Molecular MRI with hyperpolarized xenon and smart sensors

The main aim of this project was to develop an understanding of both the theoretical and experimental aspects of MRI and NMR spectroscopy, while also gaining expertise in hyperpolarized xenon MRI methods. The first chapter will introduce the basics of NMR required to understand the work presented in subsequent chapters. Chapter 2 explores the area of spectroscopic biomarkers for certain pathologies, including those linked to neuroinflammation and a pilot study was performed examining the effect of induced neuroinflammation on metabolite levels in the mouse brain. Neuroinflammation plays a key role in a wide range of brain disorders including chronic pain, stroke, Parkinson's and Alzheimer's disease. The purpose of this pilot study was to investigate how the concentration levels of certain metabolites believed to be biomarkers of neuroinflammation (in particular myo-inositol) can be monitored non-invasively using MR spectroscopy and thus assist in validating them as biomarkers for neuroinflammation. This gives us specificity, one of the key aims for molecular imaging. Ultimately this may lead to an increased understanding of the disease mechanisms and assist in monitoring disease progression. Chapter 3 contains results from a D2O relaxometry study. Through this work a greater understanding of the fundamentals of NMR relaxation measurements was gained. It also lead to an increased understanding the role of contrast agents for MRI. Contrast agents can improve the relative difference in signal intensity between two adjoining tissues. This is important as sometimes distinction between a region of interest and its surrounding environment is impossible due to tissue properties being too similar or cancellation of signals by space averaging. Chapter 4 contains an overview of current developments in hyperpolarized xenon biosensors. MRI suffers from an inherent lack of sensitivity compared to other imaging modalities, something which can be overcome in hyperpolarization via optical pumping. The concept of a hyperpolarized xenon biosensor along with some relevant background theory will be presented here. Finally, conclusions on the research conducted will be presented along with a description of a future project being carried out which is of great interest due to its relevance to work presented here