Using SABRE in NMR and MRI

Highton, Louise Ariadne Ruth

September 2013

Thesis or dissertation

© 2013 Louise Ariadne Ruth Highton. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

This thesis describes the use of SABRE as a hyperpolarisation technique in both NMR spectroscopy and MRI. Hyperpolarisation is a method of generating enhanced magnetic resonance signals to improve signal to noise, contrast and resolution within those techniques. The primary aim of this thesis was to develop the SABRE method in the context of enabling applicability to biomedical systems.

Initial results focus on optimising the SABRE technique through catalyst modifications. The relationship between signal enhancement and a range of dependencies such as temperature, field and substrate choice are examined. Results show that the rate of exchange for hydride and substrate ligands can be the determining factor when optimising conditions. A range of biologically relevant substrate molecules were investigated. The first measurements using the SABRE method utilise NMR spectroscopy, but results in Chapter 4 shows how the method can be applied to hyperpolarised MRI acquisition using phantoms.

Chapter 5 discusses the advances obtained in the development of hyperpolarised signals in a biologically compatible solvent system. There are two strands to this chapter, the first being the synthesis of water soluble SABRE pre-catalysts. The second part uses the previously published SABRE catalyst but in aqueous solutions. A possible biologically compatible solvent would be a 30% aqueous ethanol solution and signal enhancement was successfully measured in this.

The results shown in Chapter 6 highlight the efforts made to progress the SABRE technique into in-vivo studies. It features both imaging in biologically compatible solvents as well as ex-vivo tissue studies. One notable result is the observation of a long-lived state which was observable for over two minutes. The final result shows an in-vivo MRI measurement without hyperpolarisation, however a clear action plan to complete the first in-vivo SABRE measurement is given as future work.

Hull York Medical School, The University of Hull and University of York
Duckett, Simon; Green, Gary; Asghar, Aziz
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