Diffusion-weighted MR imaging of anisotropic water diffusion in cat central nervous system.

TLDR

Diffusion‑weighted MR imaging with gradients applied along the x, y, and z axes was used to probe water diffusion in the cat brain and spinal cord. No anisotropic diffusion was seen in gray matter, whereas white matter exhibited orientation‑dependent signal attenuation, with faster diffusion when gradients were parallel to tracts, a pattern observed in all imaging planes pre‑ and post‑mortem. The technique may be applied stereospecifically to assess white matter and to characterize demyelinating or dysmyelinating disorders.

Abstract

The diffusion behavior of intracranial water in the cat brain and spine was examined with the use of diffusion-weighted magnetic resonance (MR) imaging, in which the direction of the diffusion-sensitizing gradient was varied between the x, y, and z axes of the magnet. At very high diffusion-sensitizing gradient strengths, no clear evidence of anisotropic water diffusion was found in either cortical or subcortical (basal ganglia) gray matter. Signal intensities clearly dependent on orientation were observed in the cortical and deep white matter of the brain and in the white matter of the spinal cord. Greater signal attenuation (faster diffusion) was observed when the relative orientation of white matter tracts to the diffusion-sensitizing gradient was parallel as compared to that obtained with a perpendicular alignment. These effects were seen on both premortem and immediate postmortem images obtained in all axial, sagittal, and coronal views. Potential applications of this MR imaging technique included the stereospecific evaluation of white matter in the brain and spinal cord and in the characterization of demyelinating and dysmyelinating diseases.