Validation of Edema-invariant Multi-shell High Angular Resolution Diffusion Imaging (msHARDI)-Based Tractography With Intra-operative Cortical Stimulation

Inclusion Criteria: * brain lesions, including but not limited to tumors, epileptic foci, and vascular abnormalities, in or around eloquent brain regions (i.e., motor, language); * clinical need for pre-operative 'advanced imaging' (which includes conventional DTI); * age between 18-80 years of age; * male or female gender. Eloquent regions include: Temporal and frontal lobes (speech/language); bilateral occipital lobes (vision); bilateral parietal lobes (sensation); and bilateral motor cortex (movement). Exclusion Criteria: * a contraindication for obtaining an MRI scan (e.g. implanted devices, retrained foreign body) * pregnancy * absence of the capacity to make medical decisions or provide informed consent.