Stenosis grading of the internal carotid artery (internal carotid artery).
| Degree of stenosis (NASCET definition) [in %]. | 10 | 20-40 | 50 | 60 | 70 | 80 | 90 | Closure | |
| Degree of stenosis, old (ECST definition) [in %]. | 45 | 50-60 | 70 | 75 | 80 | 90 | 95 | Closure | |
| Main criteria | 1. b-picture | +++ | + | ||||||
| 2nd color doppler image | + | +++ | + | + | + | + | + | +++ | |
| 3. peak systolic velocity at stenosis maximum (cm/s) ca. | 200 | 250 | 300 | 350-400 | 100-500 | ||||
| 4. peak systolic velocity poststenotic (cm/s). | > 50 | < 50 | < 30 | ||||||
| 5. collaterals (lateral or collateral branches of a conduction pathway addressing the same supply area) and precursors (periorbital arteries/ACA) | (+) | ++ | +++ | +++ | |||||
| Additional criteria | 6. diastolic flow slowing prestenotic (ACC). | (+) | ++ | +++ | +++ | ||||
| 7. flow disturbances poststenotic | + | + | ++ | +++ | (+) | ||||
| 8. endiastolic flow velocity at stenosis maximum (cm/s) ca. | up to 100 | up to 100 | > 100 | > 100 | |||||
| 9. confetti sign (perivascular tissue vibration). | (+) | ++ | ++ | ||||||
| 10. stenosis index ACI/ACC | ≥ 2 | ≥ 2 | ≥ 4 | ≥ 4 | |||||
Legend:
- Notes: ACA: anterior cerebral artery (anterior cerebral artery). ACC: common carotid artery (common carotid artery). ACI: internal carotid artery (internal carotid artery), degree of stenosis (degree of narrowing) according to NASCET [%]: the figures each concern a 10% range (± 5%).
- Ad 2: Detection of low-grade stenosis (local alias effect) in differentiation from non-stenosing plaque, representation of the direction of flow in medium- and high-grade stenosis, and detection of vessel occlusion.
- Ad 3. criteria apply to stenoses with a length of 1-2 cm and only limited in multi-vessel processes.
- Ad 4. measurement far distal, outside the zone with jet stream and flow disturbances.
- Ad 5: Possibly only one of the collateral connections is affected: if extracranial alone is examined, the value of the findings is lower
- Ad 9: Confetti sign is only detectable when pulse repition frequency (PRF) is set low.
