There is an extrinsic compression of the proximal portion of the left brachiocephalic vein between the innominate artery and medial end of the right clavicle. This is causing a moderate grade partial obstruction with numerous collaterals noted within the lower neck.
Test done by cat scan with contrast.
My symptoms are pinched nerve in arm and pain in left three fingers in my left hand. Upper back pain mostly when sitting when I use the I pad and even doing task through out the day.
There are a host of possibilities, and some relatively serious "medical" conditions need to be considered. Smoker? The apex of the lung is close by and can cause these symptoms and signs.
The collaterals are a good sign, suggesting a long standing chronic condition. The body has built up alternative paths for the blood to return to the heart.
Does placing your hand on your head increase the symptoms? That would point to a TOS indeed, confirmed by the tingling in fingers beyond the normal "dermatomal" pattern. The definitive test is called Adson's test - has any one taken your pulse whilst turning the head, looking up and taking in a deep breath? It's a difficult test, quite subjective and conclusions made only by a practitioner experienced in using the test.
Any swelling in the lower arm?
This is a condition with both "medical" and "chiropractic" causes. I recommend you consult both.
I hope this contributes.