Fig. 1

Diffusion-weighted imaging over time. Each row shows diffusion-weighted imaging at different times (from top to bottom: Oct 2019, Dec 2019, Feb 2020, and Apr 2020). The lesions showed restricted diffusion during progression, which lasted for 8 months. The foci were point-like (a, b red arrows), cord-like (a yellow arrows), patchy (c, d arrows), and incompletely symmetric (c, d, arrows) in the early stage. Subsequently, the lesions revealed progressive confluency (g and l arrows), and the lesions gradually enlarged (l, m arrows) and increased in areas such as the corpus callosum (n, o arrows)