Dissertations / Theses on the topic 'Echocardiography'
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Karagiannis, Stefanos E. "Clinical stress echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10524.
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Voormolen, Marco Marien. "Three dimensional harmonic echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10598.
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Krenning, Boudewijn Juriaan. "Quantitative Three-dimensional Echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10695.
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Williams, Quentin. "Contrast echocardiography perfusion imaging." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427650.
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Yao, Cheng. "3D echocardiography image compounding." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/3d-echocardiography-image-compounding(5e1b0ddd-6d47-4305-8de4-aa2260489131).html.
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Echocardiography (echo) is a widely available method to obtain images of the heart, however, echo can suffer due to the presence of artefacts, high noise and a restricted field-of-view. One method to overcome these limitations is to use multiple images, using the "best" parts from each image to produce a higher quality "compounded" image. This thesis describes a new method to allow multiple 3D echo images to be compounded into a single better quality volume. I have proposed a definition for an "ideal" compounded image and have used this to guide the design of my compounding method, in particular designing a method to reduce the effect of image artefacts and to make use of larger numbers of images. My compounding method has been validated using phantom, volunteer and clinical images. The overall motivations for improving echo image quality are twofold: Firstly to provide clinicians with higher quality images which I hope will improve the accuracy of clinical decision making. Secondly to provide higher quality images for subsequent post-processing algorithms. A number of methods have been proposed to compound sets of ultra-sound images, all of which have reported improvements in image quality. However, previous 3D compounding methods have typically been applied to a relatively small number of images (most of them only use two images, and only one uses six images). I have investigated the effect of compounding with larger numbers of images. Results showed continued improvement in image quality up to ten images (the maximum number we deemed feasible to acquire in a clinical setting and it is approximately double of images used previously). Artefacts occur regularly within echo images, particularly shadowing artefacts (due to the highly reflecting interfaces caused by the ribs and lungs when imaging the heart). However, previous 3D compounding methods haven’t directly claimed and demonstrated the effect of artefacts. Therefore, I have proposed a 3D compounding algorithm which specifically aims to reduce the effect of echo artefacts (shadowing) as well as improving the signal-to-noise ratio, contrast, and extending the field-of-view. My method to reduce the effect of artefacts is to weight image information from different views based on a local feature coherence/consistency. I hypothesize that the presence of an artefact in an image varies greatly depending on view direction, therefore much lower consistency values will be calculated for artefact regions enabling them to be detected, and their influence on the compounded image to be greatly reduced. The accuracy of the image registration is important and errors will likely affect the final compounded images quality. In addition to registration ac-curacy my system needs to work robustly and have a large enough capture range to enable automatic registration from a suitable starting position.
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Chykeyuk, Kiryl. "Analysis of 3D echocardiography." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:823cd243-5d48-4ecc-90e7-f56d49145be8.
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Heart disease is the major cause of death in the developed world. Due to its fast, portable, low-cost and harmless way of imaging the heart, echocardiography has become the most frequent tool for diagnosis of cardiac function in clinical routine. However, visual assessment of heart function from echocardiography is challenging, highly operatordependant and is subject to intra- and inter observer errors. Therefore, development of automated methods for echocardiography analysis is important towards accurate assessment of cardiac function. In this thesis we develop new ways to model echocardiography data using Bayesian machine learning methods and concern three problems: (i) wall motion analysis in 2D stress echocardiography, (ii) segmentation of the myocardium in 3D echocardiography, and (iii) standard views extraction from 3D echocardiography. Firstly, we propose and compare four discriminative methods for feature extraction and wall motion classification of 2D stress echocardiography (images of the heart taken at rest and after exercise or pharmalogical stress). The four methods are based on (i) Support Vector Machines, (ii) Relevance Vector Machines, (iii) Lasso algorithm and Regularised Least Squares, (iv) Elastic Net regularisation and Regularised Least Squares. Although all the methods are shown to have superior performance to the state-of-the-art, one conclusion is that good segmentation of the myocardium in echocardiography is key for accurate assessment of cardiac wall motion. We investigate the application of one of the most promising current machine learning techniques, called Decision Random Forests, to segment the myocardium from 3D echocardiograms. We demonstrate that more reliable and ultrasound specific descriptors are needed in order to achieve the best results. Specifically, we introduce two sets of new features to improve the segmentation results: (i) LoCo and GloCo features with a local and a global shape constraint on coupled endoand epicardial boundaries, and (ii) FA features, which use the Feature Asymmetry measure to highlight step-like edges in echocardiographic images. We also reinforce the traditional features such as Haar and Rectangular features by aligning 3D echocardiograms. For that we develop a new registration technique, which is based on aligning centre lines of the left ventricles. We show that with alignment performance is boosted by approximately 15%. Finally, a novel approach to detect planes in 3D images using regression voting is proposed. To the best of our knowledge we are the first to use a one-step regression approach for the task of plane detection in 3D images. We investigate the application to standard views extraction from 3D echocardiography to facilitate efficient clinical inspection of cardiac abnormalities and diseases. We further develop a new method, called the Class- Specific Regression Forest, where class label information is incorporating into the training phase to reinforce the learning from semantically relevant to the problem classes. During testing the votes from irrelevant classes are excluded from voting to maximise the confidence of output predictors. We demonstrate that the Class-Specific Regression Random Forest outperforms the classic Regression Random Forest and produces results comparable to the manual annotations.
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Hergum, Torbjørn. "3D Ultrasound for Quantitative Echocardiography." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for sirkulasjon og bildediagnostikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5937.
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Medical ultrasound imaging is widely used to diagnose cardiacdiseases. The recent availability of real time 3D ultrasound posesseveral interesting challenges and opportunities, and the work of thisthesis is devoted to both challenges and opportunities. One of the key benefits of ultrasound imaging is that its images arereal time. This has been challenged with the recent introduction of 3Dimages, where the number of ultrasound beams is squared compared totraditional 2D images. One common way to alleviate this is byreceiving several closely spaced ultrasound beams from each pulsetransmission, which increases acquisition speed but affects the imagequality. Specifically, B-mode images are irregularly sampled and losespatial shift invariance while a bias in the Doppler velocityestimates causes a discontinuity in the velocity estimates in colorflow images. We have found that these artifacts can be reducedsignificantly by interpolation of the beamformed data from overlappingbeams, with the limitation of requiring at least twice the number ofbeamformers. We have also found that valvular regurgitation is one of thecardiac diseases that can benefit greatly from quantification ofseverity using 3D ultrasound. We have devised a modality that useshigh pulse repetition frequency 3D Doppler to isolate thebackscattered signal power from the vena contracta of a regurgitantjet. This measure is calibrated with a narrow reference beam insidethe jet to estimate the cross-sectional area of the vena contracta. Wehave validated this method with computer simulations, with an in vitrostudy and finally in vivo with 27 patients who had mitralregurgitation. We found that the cross-sectional area and regurgitantvolume of the vena contracta could be quantified without bias as long as the orifice was sufficiently large for a calibration beam tofit inside it. The severity of smaller regurgitations will beoverestimated, but this does not pose a clinical problem, as thesepatients can easily be identified by standard 2D Doppler examination and donot typically need further quantification. Finally, we have developed a new, fast 3D ultrasound simulation methodthat can incorporate anisotropic scattering from cardiac muscle cells. This approach is three orders of magnitudefaster than the most commonly used simulation methods, making it wellsuited for the simulation of dynamic 3D images for development and testingof quantitative diagnostic methods such as 3D speckle tracking andvolumetric measurements.
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Deng, Jing. "Dynamic three-dimensional fetal echocardiography." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412515.
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Pell, Alastair Charles Hamish. "Novel applications of transoesophageal echocardiography." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/20733.
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Transoesophageal echocardiography has become a widely used diagnostic imaging technique by virtue of its ability to yield high quality images of the heart and great vessels. This thesis is based on work performed between January 1991 and July 1992 during which novel applications of transoesophageal echocardiography were investigated in the intraoperative and critical care settings. The mechanism by which closed chest cardiopulmonary resuscitation (CPR) generates forward blood flow has long been debated. Use of transoesophageal echocardiography allowed the physiology of CPR to be elucidated in 18 human subjects with cardiac arrest. These observations supported the cardiac pump theory of CPR and suggested that transoesophageal echocardiography might be utilised to monitor the efficacy of CPR. A preliminary investigation of CPR performed with the active compression-decompression device is described. The pathophysiology of the fat embolism syndrome (FES) is poorly understood. Transoesophageal echocardiography detected intraoperative fat embolism in 24 patients with traumatic injuries, three of whom subsequently developed clinical evidence of FES. Paradoxical embolism through a patent foramen ovale occurred in one subject with fulminating fat embolism. These results support the mechanical theory of the aetiology of fat emboli, and suggest that transoesophageal echocardiography might be used to identify patients at greatest risk of FES. The role of transoesophageal echocardiography in monitoring regional and global myocardial function was explored in a study of the cardioprotective properties of acadesine in patients undergoing coronary artery bypass surgery. No differences were observed between the acadesine and control groups in the incidence of new regional wall motion abnormalities or in changes in the areas ejection fraction. The strengths and limitations of transoesophageal echocardiography are discussed.
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Telford, Lisa Helen. "Standard echocardiography versus handheld echocardiography for the detection of subclinical rheumatic heart disease: A systematic review." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29528.
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Rheumatic heart disease (RHD) is a permanent heart valve condition resulting from an abnormal immune reaction to group A streptococcal (GAS) infection typically occurring in childhood. If left untreated, disease progression can result in irreversible heart valve damage, cardiac failure, stroke and premature death. Significantly, RHD is a preventable and treatable chronic condition which mostly effects disadvantaged populations across the world. Moreover, the continued persistence of RHD contributes to considerable amounts of preventable morbidity and mortality, predominantly among adolescents and young adults. The accurate detection of subclinical RHD in children and adolescents, however, remains hampered by the cost of diagnostic machinery and scarcity of trained personnel. Alternative RHD screening tests, which are both accurate and affordable, are therefore needed in many endemic areas. Recently, handheld echocardiography has become widely available with a variety of clinical uses. If shown to be sufficiently accurate, use of these handheld devices could potentially expand access to echocardiographic screening in RHD endemic areas. The research undertaken for this MPH dissertation compares the accuracy of handheld echocardiography for the detection of rheumatic heart disease to the reference standard using systematic review methods. The dissertation is structured into three parts.
PART A is a research protocol which describes the background and process of the proposed review. This section details the quantitative methods to be used in the systematic review and meta-analysis of studies which assess the diagnostic accuracy of handheld echocardiography for rheumatic heart disease detection in children and adolescents. The proposed systematic review methods are based on those of the Cochrane Collaboration.
PART B is an extended literature review which expands on some of the topics raised in the background section of the protocol. A more in depth insight into the context surrounding the proposed research is offered and its importance highlighted. By reviewing the current body of evidence, this literature review aimed to both describe and contextualise the global burden of rheumatic heart disease whilst providing a rationale for further research into better screening modalities. Similarly, it also sought to describe the importance of understanding rheumatic heart disease epidemiology so that future research and screening programmes may be targeted accordingly.
PART C is a full systematic review of diagnostic test accuracy studies presented as a journal ‘ready’ manuscript in a format suitable for submission to PLoS ONE. The background to the systematic review is briefly summarised after which the results are then presented and discussed. The main findings, from seven included studies, provide some evidence for the potential of handheld echocardiography to increase access to echocardiographic screening for rheumatic heart disease. Lastly and in conclusion, implications arising from the findings of the review are posited and suggestions for future research offered.
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Manser, Sarina. "Wall motion classification of stress echocardiography." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526081.
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Storaa, Camilla. "Reproducibility and interpretation in tissue Doppler echocardiography." Doctoral thesis, KTH, Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3818.
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As cardiovascular disease is the single most common cause ofdeath in the western world, and since there is a closeconnection between cardiovascular disease and left ventricular(LV) function, good methods for the assessment of LV functionis highly needed. A widely used tool for the diagnosis of LVdisease is echocardiography, a technique which today faces twodi_culties; the low reproducibility and the subjectiveinterpretation. The present dissertation aims to quantifyreproducibility, to study the factors that influencereproducibility and to provide tools for simplifying theinterpretation of tissue velocities measured by Dopplerultrasound.
The reproducibility has been studied by letting twoindependent observers measure tissue Doppler velocities toinvestigate how well their measurements agree. To improvereproducibility an algorithm for the automatic detection ofpre-defined echocardiographic localizations is presented. Oneof the most difficult skills for the sonographer to master,thus leading to reduced reproducibility, is the transducermanipulation. The effect of poor transducer manipulation hasbeen modeled, and we show that even a poorly placed transducermay yield images which are easily mistaken for good, however,when scanning in two orthogonal planes the transducermisplacement is easily detected.
Interpretation of the echocardiograms is influenced byseveral parameters. As the tissue velocities are measured byutilizing the Doppler effect, only the velocity componentdirected towards the transducer can be measured, thus thealignment of the heart within the view of the transduceraffects the tissue velocity measurements. The effect of thishas been investigated, and it is demonstrated that since themyocardium primarily has longitudinal motion and thus thevelocity vectors are mainly longitudinal, imaging in the apicalview will give little error in the velocity measurements.
Filtering of the tissue velocity signals have becomecommercially available with the hope that it will improvereproducibility and simplify interpretation. One set of lowpass filters has been tested, and it is seen that there is arisk of overdoing the filtering and cause an underestimation oftissue velocity parameters. A similar effect to low passfiltering is seen when using too low sample rate when recordingthe tissue velocities.
Finally a new imaging modality, tissue motion imaging, ispresented, where myocardial displacement, velocity, strain andacceleration may be interpreted from one single image, insteadof the situation today where several measurements must beperformed to get an overview of all these parameters.
The thesis concludes that reproducibility can be improved bycurve smoothing and that interpretation can be simplified usingadvanced methods of parametric imaging.
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Mishra, Mamata. "Clinical and physiological aspects of stress echocardiography." Thesis, Queen Mary, University of London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267303.
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Hang, Xiyi. "Compression and segmentation of three-dimensional echocardiography." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1089835123.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xvii, 151 p.; also includes graphics (some col.). Includes bibliographical references (p. 145-151). Available online via OhioLINK's ETD Center
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Huez, Sandrine. "Contribution à l'étude de la circulation pulmonaire et de la fonction ventriculaire droite dans l'hypertension pulmonaire: apports de l'échocardiographie et de l'imagerie par Doppler tissulaire." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210379.
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Soliman, Osama Ibrahim Ibrahim. "Advanced quantitative echocardiography: guiding therapy for heart failure." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10652.
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Rhodes, Caroline Lee. "Motion artifact detection in transthoracic 3-D echocardiography." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16719.
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Geenty, Paul. "Echocardiography in Infiltrative Cardiomyopathy: Amyloidosis and Fabry Disease." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/29152.
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The infiltrative cardiomyopathies are a heterogeneous group of disorders classically characterised by increased wall thickness and progressive diastolic dysfunction. While considered relatively rare, they are likely underdiagnosed, and are increasingly recognized as a significant cause of heart failure with preserved ejection fraction, particularly in the case of amyloidosis. Despite varying markedly in their natural histories and treatments available, they are often difficult to distinguish using conventional echocardiographic techniques. For this reason, novel imaging techniques, and multi-modality imaging are playing an increasing role in the diagnosis, prognostication and monitoring of infiltrative cardiomyopathies.
This thesis aims to investigate the role of both conventional and novel echocardiographic techniques in the diagnosis and management of amyloidosis and Fabry disease, two of the more common forms of infiltrative cardiomyopathy.
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Fayssoil, Abdallah. "Phénotypage cardiaque des dystrophies musculaires à l'aide des ultrasons." Thesis, Versailles-St Quentin en Yvelines, 2014. http://www.theses.fr/2014VERS0062/document.
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Les myopathies d’origine génétique sont des pathologies musculaires en rapport avec des anomalies génétiques. Les myopathies sont à l’origine d’un handicap physique majeur et affectent souvent la fonction respiratoire et parfois le cœur. Nous nous sommes intéressés à la caractérisation myocardique de 4 types de myopathies d’origine génétique à l’aide de l’échocardiographie Doppler : myopathie de Duchenne, sarcoglycanopathies, MELAS syndrome et maladie de Pompe.Nous avons analysé la fonction cardiaque dans 2 modèles murins de dystrophies musculaires: la souris mdx et la souris sgca null. En clinique, nous avons analysé la fonction cardiaque des sujets atteints de myopathie de Duchenne, de sarcoglycanopathies, de MELAS syndrome et de maladie de Pompe en échocardiographie Doppler.Dans les modèles animaux, nous avons retrouvé des anomalies myocardiques chez la souris mdx et chez la souris sgca null. Chez l’homme, l’atteinte myocardique est sévère chez les sujets atteints de myopathie de Duchenne et certains patients présentent un asynchronisme ventriculaire soulevant les indications éventuelles de resynchronisation myocardique. Les sujets atteints de gamma sarcoglycanopathies présentent de façon significative des anomalies de contraction du ventricule gauche comparativement aux sujets atteints d’alpha-sarcoglycanopathies. La fonction ventriculaire droite et gauche est préservée chez les sujets atteints de maladie de Pompe. Les sujets atteints de MELAS présentent des hypertrophies du ventricule gauche. L’analyse génétique retrouve une corrélation significative entre le taux d’hétéroplamie et la survenue d’événements cliniquesMuscular dystrophies are genetic neuromuscular disorders that affect skeletal muscle. We sought to assess heat involvement in four genetic muscular disorders : Duchenne muscular dystrophy, sarcoglycanopathies, MELAS and adulte Pompe disease. In animal models, we sought to assess, using Echocardiography Doppler, mdx mice and sgca null mice. Myocardiac abnormalities were found in mdx mice and sgca null mice. Clinical studies found severe cardiac impairment in Duchenne muscular dystrophies and ventricular asynchrony was found in patients with severe heart failure. Patients with gamma sarcoglycanopathy have significant alteration of left ventricular function in comparison with patients with alpha sarcoglycanopathy. Left and right ventricular function were preserved in patients with Pompe disease. Left ventricular hypertrophy was found in patients with MELAS. Genetic analysis disclosed significant correlation between heteroplasmy and significant clinical events
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Orde, Sam. "Use of advanced echocardiography imaging techniques in the critically ill." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21623.
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Background: Critical care echocardiography has become standard of care in the ICU. New technologies have been developed and have shown potential clinical utility to elucidate myocardial dysfunction not seen with conventional imaging. We sought to determine the feasibility and potential clinical benefit of these techniques in common situations seen in the ICU. Hypothesis: Advanced echo techniques would be feasible in the majority of critically ill patients and have prognostic significance, clinical utility and diagnose cardiac abnormalities, potentially in a more sensitive manner than conventional techniques. Results: (a) Speckle tracking echocardiography (STE) Left ventricle and RV analysis with STE was feasibly in ~80% of patients. More dysfunction was found using STE vs conventional analysis. RV dysfunction assessed by STE held significant prognostic relevance in those with septic shock and highlighted subtle dysfunction induced by mechanical ventilation, both in animal and human studies. (b) 3D transthoracic echocardiography (3D TTE) Despite finding 3D TTE feasible in mechanically ventilated ICU patients (LV 72% and RV 55%), it lacked necessary low variability and high precision vs standard measures. (c) Myocardial contrast perfusion echocardiography (MCPE) Assessing acute coronary artery occlusion in the ICU patient is challenging. Troponin elevation, acute ECG changes, regional wall motion analysis on echo and overall clinical acumen often lack diagnostic capabilities. MCPE was found to be feasible in the critically ill and had better association predicting acute coronary artery occlusion vs clinical acumen alone. Conclusions: STE, 3D TTE and MCPE are feasible in the majority of ICU patients. STE may show dysfunction not recognised by conventional imaging. 3D TTE for volumetric analysis is likely not suitable for clinical use at this stage. MCPE may help guide interventions in acute coronary artery occlusion.
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Nemes, Attila. "Advances in the evaluation of cardiovascular function by echocardiography." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10416.
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Kydd, Anna Christine. "Utility of echocardiography in guiding cardiac resynchronisation therapy (CRT)." Thesis, University of Cambridge, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709470.
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Roberts, Elved Bryn. "Assessment of coronary artery stenosis using myocardial contrast echocardiography." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1445931/.
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The theoretical advantage of perfusion data over wall motion data for diagnosing coronary artery stenosis relates to the temporal sequence of these phenomena in the ischaemic cascade. Myocardial perfusion evaluation could thus provide earlier information than wall motion assessment, with important clinical consequences. This thesis examines myocardial perfusion assessment using ultrasound and micro-bubble contrast in stable coronary artery stenosis. The first set of experiments were undertaken to establish both a means of infusing Optison (GE Healthcare, UK), and of displaying static frame contrast signal using Power Contrast Imaging (Acuson Sequoia, Siemens Medical Solutions, Mountain View, CA, USA.). Three Optison concentrations, five infusion rates, and five trigger intervals were evaluated. This revealed an appropriate concentration and infusion rate for Optison and identified an ideal trigger interval of one in four cardiac cycles. The second part of this study evaluated Power Contrast Imaging with Optison infusion in stable single or double vessel coronary artery stenosis. Perfusion assessment during Adenosine vasodilator stress was compared with standard wall motion assessment during Dobutamine stress, coronary angiography being the diagnostic standard. Among twenty-eight subjects and eighty-four coronary territories, Power Contrast Imaging had low sensitivity but equivalent specificity compared to wall motion assessment. The third component of this research evaluated micro-bubble preserving real time Coherent Contrast Imaging (Acuson Sequoia , Siemens Medical Solutions) alongside Optison infusion in stable single or double vessel coronary stenosis. Thirty-eight subjects and one hundred and fourteen coronary arteries were evaluated. Each subject underwent Dobutamine stress, during which standard wall motion, contrast wall motion, and contrast perfusion imaging were all assessed, the diagnostic standard being coronary angiography. This demonstrated that contrast wall motion evaluation is accurate and that combined contrast wall motion and perfusion imaging is at least equivalent to standard wall motion imaging alone for detecting underlying coronary stenosis.
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Bedeker, Wiaan Francois. "Impact of basic transthoracic echocardiography at district hospital level." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16935.
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Includes bibliographical referencesThe use and demand of echocardiography has increased worldwide. In developed countries, this has not been translated into improved access outside tertiary centres. Previous studies have favoured the appropriate use of echocardiography over its clinical impact, limiting generalisability to resource constrained settings. Objectives: To assess the impact of an echocardiographic service at district hospital level in Cape Town, South Africa. Methods: A prospective, cross-sectional study was performed. A total of 210consecutive patients, referred to the echocardiography clinic over a five-month period, were recruited. Transthoracic echocardiography was evaluated by its indication, new information provided, correlation with referring doctor's diagnosis and subsequent management plan. Impact included the escalation and de-escalation in treatment, as well as usefulness without a change in management. Results: The results show that 84% of the patients' management was impacted by echocardiography. Valvular lesions were the main indication. The most frequent contribution was information provided towards the diagnosis of heart failure and assessment post-myocardial infarction. Fifty-six per cent of the echocardiograms confirming the referring doctor's diagnosis still had a significant impact. The rational prescription of medication had the major impetus, followed by de-escalation of therapy and screening patients for referral to tertiary facilities. Conclusion: Echocardiography has a positive impact on patient management outside tertiary settings, where the definition of impact appears to be different. The value of a normal study, screening prior to upstream referral and usefulness irrespective of change has been established. This should alert policy makers towards the risk of restricted access and promote training.
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Spalla, I. "SPECKLE-TRACKING ECHOCARDIOGRAPHY IN DOGS WITH PATENT DUCTUS ARTERIOSUS." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/233990.
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PDA is one of the most common congenital cardiac malformation in the dog. Echocardiography has been the cornerstone in diagnosing and providing hemodynamic information in a wide variety of disease.Recently, speckle tracking echocardiography has been regarded as a useful tool to assess cardiac function. Aim of the study was to compare cardiovascular hemodynamics in dogs with PDA with healthy control dogs and evaluate any change in cardiac contractility before and after PDA closure. A statistically significant difference was found between standard and advanced echocardiographic techniques, with absolute higher values in dogs with PDA as compared to healthy controls. Cardiovascular hemodynamics were markedly different before and after PDA closure. Based on the results, STE should be considered in echocardiographic assessment of dogs with PDA, as they represent an animal model of congenital left ventricular overload not affected.
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Trivedi, Siddharth Jagdish. "Clinical utility of speckle tracking echocardiography in the assessment of cardiovascular disease." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25705.
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Left ventricular (LV) ejection fraction (EF) derived from two-dimensional echocardiography has been the cornerstone for LV function assessment for more than half a century. However, EF is only an indirect measure of cardiac output obtained from changes in LV volume, and does not necessarily reflect intrinsic myocardial contractile properties. Furthermore, LVEF measurement has a number of challenges that relate to image quality, LV geometry assumptions, and technical expertise, and has significant issues with intra-observer, inter-observer, and test-retest variability. A more contemporary marker of LV systolic function is speckle tracking echocardiography (STE)-based global longitudinal strain (GLS). Based on deformation of the cardiac muscle, GLS provides a more direct evaluation of myocardial contractile function. GLS is highly sensitive for the detection of overt LV dysfunction, as well as subclinical LV systolic impairment when LVEF is still considered normal. Furthermore, longitudinal strain has great utility in the evaluation of right ventricular (RV) function, as well as atrial function. Two-dimensional GLS, derived from semiautomatic software, has a high temporal and spatial resolution and consequently, improved inter- and intra-observer reproducibility, compared to LVEF. The overall aim of this thesis was to explore the role of STE-derived GLS in a variety of cardiovascular conditions. Firstly, the utility of GLS in patients with ventricular arrhythmias was assessed, including patients with and without structural heart disease. GLS in cardio-oncology, specifically left-sided breast cancer patients undergoing radiation therapy, was also evaluated. RV strain in patients with pulmonary embolism was studied in order to identify its role in the management of these patients. Finally, left atrial function, including left atrial strain, was addressed in a population of elite athletes with and without atrial fibrillation and compared to non-athletes.
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方乃聰 and Nai-chung Fong. "Real time three dimensional echocardiographic assessment on patients with beta-thalassaemia major." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31970242.
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Hancock, Jane. "The utilisation of ultrasonic tissue characterisation for the evaluation of myocardial status in patients with acute myocardial infarction." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274662.
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Dawson, Ellen Adele. "The impact of exercise duration, exercise intensity, fitness and environmental conditions on the development of exercise induced cardiac fatigue." Thesis, Manchester Metropolitan University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268982.
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Fong, Nai-chung. "Real time three dimensional echocardiographic assessment on patients with beta-thalassaemia major." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23340095.
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Palmgren, Ingrid. "Transesophageal Echocardiography in Patients Undergoing Elective Coronary Artery Bypass Surgery." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/91-554-5238-8/.
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Zabair, Adeala Tuffail. "Segmentation of stress echocardiography sequences using a patient-specific prior." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534181.
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Amini, Richard, Lori Stolz, Parisa Javedani, Kevin Gaskin, Nicola Baker, Vivienne Ng, and Srikar Adhikari. "Point-of-care echocardiography in simulation-based education and assessment." DOVE MEDICAL PRESS LTD, 2016. http://hdl.handle.net/10150/614981.
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Background: Emergency medicine milestones released by the Accreditation Council for Graduate Medical Education require residents to demonstrate competency in bedside ultrasound (US). The acquisition of these skills necessitates a combination of exposure to clinical pathology, hands-on US training, and feedback. Objectives: We describe a novel simulation-based educational and assessment tool designed to evaluate emergency medicine residents' competency in point-of-care echocardiography for evaluation of a hypotensive patient with chest pain using bedside US. Methods: This was a cross-sectional study conducted at an academic medical center. A simulation-based module was developed to teach and assess the use of point-of-care echocardiography in the evaluation of the hypotensive patient. The focus of this module was sonographic imaging of cardiac pathology, and this focus was incorporated in all components of the session: asynchronous learning, didactic lecture, case-based learning, and hands-on stations. Results: A total of 52 residents with varying US experience participated in this study. Questions focused on knowledge assessment demonstrated improvement across the postgraduate year (PGY) of training. Objective standardized clinical examination evaluation demonstrated improvement between PGY I and PGY III; however, it was noted that there was a small dip in hands-on scanning skills during the PGY II. Clinical diagnosis and management skills also demonstrated incremental improvement across the PGY of training. Conclusion: The 1-day, simulation-based US workshop was an effective educational and assessment tool at our institution.
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Amini, Richard, Lori A. Stolz, Parisa P. Javedani, Kevin Gaskin, Nicola Baker, Vivienne Ng, and Srikar Adhikari. "Point-of-care echocardiography in simulation-based education and assessment." Dove Press, 2016. http://hdl.handle.net/10150/617183.
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UA Open Access Publishing FundBackground: Emergency medicine milestones released by the Accreditation Council for Graduate Medical Education require residents to demonstrate competency in bedside ultrasound (US). The acquisition of these skills necessitates a combination of exposure to clinical pathology, hands-on US training, and feedback. Objectives: We describe a novel simulation-based educational and assessment tool designed to evaluate emergency medicine residents’ competency in point-of-care echocardiography for evaluation of a hypotensive patient with chest pain using bedside US. Methods: This was a cross-sectional study conducted at an academic medical center. A simulation-based module was developed to teach and assess the use of point-of-care echocardiography in the evaluation of the hypotensive patient. The focus of this module was sonographic imaging of cardiac pathology, and this focus was incorporated in all components of the session: asynchronous learning, didactic lecture, case-based learning, and hands-on stations. Results: A total of 52 residents with varying US experience participated in this study. Questions focused on knowledge assessment demonstrated improvement across the postgraduate year (PGY) of training. Objective standardized clinical examination evaluation demonstrated improvement between PGY I and PGY III; however, it was noted that there was a small dip in hands-on scanning skills during the PGY II. Clinical diagnosis and management skills also demonstrated incremental improvement across the PGY of training. Conclusion: The 1-day, simulation-based US workshop was an effective educational and assessment tool at our institution.
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Pudiak, Kh I. "Cardiovascular complications according to echocardiography among asymptomatic HIV-infected patients." Thesis, БДМУ, 2020. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18224.
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Radin, Umar Radin Zaid. "Ergonomic Interventional Design of an Articulated Arm for Echocardiography Application." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1293678856.
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Li, Xiang-Ning. "Quantitative assessment of mitral regurgitation with three-dimensional doppler echocardiography /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8039.
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Belous, Gregg R. "Novel Machine Learning Techniques for Left Ventricular Analysis in Echocardiography." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/400568.
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Transthoracic (TTX) echocardiography (echo) is vital for the diagnosis and treatment of heart disease. It is also essential for the determination of appropriate therapeutic procedures and monitoring disease progression and response. An important requisite of TTX echo is the quantitative assessment of left ventricular (LV) size and function from its manually traced endocardial border. However, the diagnostic accuracy of this routine task is often adversely affected by artifact and signal dropout, producing substantial observer variability and uncertainty in clinical diagnosis. With the advent of machine learning, computer aided detection (CAD) systems have addressed organ segmentation through robust landmark localization techniques and a reliance on anatomical shape prior models to guide the segmentation process. Shape priors models are most effective when shape variations can be captured by a parametric distribution, and suffcient training data is available. However, in the absence of these conditions, results are invariably much poorer. In addition, the problem of insuffcient training data not only presents challenges to shape prior models, but also classification algorithms, as well.
Stress echo (SE) is a widely used functional test for the detection of obstructive coronary artery disease. The interpretive process involves the careful comparison of pre- and post-exercise echo sequences across a number of echocardiographic views. This is a time consuming and highly subjective task. While CAD systems have been shown to be feasible for automated reporting in other areas of medical imaging, they have not been applied to the task of identifying abnormal stress echocardiograms. An automated approach would not only be a useful adjunct to physicians reporting SE, but also aid in physician training of SE reporting.
Motivated by these challenges, this thesis presents four novel machine learning techniques for LV analysis in echo. Firstly, two anatomical shape prior models are proposed: online relational manifold learning (ORML) and dual subspace segment projection learning (DSSPL). ORML is formulated to address the challenge of modelling complex shape subspaces. ORML serves to learn a mapping function between a low dimension image manifold and shape manifold. However, different to existing subspace learning approaches, ORML leverages the input image to target more contextually relevant regions between both manifold structures, leading to robust LV shape inference for volume prediction, and the formulation of a shape prior model through a more principled shape selection strategy. ORML demonstrates improved segmentation performance over current benchmark methods, and shows an excellent level of agreement with an expert.
DSSPL addresses the challenges of modelling complex shape variations under the scenario of high dimension low sample size (HDLSS) training data. It serves to compose shapes from an ensemble of shape segments where each segment is formed using two subspaces: global shape subspace and segment-specific subspace, each necessary for extracting global shape patterns and local patterns, respectively. This ensures general shape plausibility in regions of signal drop-out or missing boundary information, and also more localized flexibility. The reconstructive properties of DSSPL reduces information loss and leverages the subspaces to provide contiguous shapes without any post-processing. Comprehensive experimental analysis is performed on three databases from different medical imaging systems across X-Ray, MRI, and echo. DSSPL outperforms all compared benchmarks in terms of its shape generalization ability and segmentation performance.
The third method proposed is dual subspace discriminative projection learning (DSDPL), which addresses the challenge of image classification, also under the HDLSS training data scenario. Unlike traditional projection learning frameworks that assume discriminative features share a common subspace, DSDPL instead serves to decompose original high dimensional data, via learned projection matrices, into class-shared and class-specific subspaces. The learned projection matrices are jointly constrained with l2;1 sparse norm and LDA terms while the reconstructive properties reduce information loss. Regression-based terms are also included to facilitate a more robust classification approach, using extracted class-specific features for better classification. Results show improved classification accuracy with DSDPL over current benchmark subspace learning methods and deep learning models.
The fourth method proposed is deep stage-coupled attentive feature extraction (DSCAFE) for identifying abnormal stress echocardiograms. DSCAFE is a deep neural network model that consists of stage-coupled attentive feature extraction (SCAFE) blocks for extracting the most salient information from connected echo sequences. SCAFE blocks are composed of 3D residual network streams and dual-attention gated mechanisms, which provide more targeted focus across each echo sequence by also taking into account the observed features from the corresponding view at the opposing exercise stage. A recurrent neural network feature aggregation strategy is then employed to model the extracted low dimension spatio-temporal features for more accurate classification. When compared against an expert reviewer, DSCAFE achieved a concordance of 86.5% from a clinical SE dataset. This research draws on machine learning knowledge across a diverse range of domains. While results show definitive improvements over current benchmark methods for LV analysis, the proposed methods are also adaptable to a wide range of computer vision tasks.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Finel, Victor. "3D ultrafast echocardiography : toward a quantitative imaging of the myocardium." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC134/document.
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L’objectif de cette thèse de doctorat était de développer l’échographie ultrarapide 3D du cœur, plus particulièrement dans le but de caractériser le muscle cardiaque. A cet effet, un échographe ultrarapide assemblé dans notre laboratoire a été utilisé. Dans la première partie de cette thèse, un mode d’imagerie temps-réel a été développé pour faciliter l’imagerie in-vivo en utilisant ce scanner, ainsi que des outils de visualisation 3D et 4D. Par la suite, l’imagerie 3D du tenseur de rétrodiffusion a été développée pour analyser l’orientation des fibres musculaires du cœur de manière non-invasive au cours du cycle cardiaque. Des résultats obtenus sur un volontaire avant et après la contraction cardiaque ont été obtenus. De plus, les effets indésirables du mouvement axial ont été étudiés, et une méthode d’estimation de la vitesse axiale et de correction des aberrations induites a été proposée et appliquée sur l’homme. Cette technique pourrait devenir un outil intéressant de diagnostic et quantification de la désorganisation des fibres musculaires dans le cadre de cardiomyopathies hypertrophiques. De plus, l’échographie ultrarapide 3D a été utilisée pour visualiser la propagation dans les parois du cœur d’ondes de cisaillement générées naturellement au cours du cycle cardiaque, et un algorithme pour déterminer leurs vitesses a été développé. Cette technique a été validée grâce à des simulations numériques puis appliquée sur deux volontaires sains, pendant les phases de contraction et relaxation du myocarde. Etant donné que la vitesse des ondes de cisaillement est directement reliée à la rigidité du cœur, cette méthode pourrait permettre d’estimer la capacité du cœur à de contracter et à se relâcher, qui sont des paramètres important pour son fonctionnement. Enfin, l’activation de la contraction cardiaque de cœurs de rats isolés a été imagée à haute cadence et en 3D dans le but d’analyser la synchronisation de la contraction. Les délais d’activation mécanique ont pu correctement être quantifiés lors du rythme naturel du cœur, de stimulations électriques extérieures ainsi qu’en hypothermie. Ensuite, la faisabilité de la technique en 2D sur des cœurs humains de manière non-invasive a été étudiée et appliquée sur des fœtus et des adultes. Cette technique d’imagerie pourrait aider la caractérisation d’arythmies et améliorer leur traitement. En conclusion, nous avons introduit dans ces travaux de thèse trois nouvelles modalités d’imagerie ultrarapide 3D permettant de quantifier des propriétés structurelles et fonctionnelles du myocarde qui jusqu’ici ne pouvaient pas être imagée en échocardiographie. L’imagerie 3D ultrarapide est une modalité très prometteuse, non ionisante, transportable et qui pourrait améliorer fortement dans le futur le diagnostic et la prise en charge des patientsThe objectives of this PhD thesis were to develop 3D ultrafast ultrasound imaging of the human heart toward the characterization of cardiac tissues. In order to do so, a customized, programmable, ultrafast scanner built in our group was used. In the first part of this thesis, a real-time imaging sequence was developed to facilitate in-vivo imaging using this scanner, as well as dedicated 3D and 4D visualization tools. Then, we developed 3D Backscatter Tensor Imaging (BTI), a technique to visualize the muscular fibres orientation within the heart wall non-invasively during the cardiac cycle. Applications on a healthy volunteer before and after cardiac contraction was shown. Moreover, the undesired effects of axial motion on BTI were studied, and a methodology to estimate motion velocity and reduce the undesired affects was introduced and applied on a healthy volunteer. This technique may become an interesting tool for the diagnosis and quantification of fibres disarrays in hypertrophic cardiomyopathies. Moreover, 3D ultrafast ultrasound was used to image the propagation of naturally generated shear waves in the heart walls, and an algorithm to determine their speed was developed. The technique was validated in silico and the in vivo feasibility was shown on two healthy volunteers, during cardiac contraction and relaxation. As the velocity of shear waves is directly related to the rigidity of the heart, this technique could be a way to assess the ability of the ventricle to contract and relax, which is an important parameter for cardiac function evaluation. Finally, the transient myocardial contraction was imaged in 3D on isolated rat hearts at high framerate in order to analyse the contraction sequence. Mechanical activation delays were successfully quantified during natural rhythm, pacing and hypothermia. Then, the feasibility of the technique in 2D on human hearts non-invasively was investigated. Applications on foetuses and adults hearts were shown. This imaging technique may help the characterization of cardiac arrhythmias and thus improve their treatment. In conclusion, we have introduced in this work three novel 3D ultrafast imaging modalities for the quantification of structural and functional myocardial properties. 3D ultrafast imaging may become an important non-ionizing, transportable diagnostic tool that may improve the patient care at the bed side
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Joos, Philippe. "Imagerie ultrasonore ultra-rapide dédiée à la quantification 3D du mouvement cardiaque." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1312/document.
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Cette thèse porte sur le développement et l’évaluation de techniques d’imagerie en échocardiographie. L’objectif est de proposer des méthodes d’imagerie ultrasonore ultrarapide pour estimer le mouvement cardiaque 2-D et 3-D.Première modalité d’imagerie du cœur, l’échocardiographie conventionnelle permet la mesure des déformations myocardiques à 80 images/s. Cette cadence d’imagerie est insuffisante pour quantifier les mouvements de la totalité du myocarde lors de tests d’efforts, utiles en évaluation clinique, au cours desquels le rythme cardiaque est augmenté. De plus, la résolution temporelle actuelle en échocardiographie 3-D limite ses applications, pourtant essentielles pour une caractérisation complète du cœur.Les contributions présentées ici sont 1) le développement et l’évaluation, pour l’application cardiaque, d’une méthode originale d’estimation de mouvement 2-D par imagerie ultrarapide et marquage des images, 2) l’étude de faisabilité de la mesure globale des déformations cardiaques avec une méthode innovante d’imagerie ultrasonore ultrarapide 2-D et 3) la généralisation de cette approche en 3-D pour l’imagerie des volumes cardiaques à haute résolution temporelle. Cette technique est basée sur l’émission d’ondes divergentes, et l’intégration d’une compensation de mouvement dans le processus de formation des volumes cardiaques.La méthode proposée permet l’estimation des mouvements cardiaques 2-D et l’échocardiographie ultrarapide 3-D. L’évaluation de notre approche pour la quantification des déformations myocardiques locales 2-D et 3-D pourrait permettre de proposer des pistes innovantes pour poursuivre nos études et améliorer le diagnostic en routine cliniqueThis PhD work focuses on the development and the evaluation of imaging techniques in echocardiography. Our objective is to propose ultrafast ultrasound imaging methods for 2-D and 3-D cardiac motion estimations.Echocardiography is one of the most widespread modality for cardiovascular imaging. Conventional clinical scanners allow measurement of myocardial velocities and deformations at 80 images / s. In some situations, it can be recommended to increase the heart rate during a stress echocardiographic examination. Motion estimation of the whole myocardium at such heart rates is challenging with the conventional imaging systems. In addition, the low temporal resolution of the current conventional 3-D echocardiography limits quantitative applications, which would be needed for a complete characterization of the heart.The three contributions presented here are 1) the development and evaluation of an original method for 2-D cardiac motion estimation, with ultrafast imaging and image tagging, 2) the feasibility study of the global myocardial deformation measurement using an innovative 2-D ultrafast ultrasound imaging method and 3) the generalization of this approach in three dimensions for high frame-rate 3-D echocardiography. This method is based on the transmission of divergent waves and the integration of motion compensation, during the imaging process, to produce high-quality volumetric images of the heart.The proposed method allows 2-D cardiac motion estimation and 3-D echocardiography at high frame-rate. The evaluation of our approach for local 2-D and 3-D myocardial deformation measurements should permit to conduct further study in order to improve medical diagnosis
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斎藤, 英彦, 博史 林, 和彦 宮口, 正嗣 岩瀬, 充弘 横田, 晃. 竹中, Hidehiko Saito, et al. "Discrepancy between systolic and diastolic dysfunction of the left ventricle in patients with Duchenne muscular dystrophy." Thesis, Oxford University Press, 1993. http://hdl.handle.net/2237/16373.
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Shahgaldi, Kambiz. "Assessment of Left Ventricular Function and Hemodynamics Using Three-dimensional Echocardiography." Doctoral thesis, KTH, Medicinsk teknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12966.
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Left ventricular (LV) volumes and ejection fraction (EF) are important predictors of cardiac morbidity and mortality. LV volumes provide valuable prognostic information which isparticularly useful in the selection of therapy or determination of the optimal time for surgery. Two-dimensional (2D) echocardiography is the most widely used non-invasive method forassessment of cardiac function, 2D echocardiography has however several limitations inmeasuring LV volumes and EF since the formulas for quantifications are based on geometricalassumptions. Three-dimensional (3D) echocardiography has been available for almost twodecades, although the use of this modality has not gained wide spread acceptance. 3D echocardiography can overcome the above mentioned limitation in LV volume and EF evaluation since it is not based on geometrical assumption. 3D echocardiography has been shownin several studies to be more accurate and reproducible with low inter- and intraobservervariability in comparison to 2D echocardiography regarding the measurements of LV volumesand EF. The overall aim of the thesis was to evaluate the feasibility and accuracy of 3D echocardiography based-methods in the clinical context. In Study I the feasibility of 3D echocardiography was investigated for determination of LV volumes and EF using parasternal, apical and subcostal approaches. The study demonstrated that the apical 3D echocardiography view offers superior visualization. Study II tested the possibility of creating flow-volume loops to differentiate patients with valvular abnormalities from normal subjects. There were significant differences in the pattern from flow-volume loops clearly separating the groups. In Study III the visual estimation, “eyeballing” of EF was evaluated with two- and tri-plane echocardiography in comparison to quantitative 3D echocardiography. The study confirmed that an experienced echocardiographer can, with a high level of agreement estimate EF both with two- and tri-plane echocardiography. Study IV exposed the high accuracy of stroke volume and cardiac output determination using a3D biplane technique by planimetrically tracing the left ventricular outflow tract and indicating that an assumption of circular left ventricular outflow tract is not reliable. In Study V, two 3D echocardiography modalities, single-beat and four-beat ECG-gated 3D echocardiography were evaluated in patients having sinus rhythm and atrial fibrillation. Thesingle-beat technique showed significantly lower inter-and intraobserver variability in LV volumes and EF measurements in patients having atrial fibrillation in comparison to four-beat ECG-gated acquisition due to absence of stitching artifact. All studies demonstrated good results suggesting 3D echocardiography to be a feasible andaccurate method in daily clinical settings.degree of Medical DoctorQC 20100629
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Whalley, Gillian Amanda. "The role of contemporary echocardiography in the management of heart failure." Thesis, University of Auckland, 2006. http://hdl.handle.net/2292/61.
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Heart failure (HF) is an increasing and leading cause of cardiovascular morbidity, hospitalisation and death. Echocardiography is often used in HF patients because it provides important aetiological, diagnostic and prognostic information to assist physician management at moderate cost. This thesis has explored contemporary echocardiographic techniques for assessment of both diastolic and systolic function to ascertain their effectiveness and optimal utility. Assessment of systolic function in HF patients is optimised by the use of harmonic imaging and not enhanced with the use of transpulmonary contrast agents, whilst diastolic filling is optimised by the use of preload manipulation. When optimised in this way, echocardiography can be used to stratify HF patients in terms of risk of death and/or hospitalisation after discharge from hospital. This was confirmed in a meta-analysis of more than 6000 patients (1000 deaths) with HF or after acute myocardial infarction (AMI), where the presence of restrictive filling pattern (the most severe form of diastolic dysfunction) was associated with a four-fold increase in mortality in both patient groups. In addition, restrictive filling pattern also predicted development of HF post AMI and hospitalisation in patients with HF. This meta-analysis also evaluated the intermediate stages of diastolic dysfunction and found a stepped relationship between each grade and prognosis. The last part of this thesis explored the role of contemporary echocardiography for management of symptomatic patients in the community and found that the diagnosis of HF in the community may be optimised by using brain natriuretic peptide (BNP) as a first test to "rule-out" heart failure and then echocardiography, which was superior to BNP in patients with intermediate BNP levels to diagnose HF. Furthermore, the systolic echocardiographic parameters were important for diagnosis, whilst the diastolic parameters predicted future hospitalisation. In summary, contemporary echocardiography in HF patients should include comprehensive assessment of systolic function (using tissue harmonics imaging) and diastolic filling (utilising preload manipulation). This approach will optimise both diagnosis and prognosis and in turn may aid physician management.
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Icenogle, David A. "Development of virtual mitral valve leaflet models from three-dimensional echocardiography." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48994.
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Mitral valve (MV) disease is responsible for approximately 2,581 deaths and 41,000 hospital discharges each year in the US. Mitral regurgitation (MR), retrograde blood from through the MV, is often an indicator of MV disease. Surgical repair of MVs is preferred over replacement, as it is correlated with better patient quality of life. However, replacement rates are still near 40% because MV surgical repair expertise is not spread across all hospitals. In addition, 15-80% of surgical repair patients have recurrent MR within 10 years. Quantitative patient-specific models could aid these issues by providing less experienced surgeons with additional information before surgery and a quantitative map of patient valve changes after surgery. Real-time 3D echocardiography (RT3DE) can provide high quality 3D images of MVs and has been used to generate quantitative models previously. However, there is not currently an efficient, dynamic, and validated method that is fast enough to use in common practice. To fill this need, a tool to generate quantitative 3D models of mitral valve leaflets from RT3DE in an efficient manner was created. Then an in vitro echocardiography correction scheme was devised and a dynamic, in vitro validation of the tool was performed. The tool demonstrated that it could generate dynamic, complex MV geometry accurately and more efficiently than current methods available. In addition, the ability for mesh interpolation techniques to reduce segmentation time was demonstrated. The tool generated by this study provides a method to quickly and accurately generate MV geometry that could be applied to dynamic patient specific geometry to aid surgical decisions and track patient geometry changes after surgery.
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Khan, Sadia N. "Tissue Doppler Echocardiography in the Assessment of Ischaemic Left Ventricular Dysfunction." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525221.
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Hui, Ling, and 許凌. "Dobutamine stress echocardiography for children with acquired and congenital cardiac diseases." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29914954.
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Ruiz, Evandro Eduardo Seron. "Static and dynamic contour definition in left ventricular two-dimensional echocardiography." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294311.
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Verhoek, Michael. "Fast segmentation of the LV myocardium in real-time 3D echocardiography." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566050.
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Heart disease is a major cause of death in western countries. In order to diagnose and monitor heart disease, 3D echocardiography is an important tool, as it provides a fast, relatively low-cost, portable and harmless way of imaging the moving heart. Segmentation of cardiac walls is an indispensable method of obtaining quantitative measures of heart function. However segmentation of ultrasound images has its challenges: image quality is often relatively low and current segmentation methods are often not fast. It is desirable to make the segmentation technique as fast as possible, making quantitative heart function measures available at the time of recording. In this thesis, we test two state-of-the-art fast segmentation techniques to address this issue; furthermore, we develop a novel technique for finding the best segmentation propagation strategy between points of time in a cardiac image sequence. The first fast method is Graph Cuts (GC), an energy minimisation technique that represents the image as a graph. We test this method on static 3D echocardiography to segment the myocardium, varying the importance of the regulariser function. We look at edge measures, position constraints and tissue characterisation and find that GC is relatively fast and accurate. The second fast method is Random Forests (RFos), a discriminative classifier using binary decision trees, used in machine learning. To our knowledge, we are the first to test this method for myocardial segmentation on 2D and 3D static echocardiography. We investigate the number of trees, image features used, some internal parameters, and compare with intensity thresholding. We conclude that RFos are very fast and more accurate than GC segmentation. The static RFo method is subsequently applied to all time frames. We describe a novel optical flow based propagation technique that improves the static results by propagating the results from well-performing time frames to less-performing frames. We describe a learning algorithm that learns for each frame which propagation strategy is best. Furthermore, we look at the influence of the number of images and of the training set available per tree, and we compare against other methods that use motion information. Finally, we perform the same propagation learning method on the static GC results, concluding that the propagation method improves the static results in this case as well. We compare the dynamic GC results with the dynamic RFo results and find that RFos are more accurate and faster than GC.
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Mulet, Parada Miguel. "Intensity independent feature extraction and tracking in echocardiographic sequences." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343557.
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Hartnick, Maria Diana. "Echocardiography for early detection of heart disease in high risk diabetic patients." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/1566.
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Masters of Technology: Radiography
in the Faculty of Health and Wellness Sciences
at the Cape Peninsula University of Technology
2015Introduction: Diabetes mellitus is a chronic disease with a significant impact on personal lifestyle and wellbeing. It is associated with a high prevalence of myocardial disease, the early detection of which is important for prevention of disease progression. Although echocardiography is recognised as a leading cardiovascular imaging modality, there has been limited work on its role in the early detection of diabetes-related myocardial dysfunction. The aim of this study was therefore to evaluate the role of echocardiography in the early detection of diabetes-related myocardial disease, in a population with a high prevalence of type 2 diabetes mellitus. Methodology: A single sonographer, blinded to individual biochemical markers conducted detailed echocardiographic examinations on 407 participants from a Cape Town community with a high prevalence of diabetes mellitus. Participants were subsequently stratified by biochemical status, as normoglyceamia or hyperglycaemia. The echocardiographic features of the two groups were compared using the Pearson chi-squared and Mann-Whitney U tests. Findings: Hyperglycaemia was associated with left atrium (LA) enlargement (p ˂ 0.0014), aortic enlargement (p ˂ 0.0067) and inter-ventricular septal (IVS) thickening (p ˂ 0.0001). Conclusion: The findings suggest that echocardiography can be a useful screening tool for myocardial dysfunction in Type 2 diabetes mellitus.