Happysexegenarian I have had 3 MRI scans at various times for various reasons, and none has lasted more than 30 minutes. yesterday was 20 minutes. It all depends on how much they want to scan.
Just lie back shut your eyes and find something to think of. As my eyes automatically shut when I lie down, like a doll, I just drift into a mousy twilight and listen to the various noises the machine makes. They are many and vared and one sounded like a voice saying boom, boom, boom.
Alternatively think of something specific. When I got bored with the sounds I took the opportunity to plan next week's menus.
The main thing not to do, is keep thinking about it reading the stories of those who did not like the experience and worrying about it.
Personally, I would sooner have an MRI scan than go to the dentist - painful injection, numb mouth, dentist with drill doing things in your mouth, unable to eat for hours afterwards until the anaesthetic wears off. Compared with lying on a bed on your back for 30 minutes, no pain, no discomfort and no after effects.