What are the common intra-axial brain lesions associated with marked surrounding edema on MRI, and how can they be differentiated?

Metastases often present as multiple lesions with significant edema and ring enhancement. Abscesses typically show restricted diffusion on DWI and may have a central necrotic core. Glioblastoma multiforme (GBM) is characterized by an irregular ring-enhancing mass with central necrosis and can cross the corpus callosum. Radiation necrosis can mimic tumor recurrence but often shows less enhancement and increased T2/FLAIR signal. Hematomas may show a fluid-fluid level and evolve over time. Be cautious of mimickers like tumefactive demyelination, which can also present with edema and ring enhancement.