Not how we use it now, but the total amount of helium needed to run an MRI machine (with recapture) isn't all that much. Devices like acoustic cold fingers can use a very very small amount of helium to create a steady heat pump. Currently, such devices are not integrated into MRI machines because tubs of liquid helium are cheaper, but there is no reason why we couldn't build a closed-cycle MRI machine that didn't use any net helium.
Again, not the point of the discussion. MRI was a simple example of how we use helium today. I could have easily said party balloons. It would help any conversation you have in general to avoid nitpicking on insignificant items and keep the discussion on the main point (which, if I have to spell it out, is the quantity of helium required to do various things)
I do understand that when helium is depleted we will probably find other ways to accomplish things, but itβs still silly to be venting a gas that we KNOW has a finite amount over the lifetime of the Earth or using it for party balloons.
https://en.wikipedia.org/wiki/Thermoacoustic_heat_engine
https://en.wikipedia.org/wiki/Pulse_tube_refrigerator