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Title: Developments in High Field MRI
Author: Jiang, Lei
ISNI:       0000 0001 3590 5828
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2007
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The technique of magnetic resonance imaging (MRI) is widely used in both structural and functional imaging. This thesis explores some important developments and applications in high field MRI. The work in this thesis has been undertaken by the author except where indicated by reference. Initially, a purpose-built dynamic functional phantom was devised and used for quality control and testing imaging pulse sequences. A multi-echo GEBPI sequence was assessed and the most efficient ways to combine multiecho data taking account of the effect of bandwidth were explored by using this phantom. Subsequently, this multi-echo sequence was applied for T-i mapping of the whole brain and cerebellum with different slice thicknesses and orientations and used for characterization of the physiological noise in the resting-state brain on 3.0 and 7.0 T systems. Furthermore, physiological noise was also investigated by using a spin echo imaging method. The physiological noise in. gradient and spin echo images was compared. The results support the hypothesis that physiological noise has similar origins as the BOLD signal. Contrast-enhanced MR angiography provides accurate information about vascular structure. The field strength dependence of Rl and R2 relaxivities of a blood pool contrast agent (Gadofosveset) was measured ex vivo in human blood. A computer simulation was performed to investigate quantitatively the performance of contrast-to-noise (CNR) ratio of Gadofosveset-enhanced MRA at different field strengths. Finally, highresolution contrast-enhanced MR angiographic imaging was performed on human subjects at 7.0 T. The initial results demonstrate that, despite posHible technical problems, high quality imaging is feasible at 7.0 T. These H)sults also show that the ultra-high field strength has the potential to offer tllgllificant improvements in CNR and spatial resolution.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available