I agree with Jo, if it is a standard MRI, not a top one done by a tos doc reading it, it is not likely to ever say TOS. MRI are generally used to rule out other items,
Oh, for it to be so easy to see TOS on a MRI.

TOs is sick nerves, sensory nerves, they are the first affected not the larger one tested in am EMG. Those larger myliented/sheathed or covered nerves are the ones that make the muscle move in the arm; as you feel heat from a candle a nerve will make the arm jerk away..motion!

These are what is tested. TOS is not affecting these nerves until later, the first nerves affected small sheathed, myliented nerves are the ones that when the candle burnt you, your skin it red, hurts and send pain to the brain....These cannot be tested by a normal EMG/NVC.'However, Rick Reed and Tom TOlson in Norristown and N.E. PA do test in a manner they can detect the "F" waves or whatever it is to show TOS.

On the forum is a technical artical of how they detected it in their EMG...I will bump up
You symptoms sound like TOS symptoms, Some have front chest pain, I also have the under the wings, underarm tenderness and above my wing feels like a butcher knife in it. The base of my skull had a huge knot it took years to get rid of. I had terrible cervogenic migraines from it. Arms, and the palms of hands are vivid red, to purple tips, and blotches with use. My ring size is up two full sizes.

Most doctors are really just trying to treat the symptoms, you are a puzzle and the pieces are all over their desk, bit and pices makeing some shape and other not fitting into any place....Unless they specialize in diagx TOS, you will likely be given a mimicing diagx.
I hope that you can find some help and answers,
Dianne