Modified Suzuki scoring
| Score | Description of classification |
|---|---|
| 0 | No evidence of disease |
| I | Mild-to-moderate stenosis around ICA bifurcation with absent or slightly developed ICA MMDa |
| II | Severe stenosis around the ICA bifurcation or occlusion of either proximal anterior or MCA branches with well-developed ICA MMD |
| III | Occlusion of both anterior and MCA branches with well-developed ICA MMD (only a few of anterior or MCA branches or both are faintly opacified in antegrade fashion through meshwork of ICA MMD) |
| IV | Complete occlusion of both anterior and MCA branches with absent or small amount of ICA MMD (without opacification of either anterior or MCA branches in antegrade fashion) |
↵a ICA Moyamoya disease indicates perforating collateral vessels at or around the terminal ICA.