🩻 Intracranial Stenosis (WASID)
Compute intracranial arterial stenosis from diameters using the WASID method (distinct from the extracranial NASCET method).
Intracranial Stenosis (WASID)
Narrowest stenosis diameter (Dstenosis) (mm)
Proximal normal diameter (Dnormal) (mm)
Vessel
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
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.