Cartoon faces on the Faraday cage of an MRI scanner, early 1970s.

Magnetic resonance imaging (MRI) builds up a picture of the human body from the magnetic behaviour of water molecules inside the body. It is used to diagnose diseases and injuries affecting the brain, nerves, bones, muscles and internal organs, especially the liver. Illustrated is a part of a Faraday cage used by Peter Mansfield to enclose the MRI coils so that radio and television signals would not interfere with them. The smiling cartoon faces were to distract and reasure frightened children.