Fisher CT Grading Scale20
| Fisher Group | Blood Pattern on Nonenhanced CT |
|---|---|
| 1 | No subarachnoid blood detected |
| 2 | Diffuse or vertical layers <1 mm thick* |
| 3 | Localized clot or vertical layers ≥1 mm thick |
| 4 | Intracerebral or intraventricular clot with diffuse or no subarachnoid hemorrhage |
* “Vertical” cisterns include interhemispheric, insular, and ambient.