Believe me, it will be ALL RIGHT! I had an MRI of the head after a suspected stroke and, like you, I was panicky about it as I am very claustrophobic. I was refused a "happy pill" or sedation (told it "wasn't necessary") but, honestly, it was not nearly as bad as I had feared and the time actually went very quickly. You have headphones on and the radiographers talk to you all the time (although I was not allowed music - possibly because it was a head scan?) and the mirror above your head allows you to see the nursing staff, so you really don't feel shut in. Concentrate on watching them (I did) and I also did a bit of deep breathing on the odd occasion I felt a bit jittery. And it was absolutely fine. Good luck - you'll feel proud of yourself when its finished!