Had vq scan they injected dye but didn't stick needle in me put little tube in my arm injected it into that what is the tube thing?

The little tube is: an IV (intravenous) catheter. Very likely a needle was used to insert it: a needle is inside the tiny plastic tube/catheter;it punctures through the skin into a vein. Then the plastic tube slides off the needle, remaining in the vein, and the needle is removed.The needle would continue to cut and damage the blood vessel if it remained in. Some IV systems sheath the needle when withdrawn for safety