Evaluate the diagnostic utility of MRI findings of the anterior optic nerve in Myelin Oligodendrocyte Glycoprotein Antibody-associated Disease (MOGAD) optic neuritis (ON) versus Aquaporin-4-IgG positive Neuromyelitis Optica Spectrum Disorder (AQP4+NMOSD) and Multiple Sclerosis (MS).

ON is the most common attack type in MOGAD and commonly involves the anterior segment. The diagnosis of MOGAD requires a combination of clinical, radiologic, and laboratory information due to the incomplete specificity of cell-based assay.

This was a retrospective study including consecutive cases of first MRI-confirmed ON from MOGAD, AQP4+NMOSD, and MS who all fulfilled their respective diagnostic criteria. Fat-suppressed orbital MRI post-gadolinium images were reviewed (blinded to diagnosis) for optic nerve tortuosity,  optic nerve enhancement and its extent including that involving the optic nerve head, sheath, or extension to orbital fat or posterior sclera and posterior flattening of the globe. Differences were compared with Fischer’s exact test.

We included 133 patients with 164 nerves involved. This included 108 nerves affected by MOGAD (82 patients), 30 with AQP4+NMOSD (27 patients), and 26 with MS (24 patients). Optic nerve head enhancement was more common in MOGAD(24%) compared to AQP4+NMOSD(10%) and MS(0%) (p-value=0.003). Posterior flattening of the globe was also more common in MOGAD(27%) than AQP4+NMOSD(10%) and MS(0%) (p-value=0.001). Optic nerve tortuosity was more common in MOGAD(23%) compared to AQP4+NMOSD(13%) and MS(4%) (p-value=0.049). Longitudinal-extension (>50% of length of nerve) was more common in MOGAD(62%) compared to AQP4+NMOSD(30%) and MS(19%) (p-value<0.001). Enhancement of the optic nerve sheath and orbital fat were more common in MOGAD(37%, 18%) than AQP4+NMOSD(17%, 0%) and MS(15%, 4%) (p-value=0.02, 0.007, respectively). There was no significant difference in posterior scleral enhancement between MOGAD(20%), AQP4+NMOSD(13%), MS(8%) (p-value=0.29).

Optic nerve head enhancement, optic nerve tortuosity, posterior flattening of the globe, longitudinally-extensive enhancement, and sheath and orbital fat enhancement favor ON secondary to MOGAD over AQP4+NMOSD or MS.