magnetic resonance imaging

A rear view of the brain using a technique called magnetic resonance imaging (MRI). This picture can be interpreted to give an understanding of the status of the brain. The radio signals given off by the nuclei of the atoms in the brain indicate each type of tissue present in the brain.

A woman being given a magnetic resonance imaging (MRI) examination. This type of examination is completely non-invasive. The atoms of the body are simply excited by radio waves. Each radio wave frequency represents a chemical element in the tissues, which can then be identified in the resulting image.

A tumour in the spine is seen via magnetic resonance imaging (MRI). This scanning method is very useful in diagnosing disease in soft tissue such as the brain and spinal cord. It also has the advantage that the patient is not exposed to harmful radiation.

A magnetic resonance imaging (MRI) scan of a human brain.

Diagnostic scanning system based on the principles of nuclear magnetic resonance (NMR). MRI yields finely detailed three-dimensional images of structures within the body without exposing the patient to harmful radiation. The technique is invaluable for imaging the soft tissues of the body, in particular the brain and the spinal cord.

Claimed as the biggest breakthrough in diagnostic imaging since the discovery of X-rays, MRI is a noninvasive technique based on a magnet that is many thousands of times stronger than the Earth's magnetic field. It causes nuclei within the atoms of the body to align themselves in one direction. When a brief radio pulse is beamed at the body the nuclei spin, emitting weak radio signals as they realign themselves to the magnet. These signals, which are characteristic for each type of tissue, are converted electronically into images on a viewing screen.

Also developed around magnetic technology, magnetic resonance spectroscopy (MRS) is a technique for investigating conditions in which there is a disturbance of the body's energy metabolism, including ischaemia and toxic damage due to drugs or other chemicals. MRS is also of value in diagnosing some cancers.