Boonsuth, Ratthaporn; (2024) Development of quantitative magnetic resonance neurography (qMRN) for assessing peripheral nerve damage in neurological conditions: Application to Multiple Sclerosis. Doctoral thesis (Ph.D), UCL (University College London).

Text PhD-thesis - Ratthaporn Boonsuth.pdf - Submitted Version Access restricted to UCL open access staff until 1 September 2024. Download (8MB)

Abstract

This PhD thesis examines the potential role of various quantitative magnetic resonance imaging (qMRI) methods for characterization of the peripheral nervous system (PNS) in healthy controls (HC) and people with multiple sclerosis (MS). The overarching goal was to gain novel insights into the PNS involvement in MS. The first study combines magnetic resonance neurography (MRN) and magnetization transfer ratio (MTR) to evaluate the lumbar nerve roots and the sciatic nerve in people with relapsing-remitting MS (RRMS) versus HC. Significant MTR reductions were identified in the sciatic nerve but not in the lumbar nerve roots of people with RRMS, suggestive of demyelination. The second study demonstrates further integration of MRN with diffusion-weighted imaging (DWI), quantitative magnetization transfer, and T1 relaxometry in the healthy sciatic nerve in vivo using a unified readout protocol. Reproducibility of the methods was assessed, and normative quantitative values obtained and reported for the first time. The third study applied the aforementioned rich multi-parametric qMRI protocol in people with RRMS, revealing alterations in sciatic nerve microstructure, also suggestive of demyelination. Regression models uncovered intriguing relationships between PNS and central nervous system (CNS) metrics. Sciatic nerve metrics also independently associated with lower limb motor impairment. The fourth study explores the feasibility of using DWI and MTR in the tibial nerve using 7 Tesla (T) MRI in HC. Key metrics exhibited high reproducibility, however larger studies are essential to fully validate the role of high field 7T imaging. This thesis demonstrates the promise of qMRI for detecting PNS damage in MS, also elucidating interdependencies between CNS and PNS pathology. The studies in this thesis provide solid foundation for the translation and implementation of qMRI for PNS evaluation in MS. Further research involving longitudinal cohorts, advanced analyses, high field MRI, and diverse patient populations is imperative to fully establish the clinical utility of these innovative methods.

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