Electromagnetism in MRI's

MRI

An MRI, or magnetic resonance imaging scan, is used to create a detailed image of tissue and muscles within a body. It uses radio waves, a large magnet, and a computer to create the image. An MRI scan can even create a 3-D image. The first MRI scanner was created in 1977 by Raymond Damadian. He nicknamed the scanner "The Indomitable". The MRI scan doesn't use ionizing radiation and is considered a non-invasive and harmless procedure. Although MRI is most frequently for the brain and spinal cord, it can also be used to look at the heart, blood vessels, bones, joints, and internal organs.

How an MRI Works

As previously mentioned, MRIs use radio waves, a large magnet, and a computer to create an image of the human body. There are two categories of MRI magnets- an electromagnet and a permanent magnet. An electromagnet is created when an electric current is conducted through coils of copper wire within the MRI machine. 

MRI scanners also contain radio frequency coils and magnetic field gradients that collect and spatially organize data. To protect the image from being damaged by radio frequency, a Faraday cage made from copper mesh exists within each MRI room. MRIs with resistive electromagnets, as opposed to permanent or superconducting magnets, have a magnetic field strength of 0.3 T or less. They require the most power out of the magnets, and because of this power consumption, they are the least popular.

Video on the basics of an MRI
In-depth video on MRI physics