Dissertations / Theses on the topic 'Huntington's disease Magnetic resonance imaging'
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Richards, Jennifer Margaret Jane. "Magnetic resonance imaging in cardiovascular disease." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8079.
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Background Superparamagnetic particles of iron oxide (SPIO) are part of a novel and exciting class of ‘smart’ magnetic resonance imaging (MRI) contrast agents that are taken up by inflammatory cells. Ultrasmall SPIO (USPIO; ~30 nm diameter) can be used to assess cellular tissue inflammation and SPIO (80-150 nm) have the potential to be used to label cells ex vivo for in vivo cell tracking studies. Objectives The aims of the thesis were therefore (i) to develop and validate quantitative MRI methodology for assessing SPIO uptake within tissues, (ii) to demonstrate USPIO accumulation within the aortic wall and its implications in patients with abdominal aortic aneurysms (AAA), and (iii) to develop and apply a Good Manufacturing Practice (GMP) compliant method of SPIO cell labelling in healthy volunteers. Methods Patients with asymptomatic AAA >4.0 cm in diameter were recruited. Imaging sequences were optimised in eight patients using a 3 tesla MRI scanner. Data were analysed using the decay constant for multi echo T2* weighted (T2*W) sequences (T2*) or its inverse (R2*) and the repeatability of these measurements was established. A further twenty-nine patients underwent MRI scanning before and 24- 36 hours after administration of USPIO. T2 and multi echo T2*W sequences were performed and ultrasound-based growth rate data were collected. Operative aortic wall tissue samples were obtained from patients undergoing open surgical aneurysm repair. A GMP compliant protocol was developed for labelling cells with SPIO for clinical cell tracking studies. The effects of SPIO-labelling on cell viability and function were assessed in vitro. A phased-dosing protocol was used to establish the safety of intravenous administration of SPIO-labelled cells in healthy volunteers. The feasibility of imaging cells at a target site in vivo following local or systemic administration was assessed. Tracking of SPIO-labelled cells to a target site was investigated by inducing an iatrogenic inflammatory focus in the skin of the anterior thigh of healthy volunteers, following which autologous SPIO-labelled cells were administered and their accumulation was assessed using MRI scanning and histology of skin biopsies. Results Robust and semi-quantitative data acquisition and image analysis methodology was developed for the assessment of SPIO accumulation in tissues. In patients with AAA, histological analysis of aortic wall tissue samples confirmed USPIO accumulation in areas of cellular inflammation. USPIO-enhanced MRI detected aortic wall inflammation and mural USPIO uptake was associated with a 3-fold higher aneurysm expansion rate. Human mononuclear cells were labelled with SPIO under GMP compliant conditions without affecting cell viability or function. Both local and intravenous administration of SPIO-labelled cells was safe and cells were detectable in vitro and in vivo using a clinical MRI scanner. SPIO-labelled cells tracked to a focal iatrogenic inflammatory focus following intravenous administration in humans and were detectable on MRI scanning and histological examination of skin biopsies. Conclusions SPIO contrast agents have an extensive range of potential clinical applications. USPIO uptake in the wall of AAA appears to identify cellular inflammation and predict accelerated aneurysm expansion. This is therefore a promising investigative tool for stratifying the risk of disease progression in patients with AAA, and may also be considered as a biomarker for response to novel pharmacological agents. The ability to label cells for non-invasive cell tracking studies would facilitate the further development of novel cell-based therapies and would enable assessment of dynamic inflammatory processes through inflammatory cell tracking.
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Manners, David Neil. "Magnetic resonance imaging and magnetic resonance spectroscopy of skeletal muscle." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269250.
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Fox, Charles Nicholas Ilya. "Magnetic resonance imaging of atrophy in Alzheimer's disease." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400512.
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Hochbergs, Peter. "Magnetic resonance imaging in Legg-Calvé-Perthes disease." Lund : Depts. of Diagnostic Radiology and Orthopedics, University Hospital, 1998. http://catalog.hathitrust.org/api/volumes/oclc/40178137.html.
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Watson, Paul J. "A magnetic resonance imaging study of degenerative joint disease." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338026.
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U-King-Im, Jean Marie Kim Sin. "Evaluation of carotid atherosclerotic disease by Magnetic Resonance Imaging." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612046.
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Shereen, Ahmed D. "Diffusion Tensor Magnetic Resonance Imaging Applications to Neurological Disease." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1300393032.
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Shalabi, Adel. "Magnetic resonance imaging in chronic achilles tendinopathy /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-811-4/.
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Cheng, Adrfian Seng Hung. "Functional assessment of coronary artery disease using magnetic resonance imaging." Thesis, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542949.
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Moore, Elizabeth Anne. "Quantitative magnetic resonance imaging in arthritis and diabetic microvascular disease." Thesis, University of Exeter, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278798.
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Oshima, Sonoko. "Neuromelanin‐Sensitive Magnetic Resonance Imaging Using DANTE Pulse." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263531.
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Gandy, Stephen James. "Magnetic resonance imaging of finger joints in osteoarthritis and acromegaly." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390151.
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Casamitjana, Díaz Adrià. "Study of early stages of Alzheimer's disease using magnetic resonance imaging." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/668251.
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Alzheimer's disease (AD) is a neurodegenerative disorder that constitutes the most common dementia pathology. It represents a global epidemic that expands exponentially as the life expectancy increases with no yet useful treatment. Currently, it represents a huge social and economic burden for our societies and it is expected to tension public health infraestructures and finances in the near future.
AD is characterized by amyloid plaque deposition and neurofibrillary tangles measured by ex-vivo examination of the brain. Recent developments in fluid biomarkers and brain imaging allow in-vivo quantification of pathophysiological processes of amyloid deposition or tau tangles formation in the brain, providing the community with highly sensitive and specific in-vivo biomarkers for Alzheimer's disease diagnosis. Abnormal levels of these biomarkers are thought as the initiating event to a cascade of subsequent events that continue with synapse loss, cell death, memory impairment, functional dysfunction and cognitive decline. All these events constitute the Alzheimer's continuum which can be broadly split into two main parts: an initial long and silent preclinical stage characterized by abnormal AD biomarkers and cognition within the normal range that could last from 15 to 30 years and a posterior clinical stage where subjects develop dementia symptoms.
The etiology of AD is still poorly understood even though several risk factors are identified. Large observational studies can help the study of AD and its related biomarkers and risk factors. In this thesis we provide methodological tools for the analysis of Alzheimer's disease using magnetic resonance imaging (MRI). We focus on the study of subjects within the preclinial stage of AD by using statistical learning and pattern recognition frameworks to perform inferential statistics and develop predictive models.
The main outcomes of this thesis are three-fold: firstly, we develop an open-source toolbox for nonlinear neuroimage analysis in population studies. While nonlinear association between medical images and several factors is already known, standard neuroimaging softwares only provide linear statistical frameworks that limit the analyses. Secondly, we study the relationship between brain structure using MRI and the underlying Alzheimer's pathology along the disease continuum and at different stages. The close relationship between MRI and clinical symptoms has been widely studied but describing AD using biomarkers instead of clinical phenotypes allows us to study preclinical stages of AD. Finally, we present a framework to predict cognitively unimpaired and amyloid positive subjects using MR imaging and machine learning. We report the results in a cross-sectional study and in a longitudinal study that compares the volumetric rate-of-change between subjects with different amyloid status. We further test the proposed methodology as a part of the triaging process in clinical trials showing great potential benefits.La malaltia de l’Alzheimer (AD, en anglès) és la patologia cerebral més comuna de totes les malalties neurodegeneratives que provoquen demència. Representa una epidèmia global que augmenta exponencialment a mesura que l’esperança de vida creix de la qual encara no se’n coneix una teràpia efectiva. Actualment, suposa una càrrega social i econòmica molt gran per a la societat fins arribar a tensionar la sanitat i la hisenda pública a curt termini. L’Alzheimer es caracteritza per una acumulació les proteïnes beta-amiloide i tau detectades en l’examinació post-mortem. Tot i això, millores tecnològiques recents en biomarcadors de líquid i en l´adquisició d’imatges mèdiques, permeten quantificar in-vivo els processos patofisiològics d’acumulació de plaques d’amiloide i de creació de neurofilaments de tau al cervell, millorant-ne així la diagnosi en vida. Es creu que un nivell anòmal en qualsevol d’aquests biomarcadors són el punt de partida d’una concatenació d’esdeveniments que segueixen amb pèrdua de teixit cerebral, disminució de connexions sinàptiques, pèrdua de la memòria, disfuncionalitats i deteriorament cognitiu. Totes aquestes característiques es mostren en diferent etapes d’un llarg continu temporal que constitueix l’Alzheimer i que a grans trets es pot dividir en dues fases: primerament, una llarga i silenciosa fase inicial anomenada etapa preclínica i que es caracteritza per contenir uns nivells anòmals de biomarcadors d’AD però que cognitivament no presenten cap símptoma. Seguidament, una etapa més curta on els pacients desenvolupen els símptomes de demència i trastorn cognitiu. Mentre les característiques i conseqüències de la malaltia de l’Alzheimer són conegudes i evidents, les seves causes no es coneixen completament. L’auge d’estudis observacionals globals, on hi participin múltiples institucions i que agrupen grans quantitats de pacients lligat amb el ràpid desenvolupament de tècniques avançades d’anàlisi de dades ajudaran a l’estudi de l’AD, els seus biomarcadors, les causes i els factors de risc. En aquesta tesi, presentem diferents eines metodològiques per l’anàlisi de la malaltia de l’Alzheimer utilitzant imatges de ressonància magnètica (MRI, en anglès). Ens centrem en l’estudi de l’etapa preclínica de l’AD utilitzant eines estadístiques i d’aprenentatge automàtic. Els tres principals resultats d’aquesta tesi són: en primer lloc, un programa de llicència lliure per l’anàlisi estadístic i no lineal de neuroimatge en estudis poblacionals. L’eina busca complementar els models lineals oferts pels programes estàndard de processament de neuroimatges que limiten l’estudi dels efectes de diferents factors sobre biomarcadors d’imatge fruit de relacions no lineals entre ells. En segon lloc, analitzarem l´associació entre l’estructura cerebral mesurada mitjançant MRI i la patologia latent al llarg del continu de la malaltia i en diferents etapes. A diferència d´utilitzar fenotips de caire clínic/cognitiu, àmpliament estudiats per la comunitat científica i que defineixen la fase més tardana de la malaltia, l’ús de biomarcadors ens permet estudiar tot l’espectre de l’Alzheimer i posar el focus en la fase més inicial i asimptomàtica. Finalment, presentem un marc conceptual on s’utilitzen mètodes d’aprenentatge automàtic i ressonàncies magnètiques per a la predicció de subjectes immersos en l’etapa preclínica, és a dir, que no presenten deteriorament cognitiu ni pèrdua de memòria però que presenten un nivell anòmal de beta-amiloide. Mitjançant un estudi transversal i un altre longitudinal, aquest marc s’avalua en el context de selecció de participants en assajos clínics per a la prevenció de la malaltia de l’Alzheimer. La metodologia desenvolupada proporciona un potencial impacte rellevant tant en l’estalvi monetari com en la reducció de tests invasius o radioactius duts a terme pels participants
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Karmouty, Quintana Harry. "Experimental pulmonary disease assessed non-invasively by magnetic resonance imaging (MRI)." Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437768.
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Jack, James. "Computer aided analysis of inflammatory muscle disease using magnetic resonance imaging." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19579.
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Inflammatory muscle disease (myositis) is characterised by inflammation and a gradual increase in muscle weakness. Diagnosis typically requires a range of clinical tests, including magnetic resonance imaging of the thigh muscles to assess the disease severity. In the past, this has been measured by manually counting the number of muscles affected. In this work, a computer-aided analysis of inflammatory muscle disease is presented to help doctors diagnose and monitor the disease. Methods to quantify the level of oedema and fat infiltration from magnetic resonance scans are proposed and the disease quantities determined are shown to have positive correlation against expert medical opinion. The methods have been designed and tested on a database of clinically acquired T1 and STIR sequences, and are proven to be robust despite suboptimal image quality. General background information is first introduced, giving an overview of the medical, technical, and theoretical topics necessary to understand the problem domain. Next, a detailed introduction to the physics of magnetic resonance imaging is given. A review of important literature from similar and related domains is presented, with valuable insights that are utilised at a later stage. Scans are carefully pre-processed to bring all slices in to a common frame of reference and the methods to quantify the level of oedema and fat infiltration are defined and shown to have good positive correlation with expert medical opinion. A number of validation tests are performed with re-scanned subjects to indicate the level of repeatability. The disease quantities, together with statistical features from the T1-STIR joint histogram, are used for automatic classification of the disease severity. Automatic classification is shown to be successful on out of sample data for both the oedema and fat infiltration problems.
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McDiarmid, Adam Kenneth. "Tissue characterisation in acquired heart disease with cardiovascular magnetic resonance imaging." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/10420/.
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Objectives: To apply and refine conventional and developing cardiac magnetic resonance (CMR) imaging tissue characterisation techniques, with the aim of applying them to better understand cardiac remodelling in health, disease and as an outcome surrogate in clinical trials. Background: Cardiac structure, function and perfusion are routinely assessed with a range of imaging modalities in both research and clinical practice. Cardiac magnetic resonance (CMR) imaging is emerging as the gold standard tool for many of these assessments. The use of gadolinium containing contrast agents in CMR protocols allows the detection of myocardial scar and focal fibrosis and provides important prognostic information. The developing field of T1 mapping allows measurement of the extracellular volume, a surrogate for fibrosis that offers further insights into diffuse myocardial change not previously possible. Methods: CMR tissue characterisation techniques were applied in sequential studies of: ischaemic cardiomyopathy, health, athletic cardiac adaptation and in a randomised controlled study examining the effects of spironolactone in heart failure with preserved ejection fraction. Results & Conclusions: Late gadolinium enhancement (LGE) imaging is of limited application in predicting functional recovery of dysfunctional segments in ischaemic cardiomyopathy (Chapter 3). Modified Look-Locker Inversion recovery (MOLLI) T1 and extracellular mapping techniques can be applied reproducibly in health and following either bolus or split dose gadolinium administration (Chapters 4 & 5). T1 mapping provides important insights into athletic cardiac remodelling that may allow its application in distinguishing between athletic and myopathic change (Chapter 6). Individuals with heart failure with preserved ejection fraction (HF-PEF) have diffuse myocardial fibrosis as measured with T1 mapping. Early results of a randomised controlled study suggest that the beneficial effects of spironolactone in HF-PEF may in part be due to regression of diffuse myocardial fibrosis (Chapter 7).
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Benjamin, Philip. "A magnetic resonance imaging study evaluating neuro-imaging markers in cerebral small vessel disease." Thesis, St George's, University of London, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.703111.
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Aims: I investigate potential MRI markers in cerebral small vessel disease (SVD), to determine their relationship to cognitive impairment and investigate whether they are feasible for use as surrogate outcome measures in clinical trials by estimating their sensitivity to longitudinal change and calculating sample sizes for a hypothetical clinical trial. I also carry out pilot work to investigate the potential use of 7T MRI in SVD. Methods: Data from the prospective St Georges Cognition and Neuroimaging in Stroke (SCANS) study of patients with symptomatic SVD was used (n=121). Neuropsychological testing was performed annually for a period of 3 years. Multimodal MRI was also acquired annually to evaluate brain volume, T2 White Matter Hyperintensities (WMH) volume, lacunes and white matter damage on diffusion tensor imaging (DTI). Results: At baseline, lacunes and brain volume were found be important predictors of cognitive impairment on conventional MRI. There is a specific association between lacunes in the anteromedial thalamus and impaired processing speed (Chapter 3). Perivascular spaces (PvS) were not associated with cognitive impairment but were associated with other MRI markers of SVD (Chapter 4). Over 3 years, longitudinal change was detectable in MRI markers but not in cognitive measures. WMH volume and diffusion tensor imaging parameters were most sensitive to change and therefore had the smallest sample size estimates for a hypothetical clinical trial (Chapter 5). The presence of new lacunes was the only MRI marker able to predict longitudinal change in cognition over a 3 year follow-up period (Chapter 6). Conclusion: Quantitative MRI markers could significantly reduce the size of clinical trials to screen treatments for efficacy in SVD, although further validation from studies with longer follow-up is required. 7T MRI has the potential to provide new information on underlying disease mechanisms and more specific surrogate markers of SVD progression (Chapter 7).
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Brevard, Mathew E. "Developing compatible techniques for magnetic resonance imaging of stroke pathophysiology." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0107103-173954.
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Kihlberg, Johan. "Magnetic Resonance Imaging of Myocardial Deformation and Scarring in Coronary Artery Disease." Doctoral thesis, Linköpings universitet, Avdelningen för radiologiska vetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-143028.
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Although improved treatments have reduced the rates of acute complications from myocardial infarction, sequelae such as heart failure and sudden death threaten the future wellbeing of those patients. Secondary prevention after myocardial infarction is related to cardiovascular risk factors and the effect of the infarct on left ventricular function. Cardiovascular magnetic resonance imaging (CMR) is necessary to determine the size of the infarct scar and can with great precision determine left ventricular volumes, left ventricular ejection fraction, and deformation (strain and torsion). The purpose of this thesis was to improve on CMR methods to facilitate image acquisition and post processing in patients with high risk of coronary artery disease (CAD). In Paper 1, a three-dimensional phase-sensitive inversion-recovery (3D PSIR) sequence was modified to measure T1 during a single breath hold. The measured T1 values were used to extrapolate a map of T1 relaxation, which avoided the time-consuming manual determination of the inversion time. The data collection consisted of phantom experiments, Monte Carlo simulations of the effect of various heart rates, and clinical investigation of 18 patients with myocardial infarction. Scar images created with the modified sequence were compared to those created with the standard sequence. The 3D PSIR sequence was able to measure T1 relaxation with a high accuracy up to 800 ms, which is in the suitable range for scar imaging. Simulated arrhythmias showed that the method was robust and able to tolerate some variation in heart rate. The modified sequence provides measurements of inversion time that can be used to facilitate standard scar imaging or to reconstruct synthetic scar images. Images of infarct scar obtained with the 3D PSIR sequence bore striking similarity to images obtained with the standard sequence. In Paper 2, 125 patients with high risk of CAD were investigated using the displacement encoding with stimulated echoes (DENSE) sequence. Image segments with infarct scar area >50% (transmurality) could be identified with a sensitivity of 95% and a specificity of 80% based on circumferential strain calculated from the DENSE measurements. The DENSE sequence was also applied in other directions, but its sensitivity and specificity to detect scar was lower than when used for circumferential strain. In Paper 3, 90 patients with high risk of CAD were examined by DENSE, tagging with harmonic phase (HARP) imaging and cine imaging with feature tracking (FT), to detect cardiac abnormalities as manifested in end-systolic circumferential strain. Circumferential strain calculated with DENSE had higher sensitivity and specificity than the competing methods to detect infarction with transmurality >50%. Global circumferential strain measured by DENSE correlated better with global parameters such as left ventricular ejection fraction, myocardial wall mass, left ventricular end-diastolic and end-systolic volume; than strain measured by FT or HARP. In Paper 4, myocardial torsion was investigated using DENSE, HARP, and FT in 48 patients with high risk of CAD. Torsion measured by each of the three methods was correlated with other global measures such as left ventricular ejection fraction, left ventricular mass, and left ventricular end-diastolic and end-systolic volumes. The torsion measurements obtained with DENSE had a stronger relationship with left ventricular ejection fraction, left ventricular mass, and volumes than those obtained with HARP or FT. DENSE was superior to the other methods for strain and torsion measurement and can be used to describe myocardial deformation quantitatively and objectively.
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Sammut, Eva Clare. "Advanced cardiac magnetic resonance imaging in heart failure and coronary artery disease." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/advanced-cardiac-magnetic-resonance-imaging-in-heart-failure-and-coronary-artery-disease(edf62114-1762-4830-a456-2aa8886ef130).html.
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Recent technical developments have increased the scope for cardiac MRI as a research tool. This work presents novel approaches to the assessment of patients with coronary disease and heart failure. The thesis explores coronary physiology and microarchitecture, ischaemia and perfusion CMR, and in particular the quantification of ischaemia. In addition, in-vivo cardiac diffusion tensor imaging is employed to characterize microarchitecture in heart failure. This work comes to a number of conclusions. We have been able to show, for the first time in patients with heart failure, that even in patients who have thinned and remodelled ventricles, quantitative assessment with high resolution quantitative CMR is feasible and reproducible. Our work is also the first to perform assessment of the prognostic use of quantitative perfusion CMR - in a large group of unselected patients presenting with suspected coronary disease, we have investigated the prognostic value of a quantitative approach. This observational study proposes that this performs at least as well as visual assessment by expert readers. Furthermore, the thesis explores the correlation between CMR and PET using a specialized cardiac phantom which simulates perfusion and a hybrid CMR-PET scanner. In this setting, we have concluded that there is excellent correlation between MR, PET and known true perfusion values. This thesis also presents work on the use of cardiac diffusion tensor imaging in dilated cardiomyopathy, the first study to do so using a dual-phase in-vivo approach. We have been able to demonstrate significant differences in fibre and sheetlet orientation by comparison to controls. Our study used biomechanical modelling and strain data from 3D tagging CMR. Overall this work adds to the body of knowledge of quantitative perfusion CMR analysis and cardiac DTI and merits further larger studies, particularly with regard to translation to the clinical setting.
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Turnbull, Lindsay W. "Volumetric analysis and tissue characterisation of cardiac disease by magnetic resonance imaging." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/20256.
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Magnetic resonance imaging (MRI) offers the unique ability to examine the heart in three dimensions and to provide tissue characterisation. This thesis aims to investigate two areas of particular interest, namely the quantification of cor pulmonale and acute myocardial infarction. The methods currently available for assessing right ventricular hypertrophy and dilatation are discussed, with particular reference to patients with chronic obstructive pulmonary disease. The results of pulmonary haemodynamic and blood gas data are compared with the results from cardiac gated MRI. A good correlation is obtained between the mean and systolic pulmonary artery pressures, the pulmonary vascular resistance and the right ventricular wall volume measured by MRI. This technique is subsequently used in a small group of patients, to determine the response to long term oxygen therapy. The various techniques employed to assess the size of myocardial infarcts are discussed, and the previous literature on the ability of MRI to detect infarction is reviewed. A new technique, which is supported by phantom experiments, is described to measure the volume of infarcted myocardium using saturation recovery - inversion recovery and spin-echo images. The T1 images are compared with radionuclide pyrophosphate scanning and serum creatine kinase-MB release and a satisfactory agreement obtained. Myocardial infarct size measured by both pulse sequences is compared directly. The spin-echo technique is used to assess alterations in myocardial infarct size with time and the response to various therapeutic options is compared. In conclusion the limitations of both techniques are discussed and future developments proposed.
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Cobbold, Jeremy Francis Lars. "Imaging techniques in chronic liver disease : applications of proton magnetic resonance spectroscopy." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11263.
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Li, Geng, and 李耕. "Brain activations on functional magnetic resonance imaging during acupuncture and/or physiological tasks in healthy volunteers andstable stroke patients." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29157511.
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Bronge, Lena. "Magnetic resonance imaging in dementia : a study of brain white matter changes /." Stockholm : Karolinska Univ. Press, 2001. http://diss.kib.ki.se/2001/91-7349-047-4/.
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Mullins, Paul Gerald Mark. "Magnetic resonance imaging in the study of animal models of cerebral ischaemia /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16186.pdf.
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Cullen, James Henry Stuart. "Magnetic resonance imaging in the assessment of myocardial perfusion in ischaemic heart disease." Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/29594.
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Five normal volunteers and twenty patients with angiographically proven IHD underwent rest/stress MRI examinations and myocardial scintigraphy for comparison. Five patients had coronary angioplasty and repeat MRI studies three months later. Five patients with Syndrome X were also studied with MRI. MPRI was significantly reduced in patients compared with normals (2.02 0.7 (mean SD), vs 4.21 1.16, p<0.02), with a significant negative correlation of MPRI with percent diameter stenosis of individual coronary lesions (r=-0.81, p< 0.01). MPRI in regions supplied by non-flow limiting lesions (<40% diameter stenosis) was significantly higher than regions supplied by stenoses of 'intermediate' (>40 % to 59%) severity, (2.80 0.77 and 1.93 0.38, p<0.02). Furthermore, MPRI predicted the functional status of the patients reasonably well after revascularisation in this small group. The sensitivity and specificity of quantitative MRI for the detection of global IHD in patients was comparable to thallium-201 scintigraphy (0.89 and 1.0 (sens/spec) vs 0.89 and 1.00) but both were superior to qualitative MRI (0.79 and 0.94). For identifying a significant coronary lesion the sensitivity of quantitative MRI was superior to both qualitative MRI and scintigraphy (0.82, 0.43, 0.75 respectively). The specificity of quantitative MRI was poorer than scintigraphy but similar to qualitative MRI (0.84, 0.89, 0.84). Finally, MPRI in patients with Syndrome X was reduced vs controls (2.17 0.72, p<0.01). Quantitative MRI perfusion studies can provide functional information to detect IHD in patients and assess adequacy of revascularisation. Furthermore, it may be able to provide insight into the mechanism of ischaemia in patients with Syndrome X.
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Selvanayagam, Joseph B. "Use of magnetic resonance imaging to characterise myocardial injury in coronary artery disease." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414226.
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Suttie, Joseph. "Characterising metabolic mechanisms of disease in cardiomyopathies using multiparametric cardiovascular magnetic resonance imaging." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555329.
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In addition to pathological ventricular remodeling, the failing heart is characterised by impaired myocardial energetics and profound alterations in glucose and fatty acid metabolism. Understanding these complex metabolic pathways is crucial to improving clinical risk stratification and developing targeted therapeutic interventions. Cardiac magnetic resonance imaging (CMR) and magnetic resonance spectroscopy (MRS) are powerful tools in the interrogation of cardiac disease. Although technically challenging, the assessment of myocardial energetics by 3'p MRS has been possible for several decades. More recent techniques have allowed for the rapid assessment of cardiac steatosis using 'H MRS. The relationship between cardiac steatosis and other parameters of myocardial function such as myocardial energetics, contractility, fibrosis and perfusion have not been previously investigated. I assessed these parameters in patients with dystrophinopathy, a cause of inherited dilated cardiomyopathy in which disease pathways have not been well described. This study found myocardial contractility is strongly correlated with the myocardial PCr/ATP ratio, and that in those patients with impaired myocardial energetics there is significant cardiac steatosis. These changes were independent of body mass index and occurred in patients with normal glucose and lipid profiles. In order to further elucidate the phenotype, we investigated these markers of myocardial dysfunction in dystrophinopathic patients with and without prior exposure to Coxsackie B infection, an acquired cause of dystrophinopathy. Previous Coxsackie B exposure predicts worsening myocardial fibrosis, but was not associated with parameters of metabolic dysfunction. 17 - Suttie J.J. In order to further investigate the significance of cardiac steatosis in inborn errors of metabolism, I phenotyped a cohort of patients with mitochondrial myopathy. Mitochondrial myopathies are associated with profound cardiac steatosis, impaired myocardial energetics, inflammation and fibrosis. Furthermore, we report cardiac steatosis also occurs in patients with impaired myocardial energetics due to hypertrophic cardiomyopathy, idiopathic dilated cardiomyopathy and asymptomatic aortic stenosis. Finally, even higher spatial resolution imaging may be achieved be achieved at higher field strength, and I therefore undertook the first validation of CMR cardiac functional imaging at 7 T. This work significantly expands our understanding of cardiac steatosis in the energetically failing heart and supports its potential role as a novel biomarker in a range of cardiomyopathies.
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Caruana, P. "Visual psychophysics and magnetic resonance imaging in demyelinating disease of the visual system." Thesis, Keele University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245886.
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Chouhan, M. D. "Magnetic Resonance Imaging haemodynamic modelling in chronic liver disease : development, validation and translation." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1464418/.
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Though haemodynamic changes underpin the pathophysiology of chronic liver disease, there are currently no robust non-invasive methods available for their assessment. I propose ‘caval subtraction’ phase contrast MRI (PCMRI) a novel method to measure total liver blood flow (TLBF) and hepatic arterial (HA) flow using PCMRI measurements of caval and portal venous (PV) flow. I validate this method at 9.4T and 3.0T to demonstrate: agreement between preclinical PCMRI and invasive transit-time ultrasound (TTUS) and fluorescent microsphere measurements of flow parameters; good consistency between clinical caval subtraction PCMRI and independent direct PCMRI measurements; encouraging correlations between PCMRI and invasive ICG clearance in patients; and good seven-day reproducibility of PCMRI derived haemodynamic parameters in normal volunteers. Using dynamic contrast enhanced (DCE) MRI on a 3.0T system, I demonstrate improved seven-day reproducibility using dual input single compartment pharmacokinetic modelling with a novel method for obtaining physiological vascular input function delays, correction of arterial input functions using PCMRI aortic flow and use of PCMRI estimations of TLBF to correct DCE MRI quantification. I also implement arterial spin labelling (ASL) at 9.4T and demonstrate a tendency for ASL to underestimate PCMRI hepatic parenchymal perfusion. Using bile-duct ligated (BDL) rats to study cirrhosis, I demonstrate that these have reduced TLBF and HA fraction at baseline, impaired HA regulation and buffer response, cirrhotic cardiomyopathy, and a failure to match hepatic circulatory demands with increased liver:body mass ratio. Acute-on-chronic liver failure (simulated using endotoxaemia) demonstrates reductions in TLBF, HA flow, absence of normal sepsis-induced hepatic hyperaemia and blunted cardiac systolic response. Studies in cirrhotic patients demonstrate increased TLBF and HA flow in higher risk portal hypertensive patients; that HA flow, HA fraction and cardiac output are important correlative parameters with hepatic venous pressure gradient and that caval subtraction PCMRI has potential in evaluating treatments for portal hypertension.
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Garg, Pankaj. "Established and emerging techniques of cardiovascular magnetic resonance imaging in coronary artery disease." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17599/.
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Background. In patients with coronary artery disease (CAD), multi-parametric cardiovascular magnetic resonance (CMR) provides detailed information about the myocardial tissue composition and its function. This thesis aims to investigate how myocardial tissue composition characteristics influence its function. Additionally, this thesis aims to develop methods for time-resolved, three-dimensional flow imaging in-vitro and in health. Methods. We have prospectively recruited and conducted multi-parametric CMR in 76 patients with ST-elevation myocardial infarction (STEMI), 44 patients with stable chest pain and 35 healthy volunteers. Results. Study 1 and 2 evaluated if CMR derived function parameters are associated with the presence of microvascular obstruction (MVO) or intramyocardial haemorrhage (IMH) in STEMI patients. Study 1 demonstrated the diagnostic accuracy of mitral annular plane systolic excursion (MAPSE) to detect MVO/IMH. Study 2 demonstrated that peak global longitudinal strain (GLS) is most strongly associated with MVO/IMH when compared to other myocardial deformation parameters. Study 3 demonstrated that during first-pass perfusion stress CMR, at peak hyperemic stress, GLS is reduced in the presence of a perfusion defect in patients being investigated for CAD. Study 4 demonstrated that acute ECV-maps can reliably quantify area at risk and final infarct size (at 3-month follow) in reperfused STEMI patients. Study 5 investigated 3 main acceleration methods for 4-dimensional flow (4D Flow) in phantoms and healthy volunteers. In phantoms, all 4D Flow methods underestimated peak velocity but their mean errors were within reasonable limits for clinical applications. In volunteers, 4D echo planer imaging (EPI) method had the shortest acquisition time, best agreement with 2-dimensional phase contrast, best internal consistency between mitral and aortic valve flows. Conclusions. CMR derived longitudinal functional parameters of the left ventricle are associated with pathologies predominantly in the sub-endocardium and could be used as a surrogate imaging markers. ECV-maps offer an alternative to IS quantification. 4D EPI is the most robust acceleration method for whole-heart flow assessment.
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Citro, Lucas Abraham. "High-field Cardiac Magnetic Resonance Imaging in Small Animal Models of Cardiovascular Disease." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365082830.
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Paschal, Cynthia Bruce. "Three-dimensional high-resolution magnetic resonance imaging of the coronary arteries." Case Western Reserve University School of Graduate Studies / OhioLINK, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=case1060266032.
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d'Arcy, Joanna Louise. "Valvular heart disease : novel epidemiological and imaging studies." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25476.
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Since living conditions have improved and antibiotics have entered routine use, valvular heart disease (VHD) in the developed world is mostly degenerative in origin, rather than rheumatic. Our population is increasing with age, and therefore the burden of VHD is likely to increase. Despite this, the epidemiology & prognostication in VHD remain poorly understood. A better understanding of the prevalence of VHD in our population, and improved methods of predicting outcomes, are essential if we are to be better equipped to meet the challenges of this new “epidemic”. This thesis aims to improve our knowledge of the prevalence of VHD in the elderly, and the potential benefits of cardiac magnetic resonance (CMR) assessment of patients with clinically significant mitral regurgitation. The prevalence of undiagnosed valvular heart disease in those aged 65 and over is examined in Chapters 2 and 3. Chapter 2 outlines a population-based screening study for VHD in primary care in Oxfordshire, which the author played a central role in establishing. The results show that VHD is extremely common in this cohort, and is strongly associated with increasing age. In chapter 4, the level of anxiety provoked by screening for VHD is looked at; this demonstrates that only a small number of patients have significant anxiety levels, but it is more likely in those with a new diagnosis of VHD, and in women. From Chapter 5 onwards, the thesis focuses on the use of CMR in patients with significant mitral regurgitation (MR). In Chapter 5, the clinical value of quantitative assessment of MR using CMR is examined, showing that it was able to predict progression to symptoms or surgery in these patients. In conclusion, this thesis offers insights into the prevalence of VHD in the elderly population, and looks at the anxiety associated with looking for VHD in this group. The potential clinical benefits of CMR in patients with MR are examined, and quantification of MR with this modality would appear to be of prognostic utility.
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Akhtar, Asim. "Molecular magnetic resonance imaging of vascular inflammation using microparticles of iron oxide." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:12bf8e4f-2909-4715-a6fe-bf42d9d8355a.
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One approach that has demonstrated success in the field of molecular imaging utilizes microparticles of iron oxide (MPIO) conjugated to specific antibodies and/or peptides to provide contrast effects on MRI in relation to the molecular expression of a specified target. The experimental aims of this thesis were 1) to investigate the ability of VCAM-1 and P-selectin targeted MPIO to detect the expression of VCAM-1 and P-selectin on the activated endothelium in-vitro and in-vivo in mouse models of renal and cerebral ischemia reperfusion injury, and 2) develop a novel contrast agent for imaging αvβ3-integrin expression in angiogenesis using RGD peptide conjugated MPIO (RGD-MPIO) in-vitro. MPIO (1.0 µm) were conjugated to monoclonal antibodies against VCAM-1 (VCAM-MPIO) or P-selectin (PSEL-MPIO). In vitro, MPIO bound in a dose-dependent manner to tumor necrosis factor (TNF)-alpha stimulated sEND-1 endothelial cells when conjugated to VCAM-1 (R² = 0.88, P<0.01) and P-selectin antibodies (R² = 0.93, P<0.01), reflecting molecular VCAM-1 and P-selectin mRNA and protein expression. Mice subjected to unilateral, transient (30 minutes) renal ischemia and subsequent reperfusion received intravenous VCAM-MPIO and PSEL-MPIO (4.5 mg iron/kg body weight). In ischemic kidneys, MR related contrast effects of VCAM-MPIO were 4-fold higher than unclamped kidneys (P<0.01) and 1.5-fold higher than clamped kidneys of PSEL-MPIO injected mice (P<0.05). VCAM-MPIO binding was less evident in IRI kidneys pre-treated with VCAM-1 antibody (P<0.001). VCAM-1 mRNA expression and VCAM-MPIO contrast volume were highly correlated (R² = 0.901, P<0.01), indicating that quantification of contrast volume reflected renal VCAM-1 transcription. In mice subjected to cerebral ischemia, contrast volume was 11-fold greater in animals injected with VCAM-MPIO versus control IgG-MPIO (P<0.05). Finally, S-nitroso-N-acetylpenicillamine (SNAP) stimulated HUVEC-C cells, which express αvβ3-integrin, showed 44-fold greater RGD-MPIO binding than unstimulated cells (P<0.001) and 4-fold greater RGD-MPIO binding than SNAP stimulated cells blocked with soluble RGD peptide (P<0.001) in-vitro. This thesis demonstrated that targeted MPIO exhibited contrast effects that defined and quantified the molecular expression of specific targets through the use of high-resolution MRI in in-vitro and in-vivo models of vascular inflammation.
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Brevard, Mathew E. "Developing Compatible Techniques for Magnetic Resonance Imaging of Stroke Pathophysiology." Digital WPI, 2001. https://digitalcommons.wpi.edu/etd-theses/20.
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Stroke is the most prevalent neurological disease facing our nation today. Treatments, however, are few and insufficient at reducing the impact of this neurological condition. Experimental animal models are important to improving our understanding of stroke, and for developing new therapies to counter the pathology of stroke. Magnetic Resonance Imaging is the leading tool for the non-invasive investigation of stroke pathophysiology. While most MRI work in animals is conducted under anesthesia, anesthesia has profound effects on cerebral circulation and metabolism, and can affect stroke outcome. Several novel methods were combined with MRI compatible physiologic monitoring equipment to conduct stroke studies in conscious animals. Stress was studied as a factor in these studies and conditioning was utilized to reduce the impact of stress on the animals' physiology. Models of both occlusive and hemorrhagic strokes were successfully implemented within the MRI apparatus. Lastly, experiments using a macrosphere model showed evidence of a pathophysiologic difference between awake and anesthetized animals that undergo stroke.
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Yamamoto, Takayuki. "Magnetic resonance angiography with compressed sensing: an evaluation of moyamoya disease." Kyoto University, 2018. http://hdl.handle.net/2433/232119.
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Reddy, H. "Cortical re-organisation of plasticity : applying fMRI to study disease." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365777.
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Houslay, Emma S. "The role of computed tomography and magnetic resonance imaging in patients with cardiovascular disease." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/24716.
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Methods: In 16 patients, coronary artery calcification was assessed twice within 4 weeks by helical computed tomography. As part of a randomised controlled trial, patients received atorvastatin 80 mg daily or matching placebo, and had coronary calcification assessed annually. Fifty patients with previous coronary artery bypass surgery who were listed for diagnostic coronary angiography underwent contrast enhanced computed tomography angiography using a 16-slice computed tomography scanner. Finally, 15 patients with recent symptoms and signs of an acute transient ischaemic attack, amaurosis fugax or stroke underwent magnetic resonance angiography of the carotid arteries using dedicated surface coils. Results: Quantification of coronary artery calcification demonstrated good reproducibility in patients with scores >100 AU. Despite reducing systemic inflammation and halving serum low-density lipoprotein cholesterol concentrations, atorvastatin therapy did not affect the rate of progression of coronary artery calcification. Computed tomography angiography was found to be highly specific for the detection of graft patency. Assessment of plaque characteristics by magnetic resonance scanning in patients with recent acute carotid plaque was feasible and reproducible. Conclusions: Coronary artery calcium scores can be determined in a reproducible manner. Although they correlate well with the presence of atherosclerosis and predict future coronary risk, there is little role for monitoring progression of coronary artery calcification in order to assess the response to lipid lowering therapy. Computed tomography can be used reliably to predict graft patency in patients who have undergone coronary artery bypass grafting, and is an acceptable non-invasive alternative to invasive coronary angiography. Magnetic resonance imaging techniques can be employed in a feasible, timely and reproducible manner to detect plaque characteristics associated with acute atherothrombotic disease.
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O'Brien, John Tiernan. "Magnetic resonance imaging and hypothalmic-pituitary-adrenal axis function in depression and Alzheimer's disease." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308774.
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Sarvghad, Razavi Reza. "Magnetic resonance imaging guided cardiac catheterisation in children and adults with congenital heart disease." Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412416.
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Schwarz, Stefan Theodor. "Magnetic resonance imaging correlates of neuronal degeneration of brain stem nuclei in Parkinson's disease." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37023/.
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Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterised by a loss of pigmented dopaminergic neurons in the substantia nigra (SN) pars compacta and loss of pigmented noradrenergic neurons in the locus coeruleus (LC). Diagnosing PD can be challenging, especially in the early stages particularly when the typical movement disorder symptoms such as tremor, rigidity, bradykinesia and postural instability are not easily identifiable. Despite well-established PD clinical diagnostic criteria there is a misdiagnosis rate of up to 15% by neurology specialists and 25 % by general practitioners. The only approved diagnostic test to confirm suspected PD in a tremulous patient is dopamine transporter single photon emission tomography (DaTScanTM). This test is costly (£800 – 1500 in the UK) and has limited geographical availability in the UK. It involves exposure to ionising radiation and can only be used to assess the integrity of the dopaminergic system. Therefore there is a strong need for better and more accessible diagnostic tests for PD. The aim of this thesis is to investigate the sensitivity and specificity of three different MRI techniques as potential biomarkers of PD. MRI at 3T field strength was used in this thesis to demonstrate PD pathology in the pigmented brain stem nuclei of SN, LC and the ventral tegmental area (VTA). The objective was to develop new, easily accessible and affordable disease markers to help clinicians to establish the correct diagnosis early. A promising technique, which is based on the assessment of free motion of water-associated protons in tissue, is termed diffusion tensor imaging (DTI). The amount of free motion in all directions of protons in tissues like the brain can be described using mean diffusivity (MD) as a measure. Diffusion in tissues like the brain is often limited (“restricted”) in certain directions. For example diffusion across the myelin sheaths of nerve-fibres in the brain white matter is constrained, whereas along the direction of the nerve fibre protons can diffuse freely. This is termed anisotropic diffusion and can be described using fractional anisotropy as a measure (FA). Microstructural PD pathological processes may alter these measures of diffusivity especially in the area of the early affected brain region of the SN. In a prospective case control study of 30 patients and 22 controls diffusion tensor imaging alterations of the SN were investigated by measuring regional alterations of fractional FA and MD. In addition, a systematic literature review and meta-analysis was performed to determine the evidence for nigral DTI alterations throughout the literature. The case control study did demonstrate a small but significant increase of nigral MD; however the meta-analysis did not confirm this result when synthesizing effect sizes of nine identified relevant studies. No significant PD induced FA alterations were found in the prospective case control study. The meta-analysis of nigral FA changes did likewise not show significant FA decrease after correcting for studies with unusual high FA measures in the control arm population. In summary the meta-analysis and the results of the case control study did not confirm that standard DTI measurements of the SN are reliable biomarkers of PD pathology. In a further case-control study MRI sequences tracking the neuromelanin content of the pigmented brain stem nuclei like the SN, LC and the ventral tegmental area were investigated. PD induced decline of neurons in these nuclei causes depigmentation due to loss of neuromelanin content. In this study (including data from 24 PD patients and 20 controls) I found that only little neuromelanin related signal could be observed in the ventral tegmental area and there was no significant difference between patients with PD and controls. However, there were significant signal alterations of the SN and LC signal when comparing between the two groups. The neuromelanin related signal loss was most pronounced in the posterior SN even in the earlier stages of the disease. The signal loss in the anterior SN was less severe and correlated with the unified PD rating scale (UPDRS) and Hoehn and Yahr score as a measure of disease severity. The neuromelanin related signal reduction was significant but less extensive in the region of the LC when compared to the SN. The signal alterations in the LC did not correlate with the UPDRS or the Hoehn and Yahr score. In the third part of the experimental section of this thesis, a further prospective case-control study of 19 participants (10 patients with PD) and retrospective study of 105 clinical cases (9 patients with PD) was performed. A high resolution SWI/T2* ‘iron sensitive’ sequence was used to assess MRI changes of the nigrosome-1. Nigrosomes are little islands of dopaminergic cells with physiologically low iron content. The healthy hyperintense signal of the linear shaped nigrosome-1 surrounded by the iron containing low signal SN regions has great resemblance to the appearance of a swallow tail. The PD induced pathological signal reduction within nigrosome-1 resulted in a loss of the typical ‘swallow tail appearance’. Visual qualitative assessment of the MRI scans for absence and presence of nigrosome-1 revealed high sensitivity and specificity (80-100% and 86-89% respectively) to allow differentiation of PD from healthy controls and non-PD patients. In summary I found that standard nigral DTI is not reliable as a PD biomarker. Nigrosome and neuromelanin weighted MRI offers great potential for development into a clinically useful biomarker. Comparing the two techniques, nigrosome imaging has some advantages over neuromelanin weighted imaging: the high resolution SWI/T2* sequence is shorter (2-5 min versus 7-14 min neuromelanin MRI. However, further optimization of neuromelanin MRI sequences may be able to shorten the acquisition time. A further advantage of nigrosome MRI is that the images can be visually assessed for pathological alterations without the need for complicated analysis or data processing. A disadvantage of high resolution SWI/T2* is that it is more prone to artefacts. An advantage of neuromelanin weighted MRI is that changes especially in the anterior substantia nigra correlate to measures of disease severity like the UPDRS, although there is some early evidence from pilot studies that nigrosome imaging (at field strengths of 7T) may also be useful to assess disease severity related changes. Which of the two techniques is better suited to monitor longitudinal progressive PD related changes has to be assessed in future studies. In conclusion standard nigral DTI measures have no proven value as a reliable diagnostic marker of PD. High resolution T2*/SWI MRI and neuromelanin weighted MRI of PD induced alteration of pigmented brain stem neurons distinguish PD from non-PD and control subjects with high sensitivity and specificity. Neuromelanin related alterations especially of the anterior SN correlate to disease severity measures like the UPDRS and therefore have potential as disease progression marker. The easy applicability of the ‘swallow tail sign’ to indicate a healthy nigrosome-1 in the SN may well prove a useful marker to help the clinical diagnosis of PD. If future studies confirm a similar diagnostic accuracy as the current clinical gold standard DaTScanTM, nigrosome MRI may replace DaTScanTM in the standard clinical setting.
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Dahlqvist, Leinhard Olof. "Quantitative Magnetic Resonance in Diffuse Neurological and Liver Disease." Doctoral thesis, Linköping : Department of Medical and Health Sciences, Linköping University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54728.
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Hiscox, Lucy Victoria. "Early characterisation of neurodegeneration with high-resolution magnetic resonance elastography." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31198.
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This thesis contributes to recent interest within medical imaging regarding the development and clinical application of magnetic resonance elastography (MRE) to the human brain. MRE is a non-invasive phase-contrast MRI technique for measurement of brain mechanical properties in vivo, shown to reflect the composition and organisation of the complex tissue microstructure. MRE is a promising imaging biomarker for the early characterisation of neurodegeneration due to its exquisite sensitivity to variation among healthy and pathological tissue. Neurodegenerative diseases are debilitating conditions of the human nervous system for which there is currently no cure. Novel biomarkers are required to improve early detection, differential diagnosis and monitoring of disease progression, and could also ultimately improve our understanding of the pathophysiological mechanisms underlying degenerative processes. This thesis begins with a theoretical background of brain MRE and a description of the experimental considerations. A systematic review of the literature is then performed to summarise brain MRE quantitative measurements in healthy participants and to determine the success of MRE to characterise neurological disorders. This review further identified the most promising acquisition and analysis methods within the field. As such, subsequent visits to three brain MRE research centres, within the USA and Germany, enabled the acquisition of exemplar phantom and brain data to assist in discussions to refine an experimental protocol for installation at the Edinburgh Imaging Facility, QMRI (EIF-QMRI). Through collaborations with world-leading brain MRE centres, two high-resolution - yet fundamentally different - MRE pipelines were installed at the EIF-QMRI. Several optimisations were implemented to improve MRE image quality, while the clinical utility of MRE was enhanced by the novel development of a Graphical User Interface (GUI) for the optimised and automatic MRE-toanatomical coregistration and generation of MRE derived output measures. The first experimental study was performed in 6 young and 6 older healthy adults to compare the results from the two MRE pipelines to investigate test-retest agreement of the whole brain and a brain structure of interest: the hippocampal formation. The MRE protocol shown to possess superior reproducibility was subsequently applied in a second experimental study of 12 young and 12 older cognitively healthy adults. Results include finding that the MRE imaging procedure is very well tolerated across the recruited population. Novel findings include significantly softer brains in older adults both across the global cerebrum and in the majority of subcortical grey matter structures including the pallidum, putamen, caudate, and thalamus. Changes in tissue stiffness likely reflect an alteration to the strength in the composition of the tissue network. All MRE effects persist after correcting for brain structure volume suggesting changes in volume alone were not reflective of the detected MRE age differences. Interestingly, no age-related differences to tissue stiffness were found for the amygdala or hippocampus. As for brain viscosity, no group differences were detected for either the brain globally or subcortical structures, suggesting a preservation of the organisation of the tissue network in older age. The third experiment performed in this thesis finds a direct structure-function relationship in older adults between hippocampal viscosity and episodic memory as measured with verbal-paired recall. The source of this association was located to the left hippocampus, thus complementing previous literature suggesting unilateral hippocampal specialisation. Additionally, a more significant relationship was found between left hippocampal viscosity and memory after a new procedure was developed to remove voxels containing cerebrospinal fluid from the MRE analysis. Collectively, these results support the transition of brain MRE into a clinically useful neuroimaging modality that could, in particular, be used in the early characterisation of memory specific disorders such as amnestic Mild Cognitive Impairment and Alzheimer's disease.
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Weatherby, Stuart J. M. "Visual, magnetic resonance, and genetic studies of outcome in multiple sclerosis." Thesis, Keele University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368980.
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Sundareswaran, Kartik Sivaram. "Characterizing single ventricle hemodynamics using phase contrast magnetic resonance imaging." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31748.
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Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Yoganathan, Ajit; Committee Member: Fogel, Mark; Committee Member: Kanter, Kirk; Committee Member: Oshinski, John; Committee Member: Skrinjar, Oskar. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Koelemay, Mark Jan Wilhelm. "Non-invasive assessment of peripheral arterial occlusive disease." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/85398.
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Lavdas, Ioannis. "Magnetic resonance imaging techniques for visualising the development of Alzheimer's disease-like neurofibrillary tau pathology in animal models." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=203818.
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This thesis describes the development of magnetic resonance imaging (MRI) techniques to visualise neurofibrillary tau pathology in transgenic mice. Neurofibrillary pathology is a prominent pathological feature of Alzheimer's disease (AD) and is closely correlated to cognitive impairment and dementia. 19F and 1H MRI methods were developed with a 4.7 T preclinical system. To facilitate these experiments, RF saddle coils were designed and constructed that show good agreement with theoretical SNR calculations and produce uniform B1 fields. A copper wire surface coil, incorporating active decoupling electronics, was built to increase the sensitivity of 19F and 1H mouse brain experiments. A stripline transmission line resonator (TLR) was also developed as a surface coil receiver and because it does not need tuning and matching adjustments, it reduces experimental set up times significantly. An ultra-short echo time (UTE) pulse sequence was developed for imaging 19F compounds, designed to attach to sites of tau pathology in the brain and which were known to exhibit very short T2 relaxation times. Ex vivo, 19F MRI experiments using these compounds indicated low penetration of the blood brain barrier and a tendency for precipitation. An RF spoiled, short TE 3D gradient echo pulse sequence was optimised to produce artefact-free T1-weighted images of the mouse brain. Measurements from a preliminary study using high resolution, T1-weighted MRI showed that the ventricular areas of a control mouse were not appreciably different from those of a transgenic mouse. Software was developed to generate automated T2 brain maps from spin echo MRI data sets and was used to compare T2 relaxation times between a control and a transgenic mouse. This experiment showed that the T2 relaxation times of the tau transgenic mouse brain were prolonged when compared to those of a control mouse.
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Fent, Graham John. "Established and emerging cardiovascular magnetic resonance imaging techniques in the evaluation of subclinical cardiovascular disease." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/20627/.
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Introduction: Cardiovascular disease (CVD) remains the number one cause of mortality in the world for both men and women, thus improving its diagnosis and treatment is a priority. Rheumatoid Arthritis (RA) is a common auto-immune disease associated with high rates of CVD. Cardiovascular magnetic resonance (CMR) offers a multi-parametric, quantitative approach to the assessment of the heart and cardiovascular system with a host of techniques allowing assessment of anatomy, ventricular function, myocardial composition, myocardial perfusion, vascular performance and myocardial metabolism during a single scan. Its quantitative nature and lack of ionising radiation lend themselves ideally to the longitudinal study of subclinical CVD. Aims: To assess 1) whether blood longitudinal relaxation (T1) can be used to estimate blood haematocrit value to allow calculation of extracellular myocardial volume fraction (ECV), 2) whether CMR feature tracking (CMR-FT) is a feasible means of assessing aortic stiffness, 3) whether global longitudinal strain (GLS) is reduced in patients with prior MI with preserved left ventricular ejection fraction versus healthy controls, 4) whether aortic stiffness is present at all time points in the disease course of RA and 5) whether subclinical CV abnormalities in newly diagnosed RA improve with treatment and if the anti-tumour necrosis α Inhibitor Etanercept offers additional benefit over standard treatment. Methods: Patients were recruited between and February 2011 and February 2017. All patients underwent a comprehensive, multi-parametric CMR study including cine and late Gadolinium enhancement imaging at either 1.5 or 3.0T. Results: 1) estimation of blood haematocrit from blood T1 value provides accurate estimation of ‘synthetic’ ECV, 2) CMR-FT assessment of aortic stiffness is feasible and provides reproducible values for descending and ascending aortic strain values, 3) GLS is reduced in prior MI patients versus healthy controls (-17.3 ± 3.7% versus -19.3 ± 1.9% respectively, p=0.012). A GLS cut-off value of 18% correctly identifies prior MI with a sensitivity of 60% and specificity of 72.5%, 4) Aortic stiffness is evident in at risk RA individuals, newly diagnosed RA as well as established RA and 5) Aortic distensibility and left ventricular mass improve significantly in newly diagnosed RA patients following treatment. Etanercept appears to offer additional benefit over standard treatment evidenced by numerical improvements in aortic distensibility.
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Peel, Sarah. "Development of native and contrast enhanced magnetic resonance imaging for the characterization of cardiovascular disease." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/development-of-native-and-contrast-enhanced-magnetic-resonance-imaging-for-the-characterization-of-cardiovascular-disease(1fb7cc9e-8c5e-4c96-b3ae-ee7fc8ccf803).html.
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Late gadolinium enhancement (LGE) imaging is a widely used cardiovascular MRI technique. My work focused on developing new LGE MRI sequences to; identify plaque in the aortic vessel wall, to visualize areas of ventricular scar after myocardial infarction and pulmonary vein and atrial wall lesions after radiofrequency (RF) ablation for atrial fibrillation (AF). The double inversion recovery (DIR) sequence is traditionally used for vessel wall imaging. It however requires a Look Locker scan to choose the correct inversion time (TI) to achieve post-contrast blood suppression. The quadruple inversion recovery (QIR) sequence was later developed to suppress blood before and after contrast using identical imaging parameters. ECG-triggering was not required for the carotid arteries as there is adequate blood flow during the entire cardiac cycle to achieve sufficient blood exchange for blood suppression. I designed a new ECG-triggered QIR implementation for vessel wall imaging of the aorta which has variable flow during the cardiac cycle. I found it improved blood suppression, vessel wall sharpness and image quality scores compared to the un-triggered QIR implementation. The inversion recovery (IR) technique is the gold standard for imaging ventricular and atrial wall scar. It also requires a Look Locker scan to define the TI that suppresses normal myocardium in order to detect regions of scar. However, there is also often high IR blood signal that can hamper the detection of small sub-endocardial infarcts and scar size and transmurality measurements. I developed a novel dual-IR sequence that achieves suppression of normal myocardium and also reduces the blood signal. I found this improved blood suppression and inter-observer variability of scar size measurement and allowed imaging at an earlier time point compared to IR imaging for both ventricular and atrial wall scar. For ventricular scar, I also found improved expert confidence and inter-observer variability for transmurality assessment.