I haven't have one of those tests but others have posted about it.

It might be called doppler also..I hope someone posts to clarify if I'm mistaken..

You might try the search tool in my siggy using terms like sonogram, doppler and such to find posts while waiting for others with more info to post.

Also arm pit sx/pain can be very much a soft tissue or lymph gland issue, there are many you tube vids on lymph massage and gentle stretches for that are.

If I hold a book for reading too long my armpit area gets sore, puffy and tender.
for me it is the static locked arm holding position, seems to clog up the lymph gland sand some massage and stretches clear it up.