Dissertations / Theses on the topic 'Cardiac function analysis'
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1
Wang, Haiyan. "Cardiac motion and function analysis using MR imaging." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/30717.
Abstract:
Cardiacvascular disease (CVD) is the single leading cause of death in the world, claiming 17.3 million lives a year according to the World Health Organisation (WHO). The development of magnetic resonance (MR) imaging has provided clinicians and researchers with effective tools to detect, assess and monitor the progress of the disease and treatments. MR imaging produces images with high spatial resolution using noninvasive and non-ionising techniques. However, quantitative analysis of the cardiovascular system from MR images remains challenging. The work presented in this thesis focuses on the utilization of cardiac motion information including motion tracking, quantification of the motion and prediction of clinical variables by incorporating motion information. The first main contributions of the thesis are approaches for sparse and dense motion tracking: a sparse set of key landmarks is detected and tracked. They are used as constraints to perform cardiac dense motion tracking using both 3D tagged and untagged image sequences from short-axis and long-axis MR views simultaneously. In order to improve speed and accuracy of the motion tracking, we also develop an approach to identify and track a sparse set of distinctive landmarks in the presence of relatively large deformations for myocardium motion tracking without applying dense motion tracking. An integrated framework is proposed to combine entropy and SVD-based sparse landmark detection with a MRF-based motion tracking framework. In addition, the regional wall thickness systolic dyssynchrony index (SDI) derived directly from sparse motion tracking provides accurate quantification of LV motion, which agrees well with the clinical measurements. In our last contribution, we successfully used manifold learning as a feature selection approach for a SVM-based classification and regression to analyse 209 cardiac MR image sequences. The SVM-based approaches directly operate on the manifold coordinates of the MR images without requiring any non-rigid registration or segmentation and is hence computationally efficient. We demonstrate that, by considering both inter- and intra-subject variation in the manifold learning, we are able to extract both anatomical and functional information. This can be used to construct powerful and reliable classifiers that are more predictive than global indices such as LV volume and mass. The manifold allows for investigating how much temporal information is needed improve the classification performance. The regression experiments demonstrate that there is a very strong correlation between manifold coordinates and obesity indices.
2
Piva, Rosa Maria Volpi. "Analysis and visualization of cardiac wall motion from magnetic resonance images." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246777.
3
Prakosa, Adityo. "Analysis and simulation of multimodal cardiac images to study the heart function." Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00837857.
Abstract:
This thesis focuses on the analysis of the cardiac electrical and kinematic function for heart failure patients. An expected outcome is a set of computational tools that may help a clinician in understanding, diagnosing and treating patients suffering from cardiac motion asynchrony, a specific aspect of heart failure. Understanding the inverse electro-kinematic coupling relationship is the main task of this study. With this knowledge, the widely available cardiac image sequences acquired non-invasively at clinics could be used to estimate the cardiac electrophysiology (EP) without having to perform the invasive cardiac EP mapping procedures. To this end, we use real clinical cardiac sequence and a cardiac electromechanical model to create controlled synthetic sequence so as to produce a training set in an attempt to learn the cardiac electro-kinematic relationship. Creating patient-specific database of synthetic sequences allows us to study this relationship using a machine learning approach. A first contribution of this work is a non-linear registration method applied and evaluated on cardiac sequences to estimate the cardiac motion. Second, a new approach in the generation of the synthetic but virtually realistic cardiac sequence which combines a biophysical model and clinical images is developed. Finally, we present the cardiac electrophysiological activation time estimation from medical images using a patient-specific database of synthetic image sequences.
4
Shi, Wenzhe. "An image segmentation and registration approach to cardiac function analysis using MRI." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10548.
Abstract:
Cardiovascular diseases (CVDs) are one of the major causes of death in the world. In recent years, significant progress has been made in the care and treatment of patients with such diseases. A crucial factor for this progress has been the development of magnetic resonance (MR) imaging which makes it possible to diagnose and assess the cardiovascular function of the patient. The ability to obtain high-resolution, cine volume images easily and safely has made it the preferred method for diagnosis of CVDs. MRI is also unique in its ability to introduce noninvasive markers directly into the tissue being imaged(MR tagging) during the image acquisition process. With the development of advanced MR imaging acquisition technologies, 3D MR imaging is more and more clinically feasible. This recent development has allowed new potentially 3D image analysis technologies to be deployed. However, quantitative analysis of cardiovascular system from the images remains a challenging topic. The work presented in this thesis describes the development of segmentation and motion analysis techniques for the study of the cardiac anatomy and function in cardiac magnetic resonance (CMR) images. The first main contribution of the thesis is the development of a fully automatic cardiac segmentation technique that integrates and combines a series of state-of-the-art techniques. The proposed segmentation technique is capable of generating an accurate 3D segmentation from multiple image sequences. The proposed segmentation technique is robust even in the presence of pathological changes, large anatomical shape variations and locally varying contrast in the images. Another main contribution of this thesis is the development of motion tracking techniques that can integrate motion information from different sources. For example, the radial motion of the myocardium can be tracked easily in untagged MR imaging since the epi- and endocardial surfaces are clearly visible. On the other hand, tagged MR imaging allows easy tracking of both longitudinal and circumferential motion. We propose a novel technique based on non-rigid image registration for the myocardial motion estimation using both untagged and 3D tagged MR images. The novel aspect of our technique is its simultaneous use of complementary information from both untagged and 3D tagged MR imaging. The similarity measure is spatially weighted to maximise the utility of information from both images. The thesis also proposes a sparse representation for free-form deformations (FFDs) using the principles of compressed sensing. The sparse free-form deformation (SFFD) model can capture fine local details such as motion discontinuities without sacrificing robustness. We demonstrate the capabilities of the proposed framework to accurately estimate smooth as well as discontinuous deformations in 2D and 3D CMR image sequences. Compared to the standard FFD approach, a significant increase in registration accuracy can be observed in datasets with discontinuous motion patterns. Both the segmentation and motion tracking techniques presented in this thesis have been applied to clinical studies. We focus on two important clinical applications that can be addressed by the techniques proposed in this thesis. The first clinical application aims at measuring longitudinal changes in cardiac morphology and function during the cardiac remodelling process. The second clinical application aims at selecting patients that positively respond to cardiac resynchronization therapy (CRT). The final chapter of this thesis summarises the main conclusions that can be drawn from the work presented here and also discusses possible avenues for future research.
5
Rehmani, Taha. "An In-vivo Analysis of SLMAP Function in the Postnatal Mouse Myocardium." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36666.
Abstract:
SLMAP is a tail anchored membrane protein that alternatively splices to generate three isoforms, SLMAP1, SLMAP2 and SLMAP3. Previous studies in our lab have shown that the postnatal cardiac-specific overexpression of SLMAP1 results in intracellular vesicle expansion and enhanced endosomal recycling. I generated a postnatal cardiac-specific knockout model using the Cre-Lox system to nullify all three SLMAP isoforms and further evaluate its role in the mouse myocardium. SLMAP knockdown and knockout mouse hearts were analyzed with western blotting and qPCR. I found that only SLMAP3 was nullified and phenotypic evaluation through echocardiography indicated that young and old SLMAP3 knockout animals showed no remarkable changes in cardiac function. Furthermore, challenge with stressor isoproterenol had a similar response to wildtype and knockout mice in cardiac structure and function. Surprisingly the level of expression of SLMAP1 and SLMAP2 was maintained in the myocardium from SLMAP3 deficient mice. Interestingly the machinery involved in endosomal recycling was not impacted by the loss of SLMAP3. These data indicate that loss of SLMAP3 does not alter cardiac structure and function in the postnatal myocardium in the presence of SLMAP1 and SLMAP2.
6
Vigneault, Davis Marc. "Quantification of regional cardiac function : clinically-motivated algorithm development and application to cardiac magnetic resonance and computed tomography." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:b158793e-5f68-4aad-9335-f143e5864886.
Abstract:
Techniques described to date for the reproducible and noninvasive quantification of regional cardiac function have been largely relegated to research settings due to time-consuming and cumbersome image acquisition and analysis. In this thesis, feature tracking algorithms are developed for 2-D+Time cardiac magnetic resonance (CMR) and 3-D+Time cardiac computed tomography (CCT) image sequences that are easily acquired clinically, while emphasising reproducibility and automation in their design. First, a commercially-implemented CMR feature tracking algorithm for the analysis of steady state free precession (SSFP) cine series is evaluated in patients with hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC), which primarily affect the left ventricle (LV) and right ventricle (RV), respectively, and functional impairment compared with control populations is found in both cases. The limitations of this implementation are then used to guide development of an automated algorithm for the same purpose, making use of fully convolutional neural networks (CNN) for segmentation and spline registration across all frames simultaneously for tracking. This study is performed in the subjects with HCM, and functional impairment is again identified in disease subjects. Finally, as myocardial contraction is inherently a 3-D phenomenon, a technique is developed for quantification of regional function from 3-D+Time functional CCT studies using simultaneous registration of automatically generated Loop subdivision surface models for tracking. This study is performed in canine mongrels, and compared with the current state of the art technique for CCT functional analysis. This work demonstrates the feasibility of automated, reproducible cardiac functional analysis from CMR and CCT image sequences. While work remains to be done in extending the principles demonstrated and modular components described to fully automated whole-heart analysis, it is hoped that this thesis will accelerate the clinical adoption of regional functional analysis.
7
Grunert, Marcel [Verfasser]. "Computational analysis of next-generation sequencing data in cardiac function and disease / Marcel Grunert." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1029963150/34.
8
Ahlsson, Anders. "Atrial fibrillation in cardiac surgery." Doctoral thesis, Örebro universitet, Hälsoakademin, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2442.
Abstract:
Atrial fibrillation (AF) is the most common arrhythmia seen in clinical practice. In cardiac surgery, one-third of the patients experience episodes of AF during the first postoperative days (postoperative AF), and patients with preoperative AF (concomitant AF) can be offered ablation procedures in conjunction with surgery, in order to restore ordinary sinus rhythm (SR). The aim of this work was to study the relation between postoperative AF and inflammation; the long-term consequences of postoperative AF on mortality and late arrhythmia; and atrial function after concomitant surgical ablation for AF. In 524 open-heart surgery patients, C-reactive protein (CRP) serum concentrations were measured before and on the third day after surgery. There was no correlation between levels of CRP and the development of postoperative AF. All 1,419 patients with no history of AF, undergoing primary aortocoronary bypass surgery (CABG) in the years 1997–2000 were followed up after 8.0 years. The mortality rate was 191 deaths/1,000 patients (19.1%) in patients with no AF and 140 deaths/419 patients (33.4%) in patients with postoperative AF. Postoperative AF was an age-independent risk factor for late mortality, with a hazard ratio (HR) of 1.56 (95% CI 1.23–1.98). Postoperative AF patients had a more than doubled risk of death due to cerebral ischaemia, myocardial infarction, sudden death, and heart failure compared with patients without AF. All 571 consecutive patients undergoing primary CABG during the years 1999–2000 were followed-up after 6 years. Questionnaires were obtained from 91.6% of surviving patients and an electrocardiogram (ECG) from 88.3% of all patients. In postoperative AF patients, 14.1% had AF at follow-up, compared with 2.8% of patients with no AF at surgery (p<.001). An episode of postoperative AF was found to be an independent risk factor for development of late AF, with an adjusted risk ratio (RR) of 3.11 (95% CI 1.41–6.87). Epicardial microwave ablation was performed in 20 open-heart surgery patients with concomitant AF. Transthoracic echocardiography was performed preoperatively and at 6 months postoperatively. At 12 months postoperatively 14/19 patients (74%) were in SR with no anti-arrhythmic drugs. All patients in SR had preserved left and right atrial filling waves (A-waves) and Tissue velocity echocardiography (TVE) showed preserved atrial wall velocities and atrial strain. In conclusion, postoperative AF is an independent risk factor for late mortality and later development of AF. There is no correlation between the inflammatory marker CRP and postoperative AF. Epicardial microwave ablation of concomitant AF results in SR in the majority of patients and seems to preserve atrial mechanical function.
9
Cloud, Jennifer Ellen 1976. "Genetic and molecular analysis of the E2F transcription factor family in mouse development, tumorigenesis, and cardiac function." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29593.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2003.Includes bibliographical references.
The E2F transcription factors are critical downstream targets of the retinoblastoma protein (pRB) pathway. A component of the pRB pathway is mutated in most human tumors resulting in deregulation of cell cycle control through the inappropriate release of E2Fs. E2F1, E2F2, and E2F3 are members of the "activating E2F" subfamily that is important for the transcriptional activation of target genes involved in DNA replication and cell cycle control. These E2F family members are essential for cellular proliferation in vitro. This study analyzes the role of the activating E2Fs in vivo using mutant mouse models. It demonstrates that E2F3 is essential for viability in a strain dependent manner. E2f3 animals die at three distinct time points from cardiac etiologies. The embryonic and neonatal lethality of these animals is consistent with proliferation defects in the myocardium that result in hypoplastic heart walls and septa. E2f animals that survive the perinatal period eventually die from highly penetrant, late-onset congestive heart failure. This is the first evidence that proliferation regulators have an important role in adult heart failure. In addition, this study examines the relative roles of E2F1 and E2F3 in vivo. It shows that E2F1 and E2F3 have functional overlap during mouse development as well as in the maintenance of a number of adult tissues. However, E2F1 appears to have a distinct function as a tumor suppressor gene. Importantly, E2F1 and E2F3 both contribute to normal cardiac function. Furthermore, mutation of the gene for the pRB protein that negatively regulates the activating E2Fs can rescue the heart failure in the E2f3 animals. These data argue strongly that proper regulation of proliferation is critical for adult cardiac function.
by Jennifer Ellen Cloud.
Ph.D.
10
Kaniewska, Malwina [Verfasser]. "Noninvasive evaluation of cardiac function using Computed Tomography and Magnetic Resonance Imaging : a meta-analysis / Malwina Kaniewska." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2017. http://d-nb.info/1140486861/34.
11
MOHAMMED, Nadiya Younis. "Study of internal jugular vein valve mechanism function: post analysis of M- mode imaging and an experimental model under cardiac monitoring." Doctoral thesis, Università degli studi di Ferrara, 2018. http://hdl.handle.net/11392/2488097.
Abstract:
Background:
Traditionally, the internal jugular vein (IJV) has served as an indicator of right side cardiac function via measurement of central venous pressure and changes in the velocity of jugular venous flow. Since the internal jugular vein valve is the only protective vessel between the brain and heart, recent studies have focused on the dynamic behavior of the valve and its importance in regulating the cerebral blood out flow pathway. It is found that the function of the IJV valve is crucial in maintaining the transcranial blood pressure gradient during cardiopulmonary resuscitation with closed-chest while the morphological incompetence (or absence) of the valve may lead to venous reflux through the IJV. However, nothing is known about the mechanism of the valve opening and closure, as well as the normal opening time. Furthermore, there is insufficient knowledge whether the venous reflux is a normal finding and it is not associated with valve incompetence or valve absence.
Aim of the study:
The project aims to add new indicators of internal Jugular valve function through: 1) post imaging analysis using ultrasound M mode image and 2) an experimental model of mimicking fluid loop to study the modality of flow and pressure wave, upstream and downstream in internal jugular vein with or without valve build up.
Methods:
Normal young subjects underwent an ultrasound scan of the neck in supine position. The internal jugular vein valve was evaluated using B-mode and M-mode images. Two methods have been demonstrated to deduce the normal open time of the valve. The first method based on calculating the area under the curve of valve leaflet separation distance ratio per cardiac cycle. The second method is based on logical tests of three thresholds to examine the valve leaflet separation distance ratio. A hydraulic mimicking fluid loop is created using a programmable pump (Compu Flow 1000, Shelley Medical Imaging/London/Canada). The flow-loop model represents the cerebral out flow pathway through internal Jugular phantoms with and without valve build up. The measurements of flow and pressure were taking at two positions upstream and downstream of the phantom.
Results:
The first method concerning the normal open time reveals a strong positive correlation with second method at the threshold 0.5. The open time of IJV valve constitutes 70% of the cardiac cycle. The experimental model yields a different modality of flow and pressure upstream and downstream of phantoms. A back flow occurs in the beginning of the pulsatile flow wave at a downstream position. The difference in pressure between the two positions increases with the mean flow rate and decreases with higher flow rate in the phantom with no valve while in phantom with valve, the pressure difference has mostly linear proportion with the flow rate.
Conclusions:
The normal open time of the internal jugular vein valve is a new physiologic metric and it gives premise for further studies in the field of neurodegeneration. The experimental finding is adding a new concept to the venous reflux in the internal jugular vein and the necessity of the valve presence in maintain an adequate pressure difference through IJV.Introduzione: Lo studio emodinamico della vena giugulare interna (IJV) fornisce indicazioni sulla funzionalità cardiaca. La vena giugulare interna è dotata di una valvola che ha una funzione protettiva, studi recenti si sono concentrati sul comportamento dinamico della valvola e sulla sua importanza nella regolazione del flusso ematico cerebrale. Questi studi hanno mostrato che questa valvola ha la funzione di regolare il gradiente della pressione nell’asse cervello – cuore. L’assenza o l'incompetenza funzionale della valvola può anche portare al fenomeno del reflusso venoso attraverso la IJV. Tuttavia, il meccanismo dell'apertura e della chiusura della valvola non è stato ancora studiato a fondo, in particolare non sono si hanno informazioni sul suo ritmo di apertura e chiusura. Inoltre, non vi sono conoscenze sufficienti per capire se il fenomeno del reflusso venoso sia normale o possa essere associato a incompetenza della valvola e quindi indicatore di possibili stati patologici. Obiettivo dello studio: Il progetto mira ad individuare nuovi indicatori della funzione della valvola giugulare interna attraverso: 1) Studio delle immagini ecografiche della valvola acquisite in M mode; 2) Utilizzo di circuito fluidodinamico sperimentale per lo studio della relazione tra impulso pressorio a monte e a valle della vena giugulare ed il suo flusso in presenza ed assenza della valvola interna. Metodi: Un gruppo soggetti normali sono stati sottoposti ad ecografia del collo in posizione supina. La valvola vena giugulare interna è stata studiata usando le immagini acquisite sia B-mode che M-mode. Sono stati utilizzati due metodi per ricavare informazioni sui tempi di apertura e di chiusura della valvola. Il primo metodo è basato sul calcolo dell'area sottesa dalla curva che rappresenta la distanza di separazione del lembo della valvola per un intero ciclo cardiaco. Il secondo metodo vuole introdurre test logici utilizzando tre soglie di riferimento per studiare la distanza di separazione delle alette della valvola. E’ stato realizzato un circuito idraulico che imita la fluidodinamica del tratto Ventricolo – Cervello – Atrio utilizzando una pompa programmabile (Compu Flow 1000, Shelley Medical Imaging / London / Canada) che immette un fluido in un circuito ad anello avente segmenti che possono simulare la vena Giugulare con e senza valvola Risultati: Il primo metodo di studio del tempo apertura ha una buona correlazione positiva con metodo logico quando si utilizza il parametro di soglia soglia 0,5. Il tempo di apertura della valvola IJV è circa il 70% della durata di ogni ciclo cardiaco. Il modello sperimentale fornisce risultati specifici per le due diverse misure di flusso e pressione (a monte e a valle) dei fantocci. Il fenomeno del reflusso si verifica all'inizio dell'onda di flusso pulsatile in una posizione a valle per il flussi più alti. La differenza di pressione tra le due posizioni aumenta con la portata media e diminuisce crescere della portata nel fantoccio senza valvola mentre nell’altro (con valvola), la differenza di pressione ha un andamento lineare con la portata. Conclusioni: Il tempo di apertura della valvola vena giugulare interna rappresenta una nuova metrica fisiologica che può essere utilizzata per ulteriori studi più approfonditi nel campo della insufficienze del ritorno venoso cerebrale. Il modello sperimentale ha aggiunto di un nuove informazioni sulla comparsa del al reflusso venoso nei simulatori della vena giugulare interna e sulla funzione della della valvola nel mantenere un'adeguata gradiente pressorio nella IJV.
12
Bowers, Mark Charles 1963. "Sequential analysis of multidrug resistance protein-1 expression and function in cardiac transplant patients: A possible mechanism of therapy-resistant acute rejection." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282822.
Abstract:
Multidrug resistance protein-1 (mdr1) is a well characterized membrane protein, expressed in a variety of cell types. In cancer cells, an overexpression of mdr1 has the function of conferring drug-resistance. The exact physiological function of mdr1 constitutively expressed in normal cells still remains unclear. A goal of this work was to determine if there is an increase in expression of mdr1, above constitutive levels, on CD4+ and CD8+ T-lymphocytes, following cardiac transplantation. The expression of mdr1 was correlated with episodes of acute cardiac rejection in order to determine if mdr1 has the functional ability to confer immunosuppressive drug resistance. Drug resistant CD4+ and CD8+ T-lymphocytes could explain episodes of acute allograft rejection observed in a number of immunosuppressed patients. Immunochemical techniques measuring mdr1 were performed on endomyocardial biopsy specimens and peripheral blood mononuclear cells (PBMCs) isolated from cardiac transplant patients. Functional mdr1 assays and flow cytometry were performed on PBMCs isolated from cardiac transplant patients prior to transplantation and at longitudinal time points post-transplantation. The expression and function of mdr1 was correlated to the histological diagnosis of acute rejection. Immunochemical analysis of endomyocardial biopsy samples showed mdr1 expression localized on the plasma membrane of graft infiltrating mononuclear cells. Immunochemical analysis of PBMC samples showed a constitutive mdr1 expression on normal volunteer PBMCs and a increased expression of mdr1 on cardiac transplant PBMCs during episodes of acute rejection. Doxorubicin cytotoxicity assays showed an increased drug resistance profile in transplant patients compared to normal individuals. An mdr1 efflux assay demonstrated an increase efflux function in PBMCs during episodes of acute rejection. Flow cytometric analysis showed significant increases in the intensity of mdr1 expression on CD4+ and CD8+ T-lymphocytes in transplant patients compared to normal individuals. Flow cytometry also confirmed a significant increase in both the number of CD4+ and CD8+ T-lymphocytes expressing mdr1 and the intensity of mdr1 on these subtypes for those patients that had an episode of acute rejection compared to those transplant patients with no episodes of acute rejection. Thus, this study demonstrates an overexpression of a functionally active multidrug resistant protein-1 during episodes of acute rejection.
13
Huang, Xueying. "Segmentation of patient-specific 3D cardiac magnetic resonance images of human right ventricle." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-030408-151600/.
Abstract:
Dissertation (Ph.D.)--Worcester Polytechnic Institute.Keywords: CMRI; segmentation; digital contour; right ventricle; ventricle function analysis. Includes bibliographical references (leaves 49-53 ).
14
Tee, Michael Weiseng. "Image analysis of cardiac computed tomography towards regional functional analysis." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:14f50b88-1af6-40b6-91b3-9e39d77fe83a.
Abstract:
Global assessment of myocardial function is widely performed by estimating ejection fraction (EF), but many common cardiac diseases initially affect the myocardium on a regional, rather than global, basis. Computed tomography (CT), most commonly applied to assess the coronary arteries, is a prime candidate for such regional analysis. This doctoral thesis makes steps towards regional CT functional analysis with two clinical and two technical contributions. The first clinical contribution focuses on evaluating the feasibility and utility of functional analysis with currently available CT technology. Our study found that CT strain analysis could identify regional wall motion abnormalities in cardiomyopathy that are not otherwise detected using conventional metrics of myocardial function such as EF. In order for cine CT of the heart to become routine clinical practice, improvements need to be made to the image acquisition protocol. The second clinical contribution focus on making these improvements with results pointing to the possibility of one millisievert range cine CT images with high (>50 milliseconds) temporal resolutions. Moving to technical considerations, a key concern has been how to better characterise the myocardium in CT. To address this, the first technical contribution examines the use of feature-based attribute vectors, which were found to improve image registration towards deriving more reliable motion estimations. The second technical contribution focus on developing a pipeline tailored towards CT strain analysis. Noting that CT naturally provides information in 3D, a 3D hyperelastic biomechanical model fitting method was evaluated. Analysis of an infarction model demonstrated that regional myocardial strain can be estimated in the 3D space and areas of infarction can be detected. By considering both technical and clinical perspectives, these advances will contribute to the the field of regional cardiac functional analysis towards improving patient care.
15
Darwich, Rami. "Functional Analysis of KLF13 in the Heart." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34317.
Abstract:
Congenital heart defects (CHD) are the largest class of birth defects in humans and are a major cause of infant mortality and morbidity. Deciphering the molecular and genetic etiologies central for heart development and the pathogenesis of congenital heart diseases (CHD) is a challenging puzzle. We have previously demonstrated that the zinc-finger kruppel-like transcription factor KLF13, expressed predominantly in the atria, binds evolutionarily conserved regulatory elements known as CACC-boxes and transcriptionally activates several cardiac promoters. KLF13 loss of function in Xenopus embryos was associated with cardiac developmental defects underscoring its critical role in the heart. In the current study, using in vivo and in vitro approaches, we examined KLF13’s mechanisms of action and its interaction with other cardiac regulators. To test the evolutionary conserved role in the mammalian heart, we deleted the Klf13 gene in transgenic mice using homologous recombination. Mice with homozygote deletion of Klf13 were born at reduced frequency owing to severe heart defects. We also report the existence of a novel isoform of KLF13, referred to here as KLF13b. Furthermore, we report that KLF13 interacts biochemically and genetically with the T-box transcription factor TBX5 which is a key regulator of heart development. Our data provide novel insight into the role of KLF13 in cardiac transcription and suggest that KLF13 maybe a genetic modifier of congenital heart disease. Furthering our knowledge of protein-protein interactions and gene transcription will enhance genotype-phenotype correlation and contribute to better understanding of the etiology of CHD.
16
Wu, Ling. "Functional Characterization of SCN5A, The Cardiac Sodium Channel Gene Associated With Cardiac Arrhythmias and Sudden Death." Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1206732295.
17
Bernardino, Gabriel. "Computational anatomy as a driver of understanding structural and functional cardiac remodeling." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/668213.
Abstract:
We present a statistical shape analysis framework to identify cardiac shape remodelling while accounting for individual´s natural variability and apply it in two clinical applications: comparing triathletes with controls, and comparing individuals who were born small-for-their-gestational-age (SGA) and controls. We were able to identify the shape remodelling due to the practice of endurance sport: it consisted a dilation of the left ventricle and an increase of the left ventricular myocardial mass. In the right ventricle (RV), the increase of volume was concentrated in the outflow. This changes in shape correlated with a better performance during exercise. In SGA, we found subtle differences in the RV that correlated with worse performance during exercise. These differences were bigger when SGA condition was combined with cardiovascular risk factors: smoking and overweight. Finally, we present a geometry processing technique for parcellating the RV cavity in 3 subvolumes for regional analysis without point-to-point correspondence.Presentamos un framework de análisis estadístico de forma para identificar remodelado cardiaco teniendo en cuenta la variabilidad natural de cada individuo. Utilizamos este framework en dos aplicaciones clínicas: triatletas e individuos nacidos pequeños-para-su-edad-gestacional (SGA). Identificamos el remodelado cardiaco en el caso de los triatletas: consistente en una dilatación del ventrículo izquierdo y un aumento de la masa miocárdica. En el ventrículo derecho (RV) la dilatación estaba concentrada en el tracto de salida. Este remodelado correlaciona con una mejor respuesta al ejercicio. En el análisis de SGA, encontramos sutiles cambios en el RV que correlacionaban con una peor respuesta al ejercicio. Estos cambios de forma fueron mayores si SGA se encontraba combinada con otros factores de riesgo cardiaco: tabaco y sobrepeso. Finalmente, presentamos una parcelación de la cavidad del RV en 3 subvolumenes para el análisis regional del RV cuando no es posible la correspondencia punto-a-punto.
18
Siriwittayawan, Duangduan. "Functional analysis of regulatory phosphorylation events in cardiac KATP channel subunits in ischaemia." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10384.
Abstract:
Protein kinase C (PKC)–mediated phosphorylation of ATP sensitive potassium channels (KATP) is believed to be involved in ischaemic preconditioning. Five consensus PKC phosphorylation sites in the Kir6.1 subunit, S354, S379, S385, S391 and S397, have been proposed as possible regulatory sites. The objective of this study was to investigate the role of these residues in regulating the functional properties of Kir6.1-containing KATP channels. HEK cells expressing Kir6.1/SUR2A or Kir6.1/SUR2B channels were used to assess electrical activity of the channels responding to PKC using the whole cell patch clamp technique. It was found that PKC activator, Phorbol 12-Myristate 13-Acetate (PMA), inhibited pinacidil-activated Kir6.1/SUR2A and Kir6.1/SUR2B currents. Mutation of serine 379 and serine 385 resulted in a significant reduction of the inhibitory effect of PKC in both Kir6.1/SUR2A and kir6.1/SUR2B channels. The inhibitory effect of PKC was also reduced in S397 mutant in Kir6.1/SUR2A channel. An endosome targeting Kir6.1/SUR2A mutant was assessed for its functional response to PKC. The inhibitory effect of PKC was abolished in this mutant. Further investigation by immunofluorescence microscopy showed that incubating HEK cells expressing Kir6.1-HA tag/SUR2A with PMA for 30 minutes resulted in internalization of the Kir6.1 protein, but not in non-treated cells. In the presence of the dynamin GTPase inhibitor, dynasore, PMA-induced internalization was blocked indicating that internalisation was via a dynamin dependent mechanism. To clarify which PKC isoform was responsible for KATP channel phosphorylation, Kir6.1 phosphorylation in rat ventricular myocytes was labelled with ³²P and stimulated with Adenosine A1 receptor agonist, 2-chloro-N6-cyclopentyl-adenosine (CCPA). The phosphorylation was investigated in the absence and presence of permeable Tat-linked PKC inhibitor peptides. Kir6.1 phosphorylation was stimulated by CCPA and inhibited in the presence of Tat-coupled PKCε inhibitor peptide but not Tat- PKCα, β, γ or δ inhibitor peptides.
19
Casero, Cañas Ramón. "Left ventricle functional analysis in 2D+t contrast echocardiography within an atlas-based deformable template model framework." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:b17b3670-551d-4549-8f10-d977295c1857.
Abstract:
This biomedical engineering thesis explores the opportunities and challenges of 2D+t contrast echocardiography for left ventricle functional analysis, both clinically and within a computer vision atlas-based deformable template model framework. A database was created for the experiments in this thesis, with 21 studies of contrast Dobutamine Stress Echo, in all 4 principal planes. The database includes clinical variables, human expert hand-traced myocardial contours and visual scoring. First the problem is studied from a clinical perspective. Quantification of endocardial global and local function using standard measures shows expected values and agreement with human expert visual scoring, but the results are less reliable for myocardial thickening. Next, the problem of segmenting the endocardium with a computer is posed in a standard landmark and atlas-based deformable template model framework. The underlying assumption is that these models can emulate human experts in terms of integrating previous knowledge about the anatomy and physiology with three sources of information from the image: texture, geometry and kinetics. Probabilistic atlases of contrast echocardiography are computed, while noting from histograms at selected anatomical locations that modelling texture with just mean intensity values may be too naive. Intensity analysis together with the clinical results above suggest that lack of external boundary definition may preclude this imaging technique for appropriate measuring of myocardial thickening, while endocardial boundary definition is appropriate for evaluation of wall motion. Geometry is presented in a Principal Component Analysis (PCA) context, highlighting issues about Gaussianity, the correlation and covariance matrices with respect to physiology, and analysing different measures of dimensionality. A popular extension of deformable models ---Active Appearance Models (AAMs)--- is then studied in depth. Contrary to common wisdom, it is contended that using a PCA texture space instead of a fixed atlas is detrimental to segmentation, and that PCA models are not convenient for texture modelling. To integrate kinetics, a novel spatio-temporal model of cardiac contours is proposed. The new explicit model does not require frame interpolation, and it is compared to previous implicit models in terms of approximation error when the shape vector changes from frame to frame or remains constant throughout the cardiac cycle. Finally, the 2D+t atlas-based deformable model segmentation problem is formulated and solved with a gradient descent approach. Experiments using the similarity transformation suggest that segmentation of the whole cardiac volume outperforms segmentation of individual frames. A relatively new approach ---the inverse compositional algorithm--- is shown to decrease running times of the classic Lucas-Kanade algorithm by a factor of 20 to 25, to values that are within real-time processing reach.
20
Petitjean, Caroline. "Recalage non rigide d'images par approches variationnelles statistiques - Application à l'analyse et à la modélisation de la fonction myocardique en IRM." Phd thesis, Université René Descartes - Paris V, 2003. http://tel.archives-ouvertes.fr/tel-00273241.
Abstract:
L'analyse quantitative de la fonction contractile myocardique constitue un enjeu majeur pour le dépistage, le traitement et le suivi des maladies cardio-vasculaires, première cause de mortalité dans les pays développés. Dans ce contexte, l'Imagerie par Résonance Magnétique (IRM) s'impose comme une modalité privilégiée pour l'exploration dynamique du coeur, renseignant, d'une part, sur l'évolution des parois (ciné IRM), et permettant, d'autre part, d'accéder à des informations cinématiques au sein du myocarde (IRM de marquage). L'exploitation quantitative de ces données est néanmoins actuellement limitée par la quasi-absence de méthodologies fiables, robustes et reproductibles d'estimation de mouvement non rigide à partir de séquences d'images acquises dans cette modalité.Cette thèse se propose de démontrer que les techniques de recalage non rigide statistique constituent un cadre approprié pour l'estimation des déformations myocardiques en IRM, leur quantification à des fins diagnostiques, et leur modélisation en vue d'établir une référence numérique de normalité. Ses contributions concernent :
1. l'élaboration d'une méthode robuste non supervisée d'estimation des déplacements myocardiques à partir de séquences d'IRM de marquage. Elle permet l'obtention de mesures de mouvement fiables en tout point du myocarde, à tout instant du cycle cardiaque et sous incidence de coupe arbitraire.
2. le développement d'un outil de quantification dynamique des déformations à l'échelle du pixel et du segment myocardique, intégrant un étape de segmentation automatique du coeur par recalage d'images ciné IRM acquises conjointement aux données de marquage. Pour le coeur sain, la comparaison des mesures obtenues à des valeurs de référence issues d'une synthèse approfondie de la littérature médicale démontre une excellente corrélation. Pour des coeurs pathologiques, les expériences menées ont montré la pertinence d'une analyse quantitative multiparamétrique pour localiser et caractériser les zones atteintes.
3. la construction d'un modèle statistique (atlas) de contraction d'un coeur sain. Cet atlas fournit des modèles quantitatifs de référence locaux et segmentaires pour les paramètres de déformation. Son intégration, en tant que modèle de mouvement, au processus de recalage des données d'IRM de marquage conduit en outre à une description très compacte des déplacements myocardiques sans perte de précision notable.
21
Dondi, Cristiana. "Molecular and functional analysis of cardiac diversification by cell specific translatomic approaches in Drosophila Melanogaster." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAS003/document.
Abstract:
Le cœur humain est un organe composé de différents types cellulaires tels que les cardiomyocytes, les fibroblastes, les muscles lisses et les cellules endothéliales. Ces cellules se diversifient grâce à des mécanismes moléculaires spécifiques en acquérant leurs propriétés fonctionnelles spécifiques. L’embryon de Drosophile est un modèle simple et adapté pour étudier la diversification des cellules cardiaques et leurs propriétés spécifiques. Le but du projet est d’améliorer notre connaissance sur les acteurs moléculaires qui contrôlent la diversification des cellules cardiaques. Pour atteindre cet objectif nous avons appliqué la méthode TRAP-rc ("rare cell Translation Ribosome Affinity Purification") suivie du séquençage ARN pour identifier les ARN messagers en cours de traduction spécifiques des cellules cardiaques Tin et Lb (Tin CBs et Lb CBs) à deux stades de développement corrélés avec la morphogenèse du cœur embryonnaire. Dans une première analyse focalisée sur l'analyse des données issues des TRAP-Seq sur cellules Tin nous avons mis en évidence que CAP et MSP-300 sont impliqués dans la migration des cardioblasts pendant la fermeture du cœur. En parallèle, nous avons également identifié deux autres gènes impliqués dans la morphogenèse, kon-tiki et dGrip qui semblent contrôler la cohésion des CBs au cours de la migration. En outre, nous avons trouvé qu'au stade 16, environ 60% des gènes enrichis sont communs entre les populations Tin et Lb. Parmi ces gènes, Src42, sqa et flr participent à la régulation du cytosquelette d'actine et nos analyses ont permis de démontrer qu'ils avaient également des fonctions dans la morphogenèse cardiaque. Nous avons également identifié des groupes de gènes plus spécifiques à chacune des populations ciblées. Une catégorie fonctionnelle fortement associée à la population Lb, comprend les gènes qui régulent l'épissage des ARN messagers et certains de ces gènes semblent être requis au cours de la morphogenèse cardiaque. Enfin, nous avons comparé nos données de TRAP-seq cardiaque avec des données de TRAP-Seq issues du muscle somatique (de l'équipe), et ainsi identifié près de 90 gènes qui présentent des isoformes protéiques spécifiques à chaque tissu notamment impliquées dans la formation de l'unité contractile sarcomérique. Ceci suggère que des mécanismes d'épissage spécifiques sont mis en place dans différents types cellulaires pour moduler les fonctions de certaines protéines musculaires. A travers ce projet, nous avons identifié de nouveaux acteurs généraux de la migration collective des cardioblastes au cours de la fermeture du cœur mais également de nouveaux gènes potentiellement impliqués dans l’acquisition des propriétés spécifiques dessous populations cardiaques Tin et Lb et de tissus musculaires distincts. Nous espérons que les données générées permettront dans le futur de mieux comprendre les mécanismes de la cardiogenèse des vertébrés ainsi que l’étiologie de maladies cardiaquesCardiac cells diversification is required for the formation of a functional heart. Human heart is a multi-lineage organ that develops through progressive diversification of progenitors derived from different heart fields. This process is underlined by numerous changes in the expression of a repertory of genes that allow cells to acquire their own identity and functions. The Drosophila embryo is a relatively simple model to study the diversification of cardiac cells and their properties. The goal of this project is to identify the repertories of genes that control the formation of different types of cardiac cells. To reach this objective we applied Translation Ribosome Affinity Purification (TRAP) method followed by RNA sequencing in order to identify mRNA engaged in translation specific to two cardiac cell types (Tinman (Tin) and Labybird (Lb) expressing cells), at two different time windows. We obtained a list of enriched genes for the different types of cardiac cells and time points. In a first part, we focused our attention on the Tindatasets and found that two genes, CAP and Msp300, are involved in cardioblasts migration during the heart closure. Then we identified two other candidate genes kontiki and dGrip that seem to contribute to maintain cohesion between CBs during heartmorphogenesis. Moreover by comparing our spatial datasets, we found that for the same time point, around 60% of Tin CBs enriched genes are common with Lb CBs enriched population and within this group we identified evolutionary conserved genes such as Src42, flr and sqa known to be involved in the cytoskeleton organization and in the actinpolymerization and depolymerisation. Our premiminary analyses show that they seem to be required for correct cardiac morphogenesis. We also identified sets of genes more specific for each cardiac cell population. Indeed, Lb CBs datasets show that in early stage there is the enrichment of genes mostly involved in transcriptional regulation and RNA splicing and some of these genes (prp8 and prp38) are involved in cardiac development. In parallel, we compared our TRAP-Seq dataset in the cardiac system with the TRAP-seqon muscle cells, and identified close to 90 genes that present cardiac or muscular specific isoforms. It is known that the alternative splicing, by increasing proteins diversity, contributes to the acquisition of specific cell properties. Furthermore, some cardiomyopathies are associated to defects in the alternative splicing of genes encoding sarcomeric proteins that we found in our dataset such as Tropomyosin and Zasp52. With this project, we have identified new actors of collective cardioblast migration and a set of genes with potential role in the acquisition of individual properties of Tin and Lbcardiac cells or of specific type of muscle tissue. We hope that our data could provide new insights into the genetic control of vertebrate cardiogenesis and into etiology of cardiac diseases
22
Arthurs, Christopher J. "Efficient simulation of cardiac electrical propagation using adaptive high-order finite elements." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:ad31f06f-c4ed-4c48-b978-1ef3b12fe7a1.
Abstract:
This thesis investigates the high-order hierarchical finite element method, also known as the finite element p-version, as a computationally-efficient technique for generating numerical solutions to the cardiac monodomain equation. We first present it as a uniform-order method, and through an a priori error bound we explain why the associated cardiac cell model must be thought of as a PDE and approximated to high-order in order to obtain the accuracy that the p-version is capable of. We perform simulations demonstrating that the achieved error agrees very well with the a priori error bound. Further, in terms of solution accuracy for time taken to solve the linear system that arises in the finite element discretisation, it is more efficient that the state-of-the-art piecewise linear finite element method. We show that piecewise linear FEM actually introduces quite significant amounts of error into the numerical approximations, particularly in the direction perpendicular to the cardiac fibres with physiological conductivity values, and that without resorting to extremely fine meshes with elements considerably smaller than 70 micrometres, we can not use it to obtain high-accuracy solutions. In contrast, the p-version can produce extremely high accuracy solutions on meshes with elements around 300 micrometres in diameter with these conductivities. Noting that most of the numerical error is due to under-resolving the wave-front in the transmembrane potential, we also construct an adaptive high-order scheme which controls the error locally in each element by adjusting the finite element polynomial basis degree using an analytically-derived a posteriori error estimation procedure. This naturally tracks the location of the wave-front, concentrating computational effort where it is needed most and increasing computational efficiency. The scheme can be controlled by a user-defined error tolerance parameter, which sets the target error within each element as a proportion of the local magnitude of the solution as measured in the H^1 norm. This numerical scheme is tested on a variety of problems in one, two and three dimensions, and is shown to provide excellent error control properties and to be likely capable of boosting efficiency in cardiac simulation by an order of magnitude. The thesis amounts to a proof-of-concept of the increased efficiency in solving the linear system using adaptive high-order finite elements when performing single-thread cardiac simulation, and indicates that the performance of the method should be investigated in parallel, where it can also be expected to provide considerable improvement. In general, the selection of a suitable preconditioner is key to ensuring efficiency; we make use of a variety of different possibilities, including one which can be expected to scale very well in parallel, meaning that this is an excellent candidate method for increasing the efficiency of cardiac simulation using high-performance computing facilities.
23
Celebi, Hatice. "Structural And Functional Analysis Of Henry James." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/597/index.pdf.
Abstract:
The aim this thesis is to analyse the narrative structure of the novel, The Portrait
of A Lady, with the aim of revealing how meaning is made and to show how certain
elements are transferred to the film version and the consequent changes in meaning and
emphasis. The structural analysis of The Portrait will chiefly rely on Shlomith Rimmon-
Kenan&rsquos scheme she draws in her book Narrative Fiction. The functional analysis to show the consequent changes in meaning and emphasis, on the other hand, will rely on Roland Barthes&rsquo
s theory of functions he discusses in his article &ldquo
Structural Analysis of Narratives&rdquo
. In order to explore the narrative structure of The Portrait of A Lady, this thesis will examine story, characterization, time and focalization and demonstrate the techniques Henry James uses in narration. In the functional analysis of the novel, on the other hand, the functions of the units discussed in the story and the characterization will be compared to the functions of the same units that are transferred to the adaptation of the novel to reveal how the meaning and emphasis of the novel changes.
24
Giardini, Francesco. "Morpho-functional investigation of cardiac remodeling in an arrhythmogenic mouse model by advanced optical methods." Doctoral thesis, Università di Siena, 2022. http://hdl.handle.net/11365/1211015.
Abstract:
Severe remodeling processes may occur in the heart due to both genetic and non-genetic diseases. Structural remodeling, such as collagen deposition (fibrosis) and cellular misalignment, can affect electrical conduction at different orders of magnitude and, eventually, lead to arrhythmias. In this scenario, arrhythmogenic cardiomyopathy (ACM) is an inherited heart disease that involves ventricular dysfunction, arrhythmias, and localized replacement of contractile fibers with fibrofatty scar tissue. Unfortunately, nowadays, redicting the impact of fine structural alterations on the electrical disfunction in entire organs is challenging, due to the inefficacy of standard imaging methods in performing high-resolution three-dimensional reconstructions in massive tissues. In this work, we developed a new full-optical correlative approach to quantify and integrate the electrical dysfunctions with three-dimensional structural reconstructions of entire hearts, both in controls and in a mouse model of ACM. We combined optical mapping of the action potential propagation (APP) with advances in tissue clearing and light-sheet microscopy techniques. First, we employed an optical platform to map and analyze the APP in Langendorff-perfused hearts. Then, we optimized the SHIELD procedure for the clearing of cardiac tissue, thus converting the previously electrically characterized samples into well-preserved and fully-transparent specimens. A high-throughput light-sheet microscope has been developed allowing the reconstruction of the whole mouse heart with a micrometric resolution allowing fine quantification of myocytes alignment and fibrosis deposition across the organ. Finally, we developed a software pipeline that employs high-resolution 3D images to analyze and co-register APP maps with the 3D anatomy, contractile fibers disarray, and fibrosis deposition on each heart. We found that although fiber disarray is not involved in this remodeling process, the accumulation of fibrotic patches found in the ACM mouse model can deform the propagating wavefront potentially facilitating the formation of reentry circuits. We believe that this promising methodological framework will allow clarifying the involvement of fine structural alterations in the electrical dysfunctions, thus enabling a unified investigation of the structural causes that lead to electrical and mechanical alterations after the tissue remodeling.
25
Yamamuro, Masaki. "Cardiac functional analysis with multi-detector row CT and segmental reconstruction algorithm : comparison with echocardiography, SPECT and MR imaging." Kyoto University, 2006. http://hdl.handle.net/2433/143834.
26
Yang, Yingyu. "Analyse automatique de la fonction cardiaque par intelligence artificielle : approche multimodale pour un dispositif d'échocardiographie portable." Electronic Thesis or Diss., Université Côte d'Azur, 2023. http://www.theses.fr/2023COAZ4107.
Abstract:
Selon le rapport annuel de la Fédération Mondiale du Cœur de 2023, les maladies cardiovasculaires (MCV) représentaient près d'un tiers de tous les décès mondiaux en 2021. Comparativement aux pays à revenu élevé, plus de 80% des décès par MCV surviennent dans les pays à revenu faible et intermédiaire. La répartition inéquitable des ressources de diagnostic et de traitement des MCV demeure toujours non résolue. Face à ce défi, les dispositifs abordables d'échographie de point de soins (POCUS) ont un potentiel significatif pour améliorer le diagnostic des MCV. Avec l'aide de l'intelligence artificielle (IA), le POCUS permet aux non-experts de contribuer, améliorant ainsi largement l'accès aux soins, en particulier dans les régions moins desservies.L'objectif de cette thèse est de développer des algorithmes robustes et automatiques pour analyser la fonction cardiaque à l'aide de dispositifs POCUS, en mettant l'accent sur l'échocardiographie et l'électrocardiogramme. Notre premier objectif est d'obtenir des caractéristiques cardiaques explicables à partir de chaque modalité individuelle. Notre deuxième objectif est d'explorer une approche multimodale en combinant les données d'échocardiographie et d'électrocardiogramme.Nous commençons par présenter deux nouvelles structures d'apprentissage profond (DL) pour la segmentation de l'échocardiographie et l'estimation du mouvement. En incorporant des connaissance a priori de forme et de mouvement dans les modèles DL, nous démontrons, grâce à des expériences approfondies, que de tels a priori contribuent à améliorer la précision et la généralisation sur différentes séries de données non vues. De plus, nous sommes en mesure d'extraire la fraction d'éjection du ventricule gauche (FEVG), la déformation longitudinale globale (GLS) et d'autres indices utiles pour la détection de l'infarctus du myocarde (IM).Ensuite, nous proposons un modèle DL explicatif pour la décomposition non supervisée de l'électrocardiogramme. Ce modèle peut extraire des informations explicables liées aux différentes sous-ondes de l'ECG sans annotation manuelle. Nous appliquons ensuite ces paramètres à un classificateur linéaire pour la détection de l'infarctus du myocarde, qui montre une bonne généralisation sur différentes séries de données.Enfin, nous combinons les données des deux modalités pour une classification multimodale fiable. Notre approche utilise une fusion au niveau de la décision intégrant de l'incertitude, permettant l'entraînement avec des données multimodales non appariées. Nous évaluons ensuite le modèle entraîné à l'aide de données multimodales appariées, mettant en évidence le potentiel de la détection multimodale de l'IM surpassant celle d'une seule modalité.Dans l'ensemble, nos algorithmes proposés robustes et généralisables pour l'analyse de l'échocardiographie et de l'ECG démontrent un potentiel significatif pour l'analyse de la fonction cardiaque portable. Nous anticipons que notre cadre pourrait être davantage validé à l'aide de dispositifs portables du monde réelAccording to the 2023 annual report of the World Heart Federation, cardiovascular diseases (CVD) accounted for nearly one third of all global deaths in 2021. Compared to high-income countries, more than 80% of CVD deaths occurred in low and middle-income countries. The inequitable distribution of CVD diagnosis and treatment resources still remains unresolved. In the face of this challenge, affordable point-of-care ultrasound (POCUS) devices demonstrate significant potential to improve the diagnosis of CVDs. Furthermore, by taking advantage of artificial intelligence (AI)-based tools, POCUS enables non-experts to help, thus largely improving the access to care, especially in less-served regions.The objective of this thesis is to develop robust and automatic algorithms to analyse cardiac function for POCUS devices, with a focus on echocardiography (ECHO) and electrocardiogram (ECG). Our first goal is to obtain explainable cardiac features from each single modality respectively. Our second goal is to explore a multi-modal approach by combining ECHO and ECG data.We start by presenting two novel deep learning (DL) frameworks for echocardiography segmentation and motion estimation tasks, respectively. By incorporating shape prior and motion prior into DL models, we demonstrate through extensive experiments that such prior can help improve the accuracy and generalises well on different unseen datasets. Furthermore, we are able to extract left ventricle ejection fraction (LVEF), global longitudinal strain (GLS) and other useful indices for myocardial infarction (MI) detection.Next, we propose an explainable DL model for unsupervised electrocardiogram decomposition. This model can extract interpretable information related to different ECG subwaves without manual annotation. We further apply those parameters to a linear classifier for myocardial infarction detection, which showed good generalisation across different datasets.Finally, we combine data from both modalities together for trustworthy multi-modal classification. Our approach employs decision-level fusion with uncertainty, allowing training with unpaired multi-modal data. We further evaluate the trained model using paired multi-modal data, showcasing the potential of multi-modal MI detection to surpass that from a single modality.Overall, our proposed robust and generalisable algorithms for ECHO and ECG analysis demonstrate significant potential for portable cardiac function analysis. We anticipate that our novel framework could be further validated using real-world portable devices. We envision that such advanced integrative tools may significantly contribute towards better identification of CVD patients
27
Jaquet, Clara. "Vers la simulation de perfusion du myocarde à partir d'image tomographique scanner." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1117/document.
Abstract:
De nos jours, les progrès de l’informatisation de l’imagerie médicale assistent au plus près les médecins dans leur soin au patient. Des modèles personnalisés computationnels sont utilisés pour le diagnostique, prognostique et planification du traitement, en diminuant lesrisques pour le patient, et potentiellement les frais médicaux.Heartflow est l’exemple même d’une compagnie qui réussit ce service dans le domaine cardiovasculaire. À partir d’un modèle extrait d’images tomographiques rayons X, les lésions avec impact fonctionnel sont identifiées dans les artères coronaires. Cette analyse qui combine l’anatomie à la fonction est néanmoins limitée par la résolution de l’image. En aval de ces larges vaisseaux, un examen fonctionnel dénommé Imagerie de Perfusion du Myocarde (IPM) met en évidence les régions du myocarde affectées par un déficit de flux sanguin. Cependant, l’IPM n’établie pas de relation fonctionnelle avec les larges vaisseaux coronaires lésés en amont.L’objectif de ce projet est de construire la connexion fonctionnelle entre les coronaires et le myocarde, en extrapolant l’analyse fonctionnelle depuis les larges vaisseaux vers le lit capillaire. À cette fin, il faut étendre le modèle vasculaire jusqu'aux microvaisseaux, et mener une analyse fonctionnelle en direction du comportement myocardique.Nous étendons une méthode de génération d’arbre vasculaire basée sur la satisfaction de principes fonctionnels, nommée Constrained Constructive Optimization (Optimization Constructive sous Contraintes), pour qu’elle s’applique à de multiples arbres vasculaires en compétition. L’algorithme simule l’angiogénèse avec minimisation du volume vasculaire sous contraintes de flux et de géométrie adaptant la croissance simultanée des arbres aux caractéristiques du patient. Cette méthode fournit un modèle hybride composé de coronaires épicardiales extraites d’images et de vaisseaux synthétiques jusqu’aux artérioles, emplissant le ventricule gauche du myocarde.Puis, nous construisons un pipeline d’analyse fonctionnelle multi-échelle pour étendre la simulation de flux depuis les coronaires vers le myocarde. Cela consiste en un modèle de flux coronaire 1D compatible avec la vasculature hybride, et l’analyse de la distribution spatiale des flux provenant des segments terminaux. Cette dernière est réalisée dans une nomenclature similaire à celle de l’IPM pour permettre la comparaison avec des données de vérité terrain fonctionnelles.Nous avons relié l’anatomie du réseau vasculaire à la distribution de flux dans le myocarde pour plusieurs patients. Cette analyse multi-échelle permet d’identifier des pistes pour affiner les méthodes de génération vasculaire et de simulation de flux. Cette extrapolation anatomique et fonctionnelle personnalisée est une première passerelle pour la simulation de perfusion du myocarde à partir d’imagerie tomographique scanner. La construction d’un tel modèle computationnel personnalisé pourrait aider à la compréhension de la physio-pathologie cardiovasculaire complexe et, enfin, à la santé du patientRecent advances in medical image computing have allowed automatedsystems to closely assist physicians in patient therapy. Computationaland personalized patient models benefit diagnosis, prognosisand treatment planning, with a decreased risk for the patient,as well as potentially lower cost. HeartFlow Inc. is a successfull exampleof a company providing such a service in the cardiovascularcontext. Based on patient-specific vascular model extracted from XrayCT images, they identify functionally significant disease in largecoronary arteries. Their combined anatomical and functional analysisis nonetheless limited by the image resolution. At the downstreamscale, a functional exam called Myocardium Perfusion Imaging (MPI)highlights myocardium regions with blood flow deficit. However,MPI does not functionally relate perfusion to the upstream coronarydisease.The goal of our project is to build the functional bridge betweencoronary and myocardium, by extrapolating the functional analysisfrom large coronary toward the capillary bed. This objective requiresextension from the coronary model down to the microvasculaturecombined with a functional analysis leading to the myocardium compartment.We expand a tree generation method subjected to functional principles,named Constrained Constructive Optimization, to generate multiplecompeting vascular trees. The algorithm simulates angiogenesisunder vascular volume minimization with flow-related and geometricalconstraints, adapting the simultaneous tree growths to patientpriors. This method provides a hybrid image-based and synthetic geometricmodel, starting from segmented epicardium coronary downto synthetic arterioles, filling the left ventricle myocardium.We then build a multiscale functional analysis pipeline to allowblood flow simulation from the coronaries to the myocardium. Thisis achieved with a 1D coronary model compatible with the hybridvasculature, and a spatial blood flow distribution analysis of the terminalsegments. The latter is performed using a similar nomenclatureto MPI, to enable patient-specific comparison with functional groundtruthdata.We connected the vascular anatomy to blood flow distribution inthe myocardium on several patient datasets. This multiscale frameworkpoints out several leads to refine the vascular network generationand fluid simulation methods. This patient-specific anatomicaland functional extrapolation is a first gateway toward myocardiumperfusion from X-ray CT data. Building such personalized computational model of patient could potentially help investigating cardiovascularcomplex physio-pathology, and, finally, improve the patientcare
28
Patout, Maxime. "Evaluation des techniques pour la prise en charge diagnostique et thérapeutique de l'insuffisance respiratoire chronique A Randomized controlled trial on the effect of needle gauge on the pain and anxiety experienced during radial arterial puncture Long term survival following initiation of home non-invasive ventilation : a European study Neural respiratory drive predicts long-term outcome following admission for exacerbation of COPD : a post hoc analysis Neural respiratory drive and cardiac function in patients with obesity hypoventilation syndrome following initiation of non-invasive ventilation Polysomnography versus limited respiratory monitoring and nurse-led titration to optimise non-invasive ventilation set-up a pilot randomised clinical trial Chronic ventilator service Step-down from non-invasive ventilation to continuous positive airway pressure : a better phenotyping is required AVAPS-AE versus ST mode : a randomized controlled trial in patients with obesity hypoventilation syndrome Technological advances in home non-invasive ventilation monitoring : reliability of data and effect on patient outcomes Efficacy of a home discharge care bundle after acute exacerbation of COPD Prediction of severe acute exacerbation using changes in breathing pattern of COPD patients on home noninvasive ventilation Charasteristics and outcome of patients set up on high-flow oxygen therapy at home Trial of portable continuous positive airway pressure for the management of tracheobronchomalacia." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR115.
Abstract:
L’insuffisance respiratoire chronique est un syndrome défini par une défaillance monoviscéralerespiratoire. Sa principale origine est aujourd’hui le syndrome obésité-hypoventilation qui concerne 4 à 5% des patients obèses. L’IRC est aussi le stade évolutif terminal de la bronchopneumopathie chronique obstructive qui touche 6 à 8% de la population adulte. L’incidence de ces pathologies et donc de l’insuffisance respiratoire est en augmentation constante. Dans cette thèse, nous avons évalué les nouvelles modalités diagnostiques et thérapeutiques qui pourraient améliorer la prise en charge des patients atteints d’insuffisance respiratoire chronique.Concernant la prise en charge diagnostique, nous avons montré que les données fournies par l’électromyographie de surface des muscles intercostaux, outil qui évalue le travail respiratoire, constituent un marqueur pronostique indépendant chez les patients atteints de bronchopneumopathie chronique obstructive. Nous avons également montré leur pertinence pour prédire l’efficacité clinique et l’observance à la ventilation non-invasive à domicile.Concernant la prise en charge thérapeutique, nous avons montré que l’utilisation d’un mode semi-automatisé de ventilation non-invasive a la même efficacité que celle de modes classiques en permettant une mise en place plus rapide du traitement. Nous avons également rapporté l’intérêt de l’oxygénothérapie à haut débit au domicile alors que ce traitement était utilisé jusque-là dans le seul cadre des soins intensifs. Enfin, nous avons rapporté les bénéfices de la pression positive continue au cours de l’effort chez les patients ayant une trachéobronchomalacie. Concernant le suivi des patients, nous avons montré que les données des logiciels de ventilation non invasive permettent de prédire la survenue d’une exacerbation sévère de BPCO mais que l’utilisation de la télémédecine chez les patients insuffisants respiratoires chroniques ne peut être encore pleinement intégrée dans la pratique clinique. Au cours de cette thèse, nous avons identifié de nouveaux outils physiologiques, de nouvelles modalités d’administration des traitements et de nouveaux outils de suivi à domicile, à même d’améliorer la prise en charge des patients insuffisants respiratoires chroniquesSingle-organ respiratory failure defines chronic respiratory failure. Obesity hypoventilation syndrome is the main cause of chronic respiratory failure and occurs in 4 to 5% of obese patients. Chronic respiratory failure is also the end-stage evolution of chronic obstructive pulmonary disease that has a prevalence of 6 to 8% in the adult population. The incidence of these diseases increases so does the incidence of chronic respiratory failure. In this thesis, we will evaluate novel diagnostic and therapeutic modalities that could improve the care of patients with chronic respiratory failure. Regarding diagnostic modalities, we have seen that evaluating the work of breathing with surface parasternal electromyography was an independent prognostic marker in patients with chronic obstructive pulmonary disease. We have also seen that it was a relevant tool to predict the clinicalefficacy and compliance to home non-invasive ventilation. Regarding therapeutic modalities, we have shown that the use of a semi-automatic mode of non-invasive ventilation had the same efficacy of a standard mode with a shorter length of stay for its setup. We have shown the relevance and feasibility of the use of high-flow oxygen therapy in the home setting whilst it was only used in intensive care units. Finally, we have shown the benefits of continuous positive airway pressure during exertion in patients with tracheobronchomalacia. Regarding patients’ follow-up, we have shown that the use of data from built-in software could predict the onset of a severe exacerbation of chronic obstructive pulmonary disease. However, we also show that the implementation of tele-medicine in patients with chronic respiratory failure cannot be included in daily clinical practice yet. In this thesis, we have identified novel physiological tools, novel ways to administer treatments and novel follow-up tools that can improve the management of patients with chronic respiratory failure
29
Lin, Chien-Chung, and 林建仲. "Motion Analysis and Assessment of Cardiac Function for Cardiac Images." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/2uhv85.
Abstract:
博士元智大學
資訊管理學系
104
This thesis proposes a series of methods in analyzing cardiac motion sequences. It is helpful to assist the cardiologist to analyze the medical images for further diagnosis. Coronary angiogram is one of the most valid methods for diagnosing the presence of coronary artery disease. Therefore, we propose a method to select the optimum phase from the image sequence. The optimum phases were selected by evaluating the correlation coefficients with minimum inconsistency of motion in the selected data. The result of the optimum image phase selection shows that the automatically determined phases yield the optimum image quality. To achieve the purpose of providing accurate information in coronary artery images, an algorithm to extract the skeletons and borders of coronary arteries in digitalized angiograms automatically is also proposed. Based on the optimum image, we develop a combination of fragment strategy and tubular enhancement to figure out the vessel structure clearly. Cardiac wall motion plays an important role in the analysis and interpretation of various kinds of cardiac diseases. However, it is difficult to find the initial contour of cardiac boundary and produce an accurate motion flow field at motion boundaries. In this study, we propose a novel and non-iterative approach to segment the boundaries in motion images based on voting processes for catheterization angiocardiography. A voting process is first used to enforce the smoothness of motion and determine an estimation of pixel velocities, motion regions and boundaries. For the purpose of locally defining a boundary tensor field, boundary estimation is combined with intensity information from the original images. Correct velocities are computed for the pixels near boundaries, as they are reassigned to different regions. Furthermore, we propose a computer aided diagnosis/detection system for cardiac motion analysis of catheterization ventriculography. The purpose of this method is to develop a computerized system which helps physicians and radiologists to automatically predict the presence of heart disease as early as possible. The adaptive ellipse active contour model is used to refine the contours. Motion analysis of cardiac are performed according to the extracted contours to form the motion vector field by Empirical Mode Decomposition (EMD) method. The results of motion detection are displayed in the formats of motion vector fields and Doppler color display. The combination of quantitative cardiac motion analysis obtained from cardiac images enable the clinician to determine whether there exists a heart disease and therefore may need treatment. The purpose of this thesis is to make use of image information to assistant the diagnosis. Experiment results show that physicians can use the proposed solid model for process of evaluation and planning before the surgeries to promote the efficiency of diagnosis, medical treatment qualities and reduce the waste of medical resource.
30
Yang, Shih-Yu, and 楊詩郁. "Motion Analysis and Assessment of Cardiac Function in Catheterization Ventriculography." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/04623345291203615943.
Abstract:
碩士元智大學
資訊管理學系
98
This study propose a computer-aided system to provide the motion analysis and assessment of cardiac function in catheterization ventriculography. First, we use the block matching method to segment the coarse contour of left ventricular region. Then, morphological operations were used to refine the contour. Secondly, a two step fuzzy logic system was used to identify the direction of heart motion. The Doppler ultrasonography representation was used to present a more intuitive and objective interpretation of cardiac information. Finally, some of the parameters such as Ejection Fraction and slope variation of ventricular are used to evaluate the cardiac function. Experimental results show that the proposed method can provide an effective motion analysis and assessment of cardiac function in catheterization ventriculography. Meanwhile, it can be further as the computer aided diagnosis system (CAD) for differential diagnosis in the future.
31
Liao, Fang-Tsu, and 廖芳足. "Cardiac function analysis of angiotensin-converting enzyme-related (ACER) in Drosophila melanogaster." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/69942220839949096941.
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VanDusen, Nathan J. "Hand2 function within non-cardiomyocytes regulates cardiac morphogenesis and performance." Thesis, 2014. http://hdl.handle.net/1805/6170.
Abstract:
Indiana University-Purdue University Indianapolis (IUPUI)The heart is a complex organ that is composed of numerous cell types, which must integrate their programs for proper specification, differentiation, and cardiac morphogenesis. During cardiac development the basic helix-loop-helix transcription factor Hand2 is dynamically expressed within the endocardium and extra-cardiac lineages such as the epicardium, cardiac neural crest cells (cNCCs), and NCC derived components of the autonomic nervous system. To investigate Hand2 function within these populations we utilized multiple murine Hand2 Conditional Knockout (H2CKO) genetic models. These studies establish for the first time a functional requirement for Hand2 within the endocardium, as several distinct phenotypes including hypotrabeculation, tricuspid atresia, aberrant septation, and precocious coronary development are observed in endocardial H2CKOs. Molecular analyses reveal that endocardial Hand2 functions within the Notch signaling pathway to regulate expression of Nrg1, which encodes a crucial secreted growth factor. Furthermore, we demonstrate that Notch signaling regulates coronary angiogenesis via Hand2 mediated modulation of Vegf signaling. Hand2 is strongly expressed within midgestation NCC and endocardium derived cardiac cushion mesenchyme. To ascertain the function of Hand2 within these cells we employed the Periostin Cre (Postn-Cre), which marks cushion mesenchyme, a small subset of the epicardium, and components of the autonomic nervous system, to conditionally ablate Hand2. We find that Postn-Cre H2CKOs die shortly after birth despite a lack of cardiac structural defects. Gene expression analyses demonstrate that Postn-Cre ablates Hand2 from the adrenal medulla, causing downregulation of Dopamine Beta Hydroxylase (Dbh), a gene encoding a crucial catecholaminergic biosynthetic enzyme. Electrocardiograms demonstrate that 3-day postnatal Postn-Cre H2CKO pups exhibit significantly slower heart rates than control littermates. In conjunction with the aforementioned gene expression analyses, these results indicate that loss of Hand2 function within the adrenal medulla results in a catecholamine deficiency and subsequent heart failure.
33
Juric, Danijel. "A comparative serial analysis of cardiac sarcoplasmic reticulum function in rats subjected to pressure or volume overload." 2007. http://hdl.handle.net/1993/20502.
34
Cantor, Elliott J. F. "A comparative serial echocardiographic analysis of cardiac structure and function in rats subjected to pressure or volume overload." 2005. http://hdl.handle.net/1993/17957.
35
Chou, Hsiao-Hsuan, and 周曉璇. "The Analysis and Applications of Optical Flow in Cardiac Functions." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/57482256576176396762.
Abstract:
碩士國立臺灣大學
電機工程研究所
84
The motion of the heart is very complicated. Understanding the wall motion of the left ventricle is especially important for analysizing the cardiac functions. Due to the development of imaging technology, it beomes easier to get the dynamic cardiac image sequence. If we can get the correct velocity information from the dynamic images, it will be helpful for the cardiac diagnosis and the heart function evalution. Optical flow is the velocity distribution of the patterns in image. With the optical flow method, we can acquire the magnitude and the direction of the velocity of each pixel in an image.We apply this method on dynamic Cardiac Magnetic Resonance Images (MRI) and Radionuclide Angiography images (RNA) , focusing on the wall motion of the left ventricle. From the optical flow we study, the complex motion pattern during the diastole and systole of a heart cycle can be observed and analyzed. In order to increase the precision, we use anisotropic diffusion and gaussian filters in space and time domain for smoothing the gray-levels in advance. A median filter is than applied on the velocity field . The velocity fields calculated from the optical flow method show many details of the heart motion. By tracing the locations of the points we interested, we can get useful physiological parameters, eg. ejection fraction(EF), peak filling rate(PFR), etc. Moreover, by calaulating the strain rate from the velocity field, one can tell the differences between the healthy and abnormal cardiac functions. Other mechanical parameters of the heart could be also derived displayed using this method noninvasively, which is not possible with traditional imaging techniques.
36
Bray, Mark-Anthony P. "Visualization and analysis of electrodynamic behavior during cardiac arrhythmias." 2003. http://etd.library.vanderbilt.edu/ETD-db/available/etd-03182003-110637/.
37
Andreopoulos, Alexander. "Statistical models of appearance for functional analysis of cardiac MRI /." 2005.
Abstract:
Thesis (M.Sc.)--York University, 2005. Graduate Programme in Computer Science.Typescript. Includes bibliographical references (leaves 160-166). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11736
38
Barakat, Amal Zohir Abo-Zeid. "Functional Analysis of Heat Shock Protein HSPA4." Doctoral thesis, 2010. http://hdl.handle.net/11858/00-1735-0000-0006-B522-E.
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von, Loesch Eckhart Thassilo. "Evaluation eines Echtzeit-Verfahrens in der kardialen Magnetresonanztomographie bei Patienten mit Herzrhytmusstörungen am Beispiel von Vorhofflimmern." Doctoral thesis, 2017. http://hdl.handle.net/11858/00-1735-0000-0023-3DC8-6.