Magnetic Resonance Imaging (MRI) produces images of your insides. Unlike an X-ray, which emits radiation to produce an image, an MRI uses an oscillating (a fancy word for “moves around a central point,”) magnetic field. This magnetic field excites the nuclei (another fancy word for “center”) of your cells, releasing a radio signal (crazy, right?) that produces an image. MRIs are especially important in MS for visualizing lesions (sites of injury) in the brain and spinal cord.