OK, got through it. It was no difficulty whatsoever. The noise didn't bother me, I'm not claustrophobic like I said (heartfelt prayers if you are). It was just a loud buzz, like if you were lying next to a buzzer alarm. It wasn't really that loud, especially with ear plugs in.

As far as lying perfectly still for 30 minutes, my years in Zen meditation has served me well. Now to wait for results...