A standardized systematic approach is essential for grading carotid stenosis using doppler ultrasound. It involves taking multiple parameters into consideration:
- B mode imaging: vessel diameter, vessel area
- plaque characterization
- assessing color flow
- documenting hemodynamic flow velocities at and beyond stenosis
- understanding collateral flow status
Low degree stenosis (0% to 40%) [NASCET]
- B-mode imaging is relevant. Measure length and thickness of plaque. Calculate diameter reduction percentage as well as residual lumen.
- PSV ≤ 125cm/sec
- carotid ratio (ICA PSV/CCA PSV) <2
Moderate degree stenosis (50% to 60%) [NASCET]
- B-mode imaging is possibly relevant.
- PSV >125cm/sec and <230cm/sec
- collateral flow is absent
- carotid ratio ≥2
Hemodynamically relevant stenosis (≥70%) [NASCET]
- independent of B mode imaging
- PSV >230cm/sec
- EDV>100cm/sec
- carotid ratio >4
- post stenotic PSV
- ≥50cm/sec – 70%
- <50cm/sec – 80%
- <30cm/sec – 90%
- positive collateral flow
To summarise,
