Magnetic resonance imaging via radio frequency gradient with examples from NMR and pure NQR

In this thesis, we explore the use of RF gradients in NMR imaging. RF gradients have advantages over gradients of the static magnetic field in that they are non-secular and offer more experimental freedom (for example they permit amplitude, phase and frequency variations). In the case of pure NQR imaging, RF gradients preserve an undistorted line-shape. RF gradients also present significant new challenges in both the probe design and the spin dynamics. All of these issues are addressed in this thesis. Potential applications of RF gradients include NMR imaging and RF gradient spectroscopy (where the RF gradients are used to average internal Hamiltonians and to select a unique coherence pathway). Pure NQR imaging is also a potentially exciting application due to the large spectral changes that are observed with physical modifications, such as radiation dose, pressure and temperature. Additional complications arise in pure NQR as compared to high field NMR since the principle axis system is defined by the crystal orientation rather than an external field. The RF field breaks this symmetry and introduces another level of complexity to the spin dynamics.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

1998

Author dc:creator

• Zhang, Guowang John, 1956-

Advisor dc:contributor.advisor

• David G. Cory.

• Nuclear Engineering

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/50496

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/50496