Magnetic resonance imaging to measure myelin : orientation dependence and application to spinal cord injury
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Morris, Sarah Rosemary
issued: 2023-04-24T16:01:28Z
issued: 2023
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Myelin, the lipid-rich sheath which wraps around axons, has complex and unique physical and chemical properties which can be used to produce magnetic resonance imaging (MRI) contrast. Developing MRI to measure myelin is vital for monitoring the brain and spinal cord in health and disease. This thesis explores four MRI techniques sensitive to myelin: myelin water imaging (MWI), magnetisation transfer (MT), inhomogeneous magnetisation transfer (ihMT) and diffusion imaging. First, these metrics were recorded in regions throughout the healthy adult and pediatric brain. Reproducibility, dynamic range and correlations between metrics were investigated. Healthy adult and pediatric atlases of the metrics were made publicly available for other neuroimaging researchers. Next, the orientation dependence of MWI, MT and ihMT was quantified. White matter is anisotropic, consisting of fiber bundles which vary in angle to the MRI main magnetic field. This can affect MRI metrics through the susceptibility of lipid-rich myelin, anisotropic vasculature, iron content, dipole-dipole and magic angle effects. We found that the orientation dependence curve for each metric varied between brain regions, suggesting that microstructural parameters other than fibre angle are affecting the orientation dependence. Then, we investigated the orientation dependence of ihMT in more detail, using a phospholipid bilayer sample rotated in a nuclear magnetic resonance (NMR) spectrometer to measure the variation with angle of the breadth of the lipid spectrum and dipolar order relaxation time. We found that the lipid linewidth had a greater effect on ihMT than the dipolar order relaxation time under our experimental conditions. Finally, ex vivo human spinal cord injury (SCI) tissue from the International SCI Biobank was scanned at 7 Tesla to obtain MWI, ihMT and diffusion metrics. This tissue then underwent histological staining for myelin lipids and inflammatory cells. We performed correlations between t…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/84433
note: Magnetic resonance imaging to measure myelin: orientationdependence and application to spinal cord injurybySarah Rosemary MorrisB. A., The University of Cambridge, 2015M. Sci., The University of Cambridge, 2016A THESIS SUBMITTED IN PARTIAL FULFILLMENTOF THE REQUIREMENTS FOR THE DEGREE OFDoctor of PhilosophyinTHE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES(Physics)The University of British Columbia(Vancouver)April 2023© Sarah Rosemary Morris, 2023The following individuals certify that they have read, and recommend to the Faculty ofGraduate and Postdoctoral Studies for acceptance, the thesis entitled:Magnetic resonance imaging to measure myelin: orientation dependenceand application to spinal cord injurysubmitted by Sarah Rosemary Morris in partial fulfillment of the requirements for thedegree of Doctor of Philosophy in Physics.Examining Committee:Cornelia Laule, Associate Professor, Physics & Astronomy, UBCSupervisorAlex MacKay, Professor, Physics & Astronomy, UBCSupervisory Committee MemberMatthew Budde, Associate Professor, Neurosurgery, MEDICAL COLLEGE OF WISCONSINExternal examinerStefan Reinsberg, Associate Professor, Physics & Astronomy, UBCUniversity examinerClaire Beasley, Associate Professor, Psychiatry, UBCUniversity examinerAdditional Supervisory Committee Members:Piotr Kozlowski, Professor, Radiology, UBCSupervisory Committee MemberBrian Kwon, Professor, Orthopaedics, UBCSupervisory Committee MemberCarl Michal, Associate Professor, Physics & Astronomy, UBCSupervisory Committee MemberWayne Moore, Clinical Professor, Pathology & Laboratory Medicine, UBCSupervisory Committee MemberiiAbstractMyelin, the lipid-rich sheath which wraps around axons, has complex and unique phys-ical and chemical properties which can be used to produce magnetic resonance imaging(MRI) contrast. Developing MRI to measure myelin is vital for monitoring the brain andspinal cord in health and disease. This thesis explores four MRI techniques sensitive tomyelin: myelin water imaging (MW…
has type: Thesis/Dissertation
date issued: 2023-05
is shown at: 10.14288/1.0431393
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Laule, Cornelia
type: Text
identifier URI: http://hdl.handle.net/2429/84433