Figure 3.

MRI axial (a) and coronal (b) T2 fat saturated [fs] images reveal features of ethmoid sinusitis [arrow] with orbital inflammatory changes manifested by orbital fat stranding (* in a), EOM enlargement and T2 hyperintensity. The left optic nerve also shows T2 hyperintensity in (b) with hyperintense diffusion restriction on axial diffusion weighted image (arrow in c) suggestive of optic nerve infarction. Post-contrast coronal T1fs in retro-ocular section shows abnormal left perioptic nerve sheath enhancement (arrowhead) consistent with optic perineuritis, abnormal orbital fat enhancement and maintained expected enhancement of the EOMs. More posterior sections (e) near the orbital apex show absent enhancement of EOMs consistent with infarction, with relative sparing of the lateral rectus. MR Angiography (f) shows non-visualization of the left ophthalmic artery, in comparison to the origin of the right OA which is seen clearly (arrowhead). Post-contrast axial T1fs (g) shows the orbital segment of the OA on the right side (arrowhead) but not on the left side