🩻 Intracranial Stenosis (WASID)
Compute intracranial arterial stenosis from diameters using the WASID method (distinct from the extracranial NASCET method).
Symptomatic 70–99% stenosis is managed primarily with intensive medical therapy.
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When to use
Quantify intracranial large-artery stenosis to guide intensive medical therapy decisions.
How it works
WASID = (1 − Dstenosis/Dnormal)×100, using the proximal normal segment (or distal if proximally diseased). Mild < 50%, moderate 50–69%, severe 70–99%.
Key points
- Symptomatic 70–99% stenosis is managed primarily with intensive medical therapy.
- SAMMPRIS showed routine stenting is not superior to medical therapy.
- Choose the reference segment carefully for the basilar artery.
References
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 stenosis diameter (Dstenosis) | 1.0 mm |
|---|---|
| Proximal normal diameter (Dnormal) | 3.0 mm |
| Vessel | Intracranial ICA |
→WASID stenosis67% · Moderate (50–69%)
- WASID：(1 − Dstenosis/Dnormal)×100 = (1 − 1/3)×100 = 67%
- Vessel：Intracranial ICA
- Grade：Moderate (50–69%)
Frequently asked questions
- What is Intracranial Stenosis (WASID)?
- Compute intracranial arterial stenosis from diameters using the WASID method (distinct from the extracranial NASCET method).
- How is Intracranial Stenosis (WASID) calculated? What is the core formula?
- WASID = (1 − Dstenosis/Dnormal)×100, using the proximal normal segment (or distal if proximally diseased). Mild < 50%, moderate 50–69%, severe 70–99%.
- When is Intracranial Stenosis (WASID) used?
- Quantify intracranial large-artery stenosis to guide intensive medical therapy decisions.
- What are the key clinical points for Intracranial Stenosis (WASID)?
- Symptomatic 70–99% stenosis is managed primarily with intensive medical therapy. SAMMPRIS showed routine stenting is not superior to medical therapy. Choose the reference segment carefully for the basilar artery.
- What are the limits and cautions when using Intracranial Stenosis (WASID)?
- 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 Intracranial Stenosis (WASID) calculated in practice? Can you show a worked example?
- Inputs: Narrowest stenosis diameter (Dstenosis) 1.0 mm, Proximal normal diameter (Dnormal) 3.0 mm, Vessel Intracranial ICA → Result: WASID stenosis 67 % · Moderate (50–69%)（WASID: (1 − Dstenosis/Dnormal)×100 = (1 − 1/3)×100 = 67%, Vessel: Intracranial ICA, Grade: Moderate (50–69%)）