An alternative to evaluation of noncompressible vessels is to go directly to
doppler/imaging--that is, go directly to the artery in question and measure
how stenotic it is.
This "direct" approach works in our lab as we "scan" all LE arteries from top
to bottom, including entire lengths of the tibioperoneal system.
When we want to know if it is raining outside, we don't listen for drops on
the roof, etc. but rather go outside and "see" if it's raining.
Bon Secours Venice Hospital VasLab