Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are well established techniques. Both require samples to be placed inside spatially-homogeneous static magnetic and radio frequency magnetic fields. This research focuses on applying the principles of NMR spectroscopy and imaging to design a system that can produce images of the NMR signal from a sample placed adjacent to it. The long term goal is to image at distances of meters from the device. The specific application of interest is locating buried utilities in fully-hydrated soils by identifying non-signal bearing features in an NMR signal rich background. This thesis asserts that a minimum of three questions need to be answered to determine if near surface MRI is feasible. 1.) Can the Earth's magnetic field (BEarth) be used as the applied static magnetic field? 2.) Is the NMR signal from the water found in fully-hydrated soils sufficient for imaging? 3.) Can a near-surface imaging technique be developed? This thesis research attempts to answer each of these questions in three stand alone investigations: 1.) In situ measurements of BEarth, 2.) laboratory-based relaxation studies of synthetic sands, and 3.) the development of a proof-of-concept near-surface magnetic resonance imaging device. It is the assertion of this thesis that the results of these three studies are needed to begin to properly understand the signal space that a viable surface instrument would have to operate within for practical use. The BEarth results showed that better selection performance would be achieved using a larger B0 field. The synthetic sands study gave results suggest that relaxation behavior of water was highly deterministic based on particle diameter. The imaging performance of the unilateral MRI device was measured and the results demonstrate that imaging at depths on the order of one centimeter is possible. Overall, the results from these three studies have advanced the understanding of near-surface inhomogeneous magnetic resonance, while giving strong indications that near-field MRI in fully-hydrated soil is promising.
Library of Congress Subject Headings
Magnetic resonance imaging; Nuclear magnetic resonance spectroscopy
Imaging Science (Ph.D.)
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
Bray, Christina L., "Near-surface magnetic resonance imaging" (2006). Thesis. Rochester Institute of Technology. Accessed from
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