Magnetic resonance imaging of myocardial strain after acute ST-segment-elevation myocardial infarction: a systematic review

The purpose of this systematic review is to provide a clinically relevant, disease-based perspective on myocardial strain imaging in patients with acute myocardial infarction or stable ischemic heart disease. Cardiac magnetic resonance imaging uniquely integrates myocardial function with pathology. Therefore, this review focuses on strain imaging with cardiac magnetic resonance. We have specifically considered the relationships between left ventricular (LV) strain, infarct pathologies, and their associations with prognosis. A comprehensive literature review was conducted in accordance with the PRISMA guidelines. Publications were identified that (1) described the relationship between strain and infarct pathologies, (2) assessed the relationship between strain and subsequent LV outcomes, and (3) assessed the relationship between strain and health outcomes. In patients with acute myocardial infarction, circumferential strain predicts the recovery of LV systolic function in the longer term. The prognostic value of longitudinal strain is less certain. Strain differentiates between infarcted versus noninfarcted myocardium, even in patients with stable ischemic heart disease with preserved LV ejection fraction. Strain recovery is impaired in infarcted segments with intramyocardial hemorrhage or microvascular obstruction. There are practical limitations to measuring strain with cardiac magnetic resonance in the acute setting, and knowledge gaps, including the lack of data showing incremental value in clinical practice. Critically, studies of cardiac magnetic resonance strain imaging in patients with ischemic heart disease have been limited by sample size and design. Strain imaging has potential as a tool to assess for early or subclinical changes in LV function, and strain is now being included as a surrogate measure of outcome in therapeutic trials

Early diagnosis of cardiovascular diseases in workers: role of standard and advanced echocardiography

Cardiovascular disease (CVD) still remains the main cause of morbidity and mortality and consequently early diagnosis is of paramount importance. Working conditions can be regarded as an additional risk factor for CVD. Since different aspects of the job may affect vascular health differently, it is important to consider occupation from multiple perspectives to better assess occupational impacts on health. Standard echocardiography has several targets in the cardiac population, as the assessment of myocardial performance, valvular and/or congenital heart disease, and hemodynamics. Three-dimensional echocardiography gained attention recently as a viable clinical tool in assessing left ventricular (LV) and right ventricular (RV), volume, and shape. Two-dimensional (2DSTE) and, more recently, three-dimensional speckle tracking echocardiography (3DSTE) have also emerged as methods for detection of global and regional myocardial dysfunction in various cardiovascular diseases, and applied to the diagnosis of subtle LV and RV dysfunction. Although these novel echocardiographic imaging modalities have advanced our understanding of LV and RV mechanics, overlapping patterns often show challenges that limit their clinical utility. This review will describe the current state of standard and advanced echocardiography in early detection (secondary prevention) of CVD and address future directions for this potentially important diagnostic strategy

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

Techniques for Identification of Left Ventricular Asynchrony for Cardiac Resynchronization Therapy in Heart Failure

The most recent treatment option of medically refractory heart failure includes cardiac resynchronization therapy (CRT) by biventricular pacing in selected patients in NYHA functional class III or IV heart failure. The widely used marker to indicate left ventricular (LV) asynchrony has been the surface ECG, but seems not to be a sufficient marker of the mechanical events within the LV and prediction of clinical response. This review presents an overview of techniques for identification of left ventricular intra- and interventricular asynchrony. Both manuscripts for electrical and mechanical asynchrony are reviewed, partly predicting response to CRT. In summary there is still no gold standard for assessment of LV asynchrony for CRT, but both traditional and new echocardiographic methods have shown asynchronous LV contraction in heart failure patients, and resynchronized LV contraction during CRT and should be implemented as additional methods for selecting patients to CRT

Left ventricular remodeling and function in ischemic heart disease and aortic valve disease

Background: Cardiac remodeling is a broad term that refers to structural and functional alterations of the heart in response to chronic changes in loading conditions or left ventricular (LV) contractile performance. Different loading conditions will affect the heart in different ways, some leading to impaired heart function, symptoms of heart failure, or even death. However, the process of remodeling may not be permanent. If the heart is relieved of the underlying cause of the remodeling, the heart function and structure may normalize in a process referred to as reverse remodeling. The complex interplay of factors that determine the process of reverse remodeling is not fully elucidated. Cardiac remodeling can be evaluated by many different diagnostic modalities, but the most widely used diagnostic tool is two-dimensional echocardiography (2DE). In recent years, three-dimensional echocardiography (3DE) has emerged with possible advantages in the assessment of LV volume and function. The thesis aimed to evaluate 3DE in the assessment of LV function and remodeling, and to study different aspects of remodeling in response to pressure and volume overload in patients with aortic stenosis (AS) and aortic regurgitation (AR), respectively. Methods: Studies I and II investigated patients with ischemic heart disease (n = 15 and n = 32, respectively). In Study I, the assessments of LV volume and ejection fraction (EF) were compared using 3DE, cardiac magnetic resonance (CMR), and single-photon emission computer tomography (SPECT). Study II compared the performance of 2DE, contrast-enhanced 2DE, 3DE, and contrast-enhanced 3DE in the assessment LV volumes and EF, using CMR as a reference standard. In Studies III and IV, 65 patients with severe AR and 120 patients with severe AS, respectively, were examined using 2DE and 3DE before and at one year after aortic valve replacement (AVR). In Study III, LV volumes, systolic and diastolic LV function, and left atrial strain (LAS) were analyzed to identify predictors of impaired LV reverse remodeling in AR. Study IV assessed LV functional indices, including 2D global longitudinal strain (GLS) and 3D strain, to assess predictors of incomplete reverse remodeling in AS. Results and conclusions: There were significant differences among 3DE, SPECT and CMR regarding the measurement of LV volumes. However, the estimation of EF showed good agreement. 3DE was more accurate and showed more favorable reproducibility than 2DE for the assessment of EF and LV volumes. Contrast enhancement improved accuracy and reproducibility for both 2DE and 3DE. One-third of patients with AR had signs of impaired LV diastolic function. After AVR, diastolic LV functional indices improved, LV and left atrial (LA) volumes decreased, and indices of LA function increased. LA conduit strain had an incremental prognostic value for the prediction of impaired LV functional and structural recovery. In patients with AS, AVR was associated with a decrease in LV mass, an improvement in 2D GLS, and a decrease in LV twist. 2D GLS and left ventricular mass index were predictive of incomplete reverse remodeling during the follow-up period. 3D GLS did not add discriminatory or predictive information over 2D GLS

Fast left ventricle tracking using localized anatomical affine optical flow

Fast left ventricle tracking using localized anatomical affine optical flowIn daily clinical cardiology practice, left ventricle (LV) global and regional function assessment is crucial for disease diagnosis, therapy selection, and patient follow-up. Currently, this is still a time-consuming task, spending valuable human resources. In this work, a novel fast methodology for automatic LV tracking is proposed based on localized anatomically constrained affine optical flow. This novel method can be combined to previously proposed segmentation frameworks or manually delineated surfaces at an initial frame to obtain fully delineated datasets and, thus, assess both global and regional myocardial function. Its feasibility and accuracy were investigated in 3 distinct public databases, namely in realistically simulated 3D ultrasound, clinical 3D echocardiography, and clinical cine cardiac magnetic resonance images. The method showed accurate tracking results in all databases, proving its applicability and accuracy for myocardial function assessment. Moreover, when combined to previous state-of-the-art segmentation frameworks, it outperformed previous tracking strategies in both 3D ultrasound and cardiac magnetic resonance data, automatically computing relevant cardiac indices with smaller biases and narrower limits of agreement compared to reference indices. Simultaneously, the proposed localized tracking method showed to be suitable for online processing, even for 3D motion assessment. Importantly, although here evaluated for LV tracking only, this novel methodology is applicable for tracking of other target structures with minimal adaptations.The authors acknowledge funding support from FCT - Fundacao para a Ciência e a Tecnologia, Portugal, and the European Social Found, European Union, through the Programa Operacional Capital Humano (POCH) in the scope of the PhD grants SFRH/BD/93443/2013 (S. Queiros) and SFRH/BD/95438/2013 (P. Morais), and by the project ’PersonalizedNOS (01-0145-FEDER-000013)’ co-funded by Programa Operacional Regional do Norte (Norte2020) through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio

Cardiovascular Magnetic Resonance Deformation Imaging By Feature Tracking For Assessment Of Left And Right Ventricular Structure And Function

The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the authorCardiac magnetic resonance (CMR) imaging is the gold standard imaging technique for assessment of ventricular dimensions and function. CMR also allows assessment of ventricular deformation but this requires additional imaging sequences and time consuming post processing which has limited its widespread use. A novel CMR analysis software package, ‘feature tracking’ (Tom Tec, Germany) can measure ventricular deformation directly from cine CMR images. This thesis seeks to further our understanding of the feasibility of feature tracking to assess myocardial deformation and volumetric measures. Chapter 3 validates normal ranges for deformation parameters and compares values against traditional tagging measures. The work identifies global circumferential strain measures as being the most reproducible. In chapters 4 and 5, feature tracking values for left and right ventricular strain are compared with echocardiography derived speckle tracking indices of deformation. For left ventricular (LV) parameters, circumferential and longitudinal strain are most consistent and for the right ventricular (RV) measures, assessment of free wall strain using feature tracking shows promise and with modifications in algorithms is likely to further improve in the future. Chapter 6 assesses the ability of feature tracking to measure diastolic function. The results show that radial diastolic velocities and longitudinal diastolic strain rates can predict diastolic dysfunction (as diagnosed by echocardiography) with acceptable levels of sensitivity and specificity, particularly when used in combination. 11 The use of feature tracking to provide automated measures of ventricular volumes, mass and ejection fraction is assessed in chapter 7. Feature tracking in this context shows acceptable correlation but poor absolute agreement with manual contouring and further adjustments to algorithms is necessary to improve its accuracy. This work offers insights into the use of feature tracking for the assessment of ventricular deformation parameters. It is a technique with advantages over CMR tagging methods and given the speed of post processing has the potential to become the CMR preferred assessment for strain quantification in the future.I am indebted to the Engineering and Physical Sciences Research Council, the British Heart Foundation and the National Institute for Health Research Oxford Biomedical Research Centre for funding this work

Cardiac Motion Analysis Based on Optical Flow on Real-Time Three-Dimensional Ultrasound Data

With relatively high frame rates and the ability to acquire volume data sets with a stationary transducer, 3D ultrasound systems, based on matrix phased array transducers, provide valuable three-dimensional information, from which quantitative measures of cardiac function can be extracted. Such analyses require segmentation and visual tracking of the left ventricular endocardial border. Due to the large size of the volumetric data sets, manual tracing of the endocardial border is tedious and impractical for clinical applications. Therefore the development of automatic methods for tracking three-dimensional endocardial motion is essential. In this study, we evaluate a four-dimensional optical flow motion tracking algorithm to determine its capability to follow the endocardial border in three dimensional ultrasound data through time. The four-dimensional optical flow method was implemented using three-dimensional correlation. We tested the algorithm on an experimental open-chest dog data set and a clinical data set acquired with a Philips' iE33 three-dimensional ultrasound machine. Initialized with left ventricular endocardial data points obtained from manual tracing at end-diastole, the algorithm automatically tracked these points frame by frame through the whole cardiac cycle. Finite element surfaces were fitted through the data points obtained by both optical flow tracking and manual tracing by an experienced observer for quantitative comparison of the results. Parameterization of the finite element surfaces was performed and maps displaying relative differences between the manual and semi-automatic methods were compared. The results showed good consistency with less than 10% difference between manual tracing and optical flow estimation on 73% of the entire surface. In addition, the optical flow motion tracking algorithm greatly reduced processing time (about 94% reduction compared to human involvement per cardiac cycle) for analyzing cardiac function in three-dimensional ultrasound data sets. A displacement field was computed from the optical flow output, and a framework for computation of dynamic cardiac information is introduced. The method was applied to a clinical data set from a heart transplant patient and dynamic measurements agreed with known physiology as well as experimental results