They'll make you take off any metal, and talk to you about possible metal slivers you might have in your body.

I had 2 MRIs of my head. The worst thing for me was holding still and being bored. The machine is very loud. They gave me ear plugs, and your techs should do so as well, but you may want to ask before you go, so you can bring your own if necessary.

I think my time in the scanner lasted about 20 minutes, but it felt like longer because I was bored and couldn't move. No lasting effects.