Date of Award


Degree Type


Degree Name

Master of Science


Medical Biophysics


Dr. Brian K. Rutt

Second Advisor

Dr. Dick J. Drost

Third Advisor

Dr. Terry M. Peters


The aim of this thesis was to investigate the capabilities of a novel gradient concept for the purpose of dynamic manipulation of imaging volume and gradient performance in Magnetic Resonance Imaging (MRI). The proposed concept exploits the natural inverse co-dependence between the gradient strength of the coil generated magnetic field profile, and the volume over which the gradient is uniform, to optimize gradient performance for a given anatomical region of interest. The design also has the potential to extend the available range of gradient performance within the operation constraints imposed by gradient induced Peripheral Nerve Stimulation (PNS). A design paradigm is proposed that expresses the gradient field needed for imaging as a weighted sum of individual harmonic-modulated gradient fields of variable order. Weighted sums of harmonic field profiles are found to agree closely in overall shape to theoretical predictions, confirming the high degree of fidelity in the coil generated field profiles to the target harmonics. A wide range of variable linear region performance is observed and power deposition characteristics of the proposed harmonic gradient set are found to be comparable to commercial gradient sets in use today. The proposed novel concept offers a comprehensive solution to the problem of optimizing gradient performance for a particular anatomical region of interest and has the potential to extend the range of PNS-constrained gradient performance beyond what is currently possible with present day gradient technology.



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