Early detection of neurodegeneration in multiple sclerosis

Multiple sclerosis (MS) is the leading cause of non-traumatic brain injury in young Australians, affecting thousands of people nationally. The disease involves the loss of myelin around axons, which over time, leads to brain cell damage and eventually, to progressive and permanent disability. This can be seen as brain shrinkage on magnetic resonance imaging (MRI) scans. However, brain atrophy can take years to be accurately detected, making it of limited use for short-term monitoring. Diffusion-weighted MRI is a technology that is sensitive to the microscopic motion of water molecules in tissue. In healthy brain white matter, densely packed axons and myelin cause water diffusion to occur preferentially along rather than across the axons. Damage to the myelin surrounding axons disrupts the diffusion of the water molecules. Using advanced diffusion MRI sequences and analysis methods, it is now possible to measure the packing density of axons. Our recent work showed that axonal density is reduced in early-stage MS, and is a more sensitive marker than atrophy. Building on this work, this research project investigates how diffusion-weighted MRI could provide a new way to measure early progressive brain damage in MS patients who are yet to exhibit progressive disability.