A 72-year-old woman with a history of hypertension and diabetes mellitus presents with acute onset of left-sided weakness and slurred speech. Non-contrast CT brain performed 2 hours after symptom onset shows a hyperdense lesion in the right putamen with extension into the internal capsule. There is no evidence of subarachnoid hemorrhage. Which imaging modality is most appropriate to assess the extent of the hematoma and detect any underlying structural lesion (such as an arteriovenous malformation or tumor)?