Spinal cord MRI
Typical spinal cord MRI changes in both children and adult MOGAD patients are TM, often in the form of LETM, but also as short myelitis (46). MOGAD patients commonly present with LETM affecting the cervical and/or thoracic cord (41,47,51,73). LETM is also a main radiological feature in AQP4-NMOSD (46). Compared to AQP4-TM, conus involvement and multiple spinal cord lesions have been more frequently observed in MOG-TM (41,93,94). Short myelitis, which is typical of MS, can similarly be found in MOG-TM, however it is not found often in AQP4-TM (27,41,47,95,96). MOG-TM may present in spinal cord MRI as a hyperintense “H-sign” observed in the axial orientation, while imaged as a longitudinal thin vertical line in the T2-weighted sagittal plane image. This suggests a predominant affection of the spinal cord grey matter, as opposed to AQP4-TM, which may not be as centrally located in the cord (41,97,98). Gadolinium contrast-enhancement of spinal cord lesions is less common in MOG-TM compared to lesions in MS or AQP4-TM (41). Importantly, spinal cord MRI can initially be normal in MOGAD, although rare (99).