I know that and we also determine flow velocities but often the stenosis can
be underestimated due to arrhytmias, subocclusive stenosis, hypertension or
contralateral stenosis. I think that except for calcified plaques, percent
stenosis is useful, but correlation with angiography is difficult.

    We do not use 2D diameter or area stenoses calculations in our lab, we
have found them to be unreliable. In our lab we use peak systolic and end
diastolic velocities and for the 70-99% category we also use the IC/CC ratio.
When there is contralateral stenosis, we usually bump the category "up one"
to compensate for it. As far as arrhythmia, I try to use the most consistent
peak and not the highest. '
    The initials I placed behind my name relate to registries that I have
passed from the American Registry of Diagnostic Medical Sonography.
RVT=Registered Vascular Technologist, RDCS= Registered Diagnostic Cardiac
Sonographer, RDMS=Registered Diagnostic Medical Sonographer( this category
has several subspecialties such as abdomen, OB-GYN and Neurosonography) RT(R)
=Registered Technologist Radiography. :-) Hope this helps!
    What criteria are you using?