How MRI Works
What is MRI?
MRI stands for Magnetic Resonance Imaging. Using MRI machines like the scanner in this picture, doctors and researchers use powerful magnets and radio waves to get clear pictures of what is going on inside your body or inside your brain, without X-rays. Worldwide more than 60 million MRI exams take place each year.
How does MRI work?
MRI works because the human body is mostly water. This means you have lots of hydrogen atoms spinning around inside of you. Inside the MRI scanner, imagine a giant magnet that pulls all those hydrogen atoms to point in the same direction, so that they line up like microscopic compass needles. Pulsing radio waves
are sent when an MRI exam is being performed. When these waves pulse through the magnetic field, the hydrogen atoms “relax” and return to their randomly spinning state. When the radio waves are switched off, the magnet realigns the hydrogen atoms, causing them to release a radio signal. Coils placed on the specific area of the body to be scanned then capture these signals in hundreds of cross-sectional pictures, like the slices in a loaf of bread.
These slice pictures are assembled by a powerful computer to produce three-dimensional images of remarkable clarity.
Unlike ordinary X-rays of computed tomography (CT) scans, MRI does not expose the body to X-radiation. Another advantage over CT is that MRI provides greater contrast between different tissues of the body. MRIs can be used to learn about tumors and problems in organs, blood vessels, joints, and bones, as well as about normal, healthy growth and development.
What‘s going on in your head?
Just think, doctors and researchers can see your brain in action. By watching changes in blood flow in your brain, doctors and researchers can view what happens when you think, talk, move or feel. Functional MRI (fMRI) provides clear pictures of brain function that would remain hidden by other imaging technology. FMRI is a powerful tool for planning surgery, and has also opened the frontier to “brain mapping” and a better understanding and treatment of mental conditions, such as depression.
Can you take it?
MRI is safe and effective for most people. Other than the sound of the machine running, people don’t experience anything unusual during the scanning.