Defined by NASCET (% +‐ 5%)	10%	20‐40%	50%	60%	70%	80%	90%	occlusion
Defined by ECST (% +‐ 5%)	45%	50‐60%	70%	75%	80%	90%	95%	occlusion
Main criteria (1‐5)
1. B‐mode image	+++	+
2. Color Duplex image	+	+++	+	+	+	+	+	+++
3. Intrastenotic PSV (cm/s)			~200	~250	~300	350‐400	100‐500	‐
4. Post‐stenotic PSV (cm/s)					> 50	< 50	< 30	‐
5. Collaterals and precursors (periorbital arteries/ACA)					(+)	++	+++	+++
Supplementary criteria (6‐10)
6. Pre‐stenotic EDV reduction					(+)	++	+++	+++
7. Post‐stenotic flow disturbances			+	+	++	+++	(+)
8. Intrastenotic EDV (cm/s)			< 100	< 100	> 100	> 100
9. Perivascular tissue vibration				(+)	++	++
10. PSV ratio (ICA/CCA)				≥ 2	> 2	≥ 4	≥ 4