What is a gray matter hyperintensity of 3mm on a brain mri result? (just trying to understand my results :))

Depends on image: Magnetic resonance imaging with and without gadolinium contrast shows hyperintensity depending on type of images, T1, T2, diffusing weighted or flair view. Each type of image views can because by various ideologies, including ischemia, plaques, infection, growth, bleed. Gray matter hyperintensity simply means changes seen based on the type of image.