My TOS was originally diagnosed by an MRA, not an MRI, of the chest.

An MRA takes a look at the blood vessels. In my case, the MRA showed a clear pinching of the subclavian artery (which is surrounded by the brachial plexus).

It seems like you usually end up at a vascular surgeon so maybe that's a route to take.

To be honest, I'd try and find somebody who can study your posture and movement vs. going right to the surgical advice first.

KY