Magnetic resonance imaging (MRI)

Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to visualize detailed internal structures. The good contrast it provides between the different soft tissues of the body make it especially useful in brain, muscles, heart, and cancer compared with other medical imaging techniques such as computed tomography (CT) or X-rays.

Unlike CT scans or traditional X-rays MRI uses no ionizing radiation. Instead it uses a powerful magnetic field to align the magnetization of some atoms in the body, then uses radio frequency fields to systematically alter the alignment of this magnetization. This causes the nuclei to produce a rotating magnetic field detectable by the scanner—and this information is recorded to construct an image of the scanned area of the body.

Magnetic resonance imaging is a relatively new technology. The first MR image was published in 1973 and the first cross-sectional image of a living mouse was published in January 1974.The first studies performed on humans were published in 1977. By comparison, the first human X-ray image was taken in 1895.