Frequency of MRI abnormalities in adult-onset MOG-IgG-associated disease at disease presentation: A cohort of Latin American patients

Introduction: The 2023 diagnostic criteria for myelin oligodendrocyte glycoprotein-associated disease (MOGAD) compiled magnetic resonance imaging (MRI) features associated with core clinical demyelinating events. We aimed to characterize the frequency and distribution of typical MRI abnormalities in adult-onset MOGAD at disease onset in a Latin American (LATAM) cohort. Methods: We retrospectively reviewed medical records and MRI studies of 144 LATAM MOGAD patients that met the 2023 MOGAD criteria at their first documented attack (Chile, n = 40; Peru, n = 36; Argentina, n = 31; Brazil, n = 26; Colombia, n = 8; Ecuador, n = 3). Demographic and clinical characteristics, including relapse type, and MRI scans features performed within 30 days of the initial manifestation were evaluated. Results: Out of 144 MOGAD patients, 129 (89.6%) had MRI scans performed within 30 days of their first attack. In ON, perineural enhancement was the most common MRI finding (52 patients, 40.3%), followed by longitudinal compromise (48 patients, 37.2%); in spinal cord MRI, longitudinal lesions were most frequent (38 patients, 29.5%), followed by the H-sign (33 patients, 25.6%). Brain MRIs most frequently showed multiple ill-defined T2-hyperintense white matter lesions (27 patients, 21%), followed by ill-defined brainstem lesions (13 patients, 10.1%). Notably, 23 patients (17.8%) showed none of the typical features described in the 2023 diagnostic criteria. Conclusion: This study highlights the variability of MRI findings in adult MOGAD patients at disease onset, in a LATAM cohort. Most patients (82.2%) exhibited MRI features consistent with the 2023 diagnostic criteria, reinforcing their applicability in clinical practice, whereas 17.8% did not, underscoring the need for a comprehensive diagnostic approach.