An MRI machine, or Magnetic Resonance Imaging, is a medical imaging device that uses a magnet in order to take detailed images inside the human body.
Other imaging devices use radiation in order to garner images of the human body, but the MRI is unique in that it uses a giant magnet measuring 5,000 to 20,000 gauss. For comparison, the Earth’s magnetic field is only 0.5 gauss! Another commonly used unit of measure for the MRI is the tesla, (named after Nikola Tesla,) and 1 tesla equals 10,000 gauss.
Magnetic fields have to be created for the MRI machine to work, and this is done by many currents of electricity passing through the wire coils inside the machine. The magnetic field is maintained by superconductivity, which is reducing the coils of wire to almost zero by bathing them in liquid helium. MRI’s also use five other magnets: three gradient magnets, the permanent magnet, and the resistive magnet. The coils inside the MRI machine correlate to different parts of the body such as the knees, head, neck, etc., and they transmit radiofrequency waves into the patient’s body in order to make an image.
MRI machines come in Closed, Open, Extremity, and Stand Up. Closed machines are the most common, having the giant round opening where the patient enters called the bore. Open MRI machines are designed for patients who experience claustrophobia, and have two magnets parallel to one another. Extremity MRI’s are designed for smaller parts of the body such as arms, legs, and feet. And Stand Up MRI’s make it possible to image patients spines and joints in their natural states.
MRI machines are used in hospitals, medical facilities, and labs and are used to diagnose a variety of disorders including strokes, aneurysms, spinal cord injuries, multiple sclerosis and eye or inner ear problems, according to the Mayo Clinic.