The document discusses various types of abnormalities that can appear on brain imaging scans. It describes different patterns of hyperintensity on T2-weighted MRI that can indicate conditions like age-related changes, small vessel disease, or multiple sclerosis. It also discusses enhancement patterns seen after administering gadolinium contrast, such as homogeneous enhancement of meningiomas or heterogeneous enhancement of tumors, metastases, and post-radiation necrosis.