Rebecca Sawbridge

Doctoral Researcher
Physical Sciences of Imaging in the Biomedical Sciences CDT

Completed in 2016 and progressed into a Pre-Registration Clinical Scientist position.

Thesis project - "Developments in MR spectroscopic imaging acquisition and analysis"

Supervisors:
Dr Martin Wilson, School of Psychology
Professor Andrew Peet, Institute of Cancer and Genomic Sciences
Dr Hamid Dehghani, School of Computer Science

Magnetic Resonance Spectroscopic Imaging (MRSI) provides non-invasive metabolite imaging, and has been shown to provide useful information on a number of brain pathologies. Whilst, MRSI is well used in the MR research community, widespread clinical adoption has been relatively slow due to the following barriers: 1) a large amount of data is produced making manual analysis and interpretation time-consuming; 2) variable data quality can make interpretation difficult for a non-expert; 3) the technique is limited to low resolution 2D slabs due to lengthy 3D acquisition times.

The PhD will act to develop and validate an optimal MRSI acquisition and automated analysis pipeline for routine paediatric brain tumour and inherited metabolic disorders. This would simplify MRSI data collection and analysis and ultimately improve the quality of MRSI spectra, aiding in the interpretation of large quantities of data extracted from a scan. A particular focus in scan time reduction will be evaluated to validate methods and increase the feasibility of MRSI in clinical use. Through the investigation and analysis of fast methods 3D acquisition could be made clinically possible allowing more information to be obtained for diagnosis and prognosis of disease.

The main component of this PhD is based on MR imaging which has a strong background in the physical sciences, in particular spin physics (nuclear magnetic resonance) and organic chemistry. Understanding of the theoretical aspects of MR will be gained and consolidated through practical experience in operating a clinical scanner and spectral simulation. Furthermore, simulation of the common MRSI pulse sequences and the influence of pulse timings on spin-coupling evolution will be investigated in the context of optimising acquisition for targeting metabolite detection. A test object for QC testing will be developed in order to validate MRSI protocols which take into account physical factors e.g. different anatomical tissues and chemical composition in the head, allowing evaluation of their effect on the resulting spectra quality. Fast-MRSI techniques (such as sensitivity encoding) and their influence on spectra will be investigated, along with the future development and design of pulse sequences for optimal data collection.