We report this case to increase the awareness of magnetic resonance imaging (MRI) features of reversible white matter abnormalities in diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps in a patient with traumatic brain injury (TBI). An eight-year-old girl, who was hit by a truck, was brought to the emergency department by the emergency medical service (EMS). Eleven days later, she experienced cognitive impairment requiring MRI evaluation. DWI and ADC maps showed restricted diffusion in the white matter of the corpus callosum, peri-atrial white matter, and in the right centrum semiovale. There were no significant hemorrhagic foci in these regions, which showed complete resolution on follow up DWI MRI 13 days later. This reported case revealed TBI-related transient reversible intramyelinic cytotoxic edema.