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Title:Magnetic resonance microscopy;
1. Four-dimensional spectral-spatial imaging;
2. Diffusional effects in magnetic resonance microscopy
Author(s):Hyslop, William Brian
Director of Research:Lauterbur, Paul C.
Department / Program:Physics
Discipline:Physics
Degree:Ph.D.
Genre:Dissertation
Subject(s):Magnetic resonance imaging (MRI)
4D spectral-spatial magnetic resonance imaging
DESIRE (Diffusionally-Enhanced Signal Intensity and REsolution)
nuclear magnetic resonance (NMR) microscopy
Abstract:An n-dimensional (nD) filtered backprojection image reconstruction algorithm has been developed and used in the reconstruction of 4D spectral-spatial magnetic resonance imaging (MRI) data. The algorithm uses n-1 successive stages of 2D filtered backprojection to reconstruct an nD image. This approach results in a reduction in computational time on the order of Nn-2 relative to the single stage technique, where Nn is the number of elements in an nD image. This work describes implementation of the algorithm, including digital filtering and sampling requirements. Images obtained from simulated data are presented to illustrate the accuracy and potential utility of the technique. The second part of this work studied the effects of restricted diffusion on the appearance of magnetic resonance microscopy images. A scaling law was used to predict the onset of motional narrowing effects for given values of diffusion, length, gradient strength, and gyromagnetic ratio. Barriers to translational diffusion were found to result in significant edge effects. Such edge effects were also predicted for semi-permeable barriers with permeability coefficients similar to those of biological membranes. DESIRE (Diffusionally-Enhanced Signal Intensity and REsolution) is a new method for nuclear magnetic resonance (NMR) microscopy which couples a spatially localized region of saturated magnetization to the surrounding medium via translational diffusion of spins, resulting in amplification of the total saturated magnetization by several orders of magnitude over that obtained in the absence of diffusion. Combined with signal detection at narrow bandwidths of the order of the transverse relaxation rate, DESIRE results in greatly increased signal-to-noise relative to traditional NMR imaging techniques and has the potential for submicron resolution. Both time dependent and steady-state simulations and analytic expressions will be presented, as well as a one-dimensional DESIRE experiment.
Issue Date:1998
Genre:Dissertation / Thesis
Type:Text
Language:English
URI:http://hdl.handle.net/2142/30818
Rights Information:© 1998 William Brian Hyslop
Date Available in IDEALS:2012-05-08
Identifier in Online Catalog:4163841


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