Maybe it's a general term for US of that whole area???
and not to only check the carotid artery??

Might be easiest to call the place that is doing the testing and ask what areas that carotid test entails?
and if it will help to verify or rule out vertebro-basilar insufficiency & subclavian steal syndrome"?

then you don't have to bother the doctor..unless you find out it is the wrong test.