Scattering approach to diffusion quantifies axonal damage in brain injury
Journal:
arXiv
Published Date:
Jan 30, 2025
Abstract
Early diagnosis and noninvasive monitoring of neurological disorders require
sensitivity to elusive cellular-level alterations that occur much earlier than
volumetric changes observable with the millimeter-resolution of medical imaging
modalities. Morphological changes in axons, such as axonal varicosities or
beadings, are observed in neurological disorders, as well as in development and
aging. Here, we reveal the sensitivity of time-dependent diffusion MRI (dMRI)
to axonal morphology at the micrometer scale. Scattering theory uncovers the
two parameters that determine the diffusive dynamics of water in axons: the
average reciprocal cross-section and the variance of long-range cross-sectional
fluctuations. This theoretical development allowed us to predict dMRI metrics
sensitive to axonal alterations across tens of thousands of axons in seconds
rather than months of simulations in a rat model of traumatic brain injury. Our
approach bridges the gap between micrometers and millimeters in resolution,
offering quantitative, objective biomarkers applicable to a broad spectrum of
neurological disorders.
