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Title: Quantitative whole brain sodium (²³Na) imaging
Author: Riemer, F.
ISNI:       0000 0004 5359 0980
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2015
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In this thesis, the challenges of establishing the very first human in vivo 23Na magnetic resonance imaging in the United Kingdom are presented. A comprehensive framework for quantitative human in vivo studies is established and translated for clinical research imaging. Quantitative measures to obtain the sodium bioscale using external calibrants are discussed and results from a scan re-scan reproducibility study on five healthy volunteers are presented. The protocol was subsequently used in a clinical research study and published by a clinical collaborator in a high impact journal. Improvements in acquisition are achieved by implementation and 23Na adapt- ation of the state of the art 3D-Cones pulse sequence. For evaluation, it is compared against more established 3D-radial k-space sampling schemes featuring cylindrical stack-of-stars (SOS) and 3D-spokes kooshball trajectories on five healthy volunteers in a clinical setting and numerical phantoms. Signal- to-noise ratio (SNR) as a measurement of sequence performance was compared between the sequences and the results are presented. The results were published in a special issue on X-nuclei imaging in the journal of Magnetic Resonance Materials in Physics, Biology and Medicine. The work was subsequently shortlisted and presented for the Young Investigator Awards at the annual meeting of the European Society for Magnetic Resonance in Medicine and Biology. Reconstruction improvements by means of sophisticated k-space weighting schemes are presented on numerical and in vivo data and its effects on image appearance, SNR and total tissue sodium concentration estimates are discussed. The work is currently in peer review for journal publication. A protocol for clinically feasible in vivo 23Na relaxometry measurements of the transverse relaxation time constant T2 is established and results for a range of anatomical white and grey matter locations is presented using both a bi-exponential two-component fit and an unrestricted continuous distribution model. The implications of the results on the underlying tissue sodium environment are discussed. This work has subsequently been presented at international conferences of the International Society for Magnetic Resonance in Medicine and European Society for Magnetic Resonance in Medicine and Biology and has been submitted for peer review as a journal publication. As a conclusion I discuss how the methods presented here can be used to obtain unprecedented spatial and temporal resolution in in vivo 23Na imaging at 3T. Preliminary results are presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available