I had to remove all of my earrings and my belly button piercing for all three of my MRIs, and for my ACL surgery. All three the hospitals had the same policy, which was no jewelry at all. It was so long since I'd taken out my belly button barbell prior to the first MRI that I was a bit concerned about getting it back in, but in the event it wasn't a problem. The one that bothered me most was having to remove my wedding ring for the surgery - it felt horrible going in without it!
I'd give the radiology department at the hospital a call and ask what their policy is. At least that way you'll know in advance, and could practice taking it in and out beforehand. I used to have my nose pierced, and it can be tricky getting the jewelry back in - especially if you use the studs with the little coil of wire at the back. Rings and straight studs are easier, so maybe have one of those on hand in case you do have to take it out and have trouble getting it back in.