With magnetic resonance imaging (MRI), you can take detailed pictures of the inside of your body by using powerful magnets, radio waves, and a computer. The results of this test can be used by your doctor for diagnosing you or to determine how well your treatment has worked. CT scans and X-rays use ionizing radiation that can damage the body, but MRIs do not.   An MRI can help a doctor diagnose a disease or injury and monitor how well you're responding to a treatment. Different parts of your body can be scanned with an MRI. In particular, soft tissues and the nervous system can be examined with this technique.