Mri file format?

Speaking with my gp today, they said that if a report can be obtained
it would only be written; that there wouldn't be any interesting images
to look at, and I'll just have to take the radiologist's word on things.
But given my track record with doctors lately, that leaves me wondering.

So they say the Mri is stored on cd-rom. And maybe I can persuade them
to let me have a copy. But what is the file format for the images they
took? I'd love to send it out by email to friends and experts everywhere,
and it would make a neat wallpaper for my x-windows desktop

Any ideas? - Melissa