Assessing early motor system degeneration in the spinal cord of ALS patients using diffusion MRI: an exploratory study

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative\ndisease affecting primarily the motor system. The loss of upper\nmotor neurons within the descending motor tracts, and lower motor neurons\nwithin the brain stem nuclei and spinal cord anterior horn gives\nrise to progressive muscle weakness. With the rapid course of the disease,\nthere is a critical need for better biomarkers of disease to help\nunderstand the mechanisms of tissue damage in ALS and, ultimately, to\nimprove diagnosis, prognosis and new treatments for patients. Diffusion\nMagnetic Resonance Imaging (dMRI) techniques, such as diffusion tensor\nimaging (DTI) and neurite orientation and dispersion density imaging\n(NODDI), provide a rich selection of parameters related to tissue\nmicrostructure. This project is a feasibility study aiming to evaluate\ndMRI metrics in the spinal cord as potential markers for ALS disease\ndiagnosis. Multi-shell diffusion MRI data was collected from 11 recently\ndiagnosed patients with ALS with upper limb symptoms, alongside 10\nage-matched healthy controls, focusing on the cervical spinal cord region.\nImages underwent both DTI and NODDI fitting to produce fractional\nanisotropy (FA) and neurite orientation dispersion index (ODI) maps.\nRegion-of-interest based statistical analyses were performed and results\nhave shown significant FA reduction and ODI increase in ALS patients\ncompared to controls, particularly in the white matter regions. These\nfindings highlight the potential of diffusion MRI to uncover the nature\nof microstructural changes within the spinal cord during the early stages\nof ALS and opens the possibility to advance our understanding of the\ndisease.<p></p>