MODEL RELEASED. MRI scanning. Radiologists looking at a magnetic resonance imaging (MRI) scan (screen at left) of the right knee of a 60-year-old woman. The patient and the MRI scanner are seen through the window in the background. The patient, only partially seen, enters the scanner through the central hole. MRI scanning uses strong magnetic fields to produce radio emissions from hydrogen atoms in the body. MRI scanning is used to produce cross-sectional body images, and is most useful for imaging soft tissues. Photographed at the American Hospital of Paris, France.