Event Time:
Friday, March 7, 2025 | 1:00 pm - 3:00 pm
Event Location:
UBC Hospital’s Koerner Pavilion, Level 1, Brain Research Centre conference room (in-person only)
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2025-03-07T13:00:00
2025-03-07T15:00:00
Characterizing white matter: Adventures with quantitative magnetic resonance imaging
Event Information:
Abstract:White matter in the central nervous system alters throughout the healthy lifespan as well as in disease. It is important to have non-invasive methods of characterizing white matter, such as through magnetic resonance imaging (MRI), so that changes to white matter in disease can be better understood. White matter is complex, and different quantitative MRI measures are sensitive to different aspects of its microstructure. In this thesis, I explored five MRI measures to characterize white matter: myelin water fraction (MWF), fractional anisotropy (FA), microscopic fractional anisotropy (µFA), a measure of tissue heterogeneity (CMD) and the magnetization transfer (MT) ratio.
I first investigated the relationship between MWF (from myelin water imaging) and FA, µFA and CMD (from tensor-valued diffusion imaging) in twenty-five healthy volunteers through correlation analysis and tract profiling, and created atlases of these measures. I also characterised the measures in five example cases of multiple sclerosis (MS), to explore how they varied in pathology. I determined from this initial investigation that MWF, µFA and CMD would be useful to explore both healthy and pathological tissue.
Next, I developed a data-driven tissue classification framework to classify tissue using only quantitative MRI measures and no spatial input, called Clustering for Anatomical Quantification and Evaluation (CAQE). In this framework, quantitative MRI measures from multiple healthy subjects were used to derive tissue classifications with specific microstructural signatures. I clustered MWF, µFA and CMD data from twenty-five healthy controls to create a classification scheme where clusters placed themselves into anatomically similar locations in healthy people even without spatial input. I applied the classification scheme to twenty-five people with MS and found regions of changes in white matter tissue classifications that were correlated with cognitive ability.
Finally, I developed MT imaging for characterizing white matter on a new point-of-care ultra-low field 64 mT scanner, to enable myelin-sensitive monitoring in demyelinating diseases such as MS. I did this using an on-resonance approach with steady state free precession imaging, validated the approach in phantoms, assessed its reproducibility, and demonstrated it in a person with MS.
Event Location:
UBC Hospital’s Koerner Pavilion, Level 1, Brain Research Centre conference room (in-person only)