Q: How does an MRI scanner work?
A: Magnetic Resonance Imaging is one of the most useful tools for looking inside the body to diagnose disease. The MRI scanner is a large magnet, FM radio and dancing protons. Each of the hydrogen atoms (protons) in your body, which are mostly in water and fat, can be thought of as very tiny magnets. The scanner has a powerful magnet that lines up a lot of these protons. We turn on the radio for a few milliseconds and give the atoms enough energy to tilt a little bit away from the scanner's magnetic field. When we turn off the radio, the atoms give up that energy in the form of radio waves that we can listen to and, after many repetitions, form into a picture. Since the MRI scanner only uses a magnet and radio waves, there is no exposure to radiation. The next time you're having an MRI scan, remember it's just a big magnet with a bunch of hydrogen atoms listening to the radio and doing the proton dance.
-Dr. R. Kent Hutson, EmCare Radiology Services; member, Chattanooga-Hamilton County Medical Society
Submit your health-related questions for a medical doctor to firstname.lastname@example.org.