Fig. 4

Representative DWI findings of NMOSD and small SCI. A 74-year-old woman noticed muscle weakness and numbness in the lower extremities. MRI was performed 5 days after symptom onset and revealed a T2 hyperintense lesion at the T4–9 level (a); moreover, small hyperintensities were observed around the T7 level on DWI (arrows, b). On ADC maps, the DWI hyperintensities were isointense (horizontal arrows, c) as compared with the intensity of the adjacent normal cord (oblique arrow, c) and surrounded by hyperintense regions. Her serum was positive for anti-aquaporin 4 antibody and these lesions were considered caused by NMOSD. Another patient is a 52-year-old man who presented with gait difficulty and mild muscle weakness in the right lower limb. Although MRI performed 5 days after symptom onset revealed no responsible lesion on the T2 sagittal image (d), an axial slice performed at the same occasion (indicated by an arrow in panel d; T8 level) demonstrated a right-sided lesion in the territory of the posterior spinal artery on T2-weighted imaging (e) and DWI (f). The lesion was hypointense on the ADC map (g) and he was diagnosed with spinal cord infarction. ADC, apparent diffusion coefficient; DWI, diffusion-weighted imaging; MRI, magnetic resonance imaging; NMOSD, neuromyelitis optica spectrum disorder