Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"Magnetic resonance spectroscopic imaging (MRSI)"”.
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Investigating brain metabolite levels in adolescents living with HIV using atlas-based magnetic resonance spectroscopic imaging (MRSI)
… studies are predominantly based on single voxel magnetic resonance spectroscopy (MRS) in younger children, with inconsistent findings. We aimed to develop atlas-based pipelines for analysing MRSI data to examine whether there are differences in brain metabolite levels between adolescents with …
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Fast magnetic resonance spectroscopic imaging using RF coil arrays
Conventional Magnetic Resonance Spectroscopic Imaging (MRSI) suffers from both low signal-to-noise (SNR), as well as long acquisition times. The development of high-fidelity gradient coils has opened opportunities for fast k-space encoding schemes that are already used in structural imaging. At the …
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Cerebral Metabolic and Neuropsychological Outcomes Following Mild Traumatic Brain Injury
… an injury. The current preliminary study used 3D magnetic resonance spectroscopic imaging (MRSI) and comprehensive neuropsychological assessment to determine if prolonged cerebral metabolic and cognitive alterations occur in individuals with persistent neurocognitive deficits following a mild TBI …
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Spectral estimation with spatio-spectral constraints for magnetic resonance spectroscopic imaging
Magnetic resonance spectroscopic imaging (MRSI) is a promising tool to acquire in vivo biochemical information, and spectral estimation (quantification) of MRSI data is an important step towards quantitative studies. Although a large body of work has been done on spectral estimation over the past …
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I. Persistent radicals for dynamic nuclear polarization : II. Synthesis of substituted indoles
… The narrow line radical applications in magnetic resonance spectroscopic imaging (MRSI) are investigated focusing on thermal mixing (TM) DNP of pyruvic acid. Design considerations and efforts toward the synthesis of bi- and multiradicals for Cross Effect (CE) DNP, and experiments …
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A machine learning based method for sensitivity estimation for accelerated magnetic resonance spectroscopy imaging using phased array coils
Magnetic resonance spectroscopic imaging (MRSI) enables in-vivo analysis of the spatial distribution of chemicals within the human body. Through MRSI, one can infer the concentration of various metabolites in different regions throughout the body. While the medical implications of such an imaging …
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Sequence-phase optimal (SPO) [d̳e̳l̳t̳a̳]B₀ field control for lipid suppression and homogeneity for brain magnetic resonance spectroscopic imaging
… and improve brain metabolite spectra in proton spectroscopic imaging. A rapidly reconfigurable 32-channel, local-multi-coil-shim-array is used to enhance lipid suppression and narrow metabolite linewidth in magnetic resonance spectroscopic imaging (MRSI) of the brain. The array is optimally …
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A subspace approach to spectral quantification for MR spectroscopic imaging
The problem of spectral quantification for magnetic resonance spectroscopic imaging (MRSI) is addressed in this thesis. We present a novel approach to solving this problem, incorporating both spatial and spectral prior information. More specifically, a new signal model is proposed which represents …
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Advancement of 31P Magnetic Resonance Spectroscopy Using GRAPPA Reconstruction on a 3D Volume
… is to improve currently available metabolic imaging techniques for clinical use in monitoring and predicting treatment response to radiation therapy in liver cancer. Liver metabolism correlates with inflammatory and neoplastic liver diseases, which alter the intracellular concentration of …
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Rank constrained denoising in magnetic resonance imaging
Noise is an important issue in magnetic resonance imaging (MRI), since the signal-to-noise ratio (SNR) is a major limiting factor for imaging speed and the achievable spatial resolution. This thesis investigates the utility of low-rank property in the denoising problem for the following two MRI …
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Development of Magnetic Resonance Spectroscopic Imaging Methods to Assess Tumour Metabolism
… nuclei such as 15N and 13C have been proposed as magnetic resonance spectroscopic imaging (MRSI) agents for investigating metabolism, perfusion and pH in tumours. However, the sensitivity of direct detection is limited by the low gyromagnetic ratios of these nuclei. Sensitivity can be increased by …
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Feasibility of selective multiple boosting in the planning of intracranial radiation therapy
… is more difficult. The limitations of functional imaging techniques are discussed in this context and resolution issues investigated for magnetic resonance spectroscopic imaging (MRSI). Interpolation experiments show that coarse resolutions are not a barrier to using data effectively for defining …
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Model-based reconstruction of magnetic resonance spectroscopic imaging
Magnetic resonance imaging (MRI) is a medical imaging technique that is used to obtain images of soft tissue throughout the body. Since its development in the 1970s, MRI has gained tremendous importance in clinical practice because it can produce high quality images of diagnostic value in an ever …
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Interrogating Cancer Metabolism using Novel Imaging Techniques
… can be interrogated using non-invasive metabolic imaging techniques, which enable the investigation of tumour metabolism in vivo and the identification of imaging biomarkers. Hyperpolarised 13C Magnetic Resonance Spectroscopic Imaging (MRSI) is a metabolic imaging technique that enables dynamic …
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Validation of magnetic resonance imaging (MRI) as a tool to detect inflammation in the brain
… MRI techniques included diffusion-weighted imaging (DWI), quantitative magnetization transfer (QMT), and magnetic resonance spectroscopic imaging (MRSI). EEGs were recorded at resting-state and during performance of an attention task. Vaccine administration induced an increase in fatigue and …
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A subspace approach to high-resolution magnetic resonance spectroscopic imaging
… profiles from the human body noninvasively, magnetic resonance spectroscopic imaging (MRSI) has been recognized as a powerful tool for in vivo metabolic studies. However, research and clinical applications of in vivo MRSI have been progressing more slowly than expected. The main reasons for …
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Further development of magnetic resonance spectroscopic imaging using subspace-based models
Magnetic resonance spectroscopic imaging (MRSI) is a powerful, non-invasive imaging modality capable of providing in vivo measurements of chemical distributions within an object. This makes it an ideal tool for metabolic studies in clinical and research settings; yet, despite more than four decades …
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Magnetic resonance spectroscopic imaging using parallel transmission at 7T
Conventional magnetic resonance spectroscopic imaging (MRSI), also known as phase-encoded (PE) chemical shift imaging (CSI), suffers from both low signal-to-noise ratio (SNR) of the brain metabolites, as well as inflexible tradeoffs between acquisition time and spatial resolution. In addition, …
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Towards high-resolution magnetic resonance spectroscopic imaging: spatiotemporal denoising and echo-time selection
Magnetic resonance spectroscopic imaging (MRSI) enables acquisition of spatial-spectral nuclear spin distributions. Compared to conventional MRI, the additional spectral information provides a powerful tool for in vivo study of biological tissues. However, considerable practical challenges, which …
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In-Vivo Three Dimensional Proton Hadamard Spectroscopic Imaging in the Human Brain
Magnetic resonance spectroscopic imaging (MRSI) is a useful tool for obtaining information on the biochemical processes underlying various pathologies. A widely used multi-voxel localization method is chemical shift imaging (CSI) which uses gradients for phase encoding. Although simple to …
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