[aidenn0]

The very first NMRI images were published in the early 70s, so at least some of what is required must be public domain now. The original diffusion and perfusion patents are both from the 80s, so should also be expired I think?

That being said it's very hard to make any even slightly novel machine (MRI or otherwise) that isn't so close to an existing patent that a judge would dismiss a suit out of hand.