Figure 1. Myelin vacuolization: MRI features and reversibility.

In megalencephalic leukoencephalopathy with subcortical cysts (A–C), T2-weighted images (A) show diffuse cerebral white matter abnormalities, which have increased diffusion leading to low signal on diffusion-weighted images (B) and high signal on apparent diffusion coefficient maps (C), indicating large water spaces. In the early stages of leukoencephalopathy with thalamus and brainstem abnormalities and lactate elevation (D–F), MRI shows extensive cerebral white matter abnormalities and involvement of the thalamus (D). Diffusion is markedly decreased in the abnormal areas with high signal on diffusion-weighted images (E) and low signal on apparent diffusion coefficient maps (F), indicating compressed water spaces. Two years later (G–I), most signal abnormalities have disappeared (G) and the diffusion has normalized (H and I).