Sequential subtraction.
D001921:Brain / Q000098:blood supply; D001932:Brain Neoplasms / Q000000981:diagnostic imaging; D002533:Cerebral Angiography; D007238:Infarction / Q000000981:diagnostic imaging; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging; D008545:Melanoma / Q000000981:diagnostic imaging; D008722:Methods; D009362:Neoplasm Metastasis; D013382:Subtraction Technique