Time is different when you’re inside an MRI machine. It both slows down - so you feel like it’s taking a lifetime, and speeds up. I have had a lot of MRI scans and now find the noise a bit hypnotic. I virtually fall asleep (I actually have done a couple of times!)
The advice from Befuddled is excellent. Try to keep calm, counting is good, or writing a mental shopping list. I tend to close my eyes too. You always have a rubber ball to hold, if you begin to panic, you can press the bulb and the radiographers will talk to you. They tend to ask regularly if you’re OK anyway.
If they don’t give you one automatically, ask for a wedge to go under your knees. It is more comfortable and helps you to stay still.
Make sure you don’t have any metal on you, including bra straps and underwiring. Wear warm comfy clothes, especially socks. It can get nippy. Think about the fact that they may want to use contrast dye, this means they pull you out midway through and inject you with the dye into a cannula that they’ll put in beforehand. The contrast helps the radiographer and neurologist see enhanced detail and any current inflammation. But you need to be wearing something that can be shoved up above your elbow because of the cannula.
Try not to worry too much, tell the radiography staff that you are nervous and claustrophobic. They’ll understand and will try to keep you comfortable and relaxed.