T. Cunningham,
Interesting that you angle at 50 degrees.  Jean may get ruffled over that.
60 degrees has been out there forever.  I give you credit for looking beyond
it though.  So much of these comments say velocity, velocity, velocity.  But
we have found in our lab that people i.e. techs and interpreting physicians
become so number oriented they forget to look for plaque that may or may not
be there.  I do perform some diameter measurements at the area of highest
velocity when I want to verify the category I am in - usually 50-70%- or if
there seems to be unusually high velocities with minimal plaque, I want to
show the interpreting doc that there is no hemodynamic stenosis.  SB