Diagnostic goals of the procedures performed
| Clarify the presence of an abnormality identified on non-invasive imaging | 16 | 31% |
| Follow-up of a previously treated cerebrovascular lesion | 15 | 29% |
| Evaluate extracranial carotid or vertebral artery disease | 8 | 15% |
| Rule out underlying cause of intracranial hemorrhage | 5 | 10% |
| Rule out blunt cerebrovascular injury | 4 | 8% |
| Rule out cerebral vasculopathy | 2 | 4% |
| Rule out unruptured mycotic aneurysm | 1 | 2% |
| Surveillance of a known untreated cerebrovascular abnormality | 1 | 2% |