(A, B, and C) 63-year-old with multifocal glioblastoma. Postcontrast T1-weighted (A) and FLAIR (B) MRIs show bifrontal rim-enhancing tumors (*). Vasogenic edema surrounds both lesions and is FLAIR hyperintense (arrows). Although there is reduced diffusivity in the tumor walls from hypercellularity on trace diffusion-weighted imaging (C), there is no reduced diffusion in the surrounding vasogenic edema.
(D, E, and F) 97-year-old with acute ischemic infarction. Noncontrast CT (D) and FLAIR (E) MRI show abnormal hypodensity and signal hyperintensity, respectively, in the right insula, parietal operculum, and inferior parietal lobule. On trace diffusion-weighted MRI (F) there is hyperintense signal consistent with reduced diffusivity associated with cytotoxic edema.