In this study, where was the CCA spectral velocity obtained for conparison
with the ICA for the ICA:CCA ratio? As you know proximal velocities are
generally higher than mid CCA velocities in a non-stenotic CCA.
Zwiebel states that the CCA component of the ratio should be the "peak
velocity obtained in a normal portion on the CCA, proximal to the stenosis (of
the ICA)". This is very non-specific leaving room for great variation in the
ICA:CCA depending on where the CCA is measured. I generally use the mid CCA
for the ratio. I don't know if there are specific guidelines for the place of
aquisition of the CCA or that these guidelines, if they exist, are uniformly
used clinically or in reasearch studies.
Any thoughts?