The Internal Consistency of ASUM Guidelines for Measuring Carotid Stenosis

Sean Westbury, A/Prof David Airey

Abstract:

In 2015 Australian Society of Ultrasound in medicine revise for velocity criteria for

carotid stenosis. The new criteria are based on three semi-independent measurements

- the ICA peak systolic velocity(PSV), the ICAPSV:CCAPSV ratio, and the St Mary’s

ratio. There is little guidance on how to deal with discrepancy between these three arms.

To study the extent to which disagreement occurs, we applied the new criteria to

velocity measurements in 663 carotid duplex studies. There was perfect agreement in

525 (88.8%) cases; partial agreement in 107 (16.1%) and no agreement in 4 (0.6%)

cases. The Fleiss Kappa measurement for inter-measurement agreement was κ=0.51.

In a significant number of clinically significant cases, further interpretation will be required.