I had a few MRIs after my first wreck..
You either can get a shot to be put to sleep, or if you can stay still for a hour, you will be put in the tube.
You stay in there for about 30-45 minutes, STAYING completely still, cant move only breath and blink. Sometimes they allow you listen to music also.
Plus, you will have to get in a certain clothing outfit, and leave all your stuff out of the tihng