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 38 for “"MRSI"”.
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¹H-MRSI at 7T using spectral-selective binomial excitation and adiabatic refocusing
Magnetic resonance spectroscopic imaging (MRSI) is a multiscale imaging modality that can noninvasively map metabolic changes in vivo. These metabolite maps have broad potential in clinical and preclinical applications, such as tumor detection and grading, and the study of metabolic alterations in …
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Investigating brain metabolite levels in adolescents living with HIV using atlas-based magnetic resonance spectroscopic imaging (MRSI)
… to develop atlas-based pipelines for analysing MRSI data to examine whether there are differences in brain metabolite levels between adolescents with PHIV and uninfected controls. The study participants were 165 adolescents, of whom 86 were adolescents living with HIV from the CHER trial and 79 …
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A subspace approach to high-resolution magnetic resonance spectroscopic imaging
… 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 this situation are the problems of long …
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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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Accelerated J-resolved proton magnetic resonance spectroscopic imaging
1H-MRSI has long been recognized as a powerful tool for noninvasive mapping of metabolites and neurotransmitters. A fundamental challenge of conventional 1H-MRSI is that resonances from different molecules overlap with one another in the crowded chemical shift frequency spectrum, which will lead to …
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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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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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Model-based reconstruction of magnetic resonance spectroscopic imaging
… called magnetic resonance spectroscopic imaging (MRSI). MRSI captures not only the relative intensities of metabolite signals at each voxel, but also their spatial distributions. While MRSI has been proven to be clinically useful, it suffers from fundamental tradeoffs due to the inherently low …
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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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Advancement of 31P Magnetic Resonance Spectroscopy Using GRAPPA Reconstruction on a 3D Volume
… by Magnetic Resonance Spectroscopic Imaging (MRSI) [1,2], can help in diagnosis and follow-up of various liver diseases. Specifically, there appears to be an immediate need of this technology for both the assessment of tumor response in patients with Hepatocellular Carcinoma (HCC) treated with …
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Rank constrained denoising in magnetic resonance imaging
… and magnetic resonance spectroscopic imaging (MRSI). For denoising magnitude diffusion weighted image series, we utilize both low-rank and edge constraints within a maximum a posteriori (MAP) framework. We propose a fast novel majorize-minimize (MM) algorithm to solve the resulting optimization …
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Fast magnetic resonance spectroscopic imaging using RF coil arrays
… 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 same …
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Sequence-phase optimal (SPO) [d̳e̳l̳t̳a̳]B₀ field control for lipid suppression and homogeneity for brain magnetic resonance spectroscopic imaging
… in magnetic resonance spectroscopic imaging (MRSI) of the brain. The array is optimally reconfigured dynamically during each MRSI repetition period, first during the lipid-suppression phase, by widening the spectral gap between spatially separate lipid and metabolite regions, and then to …
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A subspace approach to spectral quantification for MR spectroscopic imaging
… 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 the spectral variations of each …
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Simultaneous multislice spiral and EPI chemical shift imaging
… of 3D slabs used for MR Spectroscopy Imaging (MRSI) include long dead times in each TR. This dead time is necessary for magnetization moments' longitudinal relaxation, and so a good SNR efficiency. The fact that SNR is one of the dominant challenges that MRSI faces makes it an expensive …
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Magnetic resonance spectroscopic imaging with 2D spectroscopy for the detection of brain metabolites
… metabolites using MR spectroscopic imaging (MRSI). Existing techniques for improved detection include so-called 2D spectroscopy, where additional encoding steps aid in the separation of compounds with overlapping chemical shift. This is achieved by collecting spectral data over a range of …
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Development of Magnetic Resonance Spectroscopic Imaging Methods to Assess Tumour Metabolism
… 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 transferring the hyperpolarization to …
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Dynamic Strength Index and Countermovement Jump Performance in Female and Male Collegiate Basketball Athletes Across a Competitive Season
… height (JH), reactive strength index modified (mRSI), countermovement depth (CMD), and relative propulsive net impulse (RPNI)), and lower extremity kinematics (hip, knee, ankle) across four timepoints in a competitive basketball season among female and male collegiate athletes. Methods: Twelve …
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Validation of magnetic resonance imaging (MRI) as a tool to detect inflammation in the brain
… 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 pro-inflammatory marker interleukin (IL)-6, and a decrease in systolic blood pressure, relative to …
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Weiterführende Techniken in der Spektroskopischen Bildgebung in vivo durch heteronuklearen Polarisationstransfer und anatomie-basierte Spektrenquantifizierung
… Messbereichs der spektroskopischen Bildgebung (MRSI) des menschlichen Gehirn die Datennachverarbeitung in der In-vivo-1H- und -31P-NMR-Spektroskopie verbessert. Es wurden Korrekturen der MRSI-Daten eingeführt, die die Varianz der Messwerte beim interpersonellen Vergleich signifikant verringern.
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