MRI Investigation of Optic Radiations in Human Brain: New Findings and Technical Considerations

Alessandro Arrigo*, Alessandro Calamuneri and Enricomaria Mormina

MRI Investigation of Optic Radiations in Human Brain: New Findings and Technical Considerations.

Optic Radiations are two white matter fiber bundles allowing direct connection between homolateral Lateral Geniculate Nucleus and visual cortex. From the anatomical point of view, ORs are
conventionally divided in three different portions, namely anterior, middle and posterior; the Meyer’s loop represents the anterior portion, and it has been shown to be a bundle with a very high variability in human brain.

The latter aspect has to be taken into account when studying ORs in clinical and surgical contexts. Indeed, ORs
represent eloquent white matter bundles often reconstructed by means of Magnetic Resonance Imaging based approaches in order to assess their involvement by pathological conditions as well as to prevent post-surgical damages.

Both these conditions can compromise visual function by causing, for instance, visual field deficits. Schematic representation of ORs’ bundles and common visual field deficits associated with ORs’ lesions.

ORs are largely studied by means of diffusion MRI based modelling techniques, such as Diffusion Tensor Imaging. These methods allow both qualitative evaluation of white matter bundles as well as quantitative
analysis of several diffusion parameters, such as Fractional Anisotropy.

The noninvasive investigation of ORs by means of diffusion MRI has provided several morphological information regarding ORs’ connectivity.  In particular, moving beyond well demonstrated link with V1 and V2, direct connections with V3, V4 and V5 have been recently shown.

Radiol Open J. 2016; 1(1): e6-e10. doi: 10.17140/ROJ-1-e002