Coming in to this kind of late, but I hope all went well today. Truly you are not alone in what you are experiencing. I do ok up until an hour before I leave for the MRI. I take my lorazepam and by the time I get there I am relaxed enough to no freak and yet not fall asleep. I jerk too much in my sleep and that makes for a bad MRI/MRI do over. NOT happening. LOL
When I find my mind starting to wander in to negative thinking, I start praying the Rosary. There is a lot of concentration in that as you are counting and praying at the same time. It works well for me.
The last time I had my MRI, and I think mentioned this on another thread, the music was so low I couldn't hear it. So in my drug induced relaxed state, I used the noises in the tube to create my own music. That kept me occupied as I was busy trying to create a symphony and my focus was on something totally different. I had to really concentrate and think - what instrument does that noise sound like and what other sounds could I hear to match it.
Also, even though it can be painful to lay still, I do my dam*edest to lay still. I don't want a do over.

I can usually get the brain and cervical spine done within 30 to 40 minutes.
Anyhow, I do hope all went well today. Check in when you can and let us know how it went.