"Aliasing" is a color-flow disturbance seen on Doppler color flow imaging associated with arterial stenosis that can help identify a stenotic arterial segment.
estimated area of renal arterial stenosis as percent of total cross-sectional area =
= (100 * (1 - ((peak systolic blood flow velocity in post-stenotic artery in cm/sec) / (peak systolic blood flow velocity in the stenotic segment in cm/sec))))
estimated area of flow in percent of cross-sectional area =
= 100 - (estimated area of stenosis in percent)
where:
• This is equation is similar to that for the renal arterial resistance index (previous section).
• Since the resistance index is determined by averaging 3 readings, I assume the same applies for this estimate.
Performance vs selective angiography in renal transplant recipients:
• Sensitivity 100%, specificity 88%.
• Positive predictive value 96% and negative predictive value 100%
