>> Simply making liquid nitrogen MRI machine (instead of liquid helium) would be a billion dollar revolution. But we already have liquid nitrogen superconducto

>> Simply making liquid nitrogen MRI machine (instead of liquid helium) would be a billion dollar revolution. But we already have liquid nitrogen superconductors and they aren't used in MRI machines. I think the reason is something-something current density something - that they aren't suitable for that particular use for some other reason.