It's a very simple and pain free procedure. If possible, you should wear sweats or drawstring shorts, avoiding metal items. Bring socks--it gets cold in those tubes! Sometimes you can bring a CD and they will play it for you during the test. The whole thing takes about 20-40 minutes depending on the number of views the doctor wants. You lie on a table that moves in and out of a big tube (your head stays out) and just relax and hold VERY still while the machine does its thing. It can get loud with thumping noises, but usually they will play music for your. The attendant talks to you over the headset.
It's completely painless and you should be fine.
Heather