I remember one of my science teachers in high school saying this back in the day...said to buy it up (jokingly...just to get his point across on the shortage).
The space shuttle launches were delayed since some magnet that is going up used a helium cooling system. They decided to scrap that powerful magnet for a "regular" one that doesn't require a helium cooling system. My guess is the MRI uses something similar.
Who knows, maybe in 50 years people will be watching old Youtube videos of us breathing in Helium to get our voices to sound weird. They'll be angry with how wasteful we've been, LOL!