Field: Magnetic resonance imaging

Nuclear magnetic resonance (NMR) – discovered in the mid 1940s – was used for decades by chemists to work out the structure of molecules. Then in the early 1970s, researchers discovered that NMR could detect differences between cancerous and normal tissue.

One such experiment was witnessed by Dr Paul Lauterbur, a chemist who had spent most of his career working with NMR. He was impressed with the design of the experiment and the results that were obtained but, not being used to animal experiments, he was not so impressed with how the samples were produced. People were speculating that the NMR technique could be used by pathologists to test for cancer. That seemed too invasive to Paul. Was there a way of using NMR to pinpoint where cancer was in the body without having to remove tissue samples?

It occurred to him that if the frequency of the signals from the atoms depended on the strength of the magnetic field, then if you varied the strength of the magnetic field across a body, you could work out where a particular signal was coming from. That meant you could create an image of a cross section of the body.

The mathematics was tricky and the computers were primitive, but Paul worked it out and produced an image of a test tube of water, followed by cross sections of a shellfish and a mouse. These were the first images produced by the technique that was to become known as magnetic resonance imaging (MRI).

Other groups of scientists were also working on MRI. One of these was led by Peter Mansfield who had read of the work of Lauterbur and saw how it could be improved. He also worked out a technique for getting extremely fast images.

The first MRI machines were introduced into hospitals in the early 1980s. In 2003, Paul Lauterbur and Peter Mansfield were awarded the Nobel prize in Medicine for their work in developing MRI. By that time, approximately 22,000 MRI machines were in use world-wide, with about 60 million examinations performed per year.

    Published 21 July 2007