Your doctor has ordered an MRI for you, now what? First, you should know that MRI stands for Magnetic Resonance Imaging. An MRI machine uses strong magnetic fields and radio waves to create images of your internal organs, tissues, joints, and other structures inside your body. Unlike Xray machines and CT Scans, MRI machines use NO radiation. They are very safe and painless; they are the gold standard when it comes to detecting soft tissue not picked up by Xray machines.