Table 3.
Definition of the classification system used to quantify the collateral vessel number and size.
| Category | Number of collateralsa |
|---|---|
| Category 0 | 0 collateral vessels |
| Category 1 | 1–3 collateral vessels |
| Category 2 | 4–7 collateral vessels |
| Category 3 | ≥8 collateral vessels |
|
| |
| Collateral vessel grade | Size of collateral vessels |
|
| |
| Grade 0 | 0 collateral vessels |
| Grade 1 | ≤5 small |
| Grade 2 | >5 |
| Grade 3 | ≤5 large ± small |
| Grade 4 | >5 large ± small |
aSmall collaterals occupy <25% of the length of the imaged thigh and <50% of the diameter of the superficial femoral artery. Large collaterals occupy >25% of the length of the imaged thigh and ≥50% of the diameter of the superficial femoral artery.