Speckle-Tracking Imaging, Principles and Clinical Applications: A Review for Clinical Cardiologists

Evaluation of myocardial mechanics, although complex, has now entered the clinical arena, thanks to the introduction of bedside imaging techniques, such as speckle-tracking echocardiography

Functional Assessment for Congenital Heart Disease

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Measurement of left ventricular deformation using 3D echocardiography

Bakgrunn: 3D speckle tracking ekkokardiografi (STE) er en hjerteultralydmetode som gir mulighet for måling av deformasjonsparametere, som strain, rotasjon, tvist og torsjon. Den største begrensningen for 3D STE er lav tids- og romlig oppløsning. Økes den ene oppløsingen vil den andre bli redusert. I tillegg vil andre faktorer som antall flettede bilder, sektorstørrelse og dybde påvirke begge oppløsningene. Denne avhandlingen har hatt som mål å finne tilstander og opptaksinnstillinger for å optimalisere nøyaktigheten til 3D STE-parametere i et kontrollert miljø. Videre har det vært som mål å finne regional deformasjon fra 3D STE i en klinisk studie på pasienter med aortaklaffestenose (AS) ved bruk av optimaliserte innstillinger. Materiale og metode: Studie 1 og 2 utforsket nøyaktigheten til 3D STE ved bruk av et in vitro-oppsett med et fantom av venstre ventrikkel. Studie 1 sammenlignet 3D STE strain mot sonomikromertri som gullstandard i longitudinell, sirkumferensiell og radiell retning. Ved å bruke et annet fantom i studie 2 ble 3D STE tvist sammenlignet mot sonomikrometri tvist for å finne nøyaktigheten til 3D STE tvistmålinger. Studie 3 inkluderte 85 pasienter med variabel grad av AS i en tverrsnittstudie. 3D ekkokardiografi ble utført og 3D STE-parametere ble sammenlignet mellom grupper av pasienter med mild, moderat og alvorlig AS. Resultater: Studie 1 fant godt samsvar mellom 3D STE og sonomikrometri med optimalt volum rate på 36,6 volumer per sekund (VPS) ved bruk av 6 sammenflettede bilder. I studie 2 hadde 3D STE godt samsvar ved bruk av både 4 og 6 sammenflettede bilder med volum rater på henholdsvis 20,3 og 17,1 VPS. Studie 3 fant lavere global longitudinal strain i pasienter med alvorlig AS sammenlignet med mild AS. Basal og midtre longitudinal strain var også lavere i alvorlig sammenlignet med mild AS. Apikal-basal ratio var høyere for moderat i forhold til mild AS. Maks apikal-basal tvist var høyere hos pasienter med alvorlig sammenlignet med mild og moderat AS. Konklusjon: Måling av venstre ventrikkelfunksjon med 3D STE er mest nøyaktig med volum rater < 40 VPS. Høy romlig oppløsning virker å være mer viktig enn tidsoppløsning. Pasienter med alvorlig AS har lavere global, basal og midtre longitudinal strain enn pasienter med mild AS, ved bruk av 3D STE. De har også høyere tvist enn mild og moderat AS. Områder som involverer apeks, har høyere spredning av data og har antagelig lavere nøyaktighet ved bruk av 3D STE.Background: 3D speckle tracking echocardiography (STE) enables measurement of multiple parameters of deformation, such as strain, rotation, twist and torsion. The main limitation of 3D STE is low temporal and spatial resolution. Increasing resolution in time will decrease resolution in space, and vice versa. In addition, other factors such as number of stitched images, sector size and depth, influence the resolution. This thesis aimed to find conditions and acquisition settings to optimize accuracy for 3D STE parameters in a controlled in vitro environment. Secondly, it aimed to evaluate regional deformation by 3D STE in a clinical study on patients with aortic valve stenosis (AS) using optimized settings. Materials and methods: Study 1 and 2 explored the accuracy of 3D STE using an in vitro setup with a left ventricle (LV) phantom. Study 1 compared 3D STE strain to strain by sonomicrometry as the gold standard. Measurements were compared in both longitudinal, circumferential and radial direction. Using a different twisting phantom in study 2, 3D STE twist was compared to twist by sonomicrometry to evaluate the accuracy of 3D STE twist. Study 3 was a cross-sectional analysis of 85 patients with variable degree of AS in a cross-sectional study. 3D echocardiography was done, and 3D STE parameters were compared between groups of patients with mild, moderate and severe AS. Results: Study 1 found 3D STE strain to have good agreement with sonomicrometry. Optimal acquisition settings were found to be volume rate 36.6 volumes per second (VPS) obtained by 6 stitched images. Study 2 found 3D STE twist to have good agreement with sonomicrometry when using both 4 and 6 stitched images with volume rates 20.3 and 17.1 VPS, respectively. Study 3 found global longitudinal strain to be lower in patients with severe AS compared to those with mild AS. Basal and mid longitudinal strains were also lower in severe AS than in mild AS. Apical basal ratio was higher for moderate than mild AS. Peak apical-basal twist was higher in patients with severe AS than in those with mild and moderate AS. Conclusion: Assessment of LV function by 3D STE is most accurate at volume rates < 40 VPS. High spatial resolution seems to be more important than temporal resolution. Patients with severe AS have lower global, as well as lower regional basal and mid longitudinal strain compared to patients with mild AS, assessed with 3D STE. They also have higher twist than mild and moderate AS. Segments involving the apex have high dispersion and probably lower accuracy in 3D STE.Doktorgradsavhandlin

Myocardial Rotation and Torsion in Child Growth

BACKGROUND: The speckle tracking echocardiography can benefit to assess the regional myocardial deformations. Although, previous reports suggested no significant change in left ventricular (LV) torsion with aging, there are certain differences in LV rotation at the base and apex. The purpose of this study was to evaluate the change and relationship of LV rotation for torsion with aging in children. METHODS: Forty healthy children were recruited and divided into two groups of twenty based on whether the children were preschool-age (2-6 years of age) or school-age (7-12 years of age). After obtaining conventional echocardiographic data, apical and basal short axis rotation were assessed with speckle tracking echocardiography. LV rotation in the basal and apical short axis planes was determined using six myocardial segments along the central axis. RESULTS: Apical and basal LV rotation did not show the statistical difference with increased age between preschool- and school-age children. Apical radial strain showed significant higher values in preschool-age children, especially at the anterior (52.8 ± 17.4% vs. 34.7 ± 23.2%, p < 0.02), lateral (55.8 ± 20.4% vs. 36.1 ± 22.7%, p < 0.02), and posterior segments (57.1 ± 17.6% vs. 38.5 ± 21.7%, p < 0.01). The torsion values did not demonstrate the statistical difference between two groups. CONCLUSION: This study revealed the tendency of higher rotation values in preschool-age children than in school-age children. The lesser values of rotation and torsion with increased age during childhood warrant further investigation.ope

Hierarchical template matching for 3D myocardial tracking and cardiac strain estimation

Myocardial tracking and strain estimation can non-invasively assess cardiac functioning using subject-specific MRI. As the left-ventricle does not have a uniform shape and functioning from base to apex, the development of 3D MRI has provided opportunities for simultaneous 3D tracking, and 3D strain estimation. We have extended a Local Weighted Mean (LWM) transformation function for 3D, and incorporated in a Hierarchical Template Matching model to solve 3D myocardial tracking and strain estimation problem. The LWM does not need to solve a large system of equations, provides smooth displacement of myocardial points, and adapt local geometric differences in images. Hence, 3D myocardial tracking can be performed with 1.49 mm median error, and without large error outliers. The maximum error of tracking is up to 24% reduced compared to benchmark methods. Moreover, the estimated strain can be insightful to improve 3D imaging protocols, and the computer code of LWM could also be useful for geo-spatial and manufacturing image analysis researchers

Left ventricular twist in children : Does LV rotation change with aging in children?

Dept. of Medicine/석사[한글] 본 연구는 소아의 연령 변화에 따른 좌심실 회전 및 심실 비틀림을 관찰한 연구이다. 현재까지 보고에 의하면 심실 비틀림은 나이에 따라 의미 있는 변화를 보이지는 않는다고 알려져 왔다. 그러나 어린이 연령에서 학동기 전 후 나이에 따른 좌심실 회전과 비틀림의 관계에 대해서는 알려진 바가 거의 없다.40명의 소아 중 학동기 전 어린이 20명 (2세 - 6세), 학동기 어린이 20명 (7세 - 12세)을 대상으로 하였고, 심초음파 단축 영상에서 심장 기저부와 심첨부를 각각 심근벽 구획에 따라 분리 분석하였다. 좌심실 회전 및 비틀림 양상은 심장 기저부와 심첨부에서 통계적 유의성은 없었으나 학동기 전 어린이 보다 학동기 어린이에서 감소하는 경향을 나타내었다. 즉 학동기 전 어린이에서 더 큰 심실 회전과 비틀림을 나타내는 경향을 보였다.소아의 심근증을 비롯한 기타 심장질환 평가 및 치료에 기여하고자 좌심실 회전 및 심실 비틀림 현상을 연령 변화에 따라 관찰하였으며, 향후 지속적인 연구가 필요할 것이다. [영문] Background The recently introduced method, speckle tracking echocardiography, represents simplified, objective, and angle-independent modality for quantification of regional myocardial deformation. As published, there was no significant change in LV torsion with aging, there might be some difference in LV rotation at base and apex. The purpose of this study was to assess the relationship of LV rotation for torsion with aging in children.Methods Forty healthy children were recruited and divided into two groups of twenty preschool age (2 ~ 6 years of age) and twenty school age children (7 ~ 12 years of age). After obtaining conventional echocardiographic data, apical and basal short axis rotations were assessed with speckle tracking echocardiography. LV rotations in basal and apical short axis planes were determined of six myocardial segments along the central axis.Results There was no significant change in apical and basal LV rotation with age between preschool and school age children. However, there was a certain trend between two age groups in each basal and apical rotation. In basal and apical rotation, the values of preschool age children are greater than those of school age children at anteroseptal, anterior, lateral, posterior, inferior, and septal all six segments.Conclusion There was some trend of incremental rotation value in preschool age children rather than school age children. Although there was no statistically significant age-related change in LV rotation between these two groups, the decrease trend with aging for rotation and torsion twist during childhood should be necessary for further investigation.ope

The effect of heat stress, dehydration and exercise on global left ventricular function and mechanics in healthy humans

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis examined the effect of heat stress, dehydration and exercise on global left ventricular (LV) function and LV twist, untwisting and strain (LV mechanics) in healthy individuals. The primary aim was to identify whether the different haemodynamics induced by heat stress, dehydration and exercise would be associated with alterations in systolic and diastolic LV mechanics as assessed by two-dimensional speckle tracking echocardiography. Study one showed that enhanced systolic and diastolic LV mechanics during progressively increasing heat stress at rest likely compensate in part for a lower venous return, resulting in a maintained stroke volume (SV). In contrast, heat stress during knee-extensor exercise did not significantly increase LV twist, suggesting that exercise attenuates the increase in LV mechanics seen during passive heat stress. Study two revealed that dehydration enhances systolic LV mechanics whilst diastolic mechanics remain unaltered at rest, despite pronounced reductions in preload. The maintenance of systolic and diastolic LV mechanics with dehydration during knee-extensor exercise further suggests that the large decline in SV with dehydration and hyperthermia is caused by peripheral cardiovascular factors and not impaired LV mechanics. During both, heat stress and dehydration, enhanced systolic mechanics were achieved solely by increases in basal rotation. In contrast, the third study demonstrated that when individuals are normothermic and euhydrated, systolic and diastolic basal and apical mechanics increase significantly during incremental exercise to approximately 50% peak power. The subsequent plateau suggests that LV mechanics reach their peak at sub-maximal exercise intensities. Together, the present findings emphasise the importance of acute adjustments in both, basal and apical LV mechanics, during periods of increased cardiovascular demand

Use of two dimensional echocardiography Speckle Tracking Echocardiography for quantitative assessment of global left ventricular function in comparison to two dimensional Ejection Fraction and three dimensional Ejection Fraction

OBJECTIVE: 1. To determine whether global strain derived from 2D speckle tracking echocardiography (STE) are as accurate as three dimensional (3D) ejection fraction and two dimensional left ventricular (LV) ejection fraction. 2. To see intra-observer and inter-observer variation in measuring 2D global strain and 2D ejection fraction and 3 D ejection fraction. METHODS: This prospective observational study was planned to include 100 patients with LV systolic dysfunction (defined as patient with EF less than 50%) from cardiology inpatient and outpatient. All the patients underwent detailed Echocardiography with 2D speckle tracking and 3D echocardiography. Baseline characteristics of patients were noted. The aim of study was to determine whether global strain derived from 2 D speckle tracking echocardiography (STE) is as accurate as three dimensional (3D) ejection fraction and two dimensional ejection fraction. RESULTS: This study showed that there is strong co-relation between speckle tracking echocardiography derived 2D global strain and LV ejection fraction. Although both global longitudinal strain (GLS) and global circumferential strain (GCS) has co-related well with LV function assessment using 2D and 3D echocardiography, but GLS has better co-relation than GCS in our study. This study also showed low inter-observer and intra-observer variability in calculating 2D STE derived global strains and 3D ejection fraction. CONCLUSION: This study has proved that the feasibility and accuracy of 2D speckle tracking echocardiography assessment in a wide range of LV function. This study population also enabled us to understand that these results can be generalised and can be applied in real life clinical practice. The strong reproducibility as shown by low intra-observer and inter-observer variability makes 2D STE derived global strains a robust marker with potential clinical use

Incremental value of advanced cardiac imaging modalities for diagnosis and patient management : focus on real-time three-dimensional echocardiography and magnetic resonance imaging

Advanced cardiac imaging modalities play a crucial role in the diagnostic process and clinical management of patients with different cardiac diseases, including heart failure, valvular heart disease, myocardial infarction and atrial fibrillation. RT3DE has made an important transition from a research tool to a clinically applicable imaging technique and has been demonstrated to provide important advantages over conventional 2D echocardiography, such as a more accurate quantification of cardiac chamber size and function and the possibility of unlimited image plane orientations for better understanding of valvular heart diseases. Contrast-enhanced echocardiography should be performed in every patient with suboptimal acoustic window, especially with RT3DE. Importantly, in patients underwent primary percutaneous coronary intervention, perfusion analysis can provide an accurate estimate of myocardial infarction size, which is crucial information for the patient management, together with more sophisticated assessment of LV mechanics. Myocardial deformation imaging has witnessed an enormous development in the last years and is now considered an accurate tool for a more sensitive assessment of LV regional and global function and for a more detailed assessment of LV mechanics and dyssynchrony. CMR represents the reference imaging modality for the quantification of LV volumes and function and for the identification of myocardial scar/fibrosis. It should be therefore considered for a comprehensive evaluation of heart failure patients, including more novel and sophisticated assessments of transvalvular flow and LV dyssynchrony. Advanced cardiac imaging modalities can be applied in heart failure patients referred for CRT to explore novel physiopathological aspects, such as the effect on LV rotation mechanics, on functional mitral regurgitation and cerebral blood flow.Philips Healthcare, Meda Pharma, Boehringer Ingelheim, Roche, Servier, Biotronik, Boston Scientific Nederland BV and ServierUBL - phd migration 201