The differential diagnosis list of ring enhancing focal brain lesion with the mnemonic "MAGIC DR":
In this case the lesions multiplicity, the significant edema and absence of restriction on DWI with absence of clinical history of trauma or symptoms of infectious process makes metastases the most likely diagnosis. Further imaging workup of this patient revealed a lung mass with multiple disseminated metastatic lesions.
The clinical presentation of hemiparesis in this patient, specially in an elderly patient who has no specific medial history, is misleading. The findings on the first non-enhanced CT, which is routinely done for patients with suspicious stroke, were missed by the reporting radiologist and were reported as a case of stroke. Even if the metastatic lesions themselves are not very evident on the non-enhanced CT, a special attention should be given to the pattern of hypodensity (edema) we see here involving the subcortical white matter and sparing the cortex, which is suggestive of edema rather than infarction as ischemic lesions usually involve a whole territory including the cortex.