I had a head one done, it was very noisy, but the thing I found most uncomfortable, or rather, disconcerting, is when they injected the tracing fluid. I though

I had a head one done, it was very noisy, but the thing I found most uncomfortable, or rather, disconcerting, is when they injected the tracing fluid. I thought they would do it all the way through, but then I suddenly heard the pump start halfway through the procedure and a slightly cooler fluid running up inside my arms.