Carotid Stenosis (NASCET / ECST) — free guideline decision tool
Compute extracranial carotid (ICA) stenosis from diameters using the NASCET method (optional ECST) with grade and management direction.
Open guideline tool →Guideline-based
Implements the decision logic from published clinical guidelines.
Runs in your browser
No installation. Enter the patient's values and get a guideline recommendation instantly.
Data stays local
Nothing is uploaded. Results are for licensed clinicians only.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Narrowest residual lumen A | 1.5 mm |
|---|---|
| Distal normal ICA diameter B (NASCET reference) | 5.0 mm |
| Estimated original bulb diameter C (ECST, optional) | 8.0 mm |
| Clinical context | Symptomatic (ipsilateral TIA/stroke/amaurosis within 6 mo) |
→NASCET stenosis70% · Severe (≥ 70%)
- NASCET：(1 − A/B)×100 = (1 − 1.5/5)×100 = 70%
- ECST：(1 − A/C)×100 = 81% (C = estimated original bulb diameter; ECST usually exceeds NASCET, ~ 70% NASCET ≈ 78% ECST)
- Grade：Severe (≥ 70%) (NASCET method: mild < 50%, moderate 50–69%, severe ≥ 70%)
Common questions
What is Carotid Stenosis (NASCET / ECST)?
Compute extracranial carotid (ICA) stenosis from diameters using the NASCET method (optional ECST) with grade and management direction.
How is Carotid Stenosis (NASCET / ECST) calculated? What is the core formula?
NASCET = (1 − A/B)×100, where A = narrowest residual lumen and B = distal normal ICA diameter. Mild < 50%, moderate 50–69%, severe ≥ 70%. ECST = (1 − A/C)×100 (C = original bulb diameter).
When is Carotid Stenosis (NASCET / ECST) used?
Quantify carotid stenosis for revascularization decisions in symptomatic and asymptomatic disease.
What are the key clinical points for Carotid Stenosis (NASCET / ECST)?
Exclude near-occlusion (distal collapse/string sign) first — the method does not apply. Symptomatic ≥ 50% usually warrants early evaluation for revascularization (CEA often preferred). For extracranial ICA only — not intracranial (use WASID), CCA/ECA or in-stent restenosis.
What are the limits and cautions when using Carotid Stenosis (NASCET / ECST)?
For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
How is Carotid Stenosis (NASCET / ECST) calculated in practice? Can you show a worked example?
Inputs: Narrowest residual lumen A 1.5 mm, Distal normal ICA diameter B (NASCET reference) 5.0 mm, Estimated original bulb diameter C (ECST, optional) 8.0 mm, Clinical context Symptomatic (ipsilateral TIA/stroke/amaurosis within 6 mo) → Result: NASCET stenosis 70 % · Severe (≥ 70%)（NASCET: (1 − A/B)×100 = (1 − 1.5/5)×100 = 70%, ECST: (1 − A/C)×100 = 81% (C = estimated original bulb diameter; ECST usually exceeds NASCET, ~ 70% NASCET ≈ 78% ECST), Grade: Severe (≥ 70%) (NASCET method: mild < 50%, moderate 50–69%, severe ≥ 70%)）
Run Carotid Stenosis (NASCET / ECST) now
Compute extracranial carotid (ICA) stenosis from diameters using the NASCET method (optional ECST) with grade and management direction.
Open guideline tool →For licensed clinicians. Not a substitute for clinical judgement.
Paste the link in Slack, Teams, X, or LinkedIn — the preview image comes from this page’s Open Graph card.