How Does an MRI Work?

MRIs use magnets that produce a strong magnetic field, forcing protons in the body to align with that field. When a radiofrequency current is pulsed through the patient, the protons are stimulated and spin out of equilibrium. When the current is off, the protons realign, release energy, and send out signals picked up by receivers. 

These signals make digital images of the body's scanned area and distinguish between various tissue types as protons realign at different speeds and produce distinct signals.