Brain magnetic resonance imaging features in multiple sclerosis and neuromyelitis optica spectrum disorders patients with or without aquaporin-4 antibody in a Latin American population.

Introduction: There is scarce evidence comparing the behavior in magnetic resonance (MRI) between positive and negative aquaporin-4 antibody neuromyelitis optica spectrum disorders (P-NMOSD and NNMOSD, respectively). The aim of this study was to describe and compare MRI features through a quantitative and qualitative analysis between P-NMOSD and NNMOSD patients in a cohort from Latin American (LATAM) patients.

Methods: We retrospectively reviewed the MRI and medical records of NMOSD patients as defined by the 2015 validated diagnostic criteria, and with at least 3 years of follow-up from disease onset (first symptom). We included patients from Argentina, Brazil and Venezuela. To be included, NMOSD patients must have had AQP4-ab status measured by a cell-based assay. Brain MRIs were obtained for each participant at disease onset and every 12 months for 3 years. Demographics, clinical and MRI variables (T2 lesion volume [T2LV], lesion distribution, cortical thickness [CT] and percentage of brain volume loss [PBVL]) were analyzed and compared between groups (P-NMOSD; NNMOSD) at disease onset and follow-up. A multiple sclerosis (MS) control group of patients was also included.

Results: We included 24 P-NMOSD, 15 NNMOSD and 35 MS patients. No differences in age, gender and follow-up time were observed between groups. Nor were differences found in lesion distribution at disease onset or in brain volumes during follow-up between P-NMOSD and NNMOSD patients (T2LV = 0.43, CT = 0.12, PBVL p = 0.45). Significant differences were observed in lesion distribution at disease onset, as well as in brain volumes during follow-up between NMOSD and MS (T2LV = p<0.001, CT = p<0.001, PBVL p = 0.01).

Conclusion: Different MRI features were observed between MS and NMOSD. However, no quantitative nor qualitative differences were observed between P-NMOSD and NNMOSD, not allowing us to differentiate NMOSD conditions by MRI.