Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 114-122). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 120-123). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, 1960. / Includes bibliography references : p. 92-94.

Thesis--University of Florida. / Description based on print version record. Manuscript copy. Vita. Bibliography: leaves 110-114.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. "Spin diffusion measurements : spin echoes in the presence of a time-dependent field gradient" [by] E.O. Stejskal and J.E. Tanner, reprinted from the Journal of chemical physics : inserted between leaves 48 and 54. Vita. Description based on print version record. Includes bibliographical references (p. 217-219).

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaf 181).

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

This thesis presents three original contributions to the field of Nuclear Magnetic Resonance (NMR): The experimental framework and analysis for the measurement of a new imaging parameter to describe perfusion; The measurement and analysis of magnetic field inhomogeneity and a practical correction system for their reduction; A novel system for the synchronous control of NMR experiments based on the microprogrammed concept. The thesis begins with an introduction to the theory of NMR. The application of NMR to imaging is also introduced with emphasis on the techniques which developed into those in common use today. Inaccurate determination of the traditional NMR parameters (T1 and T2 and the molecular diffusion coefficient) can be caused by non-diffusive fluid movement within the sample. The experimental basis for determining a new imaging parameter - the Perfusion coefficient - is presented. This provides a measure of forced isotropic fluid motion through an organ or tissue. The instrumentation required for conducting NMR experiments is described in order to introduce the contribution made in this area during this research: A sequence controller. The controller is based on the concept of microprogramming and enables completely synchronous output of 128 bits of data. The software for the generation and storage of control data and the regulation of the data to provide experimental control is microcomputer based. It affords precise and accurate regulation of the magnetic field gradients, the rf synthesizer and the spectrometer for spectroscopic and imaging applications. Fundamental to the science of NMR is the presence of a magnetic field. A detailed study of the analysis of magnetic field inhomogeneity in terms of spherical harmonics is presented. The field of a whole body imaging system with poor inhomogeneity was measured and analyzed to determine and describe the components of the inhomogeneity. Finally a description is given of the design and application of practical methods for reducing the dominant inhomogeneities.

The design, construction and calibration of an intermediate scale NMR imaging system is described. The system is based on a 7" diameter, room temperature bore superconducting magnet at a field of 0.4T. Using selective excitation and projection reconstruction techniques, the production of density, spin-lattice and spin-spin relaxation weighted images has been achieved. An investigation of the feasibility of in-vivo tissue characterisation using NMR parameters has been carried out. Tissue characterisation using healthy animals of different ages, sex and species has shown that characterisation with the NMR parameters of T1** and T2** is feasible on a given system, where 1/T1** and 1/T2** are the spin-lattice and spin-spin relaxation rates calculated from the images assuming these rates to be mono-exponential. It is shown that the scatter in results which previously was believed by other authors to be due to biological variation is in fact due to experimentation and instrumentation, and that the biological limit has yet to be reached. The successful employment of quantitative characterisation in the observation and monitoring of diseased states is illustrated by two examples. The first shows the growth of a tumour and the second uses T1* to observe the effect of toxic drugs on the kidney. In the latter case, little evidence of damage was visible on the image. Following characterisation, it is demonstrated that it is possible to optimise an imaging sequence by careful selection of the timing parameters. Optimisation of the sequences used in this work gave an increase of upto a factor of two in the signal-to-noise ratio and increased the accuracy of the relaxation rate evaluation. Finally, a technique for obtaining a map of the spatial distribution of the molecular translational diffusion coefficient together with perfusion and flow information has been developed. These parameters may well enhance the contrast as well as providing new information on the biological system.