Development of Novel Physical Methods to Enhance Contrast and Sensitivity in Magnetic Resonance Imaging

The purpose of this thesis is to report technological developments in contrast mechanisms for MRI. The search for new forms of contrast is on-going, with the hope that new contrast mechanisms and new contrast agents will provide unique insights into various molecular processes and disease states. In this thesis, we will describe new contrast mechanisms developed by manipulating the inherent physics of the system, as well as the development of exogenous contrast agents. More specifically, we will describe the application of iMQCs (intermolecular multiple quantum coherences) to thermometry and structural imaging, and the unique information provided from these studies. We will also describe methods for migrating iMQC-based pulse sequences from a Bruker research console onto a clinical GE console, thus enabling the application of iMQCs to humans. We will describe the development of hyperpolarized contrast agents which have the potential to provide an unprecedented level of molecular contrast to MRI and the development of techniques to enhance the lifetime of these hyperpolarized contrast agents. Finally, we will discuss a new type of T2 -weighted imaging which significantly improves the refocusing of CPMG-type sequences.