CT scans and MRIs are two different types of scans, done in different machines. A CT machine like a doughnut on its side - the hole you go in is wider and shorter. MRIs are more coffin-tubed shaped. If you go in feet first (for an MRI scan on your knee say) it’s ok because your head is on the outside. If you’re having a brain scan you go in head first, your head stabilised by a plastic support so you can’t move it. It’s so narrow in there you can bend your arm up 90 degrees, let alone sit up. The stabiliser stops you from moving at all. They put foam ear plugs in your ears and then big over ear headphones over that so the tech can talk to you and you’re not crippled by the noise. There’s a tiny mirror above your eyes, angled to you can see out of the tube. I’m not claustrophobic at all and I have to fight panic when I’m im in there. I think you may have had CT scans in the past, not MRIs. And if you had a MRI, you probably didn’t go in head first because it’s not really an experience anyone could describe as relaxing. Well maybe cave divers, or people who make homemade submarines might find it relaxing, but for your average joe it’s unpleasant.