Introduction
Myelin oligodendrocyte glycoprotein (MOG) IgG antibody associated disorders (MOGAD) describe a new entity of demyelinating neurological syndromes defined by the presence of serum IgG autoantibodies against MOG detected by cell-based assays (1–3). MOGAD occur in both children and adults and comprise a heterogeneous disease spectrum (4,5). Clinical presentation can include monophasic or recurrent episodes of optic neuritis (ON), myelitis, brainstem syndromes, acute disseminated encephalomyelitis (ADEM), and symptoms of encephalitis such as seizures (6,7). Overall, MOGAD are rare with an incidence of around 1.1 - 2.4 per million people (8) and are more frequent in children compared with adults, as shown in a recent Dutch cohort with an incidence of 3.1 per million in children (9).
Importantly, a direct pathophysiological effect of the MOG-IgG in the central nervous system has yet to be elucidated (2). Therefore, it remains unclear whether MOG-IgG has a direct pathogenic role or whether it is rather a biomarker, that is a possible reflection of an immunological response from disrupted myelin in the MOG-IgG associated demyelinating disease spectrum. However, increasing clinical and pathological evidence now strongly indicates that MOGAD represent a distinct disease entity different from other neuroinflammatory and demyelinating diseases, such as multiple sclerosis (MS) or aquaporin-4 (AQP4) IgG positive neuromyelitis optica spectrum disorder (NMOSD) (10–15). Moreover, these conditions apparently exhibit differential responses to immunotherapies, underscoring the necessity for accurate and timely diagnostic procedures during which neuroimaging play a paramount role (16–21). Due to the widespread nervous system affection in MOGAD, magnetic resonance imaging (MRI) and optical coherence tomography (OCT) are important imaging tools in gaining more knowledge about the disease and for the monitoring of patients with this rare set of disorders (22,23). This review article will give an overview of the clinical, radiological, and advanced imaging aspects which are currently of high interest in the MOGAD clinical research community.