The differential diagnosis for ring-enhancing cerebral lesions includes cerebral abscess, tuberculoma, neurocysticercosis, metastases, glioblastoma multiforme, demyelination (incomplete ring), etc. See mnemonic  MAGIC DR.

The dual rim sign is a very specific imaging feature that is typically seen in pyogenic brain abscesses.

DWI is very useful and shows a high DWI signal that is usually present centrally.