MRI

MRI is brilliant for imaging our bodies, it does so non-invasively meaning theres no injections or cutting. You do however, have to stay extremely still in a very uncomfortable environment. It is well worth the discomfort when you get to see your body, inside-out.

Radiofrequency, RF waves are a form of electromagnetic energy and can excite the protons in living tissue. The protons get excited to a higher energy level, then a photon (light), is released as the proton 'relaxes' back to it's resting energy level. Protons act like tiny magnets with their own associated field which can cancel out. This along with all the noise generated by protons in areas that are not the focus, make the information the photons are sending out very difficult to pick up and interpret. An analogy is a room full of people talking at the same time, each person is saying something meaningful, but the room from a distance sounds like a meaningless cloud of noise. By setting up an external magnetic field, an environment is set up in which protons will line up either upward or downward, parallel to the field. A net magnetic field is then created by the protons with a strength that is proportionate to the strength of the magnet. The stronger the magnet, the more protons align, the less noise from "other voices".
RF pulses help each proton to rotate and move in unison at 90degrees to the magnetic field. Aligning to 90degrees from the field, reexcites the protons to higher energy states which takes to steps to return to a resting state from.