What is the definition of "magnetic resonance imaging"?

Magnetic resonance imaging (MRI) is a medical test for examining the internal organs and anatomy of the body through magnetic fields and radio waves. It allows doctors to diagnose patients without the need for invasive surgical procedures.

Most MRI tests are done by having the patient lie inside a large machine with tube-shaped magnets, which produce a strong magnetic field to rearrange hydrogen atoms in the body. As radio waves pass through them, these atoms emit faint signals that can be used to create images. MRI scans may show problems in the body that other medical imaging techniques fail to discover.