Figure 5.

T2 intensities of the optic nerve. A peripheral hypointensity represents the optic nerve sheath. The outer hyperintensity represents CSF signal within the optic nerve sheath enveloping a concentric T2-hypointense rim (which may represent peripheral myelinated fibers of the optic nerve or flow void from the pial vasculature. The central T2 intermediate intensity is thought to represent the non-myelinated fibers of the optic nerve. In the center of this region, a central hypointensity is present which could be due to flow void artifacts corresponding to the central retinal artery.