heart rate in mice. Moreover, this new technology allows to better characterize the aortic wall biomechanical properties by evaluation of the PWV-BP slope. We hope that this breakthrough will allow in the near future to better evaluate aorta biomechanical properties in preclinical models of vascular disease.

Evaluation of Coronary Steal in Myocardium Supplied by Coronary Collaterals: The Role of Speckle Tracking Analysis in Resting and Stress Echocardiography

Coronary steal could develop in patients with chronic coronary artery disease (CAD) with collateral circulation, and adversely affect ventricular function and long-term clinical outcome. Poorly developed collaterals are more prone than well-developed collaterals to withdrawing their blood support to the collateralized myocardium due to higher collateral pathway resistance and lower vasodilatory reserve of the collateral bed. Even with well-developed coronary collaterals, coronary steal could still occur when perfusion pressure in the donor artery becomes low, or the recipient microvasculature is maximally dilated with exhaustion of vasodilatory reserve. The evaluation of distinctive coronary collateral function with or without steal provides important therapeutic and prognostic information in patients with chronic CAD. However, due to lack of reliable assessment methods, the detection and quantitative measurement of coronary steal remains a challenge. In this article, we present typical clinical scenarios to illustrate the major mechanisms underlying coronary steal in patients with chronic CAD and coronary collateral circulation, and review invasive and noninvasive methods currently available to assess coronary steal in myocardium supplied by coronary collaterals. We specifically focus on recent advances in the resting and stress echocardiography with speckle tracking techniques.

Near-field effects in Green's function retrieval from cross-correlation of elastic fields: Experimental study with application to elastography

In a lossless system, the causal and acausal Green's function for elastic waves can be retrieved by cross-correlating the elastic field at two positions. This field, composed of converging and diverging waves, is interpreted in the frame of a time-reversal process. In this work, the near-field effects on the spatio-temporal focusing of elastic waves are analyzed through the elastodynamic Green's function. Contrary to the scalar field case, the spatial focusing is not symmetric preserving the directivity pattern of a simple source. One important feature of the spatial asymmetry is its dependency on the Poisson ratio of the solid. Additionally, it is shown that the retrieval of the bulk wave speed values is affected by diffraction. The correction factor depends on the relative direction between the source and the observed field. Experimental verification of the analysis is carried out on the volume of a soft-solid. A low-frequency diffuse-like field is generated by random impacts at the sample's free surface. The displacement field is imaged using ultrasound by a standard speckle tracking technique. One important application of this work is in the estimation of the shear elastic modulus in soft biological tissues, whose quantification can be useful in non-invasive diagnosis of various diseases.

X-ray phase microscopy using the speckle tracking technique

Hard X-ray phase microscopy using the Speckle Tracking technique is presented and the practical implementation of this microscope explained. It is demonstrated that the spatial resolution of the Speckle Tracking technique can be pushed down to the nanometer scale without sacrificing the angular sensitivity, which is in the tens of nanoradians range. Moreover, the method is suitable for the analysis of dynamic samples. Experimental demonstration of the method is given for the case of phase imaging of micrometer size polystyrene spheres using a Fresnel zone plate as a magnifying optical element.

At-wavelength metrology using the X-ray speckle tracking technique: case study of a X-ray compound refractive lens

The X-ray speckle tracking technique has been established on the Test beamline B16 at Diamond and is being used as a valuable tool for at-wavelength metrology. We show here the possibilities and the achievable performances of the X-ray Speckle Tracking technique for optics characterization: the description is illustrated with the case study of the characterization of a compound refractive lens. This optical element was characterized online using the speckle tracking method with nanoradian accuracy and micrometer spatial resolution. For discussion purpose, the results are compared to the ones obtained under similar conditions using a grating interferometer.

Myocardial sympathetic innervation, function, and oxidative metabolism in non-infarcted myocardium in patients with prior myocardial infarction

The purpose of this study was to investigate the relationship between sympathetic innervation, contractile function, and the oxidative metabolism of the non-infarcted myocardium in patients with prior myocardial infarction. In 19 patients (14 men, 5 women, 65 ± 9 years) after prior myocardial infarction, sympathetic innervation was assessed by (11)C-hydroxyephedrine (HED) positron emission tomography (PET). Oxidative metabolism was quantified using (11)C-acetate PET. Left ventricular systolic function was measured by echocardiography with speckle tracking technique. The (11)C-HED retention was positively correlated with left ventricular ejection fraction (LVEF) (r = 0.566, P < 0.05), and negatively with peak longitudinal strain in systole in the non-infarcted myocardium (r = -0.561, P < 0.05). Kmono, as an index of oxidative metabolism, was significantly correlated with rate pressure product (r = 0.649, P < 0.01), but not with (11)C-HED retention (r = 0.188, P = 0.442). Furthermore, there was no significant correlation between Kmono and LVEF (r = 0.106, P = 0.666) or peak longitudinal strain in systole (r = -0.256, P = 0.291) in the non-infarcted myocardium. When the patients were divided into two groups based on the median value of left ventricular end-systolic volume index (LVESVI) (41 mL), there were no significant differences in age, sex, and rate pressure product between the groups. However, the large LVESVI group (>41 mL) was associated with reduced (11)C-HED retention and peak longitudinal strain in systole, whereas Kmono was similar between the groups. This study indicates that remodeled LV after myocardial infarction is associated with impaired sympathetic innervation and function even in the non-infarcted myocardial tissue. Furthermore, oxidative metabolism in the non-infarcted myocardium seems to be operated by normal regulatory mechanisms rather than pre-synaptic sympathetic neuronal function.

Independent Role of Left Ventricular Global Longitudinal Strain in Predicting Prognosis of Chronic Heart Failure Patients

To evaluate the independent prognostic role of two-dimensional (2D) strain measures reflecting global longitudinal left ventricular (LV) systolic function in outpatients affected by chronic heart failure (CHF). Global longitudinal LV systolic strain (GLS) was assessed in 308 outpatients affected by CHF, by analyzing standard views with 2D speckle tracking technique. During a mean follow-up of 26 ± 13 months 37 patients died (29 due to cardiovascular causes), 10 patients underwent heart transplantation, and 75 patients experienced at least 1 episode of hospitalization due to acute decompensated heart failure (ADHF). Thirty-one patients without a history of major ventricular arrhythmic events experienced the occurrence of ventricular fibrillation and/or tachycardia or sudden death was observed. Multivariate Cox regression analysis showed that GLS was significantly associated with all-cause mortality (HR: 1.15; 95%CI: 1.02-1.30; P: 0.026), cardiovascular death (HR: 1.20; 95%CI: 1.04-1.39; P: 0.011), cardiovascular death or heart transplantation (HR: 1.24; 95%CI: 1.09-1.41; P: 0.001), ADHF-related hospitalizations (HR: 1.15; 95%CI: 1.05-1.25; P: 0.003), and arrhythmic events (HR: 1.17; 95%CI: 1.03-1.33; P: 0.018). Quantifying LV longitudinal systolic function in CHF outpatients on the basis of 2D speckle tracking analysis provides a new parameter that independently predicts patient outcome, thus, strengthening its possible role in current clinical practice.

Usefulness of Vascular Wall Deformation for Assessment of Carotid Arterial Stiffness and Association With Previous Stroke in Elderly

Carotid arterial stiffness measured by techniques of speckle tracking echocardiography is helpful to assess vascular wall deformation. We conducted a study to investigate the relationship between vascular deformation of the carotid artery and ischemic stroke in the elderly. We recruited 89 consecutive individuals aged ≥60 years (mean age = 72±6 years; 31 men) from a community health survey program. Ten (11%) had a history of ischemic stroke. Carotid B-mode images were acquired using a high-resolution vascular probe equipped on an echocardiographic system. Circumferential strain (CS) and strain rate (CSR) were obtained by speckle tracking techniques with a region of interest covering the entire depth of the common carotid arterial wall. Both CS and CSR were significantly correlated with beta index and distensibility but not with carotid intima-medial thickness and pulse wave velocity. In the comparison between patients with or without history of stroke, carotid CS (1.46% ± 0.54% vs. 2.75% ± 1.23%; P = 0.002) and CSR (0.30±0.13 1/s vs. 0.47±0.18 1/s; P = 0.007) were significantly lower in patients with stroke. Multivariable analysis showed that both carotid CS and CSR were independent factors associated with previous strokes. Carotid wall deformation indices are useful for assessment of local carotid arterial stiffness. CS and CSR of carotid artery measured by speckle tracking techniques were associated with previous ischemic stroke in the elderly.