A magnetic resonance imaging (MRI) scan takes detailed pictures of the inside of the body. It can show up problems in the soft tissues without the need for surgery. It is also useful for planning some treatments of the same areas. When you have an MRI, you usually lie on a table that slides through a tunnel in the middle of the scanner. The scanner uses strong magnetic fields and radio waves to generate signals from the body. These are picked up by a radio antenna and processed by a computer to create detailed pictures. The benefits of an are that it produces very detailed pictures, does not use radiation, and is painless.