Design algorithms for parallel transmission in magnetic resonance imaging

The focus of this dissertation is on the algorithm design, implementation, and validation of parallel transmission technology in Magnetic Resonance Imaging (MRI). Novel algorithms are proposed which yield excellent excitation control, low RF power requirements, methods that extend to non‐linear large‐flip‐angle excitation, as well as a new algorithm for simultaneous spectral and spatial excitation critical to quantification of low‐SNR brain metabolites in MR spectroscopic imaging. For testing and validation, these methods were implemented on a newly developed parallel transmission platform on both 3 T and 7 T MRI scanners to demonstrate the ability of these methods for high‐ fidelity B1+ mitigation, first by excitation of phantoms and then by human imaging. Further, spatially tailored RF pulses were demonstrated beyond conventional slice‐ or slab‐selective excitation. Thesis Supervisor: Elfar Adalsteinsson Title: Robert J. Shillman Assistant Professor of Electrical Engineering and Computer Science; Harvard-MIT Division of Health Science and Technology