What are used in magnetic resonance imaging to map body tissues?

In magnetic resonance imaging (MRI), radio waves and a strong magnetic field are used to map the body's tissues. The magnetic field causes protons in the body to align with the field. When a radio wave is pulsed through the body, the protons absorb energy and flip their spins. When the radio wave is turned off, the protons release the absorbed energy and return to their original alignment, emitting a signal.

The strength of the emitted signal depends on the density of protons in the tissue. This allows MRI to create images of the body based on the distribution of protons in different tissues. For example, water-rich tissues, such as blood and cerebrospinal fluid, appear bright on MRI images, while fat-rich tissues, such as bone and muscle, appear dark.

MRI is a versatile imaging technique that can be used to study a wide variety of tissues and organs in the body. It is particularly useful for imaging soft tissues, such as the brain, heart, and kidneys. MRI is also used to diagnose and monitor a variety of medical conditions, including cancer, stroke, and heart disease.