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Dissertations / Theses on the topic 'Functional magnetic resonance imaging'
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Yoo, Seung-Schik 1970. "Adaptive functional magnetic resonance imaging." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/70893.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2000.Some research performed with the Harvard-M.I.T. Division of Health Sciences and Technology.
Includes bibliographical references (leaves 132-140).
Functional MRI (fMRI) detects the signal associated with neuronal activation, and has been widely used to map brain functions. Locations of neuronal activation are localized and distributed throughout the brain, however, conventional encoding methods based on k-space acquisition have limited spatial selectivity. To improve it, we propose an adaptive fMRI method using non-Fourier, spatially selective RF encoding. This method follows a strategy of zooming into the locations of activation by progressively eliminating the regions that do not show any apparent activation. In this thesis, the conceptual design and implementation of adaptive fMRI are pursued under the hypothesis that the method may provide a more efficient means to localize functional activities with increased spatial or temporal resolution. The difference between functional detection and mapping is defined, and the multi- resolution approach for functional detection is examined using theoretical models simulating variations in both in-plane and through-plane resolution. We justify the multi-resolution approach experimentally using BOLD CNR as a quantitative measure and compare results to those obtained using theoretical models. We conclude that there is an optimal spatial resolution to obtain maximum detection; when the resolution matches the size of the functional activation. We demonstrated on a conventional 1.5-Tesla system that RF encoding provides a simple means for monitoring irregularly distributed slices throughout the brain without encoding the whole volume. We also show the potential for increased signal-to-noise ratio with Hadamard encoding as well as reduction of the in-flow effect with unique design of excitation pulses.
(cont.) RF encoding was further applied in the implementation of real-time adaptive fMRI method, where we can zoom into the user-defined regions interactively. In order to do so, real-time pulse prescription and data processing capabilities were combined with RF encoding. Our specific implementation consisted of five scan stages tailored to identify the volume of interest, and to increase temporal resolution (from 7.2 to 3.2 seconds) and spatial resolution (from 10 mm to 2.5-mm slice thickness). We successfully demonstrated the principle of the multi- resolution adaptive fMRI method in volunteers performing simple sensorimotor paradigms for simultaneous activation of primary motor as well as cerebellar areas.
by Seung-Schik Yoo.
Ph.D.
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Gibson, Andrew Mark. "High speed functional magnetic resonance imaging." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252032.
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Wowk, Brian. "Artifact reduction in functional magnetic resonance imaging." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23677.pdf.
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Devlin, Hannah. "Physiological variability in functional magnetic resonance imaging." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496847.
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Clare, Stuart John. "Functional magnetic resonance imaging : methods and applications." Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/13223/.
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The technique of functional magnetic resonance imaging is rapidly moving from one of technical interest to wide clinical application. However, there are a number of questions regarding the method that need resolution. Some of these are investigated in this thesis. High resolutionf MRI is demonstrated at 3.0 T, using an interleaved echo planar imaging technique to keep image distortion low. The optimum echo time to use in fMRI experiments is investigated using a multiple gradient echo sequence to obtain six images, each with a different echo time, from a single free induction decay. The same data are used to construct T2* maps during functional stimulation. Various techniques for correcting the N/2 ghost are tested for use in fMRI experiments, and a method for removing the image artefact caused by external r. f. interference in a non-linearly sampled matrix is presented. The steps in the analysis of fMRI data are detailed, and two new non-directed analysis techniques, particularly for data from single events, as opposed to epoch based paradigms, are proposed. The theory behind software that has been written for fMRI data analysis is also given. Finally, some of the results from an fMRI study into the initiation of movement are presented, illustrating the power of single event experiments in the separation of cognitive processes.
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Alwatban, Adnan Z. W. "Clinical application of functional magnetic resonance imaging." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247576.
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Lowe, Andrew Sheridan. "Functional magnetic resonance imaging of neuropathic pain." Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419854.
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Liau, Joy. "Baseline effects in functional magnetic resonance imaging." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3330237.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed February 6, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 125-131).
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Miranda, João Pedro Ribeiro. "Functional studies on magnetic resonance." Master's thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/4941.
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Dissertation submitted in Faculdade de Ciências e Tecnologia of Universidade Nova de Lisboa for the degree of Master in Biomedical EngineeringBackground: Magnetic Resonance Imaging (MRI) is an imaging technique used primarily to produce high quality structural and functional images of the human body. Functional MRI techniques, among which are included the Arterial Spin Labeling (ASL) and the Blood Oxygenation Level-Dependent (BOLD), are used to measure brain activity. Several studies have shown that ASL holds several advantages when compared with BOLD, namely the fact of being more reproducible and perfusion quantitative. Purpose: The main aim of this work is to obtain perfusion quantification of the human brain within several of its territories and to compare the results obtained using two different ASL protocols. Secondarily this study aimed to validate an ASL protocol to be used in clinical exams – Protocol #2 by comparing the values obtained for all the regions considered with the ones present in literature. Methods: The methodology used in this study was applied to fifteen adult volunteers. Two ASL protocols were used in a single functional imaging session. Subjects were asked to perform a motor finger tapping task with their right hand while being scanned. Images were acquired on a 3 Tesla equipment – Magnetom Verio MRI System from SIEMENS in Hospital da Luz. For the definition of the regions to study the Talairach anatomical atlas was used and the brain was segmented considering five different segmentation levels. Results: Perfusion quantification studies have demonstrated that ASL allows a correct calculation of Cerebral Blood Flow (CBF), especially when compared to other studies which used other invasive perfusion measuring techniques. The perfusion values obtained for several regions considered are in agreement with the ones available in literature. Conclusions: ASL protocols are now becoming commercially available and have been demonstrating coherent results with other techniques already established. The current study presents one of the first detailed perfusion studies using this technique to evaluate several structures of the brain. The adequacy of Protocol 2 for functional studies was also proved considering the stimulus used.
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Björnfot, Cecilia. "Multiband functional magnetic resonance imaging (fMRI) for functional connectivity assessments." Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-149906.
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During resting state the brain exhibits synchronized activity within all major brain networks. Using blood oxygen level dependent (BOLD) resting state functional magnetic resonance imaging (fMRI) based detection it is possible to quantify the degree of correlation, connectivity, between regions of interest and assess information regarding the integrity of the inter-regional functional integration. A newly available multiband echo planar imaging (EPI) fMRI sequence allows for faster scan times which possibly allows us to better examine large-scale networks and increase the understanding of brain function/dysfunction. This thesis will assess how the newly developed sequence compares to a conventional EPI sequence for detecting resting state connectivity of canonical brain networks. The data acquisitions were made on a 3 Tesla scanner using a 32 channel head coil. The hypothesis was that the multiband sequence would produce a better result since it has faster sampling rate, thus more data points in its time-series to support the statistical analyses. Using Pearson’s linear correlation between the average time-series (approximately 12 minutes long) within a seed-region and all voxels contained in the image volume, correlation maps where created for each of the eight participants using data normalized to Montreal Neurological Institute (MNI) space. The resting state networks (RSN) were then found by performing a one sample T-test on group level. Six seed-coordinates, based on literature, where used revealing the the homotopic connections in anterior Hippocampus, Motor cortex, Dorsal attention, Visual and the Default mode network (DMN) as well for an anterior-posterior connection in the DMN. By comparing the maximum T-values within the regions for the RSN no systematic difference could be found between the multiband and conventional fMRI data. Further tests were conducted to evaluate if the sequences would differentiate in their results if the acquisition time was shortened, i.e shortening the time-series in the voxels. However no such difference could be established.Importantly, the results are specific to the 32 channel head coil used in the current study. Presumably recently available and improved coil designs could better exploit the multiband technique.
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Hotrakool, Wattanit. "Compressed sensing for functional magnetic resonance imaging data." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/15704/.
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This thesis addresses the possibility of applying the compressed sensing (CS) framework to Functional Magnetic Resonance Imaging (fMRI) acquisition. The fMRI is one of the non-invasive neuroimaging technique that allows the brain activity to be captured and analysed in a living body. One disadvantage of fMRI is the trade-off between the spatial and temporal resolution of the data. To keep the experiments within a reasonable length of time, the current acquisition technique sacrifices the spatial resolution in favour of the temporal resolution. It is possible to improve this trade-off using compressed sensing. The main contribution of this thesis is to propose a novel reconstruction method, named Referenced Compressed Sensing, which exploits the redundancy between a signal and a correlated reference by using their distance as an objective function. The compressed video sequences reconstructed using Referenced CS have at least 50% higher in terms of Peak Signal-to-Noise Ratio (PSNR) compared to state-of-the-art conventional reconstruction methods. This thesis also addresses two issues related to Referenced CS. Firstly, the relationship between the reference and the reconstruction performance is studied. To maintain the high-quality references, the Running Gaussian Average (RGA) reference estimator is proposed. The reconstructed results have at least 3dB better PSNR performance with the use of RGA references. Secondly, the Referenced CS with Least Squares is proposed. This study shows that by incorporating the correlated reference, it is possible to perform a linear reconstruction as opposed to the iterative reconstruction commonly used in CS. This approach gives at least 19% improvement in PSNR compared to the state of the art, while reduces the computation time by at most 1200 times. The proposed method is applied to the fMRI data. This study shows that, using the same amount of samples, the data reconstructed using Referenced CS has higher resolution than the conventional acquisition technique and has on average 50% higher PSNR than state-of-the-art reconstructions. Lastly, to enhance the feature of interest in the fMRI data, the baseline independent (BI) analysis is proposed. Using the BI analysis shows up to 25% improvement in the accuracy of the Referenced CS feature.
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Malhi, Gurjhinder Singh Psychiatry Faculty of Medicine UNSW. "Functional magnetic resonance imaging studies in bipolar disorder." Awarded by:University of New South Wales. Psychiatry, 2005. http://handle.unsw.edu.au/1959.4/23299.
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Aim To determine the neural correlates of Bipolar Disorder (BD) using functional Magnetic Resonance Imaging (fMRI) in different phases of the illness. Methods Five fMRI studies were conducted in adult female BD patients and healthy matched comparison subjects. The first two studies examined patients with bipolar depression and hypomania using captioned-pictures to characterize mood-state related patterns of activation. The subsequent three studies investigated BD euthymia using emotional words and faces to identify a potential trait-marker. Results During depression, bipolar patients demonstrated additional subcortical activation in the thalamus, amygdala, hypothalamus and medial globus pallidus. In hypomania, patients again had additional subcortical activation involving the caudate and the thalamus. In both studies patients had prefrontal cortex activation, but the pattern differed from that in healthy subjects. These studies suggested a pattern of mood-state related subcortical recruitment for emotional processing in BD. The next set of studies examined euthymic BD patients to partition trait and state-markers. The first study used implicit positive and negative word-associated affect and found diminished responses to positive and negative affective words as compared to healthy subjects in both cortical and subcortical brain regions, in particular the cingulate, thalamus and caudate. The second study used the emotional Stroop task to elicit implicit affective processing and euthymic patients had less cortical and subcortical activation in response to affect, in particular decreased left ventral prefrontal cortex (BA47) activation. The final study used explicit emotional processing of fear and disgust to examine affective responses, and showed that patients were generally less responsive to disgust, but had comparatively greater activations to fear. Conclusions BD patients have a likely deficit in the ventral prefrontal cortex that is evident in euthymia. Prefrontal cognitive appraisal of emotions is constrained in euthymic, depressed and hypomanic phases, reflected in subcortical changes that suggest additional processing. The likely cause for this is a functional prefrontal cortex deficit that results in compensatory changes in emotional processing systems. Treatment probably stabilizes these systems without normalizing them. Our studies demonstrate the benefits of examining BD in its different phases, and future studies should attempt to emulate this in medication-free patients.
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Stefanovic, Bojana. "Functional magnetic resonance imaging of cerebral blood volume." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85650.
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This dissertation describes a novel method for quantifying venous cerebral blood volume (CBVv) changes accompanying normal functional activation and employs quantitative functional magnetic resonance imaging (fMRI) methods to study the hemodynamic and metabolic changes accompanying neuronal inhibition. An in vivo occipital lobe relaxometry study was performed first to investigate the dependence of the spin-spin relaxation time constant of tissue, T2tissue , on the refocusing interval over the range of interest and thus test the basis of the proposed CBVv method. The small decrease of the apparent T2tissue with refocusing interval elongation is consistent with blood being the only significant source of refocusing interval dependence of apparent T2 in grey and white matter of the occipital lobe. In ensuing in vitro blood relaxometry studies, ensemble fitting of the entire set of T2blood estimates, obtained over an extensive range of blood oxygenation levels and refocusing intervals, was performed using both the fast chemical exchange model and the model of diffusion in weak magnetic field inhomogeneities. The results support the application of a diffusion model in describing the deoxyhemoglobin-induced enhancement in blood transverse relaxation rate at 1.5 T. Given the uniqueness of T2blood dependence on the refocusing rates over the range of interest, the novel CBVv method - venous refocusing for volume estimation (VERVE) - successfully isolates the blood signal by refocusing rate variation. A model of functional brain activation was developed and in vitro blood relaxometry data used to assess the effect of the intravascular spin-echo blood oxygenation level dependent (BOLD) contrast on the activation-induced VERVE signal change, allowing robust estimation of venous CBV changes. The method was demonstrated in a visual stimulation study of healthy young adults, where an average venous blood volume in the visual cortex increase was estimated
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Beckmann, Christian F. "Independent component analysis for functional magnetic resonance imaging." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404108.
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Butterworth, Stephen. "Functional magnetic resonance imaging studies in focal dystonia." Thesis, University of Leicester, 2004. http://hdl.handle.net/2381/29465.
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Dystonia is a movement disorder that manifests itself in many forms, from the relatively benign to the extremely severe. It is a disabling condition whose aetiology is unclear and whose treatments are largely unsatisfactory.;The purpose of the work presented in this thesis is to explore the pathophysiology of focal dystonia by utilising the relatively new and powerful tool of Functional Magnetic Resonance Imaging (fMRI). By understanding the benefits and limitations of this technique a number of different studies were designed to further explore the role of the brain in the genesis of this condition. It is hoped that from these investigations a greater understanding of the cortical activations associated with focal dystonia can be elucidated and further theories as to it pathogenesis proposed.;This thesis will be presented in seven chapters outlining the clinical condition of focal dystonia and its place amongst the larger group of dystonias. This includes a review of the current literature on dystonia pathophysiology. Following this the methods used in the investigations will be presented. In the following four chapters the four studies undertaken will be presented and discussed. Finally a summary of the thesis, its findings and limitations and ideas for future investigation will be presented.;In addition to the work presented in this thesis a number of other projects were undertaken in collaboration with others these will be referred to within the thesis, albeit in much less detail.
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Niranjan, A. "Functional magnetic resonance imaging of the mouse brain." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1543368/.
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Functional magnetic resonance imaging (fMRI) measuring a blood-oxygen-level dependent (BOLD) signal is the most commonly used neuroimaging tool to understand brain function in humans. As mouse models are one of the most commonly used neuroscience experimental models, and with the advent of transgenic mouse models of neurodegenerative pathologies, there has been an increasing push in recent years to apply fMRI techniques to the mouse brain. This thesis focuses on the development and implementation of mouse brain fMRI techniques, in particular to describe the mouse visual system. Multiple studies in the literature have noted several technical challenges in mouse fMRI. In this work I have developed methods which go some way to reducing the impact of these issues, and I record robust and reliable haemodynamic-driven signal responses to visual stimuli in mouse brain regions specific to visual processing. I then developed increasingly complex visual stimuli, approaching the level of complexity used in electrophysiology studies of the mouse visual system, despite the geometric and magnetic field constraints of using a 9.4T pre-clinical MRI scanner. I have also applied a novel technique for measuring high-temporal resolution BOLD responses in the mouse superior colliculus, and I used this data to improve statistical parametric mapping of mouse brain BOLD responses. I also describe the first application of dynamic causal modelling to mouse fMRI data, characterising effective connectivity in the mouse brain visual system. This thesis makes significant contributions to the reverse translation of fMRI to the mouse brain, closing the gap between invasive electrophysiological measurements in the mouse brain and non-invasive fMRI measurements in the human brain.
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Tang, Mei-yee. "Medical imaging : applications of functional magnetic resonance imaging and the development of a magnetic resonance compatible ultrasound system /." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36749710.
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Bannister, Peter R. "Motion correction for functional magnetic resonance images." Thesis, University of Oxford, 2004. http://ora.ox.ac.uk/objects/uuid:f01d9fcb-e8bc-44ae-99a5-cc3e0bc12956.
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This work addresses the distortions in Functional Magnetic Resonance Images (FMRI) caused by subject motion. FMRI is a non-invasive technique which shows great promise in providing researchers and clinicians with neurological information both about healthy subjects and clinical patients by mapping functional activation within the brain using Echo Planar Imaging (EPI). If reliable information is to be obtained from these images, motion correction must be carried out in order to remove or suppress the artefacts arising from subject movement. This work begins by using exploratory data techniques to describe these artefacts so that they can be characterised according to their origin and spatio-temporal manifestation. Based on testing of the accuracy and consistency of existing rigid-body motion correction methods on FMRI data, a new registration algorithm Motion Correction using the FMRIB Linear Image Registration Tool (MCFLIRT) has been developed. It is shown that while MCFLIRT is both more accurate and more robust than previous methods, rigid-body registration schemes in general cannot completely remove the distortions associated with motion and so subsequent analysis of the images may still be inaccurate. Furthermore, it is demonstrated that failure to use a sufficiently detailed model of subject motion in FMRI can in fact lead to degradation of the images through the use of existing motion correction algorithms. Based on these findings, alternative schemes including non-rigid registration and adaptive real-time methods are evaluated. Leading on from this investigation, a framework for Temporally-Integrated Geometric EPI Realignment (TIGER), incorporating both spatial and temporal information about the images, is proposed. An implementation based on this novel modality-specific model is developed and tested against existing rigid-body registration methods. Results show that this new approach is able to achieve significantly more accurate results than previous methods. The quality of correction provided by this new approach brings more subtle artefacts in the data to the fore, suggesting a number of avenues of further research in this area. These are outlined in the final chapter of the thesis.
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Matin, Tahreema Nihad Hashmi. "Functional lung assessment using hyperpolarised xenon gas magnetic resonance imaging." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:61e77bfb-67d9-4221-b246-4a5cd66b5144.
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Purpose Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality worldwide. The standard method for assessing lung function in COPD is spirometry, which provides global lung function information but is a poor predictor of disability and quality of life. The overall aim of this thesis is to develop utility of hyperpolarised xenon gas magnetic resonance imaging (HP 129Xe-MRI) as a technique to evaluate regional lung function. Methods Studies were approved by the National Research Ethics Service (NRES). Eleven volunteers and 25 patients with COPD underwent HP 129Xe-MRI, pulmonary function tests (PFTs) and quantitative computerised tomography (QCT). Gravitational-dependent gradients of HP 129Xe-MRI were compared between prone and supine postures in healthy volunteers. Lobar quantification of HP 129Xe-MRI was completed in COPD patients, who also underwent time-resolved HP 129Xe-MRI and HP 129Xe-MRI pre- and post-salbutamol to determine feasibility of detecting regional delayed ventilation and post-intervention change. The relationship between study measures was assessed using Pearson's correlation coefficient. Results HP 129Xe-MR ventilation gradients were more marked in the supine than prone posture in healthy volunteers, whereas diffusion-weighted gradients were more uniform. HP 129Xe-MRI was successfully quantified according to pulmonary lobes and correlated with lobar lung anatomy (QCT) and global functional transfer capability (TLCO) (r=-0.61, p<0.005). Delayed ventilation was observed with time-resolved breath-hold HP 129Xe-MRI. Differential regional ventilation change was detected with HP 129Xe-MRI post-salbutamol. Conclusion These data demonstrate technical optimisation of HP 129Xe-MRI in healthy volunteers and COPD patients. Successful generation of lobar HP 129Xe-MRI parameters offers an automated analysis method that can be adopted into the clinical workflow. Finally proof-of-principle data have identified roles for HP 129Xe-MRI in evaluating regional treatments and assessing therapeutic response. Future work will evaluate the role of HP 129Xe-MRI in patient selection for lung volume reduction therapy and as a surrogate end-point in drug development studies.
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Ng, Bernard. "Prior-informed multivariate models for functional magnetic resonance imaging." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37483.
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Neurological diseases constitute the leading disease burden worldwide. Existing symptom-based diagnostic methods are often insufficient to detect many of these diseases in their early stages. Recent advances in neuroimaging technologies have enabled non-invasive examination of the brain, which facilitates localization of disease-induced effects directly at the source. In particular, functional magnetic resonance imaging (fMRI) has become one of the dominant means for studying brain activity in healthy and diseased subjects. However, the low signal-to-noise ratio, the typical small sample size, and the large inter-subject variability present major challenges to fMRI analysis. Standard analysis approaches are largely univariate, which underutilize the available information in the data. In this thesis, we present novel strategies for activation detection, region of interest (ROI) characterization, functional connectivity analysis, and brain decoding that address many of the key challenges in fMRI research. Specifically, we propose: 1) new formulations for incorporating connectivity and group priors to better inform activation detection, 2) the use of invariant spatial features for capturing the often-neglected spatial information in ROI characterization, 3) an evolutionary group-wise approach for dealing with the high inter-subject variability in functional connectivity analysis, and 4) a generalized sparse regularization technique for handling ill-conditioned brain decoding problems. On both synthetic and real data, we showed that exploitation of prior information enables more sensitive activation detection, more refined ROI characterization, more robust functional connectivity analysis, and more accurate brain decoding over the current state-of-the-art. All of our results converged to the conclusion that integrating prior information is beneficial, and oftentimes, essential for tackling the challenges that fMRI research present.
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Chiarelli, Peter Anthony. "Investigation of neurovascular coupling using functional magnetic resonance imaging." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441081.
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Davis, Claude Ervin. "FUNCTIONAL MAGNETIC RESONANCE IMAGING STUDY OF PAIN AND EMOTION." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_diss/403.
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Neuroscience research has followed two fairly distinct paths in investigating central neural mechanisms of pain and emotion. Rarely have studies been conducted which intentionally combined painful and emotional stimulation while observing brain function. Theories of emotion and pain processing predict an interaction between pain and emotion such that emotional states may serve to both increase or decrease pain. This increase or decrease may also correspond to different effects on different dimensions of the overall pain experience as defined in pain neuromatrix theory. Theories of emotion begin with emotions as interpretations of bodily states, to more contemporary theories focusing on the functions of emotions. These emotion theories predict neuroanotomic relations between emotion and pain in the brain. Similarly neuromatrix theory predicts an affective dimension of pain experience, which has been defined in terms of pain unpleasantness and secondary affect, emphasizing the role of emotion in pain experience. To further explore the relationship between pain and emotion, in the present study, painful heat stimulation is applied to the face while simultaneously conducting whole brain imaging using functional magnetic resonance imaging (fMRI). Also personal episodes involving anger, fear, and neutral emotion are recalled during fMRI both with, and without, painful heat stimulation. Similar brain regions are involved in processing pain, anger, and fear, and these responses compare favorably with those in the literature. The results also demonstrate that simultaneous emotional episode recall modulates the patterns of brain activity involved in pain. Anger recall especially seems to increase pain-related activity. The study allows greater understanding about the way that the brain's emotional processing networks for fear and anger affect pain experience and how pain affects the emotional processing network to produce affective experience, such as fear and anger, related to pain. Further application of these procedures to patients with chronic pain can aid understanding of central pathological mechanisms involved.
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Maas, Luis C. (Luis Carlos). "Processing strategies for functional magnetic resonance imaging data sets." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/85262.
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Thesis (Ph.D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 1999.Includes bibliographical references (leaves 108-118).
by Luis Carlos Maas, III.
Ph.D.
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Delzell, Darcie Ann Pace. "Optimal statistical design for functional magnetic resonance imaging experiments." Ann Arbor, Mich. : ProQuest, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3336813.
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Thesis (Ph.D. in Statistical Science)--S.M.U.Title from PDF title page (viewed Mar. 16, 2009). Source: Dissertation Abstracts International, Volume: 69-12, Section: B, page: . Adviser: Richard F. Gunst. Includes bibliographical references.
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Allen, Douglas Gregory. "Functional magnetic resonance imaging of the cerebellum in autism /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9981974.
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Matthes, Jessica Marie Williams J. Michael. "Auditory localization as revealed by functional magnetic resonance imaging /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/356.
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Xing, Kai, and 邢锴. "Functional magnetic resonance imaging (fMRI) of rodent visual and auditory system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47849939.
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Functional MRI or Functional Magnetic Resonance Imaging (fMRI) is a type of specialized MRI scan which measures the hemodynamic response related to neural activity in the brain or spinal cord of humans and animals. Due to its relatively low invasiveness, absence of radiation exposure, and relatively wide availability, functional MRI has come to dominate the brain mapping field since the early 1990s. The objective of this thesis work is to develop and apply functional MRI methods at 7 Tesla, for in vivo investigation of rodent visual and auditory system. Firstly, the development of the rat visual pathway was studied by blood oxygenation level–dependent (BOLD) contrast from the time of eyelid opening (P14) to adulthood (P60) in normal rat brain. By studying BOLD-fMRI measurements in the normal brain superior colliculus (SC), we determined that the regional BOLD response undergoes a systematic increase in amplitude especially over the third postnatal week.
Secondly, the potential for plasticity of the rodent superior colliculus (SC) was studied using BOLD fMRI. By studying BOLD-fMRI measurements in the SC of three groups of rats (normal, HI-injured with left SC partially damaged and HI-injured with left SC completely damaged), we can evaluate the extent of plastic changes, compensatory and transneuronal plasticity after varying degrees of SC injury. We also applied BOLD-fMRI using very short repetition time (TR) of 0.2s on rats to measure the difference in response temporal dynamics between the SC and LGN, which has not been measured conclusively or with high temporal resolution. The primary finding in this study is that there is an approximately 0.8s difference between the BOLD responses of the rat contralateral SC and LGN to the visual stimuli. In addition, the amplitude of the SC response is larger than that of the LGN. Thirdly, BOLD-fMRI is used to measure the SC hemodynamic responses, in normal adult Sprague-Dawley (SD) rats, during a dynamic visual stimulus similar to those used in long-range apparent motion studies. The stimulation paradigm mimic effective speeds of motion between 7 and 164?/s, the results suggest that the SC is sensitive to slow moving visual stimuli but the hemodynamic response is reduced at higher speeds.
Finally, BOLD-fMRI is used to study hemodynamic response temporal dynamics in the superior colliculus (SC) and inferior colliculus (IC) following visual and auditory associated stimulation. Our results show the baselines of SC BOLD signal (in two sides) increase during the ON period of auditory stimulation, which demonstrate that auditory stimulation can increase ROI activation signal intensity in superior colliculus (SC). The previous dominant theory is that individual senses each have separate areas of the brain dedicated to processing each sense, while the individual sense perceptions are integrated together to produce a multi-sensory experience. As a result of new research over the past several years, however, this view has been challenged by studies showing that processing in the visual area of the brain can be directly influenced by hearing and touch. All these discoveries represent a new view of how the brain is actually organized.published_or_final_version
Electrical and Electronic Engineering
Master
Master of Philosophy
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吳文卓 and Man-cheuk Ng. "Functional magnetic resonance imaging (FMRI) of brain and cervical spinal cord." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557777.
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Cayetano, Kenroy (Kenroy Richard) 1977. "Analysis of surface coils using Green Functions for functional magnetic resonance imaging." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86644.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (leaves 47-48).
by Kenroy Cayetano.
M.Eng.
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Elliott, Michael Ramsay. "New approaches in functional brain imaging." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299581.
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Fransson, Peter. "Analysis and development of strategies for magnetic resonance functional neuroimaging /." Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3365-0/.
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Cheung, Man-hin Matthrew, and 張文騫. "Development of diffusion and functional magnetic resonance imaging techniques for neuroscience." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47147635.
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Döhnel, Katrin. "Functional Magnetic Resonance Imaging (fMRI) of Intention-Based Emotion Attribution." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-125913.
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Rose, Emma Jane. "Working memory in depression : a functional magnetic resonance imaging study." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/25133.
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Both resting state and activation studies of patients with major depressive disorder (MDD) have identified functional impairments in regions of cortex commonly associated with normal working memory function in healthy adults. However, attempts to determine whether or not depressed individuals are in fact impaired on tasks reliant on working memory have produced contradictory results. The main aims of this series of investigations were to determine (1) whether individuals with a diagnosis of major depression were significantly impaired on a working memory task (i.e. the N-back task), compared to control participants, and (2) whether any behavioural difference between the experimental groups was associated with a significant group difference in cortical activation during performance of the task (i.e. using blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI)). Given that the prescription of anti-depressant medication in the patient group was a potential confounder of any significant observations, additional aims of the study were to (3) determine the impact of anti-depressant medication on performance on the N-back task, and (4) determine the effect of anti-depressants upon the pattern of cortical activation observed during performance on the task. In order to address these aims three experimental studies were conducted. Overall, the results of this investigation are indicative of a significant dysfunction of working memory in individuals with major depression. Furthermore, it would appear that this observed dysfunction is associated with a significant quantitative difference in the level of functional activation in a number of regions of cortex, which have been previously purported to support working memory function in normal, healthy adults. Moreover, the outcomes in experiment three allow us to speculate that the differences, both behavioural and functional, noted between patients and controls are the result of a factor in the aetiology of depressive illness rather than an effect of anti-depressant medication per se.
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Lin, Qihua. "Bayesian hierarchial spatiotemporal modeling of functional magnetic resonance imaging data." Ann Arbor, Mich. : ProQuest, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3245023.
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Thesis (Ph.D. in Statistical Science)--S.M.U., 2007.Title from PDF title page (viewed Mar. 18, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: B, page: 7154. Adviser: Richard F. Gunst. Includes bibliographical references.
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Bethel, Susannah. "Functional magnetic resonance imaging of recovery from post-stroke aphasia." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/12635/.
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This thesis presents the design, development and application of a novel overt picture-naming paradigm through a series of exploratory behavioural and imaging experiments. The paradigm is subsequently used in a functional magnetic resonance imaging study of recovery from post-stroke aphasia. The possibility of comparing correct and error naming responses in aphasic patients and unimpaired subjects induced to make errors was investigated and successfully trialled. This research improves on techniques currently favoured in imaging studies to explore the processes involved in functional recovery in a more analytical way. The novel study design provides a new way to interrogate processing involved in the production of aphasic responses. The intentions of this project were to drive the research field of post-stroke aphasia recovery forward by suggesting and applying new methods of using functional imaging to investigate the current pertinent research questions. In addition to this, it was aimed that data collected from participants who have an aphasic deficit, and those with a healthy language system, would be analysed to provide evidence of how a stroke damaged brain may recover functional language. It was hypothesised that results from aphasic patients would show that successful language performance is associated with cortical activation of the patients' normal left hemispheric language areas, around their lesion site. Conversely, the hypotheses state that production of linguistic errors would correlate with an increase in activation in areas of the right hemisphere homologous to the left lateralised fronto-temporal language production network. It was thought that further investigation of successful and unsuccessful language performance in unimpaired speakers would echo this finding. The current debate in this research field centres on the role of the undamaged hemisphere in successful recovery. Five chronic stage aphasics were tested using the developed continuous scanning, event-related paradigm and their correct and error naming trials were compared. Results indicate that recruitment of cortical areas homologous to the stroke lesion can support successful language processing. This is contrary to the theory that disinhibition of non-dominant language areas may contribute to the production of aphasic errors. An investigation of forced errors in unimpaired speakers was also conducted to provide comparisons with the aphasic patient group. Imaging results showed that the naming-to-deadline paradigm used may provide a useful baseline for the normal processes involved in the monitoring and control of task performance.
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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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Alhussain, Amer Qassim Mallah. "Development of a touch stimulator for functional magnetic-resonance imaging." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14053.
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A tactile display system has been built with 25 contactors in a 5 × 5 array with 2mm spacing, designed to stimulate the fingertip. The drive mechanism for each contactor is a piezoelectric bimorph, allowing the display to use in functional magnetic resonance imaging experiments (fMRI). The amplitude and frequency of stimulation can be pre-set, and each contactor can be activated separately using a personal computer. The tactile produce a wide variety of time-varying spatial patterns of touch stimulation. The sensation is “natural” and the participants do not find the experience unpleasant. The psychophysics experiment and the first fMRI experiment involved identification of various patterns on the display: the tactile stimulus was stationary or moved in a circle or in a “random” trajectory with no obvious shape. Response was by push buttons. The second fMRI experiment focused on the relationship between the speed of tactile motion and the corresponding activation in the brain, using stimuli moving in a circular trajectory on the tactile display at various speeds in the range 2.9 to 77.9 mm s –1. In the psychophysics experiment, the mean identification score was 80% after only a few minutes’ practice. The results of the first fMRI experiment showed highly significant activations in primary and secondary somatosensory cortices for contrasts of circle or random stimuli with the rest condition; low significant activations in SI and SII were observed for the contrast of stationary stimuli with rest. Broca's area was found to be activated for circle and random stimulation but not for stationary stimulation. Results from the second fMRI experiment showed small speed-sensitive activations in the left side of the brain, mostly in the primary somatosensory cortex. The conclusion in present study was our tactile system can produce different types of tactile patterns and it works inside MRI scanner.
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Bernheim, Kyle Alan Fraser Scott E. "Functional and structural magnetic resonance imaging of humans and macaques /." Diss., Pasadena, Calif. : California Institute of Technology, 2004. http://resolver.caltech.edu/CaltechETD:etd-05192004-153312.
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Vogt, Keith M. "Optimization of physiologic noise correction in functional magnetic resonance imaging." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1243544877.
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De, Ridder Michael. "An Uncertainty Visual Analytics Framework for Functional Magnetic Resonance Imaging." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18750.
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Improving understanding of the human brain is one of the leading pursuits of modern scientific research. Functional magnetic resonance imaging (fMRI) is a foundational technique for advanced analysis and exploration of the human brain. The modality scans the brain in a series of temporal frames which provide an indication of the brain activity either at rest or during a task. The images can be used to study the workings of the brain, leading to the development of an understanding of healthy brain function, as well as characterising diseases such as schizophrenia and bipolar disorder. Extracting meaning from fMRI relies on an analysis pipeline which can be broadly categorised into three phases: (i) data acquisition and image processing; (ii) image analysis; and (iii) visualisation and human interpretation. The modality and analysis pipeline, however, are hampered by a range of uncertainties which can greatly impact the study of the brain function. Each phase contains a set of required and optional steps, containing inherent limitations and complex parameter selection. These aspects lead to the uncertainty that impacts the outcome of studies. Moreover, the uncertainties that arise early in the pipeline, are compounded by decisions and limitations further along in the process. While a large amount of research has been undertaken to examine the limitations and variable parameter selection, statistical approaches designed to address the uncertainty have not managed to mitigate the issues. Visual analytics, meanwhile, is a research domain which seeks to combine advanced visual interfaces with specialised interaction and automated statistical processing designed to exploit human expertise and understanding. Uncertainty visual analytics (UVA) tools, which aim to minimise and mitigate uncertainties, have been proposed for a variety of data, including astronomical, financial, weather and crime. Importantly, UVA approaches have also seen success in medical imaging and analysis. However, there are many challenges surrounding the application of UVA to each research domain. Principally, these involve understanding what the uncertainties are and the possible effects so they may be connected to visualisation and interaction approaches. With fMRI, the breadth of uncertainty arising in multiple stages along the pipeline and the compound effects, make it challenging to propose UVAs which meaningfully integrate into pipeline. In this thesis, we seek to address this challenge by proposing a unified UVA framework for fMRI. To do so, we first examine the state-of-the-art landscape of fMRI uncertainties, including the compound effects, and explore how they are currently addressed. This forms the basis of a field we term fMRI-UVA. We then present our overall framework, which is designed to meet the requirements of fMRI visual analysis, while also providing an indication and understanding of the effects of uncertainties on the data. Our framework consists of components designed for the spatial, temporal and processed imaging data. Alongside the framework, we propose two visual extensions which can be used as standalone UVA applications or be integrated into the framework. Finally, we describe a conceptual algorithmic approach which incorporates more data into an existing measure used in the fMRI analysis pipeline.
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Moosmann, Matthias Walter. "Characterization of human background rhythms with functional magnetic resonance imaging." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2007. http://dx.doi.org/10.18452/15593.
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Diese Dissertation zeigt, dass Hintergrundrhythmen mit Hilfe der gleichzeitigen Messung von EEG und fMRI Signalen untersucht werden können. Die Methodik dieses Ansatzes wurde durch den Einsatz einer speziellen fMRI Sequenz weiterentwickelt, und die Signalqualität durch visuell evozierte Potentiale überprüft. Der prominente okzipitale Alpha-Rhythmus und die vergleichsweise schwächeren rolandischen Rhythmen konnten in der elektromagnetisch störenden Umgebung des Magnetresonanztomografen, auch und gerade während der funktionellen Messsequenzen identifiziert werden. Durch den Einsatz der in dieser Arbeit vorgestellten Nachverarbeitungsmethoden kann die simultane Aufnahme von EEG und fMRI Signalen wertvolle Informationen über die neuronale Grundlage von Hirnrhythmen und ihrer hemodynamischer Korrelate liefern. Die hier vorgestellten Daten bekräftigen die Hypothese, dass die Amplitude der Hintergrundrhythmen mit spezifischen Deaktivierungen in sensorischen Hirnarealen einhergehen. Eine erhöhte Amplitude aller untersuchter Rhythmen war mit einem negativen BOLD Signal in sensorischen kortikalen Arealen verknüpft, was auf einen erniedrigten Energieverbrauch in Arealen mit höherer Synchronizität schliessen lässt. Der posteriore Alpha Rhythmus, ist invers mit dem hemodynamischen Signal in primären visuellen Arealen gekoppelt, während hämodynamische Korrelate der rolandischen Alpha und Beta Rhythmen in somatomotorischen Arealen lokalisiert wurden. Für den rolandischen Alpha und Beta Rhythmus wurden unterschiedliche regionale Netzwerke gefunden. Der rolandische Beta Rhythmus ist mit dem Motornetzwerk, während der rolandische Alpha Rhythmus mit einen somatosensorischen bzw. Assoziationsnetzwerk assoziert ist, was eine fundamentale Eigenschaft des Somatomotorischen Systems zu sein scheint. Die rolandischen Rhythmen könnten dadurch somatomotorische Areale während der Erhaltung oder Planung von Bewegungsabläufen funktional koppeln [Brovelli, et al., 2004]. Desweiteren wurde gezeigt, dass thalamische und cinguläre Strukturen mögliche Generatoren oder Modulatoren der hier untersuchten Hintergrundrhythmen sind. Die experimentellen Daten der hier vorgestellten Studien legen nahe, dass eine inverse Beziehung der Stärke eines Hintergrundrhythmus mit regional kortikalem Metabolismus und gleichzeitig eine „antagonistische“, positive Beziehung mit thalamischen oder cingulären Struktuen ein gernerelles orgnaisatorisches Prinzip des Gehirns zu sein scheint. Der Begriff der Grundaktivität des Gehirns [Gusnard, et al., 2001] müsste daher in verschiedene Netzwerke der Grundaktivität unterteilt werden, die elektrophysiologisch durch Hintergrundrhythmen definiert wären.The data provided by this thesis show that imaging of brain rhythms can be achieved by simultaneous EEG-fMRI recordings. This methodology was developed further by implementing an adapted MR sequence and the EEG-fMRI signal quality was confirmed by means of visual evoked potentials. Together with the post processing methods applied in this work, simultaneous EEG-fMRI recordings can thus provide valuable information about the neuronal basis of brain rhythms and their regional hemodynamic correlates. The data further substantiate the hypothesis that ‘idling’ rhythms indicate distinct deactivated sensory cortical areas. Increased power of all examined rhythms was associated with negative BOLD signal in sensory cortical areas, indicating less energy consumption in those areas with higher synchronicity. The posterior alpha or so-called Berger rhythm is coupled inversely to the hemodynamics in primary visual areas, whereas rolandic alpha and beta rhythm could be localized to somatomotor areas. Different networks were found for rolandic alpha and beta rhythms. The rolandic beta rhythm is more associated with a motor-network whereas the rolandic alpha rhythm is more associated with a sensory and association network which represents a fundamental characteristic of the sensorimotor system. The rolandic oscillations may bind sensorimotor areas into a functional loop during pre-movement motor maintenance behaviour [Brovelli, et al., 2004]. Furthermore thalamic and cingulate structures were shown to be possible generative or modulatory structures for the brain rhythms examined in this study. The experimental data obtained in this work suggest that the inverse correlation of an ‘idling’ rhythm’s strength with the metabolism in ‘its cortical areas’, and the positive correlation with cingulate or thalamic areas are both general organizational principles. The notion of a default mode of the brain [Gusnard, et al., 2001] may perhaps be further subdivided into different networks with a “default mode”, each of them electro-physiologically defined by its “idle rhythm”.
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Tang, Mei-yee, and 鄧美宜. "Medical imaging: applications of functional magnetic resonance imaging and the development of a magnetic resonancecompatible ultrasound system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37897688.
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Shin, Jaemin. "Characterization and compensation of physiological fluctuations in functional magnetic resonance imaging." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44862.
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Functional magnetic resonance imaging (fMRI) based on blood oxygenation level dependent (BOLD) contrast has become a widespread technique in brain research. The central challenge in fMRI is the detection of relatively small activity-induced signal changes in the presence of various other signal fluctuations. Physiological fluctuations due to respiration and cardiac pulsation are dominant sources of confounding variability in BOLD fMRI. This dissertation seeks to characterize and compensate for non-neural physiological fluctuations in fMRI.
First, the dissertation presents an improved and generalized technique for correcting T1 effect in cardiac-gated fMRI data incorporating flip angle estimated from fMRI dataset itself. Using an unscented Kalman filter, spatial maps of flip angle and T1 relaxation are estimated simultaneously from the cardiac-gated time series. Accounting for spatial variation in flip angle, the new method is able to remove the T1 effects robustly, in the presence of significant B1 inhomogeneity. The technique is demonstrated with simulations and experimental data. Secondly, this dissertation describes a generalized retrospective technique to precisely model and remove physiological fluctuations from fMRI signal: Physiological Impulse Response Function Estimation and Correction (PIRFECT).
It is found that the modeled long-term physiological fluctuations explained significant variance in grey matter, even after removing short-term physiological effects. Finally, application of the proposed technique is observed to substantially increase the intra-session reproducibility of resting-state networks.
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Yuen, Sung-lai, and 袁崇禮. "Plasticity of human brain networks as revealed by functional magnetic resonance imaging." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38837602.
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The best for PhD thesis in the Faculties of Arts, Architecture, Business & Economics, Education, Law and Social Sciences (Universityof Hong Kong), Li Ka Shing prize, 2006-2007published_or_final_version
abstract
Psychology
Doctoral
Doctor of Philosophy
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Placidi, Elisa. "Magnetic resonance imaging of colonic function." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/13886/.
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The overall aim of this work was to develop MRI methods and techniques to study the physiology and the pathology of the gastrointestinal tract, with particular attention to the colon. Besides, the development of new methods was aimed in order to perform quantitative analysis using proton and fluorine MRI. In particular the first experimental chapter describes the development and the optimisation of imaging protocols for studying colonic function in undisturbed physiologically relevant conditions. In addition a texture analysis method based on Gabor filters is developed and used for the objective assessment of colonic content characteristics. The mechanisms of action of common anti-diarrhoeal and anti-constipation agents are also investigated. The last experimental chapter describes the development of methods for using markers to measure GI transit. Transit time, i.e. the time it takes for a marker to pass through the entire gut, is often affected by functional gastrointestinal disorders, therefore it is of primary importance to develop a non-invasive and effective technique for the diagnosis of such gastrointestinal diseases. The use of fluorinated agents and its many advantages compared to other techniques is outlined and the first in vivo studies at high field are presented. The use of gadolinium based compounds as an additional marker is also discussed.
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Robson, Philip Martyn. "Magnetic resonance imaging of filter function." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613956.
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Bestmann, Sven. "Physiological characterisation of transcranial magnetic stimulation (TMS) using functional magnetic resonance imaging (fMRI)." Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446494/.
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Despite its widespread use, a striking lack of knowledge exists regarding the mechanism of action of transcranial magnetic stimulation (TMS). This thesis describes the physiological characterisation of repetitive TMS (rTMS) to the motor system by means of functional magnetic resonance imaging (fMRI). A detailed analysis of imaging artefacts arising from the simultaneous application of TMS-fMRI was conducted and subsequently, strategies were presented for unperturbed TMS-fMRI. Physiological responses during subthreshold high-frequency rTMS of the primary sensorimotor cortex (Ml/Sl) were visualised within distinct cortical motor regions, comprising PMd, SMA, and contralateral Ml/Sl, while no significant responses were evidenced in the area of stimulation. Repetitive TMS during or before motor behaviour illustrated the context- dependence of rTMS-induced activity changes. The first demonstration of TMS-fMRI at 3 Tesla provided evidence that subthreshold rTMS can activate distinct networks including subcortical motor regions. The subthreshold nature of rTMS was confirmed by simultaneous electromyographic recordings from the target muscle. Stimulation of the dorsal premotor cortex provided evidence that rTMS- evoked local activity changes depend on the input function. The capability of TMS to target distinct networks in the human brain was confirmed. TMS targets a set of cortical and subcortical structures. Local responses may not invariably be elicited, indicating that low levels of synaptic activity, as occurring at low-intensity stimulation, do not necessarily evoke corresponding changes in cortical haemodynamics. It is concluded that combined TMS-fMRI offers a means to assess the mechanism of action of TMS at high spatial and temporal resolution.
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Tivarus, Madalina E. "Functional magnetic resonance imaging of language processing and its pharmacological modulation." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1138118630.
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Friman, Ola. "Adaptive analysis of functional MRI data /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/tek836s.pdf.
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