The so-called “1/3” criteria for magnetic resonance imaging (MRI) are useful for distinguishing multiple sclerosis (MS) from neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody (MOG-Ab)-associated disease (MOGAD), according to a new study published in Multiple Sclerosis and Related Disorders.

The researchers assessed the ability of 3 MRI criteria to distinguish between MS and conditions antibody-mediated conditions: 1) a lesion adjacent to the lateral ventricle and in the inferior temporal lobe, 2) a juxtacortical lesion, or 3) a Dawson finger-type lesion.

In addition to using the original 3 criteria to distinguish MS from NMOSD and MOGAD, the researchers assessed the impact of 2 additional criteria: fluffy infratentorial (FIT) lesions and longitudinally extensive transverse myelitis (LETM) lesions. The absence of FIT lesions further increased the precision of an MS diagnosis in those patients with brain symptoms, and the presence of LETM lesions (as determined by spinal MRI) slightly increased the overall accuracy of the criteria.

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“The ‘1/3’ criteria perform well in discriminating MS from NMOSD and MOGAD regardless of ethnic background and clinical scenario,” the authors said. “Adding the absence of FIT lesions increases the specificity in those presenting with brain/brainstem symptoms.”

Read more about NMOSD differential diagnosis

The authors reviewed MRI data from a total of 577 patients in Europe, Asia, and Latin America. In addition to assessing the power of the original and modified MRI criteria in distinguishing the patients’ neurological conditions, they also evaluated their performance in terms of the White, Asian, and mixed ethnic groups in the study cohort.

The criteria were found to be effective regardless of the patients’ ethnic background, although patients in Asia were observed to have more FIT lesions, especially in the patient groups with antibody-mediated conditions. Given that the final criteria, LETM lesions, requires a spinal MRI in addition to a brain MRI, the authors recommend further studies to determine whether there might be a brainstem criterion that could serve in its place.


Contentti EC, Rojas JI, Criniti J, et al. Towards imaging criteria that best differentiate MS from NMOSD and MOGAD: large multi-ethnic population and different clinical scenarios. Mult Scler Relat Disord. Published online March 27, 2022. doi:10.1016/j.msard.2022.103778