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Spatially localized nuclear magnetic resonance

University of British Columbia

The work presented in this thesis has involved the development and experimental implementation of a new method incorporating Nuclear Magnetic Resonance (NMR) methodology, and which enables a volume to be accurately defined and non-invasively interrogated within a larger object, by a sequence of radiofrequency (RF) and linear magnetic field gradient pulses. The most important feature of the VOISINER (volume of interest by selective inversion, excitation and refocusing) sequence is its flexibility with respect to the location and size of the region of interest. The spatial coordinates and the size of the volume of interest can be directly selected from conventional NMR images and then converted into the VOISINER sequence by an appropriate setting of the radiofrequency carrier frequencies of the frequency-selective RF pulses and an appropriate scaling of the field gradient strengths used during those RF pulses. As part of the experimental protocol, the VOISINER sequence was actually combined with conventional spin echo imaging in order to facilitate the selection of the region of interest and the optimization of the spatial sensitivity profile of the localization process. The applicability of the VOISINER sequence was then examined under various experimental conditions in order to evaluate the factors that can deteriorate or improve the efficiency of its spatial selectivity and detection sensitivity. Potential extensions of the VOISINER technique for extracting a variety of high-resolution NMR information have been explored and experimentally demonstrated by combining it with conventional NMR methodology. In particular, it was combined with the inversion recovery method to measure on a model system, spatially localized spin-lattice (T₁) relaxation times. With regard to imaging, studies of a model system have been used to evaluate the technical prospects for using the VOISINER sequence as the basis for high-resolution imaging of small regions within a large object. Finally, to demonstrate that the technique is applicable for studies of living systems, it was tested on a human forearm and spatially localized ¹H high-resolution spectra were successfully obtained from muscle tissue and bone marrow.

Text

2010-10-10

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http://hdl.handle.net/2429/29062

Chemistry

University of British Columbia

Graduate