Diffusion-weighted 2D cortical slice mapping to spatially resolve distinct neurofluid flow regimes

Motivation: While glymphatic-lymphatic function has been observed using two-photon imaging and contrast-enhanced MRI, noninvasively quantifying CSF neurofluid flow regimes poses significant challenges. Goal(s): This study aims to establish methods to noninvasively map CSF flow regimes, namely within the perivascular space and parenchyma. Approach: Using diffusion-weighted 2D cortical slice mapping, we resolve vessels tangent to the surface of the rat cortex under varying anesthesia conditions of isoflurane and dexmedetomidine. We segmented individual vessels and their corresponding perivascular and parenchymal spaces then classified apparent arterioles and venules. Results: Diffusion coefficients within these regions of interest show significant differences between the isoflurane and dexmedetomidine anesthesia conditions. Impact: The measurement of spatially resolved flow regimes using the novel technique of 2D cortical slice diffusion-weighted MRI has the potential to improve clinical assessments of CSF neurofluid dynamics in the glymphatic-lymphatic system.