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Optic chiasm lesions in myelin oligodendrocyte glycoprotein (MOG)–experimental autoimmune encephalomyelitis (EAE) mice were characterized using magnetic resonance imaging (MRI) and validated using electron microscopy (EM). MR images were collected from 3 days after induction to remission, approximately 20 days after induction. Hematoxylin and eosin, solochrome cyanin–stained sections, and EM images were obtained from the optic chiasms of some mice approximately 4 days after disease onset when their scores were thought to be the highest. T2-weighted imaging and apparent diffusion coefficient map hyperintensities corresponded to abnormalities in the optic chiasms of EAE mice. Mixed inflammation was concentrated at the lateral surface. Degeneration of oligodendrocytes, myelin, and early axonal damage were also apparent. A marked increase in chiasm thickness was observed. T2-weighted and diffusion-weighted MRI can detect abnormalities in the optic chiasms of MOG-EAE mice. MRI is an important method in the study of this model toward understanding optic neuritis.

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MRI and Monte Carlo simulated data of pulsed gradient spin echo experiments were used to study the effects of diffusion time, gradient strength and b-value on diffusion tensor (DT) metrics using real and simulated fixed rat spines. Radial (λ ⊥ ) in grey matter and simulation data, axial (λ || ) in both grey and white matter in fixed rat spinal cords and mean diffusivity in all tissues showed a significant decrease with diffusion time at b = 1 µm 2 /ms. All diffusivities significantly decreased with b-value at g = 116 mT/m and at ∆ eff = 23 ms. The fractional anisotropy (FA) significantly increased with diffusion time at b = 1 µm 2 /ms in the simulation data and grey matter. FA significantly increased in white matter and simulation data and significantly decreased in grey matter with b-value at g = 116 mT/m and at ∆ eff = 23 ms. These data suggest that DTI metrics are highly dependent on pulse sequence parameters.

Interstitial models with OG inferred 3-10 μm bead diameters from 0.54±0.06 μm to 1.0±0.1 μm pore radii and 151 μm tube diameters from 0.06±0.02 μm surface-to-volume ratios.