Non-invasive imaging of the viscoelastic properties of intracranial tumors assessed by magnetic resonance elastography (MRE). Anatomical T2-weighted MR images, and parametric maps of elasticity (Gd) and viscosity (Gl), acquired from a non-tumor bearing mouse, and mice bearing tumors derived from human adult U-87 MG glioblastoma, N-ethyl-N-nitrosourea-induced RG2 rat glioma, or human triple negative MDA-MB-231 breast carcinoma cells are shown. (---) indicates the tumor boundaries defined on T2-weighted images. Images of whole hematoxylin and eosin stained sections obtained from the same mice are also shown, with the tumor location arrowed.