Velocity Criteria for ICA Stenosis: PSV, EDV, and ICA/CCA Table (IAC 2021)
According to the current criteria (IAC 2021 modification), the PSV threshold for ICA stenosis ≥50% is 180 cm/s, and for ≥70% it is more than 230 cm/s. The clinical significance threshold is 50%.
ICA Stenosis Criteria Table
| Degree | ICA PSV, cm/s | Plaque | ICA/CCA | EDV, cm/s |
|---|---|---|---|---|
| Normal | <180 | none | <2.0 | <40 |
| <50% | <180 | <50% | <2.0 | <40 |
| 50–69% | 180–230 | ≥50% | 2.0–4.0 | 40–100 |
| ≥70% (up to near occlusion) | >230 | ≥50% | >4.0 | >100 |
| Near Occlusion | any/undefined | — | variable | variable |
| Occlusion | no flow | lumen not visible | — | — |
Table 3.2 (IAC 2021 modification). 50–69% is permissible with PSV <180 cm/s if ICA/CCA >2.0 with significant plaque and post-stenotic turbulence.
Main Principle: By Combination, Not by PSV Alone
Velocity increases with the degree of stenosis, but variability is significant even in the ICA. The degree is determined by a combination: PSV + ICA/CCA ratio + EDV + post-stenotic turbulence + distal effects (tardus–parvus). IAC-VT standards (2024) require confirming severity, location, extent, and, if possible, etiology with images and spectra in the report.
Why There Are No Percentage Criteria for CCA, ECA, and Vertebral Artery
Velocity thresholds for ICA are validated against angiography (NASCET). For the common carotid, external carotid, and vertebral arteries, there is no validated percentage apparatus — instead of strict percentages, signs of hemodynamically significant stenosis are described.
Protocol and IMT — Briefly
A unified reproducible protocol is eight-step: starting with bringing the CCA strictly "on axis" and angiomorphometry. IMT is measured on the far wall of the CCA, about 1 cm proximal to the bifurcation, at the end of diastole (by ECG), using only edge-detection. Plaque is a separate finding, not included in IMT.
Structure of the Conclusion
The report separates the descriptive part and the conclusion and should be reproducible. The degree of stenosis is determined by the spectrum (PSV and PSV ratio), not by B-mode.
Частые вопросы
What is the PSV threshold for ICA stenosis ≥50%?
According to the IAC 2021 modification, it is 180 cm/s; for 50–69%, PSV is 180–230 cm/s with ICA/CCA 2.0–4.0 and EDV 40–100 cm/s.
How to distinguish stenosis ≥70% from 50–69%?
For ≥70% (up to near occlusion): PSV is more than 230 cm/s, ICA/CCA is more than 4.0, EDV is more than 100 cm/s with plaque ≥50%.
Are there velocity percentages for the vertebral artery?
No. For CCA, ECA, and vertebral artery, there are no validated percentage criteria — signs of hemodynamically significant stenosis are assessed.
Blagodir B.V. "Ultrasound Examination of Vessels", 2026 (ch. 3, Table 3.2 — IAC 2021 modification; ch. 4; BCA methodology; IMT). Consensuses: IAC/IAC-VT 2021/2024, SRU, NASCET.