Neuromyelitis optica spectrum disorder MRI
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Julinka Auta Fernandes
Overview
Magnetic resonance imaging (MRI) helps evaluate optic nerve, spinal cord, and brain involvement in neuromyelitis optica spectrum disorder (NMOSD). Findings must be interpreted together with the clinical presentation and antibody results.[1]
The 2026 Magnetic Resonance Imaging in Multiple Sclerosis (MAGNIMS) consensus addresses MRI for diagnosis, attack assessment, monitoring, and post-attack recovery in NMOSD associated with immunoglobulin G (IgG) antibodies against aquaporin-4 (AQP4), abbreviated AQP4-IgG. It also discusses imaging overlap with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).[2]
Key MRI Findings in Neuromyelitis Optica Spectrum Disorder
MRI Acquisition
Neuromyelitis optica spectrum disorder assessment follows the Neuromyelitis Optica Study Group (NEMOS) recommendations for baseline brain and spinal cord MRI, with orbital imaging to characterize optic nerve involvement.[3]
- Brain: Include transverse relaxation time–weighted (T2-weighted), fluid-attenuated inversion recovery (FLAIR), and longitudinal relaxation time–weighted (T1-weighted) imaging. Contrast-enhanced T1-weighted imaging aids differential diagnosis.[3]
- Spinal cord: Cover the entire cord, including the conus and craniocervical junction, using sagittal and axial T2-weighted images.[3]
- Orbits: For optic neuritis, the Indian Neuro-Ophthalmology Society (INOS) consensus supports dedicated brain and orbital MRI. Use fat-suppressed T2-weighted and post-gadolinium T1-weighted sequences to assess optic nerve signal, enhancement, and lesion extent.[4]
- Contrast: Prefer macrocyclic gadolinium agents and avoid unnecessary repeat exposure.[3]
Optic Nerve MRI
Neuromyelitis optica spectrum disorder-associated optic neuritis may show the following MRI features:[4]
- Increased optic nerve signal on T2-weighted images and enhancement on post-gadolinium T1-weighted images.[4] - Long lesions involving more than half the optic nerve length, with posterior intracranial, chiasmal, or optic tract involvement.[4] - Unilateral or bilateral involvement; bilateral disease is not required for diagnosis.[4]
Spinal Cord MRI
Neuromyelitis optica spectrum disorder commonly produces longitudinally extensive, centrally located spinal cord lesions.[5]
- Longitudinally extensive transverse myelitis (LETM): T2 hyperintensity spanning at least three contiguous vertebral segments, often involving central gray matter.[5]
- Associated changes: Cord swelling, T1 hypointensity, gadolinium enhancement, and extension of cervical lesions into the medulla may occur.[1]
- Bright spotty lesions: Very high-signal foci on axial T2 images support NMOSD over multiple sclerosis but are not independently diagnostic.[6]
- Short lesions: Lesions shorter than three vertebral segments can occur, including at the initial myelitis attack, and do not exclude AQP4-IgG-positive NMOSD.[7]
- Evolution: LETM may fragment into shorter lesions after treatment or during remission; residual cord atrophy may follow recurrent attacks.[5]
Brain MRI
Neuromyelitis optica spectrum disorder may occur with a normal brain MRI.[1] When abnormal, recognized patterns include:[5]
- Dorsal medullary lesions involving the area postrema.[5]
- Periependymal lesions around the lateral, third, or fourth ventricles and cerebral aqueduct.[5] - Hypothalamic and other diencephalic lesions.[5]
- Extensive corpus callosum or corticospinal tract involvement and large, confluent hemispheric white matter lesions.[5]
- Patchy, poorly defined cloud-like enhancement or thin linear enhancement along ventricular ependymal surfaces.[5]
MRI Requirements in AQP4-IgG-Negative or Unknown-Status NMOSD
Neuromyelitis optica spectrum disorder diagnosis continues to use the 2015 International Panel for Neuromyelitis Optica Diagnosis (IPND) criteria, also endorsed by the 2026 Middle East and North Africa Committee for Treatment and Research in Multiple Sclerosis (MENACTRIMS) guidelines.[8]
For negative or unknown AQP4-IgG status, additional MRI requirements apply to the corresponding syndromes within the full IPND criteria; imaging alone is insufficient:[1]
- Acute optic neuritis: Normal or nonspecific brain MRI, or an optic nerve lesion showing T2 hyperintensity or gadolinium enhancement over more than half its length or involving the chiasm.[1]
- Acute myelitis: LETM, or focal cord atrophy spanning at least three contiguous vertebral segments with a compatible prior myelitis history.[1]
- Area postrema syndrome: An associated dorsal medullary/area postrema lesion.[1]
- Acute brainstem syndrome: An associated periependymal brainstem lesion.[1]
MRI Differential Diagnosis
Neuromyelitis optica spectrum disorder shares some MRI appearances with multiple sclerosis and MOGAD.[2]
- Multiple sclerosis: Short peripheral cord lesions and periventricular Dawson fingers favor multiple sclerosis.[1]
- MOGAD: Prominent optic nerve sheath enhancement, conus involvement, or an axial spinal cord H-sign favors MOGAD.[3] MOGAD is a distinct disease and should not be classified as an NMOSD subtype when its diagnostic criteria are fulfilled.[9]
- Other causes of LETM: A longitudinally extensive lesion is not specific to NMOSD; infectious, vascular, granulomatous, and neoplastic disorders also require consideration.[5]
Follow-up MRI
Neuromyelitis optica spectrum disorder follow-up MRI helps assess suspected attacks, lesion evolution, and post-attack recovery.[2]
- Early imaging may underestimate lesion extent; repeat MRI can help when suspicion persists or symptoms worsen.[3]
- Enhancement can persist after an attack, and true attacks can occur without new enhancement; interpret MRI with clinical findings.[3]
- New asymptomatic T2 lesions during remission are uncommon in AQP4-IgG-positive NMOSD, but can occur and may precede clinical relapse.[10]
MRI Examples of Neuromyelitis Optica Spectrum Disorder
The following initial and one-year follow-up brain MRI examples are from a Radiopaedia teaching case of NMOSD.[11]
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