Interesting fact for the day - mate had a conversation with a radiographer who has a thing against balloons. Helium Balloons.

Why? You ask, they're floaty and coloured and fun! And a potential choking hazard for marine life! Hoorah! The reason is that helium is relatively rare, and growing increasingly rarer, and it is used in MRI machines to cool the superconducting magnets. In his lifetime, he said, they will have to develop another way around this if they want to keep MRIs running. I thought this was so interesting and disturbing that I looked it up on the most reliable source on the web - Wikipedia.

Here's what it has to say on the matter:

"Helium is used in cryogenics (its largest single use, absorbing about a quarter of production), particularly in the cooling of superconducting magnets, with the main commercial application being in MRI scanners. Helium's other industrial uses- as a pressurizing and purge gas, as a protective atmosphere for arc welding and in processes such as growing crystals to make silicon wafers- account for half of the gas produced. A well-known but minor use is as a lifting gas in balloons and airships.[2] As with any gas with differing density from air, inhaling a small volume of helium temporarily changes the timbre and quality of the human voice. In scientific research, the behavior of the two fluid phases of helium-4 (helium I and helium II), is important to researchers studying quantum mechanics (in particular the property of superfluidity) and to those looking at the phenomena, such as superconductivity, that temperatures near absolute zero produce in matter. Helium is the second lightest element and is the second most abundant in the observable universe, being present in the universe in masses more than 12 times those of all the heavier elements combined. Its abundance is similar to this figure in our own Sun and in Jupiter. This is due to the very high binding energy (per nucleon) of helium-4 with respect to the next three elements after helium (lithiumberyllium, and boron). This helium-4 binding energy also accounts for its commonality as a product in both nuclear fusion and radioactive decay. Most helium in the universe is helium-4, and is believed to have been formed during the Big Bang. Some new helium is being created currently as a result of the nuclear fusion of hydrogen in stars greater than 0.5 solar masses.
On Earth, the lightness of helium has caused its evaporation from the gas and dust cloud from which the planet condensed,[citation needed] and it is thus relatively rare—0.00052% by volume in the atmosphere. Most terrestrial helium present today is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium), as the alpha particles emitted by such decays consist of helium-4 nuclei. This radiogenic helium is trapped with natural gas in concentrations up to 7% by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation."

Had to share! :)