A note about MRI machines: they use liquid helium, not liquid nitrogen. LN2 isn't cold enough. Being able to eliminate liquid helium would be huge, as helium is scarse and quite expensive. Its roughly 10x the cost of LN2 and only going to get more expensive.
Previous improvements in high-temperature superconductors already made it possible to build a MRI machine using LN2 instead of LHe. I think all existing operational units still use LHe, but using LN2 has been demonstrated in lab conditions, and the next generation of machines will almost certainly use it instead of helium.
It still might be worth cooling this with LN2, in many applications, assuming critical current and critical field scale up as temperature decreases as they do with other superconductors.
It takes a long time to validate new stuff for medical devices. Even if this discovery completely pans out, there will be two or three generations of MRI machines based on LN2-cooled superconductors.
They use both liquid helium and liquid nitrogen. The nitrogen is used to cool the helium. On MRI scanners that have come to market in the last few years, helium volume has been reduced at least 100x and is now only a few liters (i.e. previously >1000L and requiring frequent top off to <1L and requiring refill only after emergency/full power loss).
