Professor Sir Peter Mansfield - Nobel Laureate

Professor Sir Peter Mansfield, from Nottingham University, was instrumental in bringing magnetic resonance (MRI) scanners into hospitals.

They use a strong magnetic field to allow doctors to see the internal organs and other tissues.

He shares the prize with US researcher Professor Paul Lauterbur.

Professor Mansfield, 70, left school at 15 to become a printer. He only entered academic life after studying part-time to complete his "A" levels before going to university.

He was responsible for creating a mathematical method of swiftly decyphering the signals coming back from the scanner, and turning them into three-dimensional images of the internal structures of the body.

This allowed extremely fast imaging to take place - and made MRI a routine technique which could be used in hospitals all over the world.

The prize includes a cheque for 10 million Swedish kronor (£775,000).

MRI expert Professor Mike Smith, Professor of Medical Physics and Faculty Dean of Research at Leeds University, said that Professor Mansfield had made a significant and sustained contribution to the development of MRI.

It is, I suppose, every scientist's hope that one day they may be singled out for such an honour Professor Sir Peter Mansfield, Nobel Laureate

"Without his contribution," he said, "it is likely that some of these advances - which make MRI practical for a medical setting - would not have happened, or would have taken much longer to happen."

Professor Mansfield himself said: "It is, I suppose, every scientist's hope that one day they may be singled out for such an honour but I must say that in my case I did think about it a few years ago, but then dismissed it."

Widely used

More than 60 million investigations using MRI scanners are performed worldwide each year.

It is an alternative to CT scanners, which use x-rays and often produce a less detailed scan.

More than 60 million MRIs are carried out each year

While doctors would prefer to restrict any individual patient's lifetime exposure to x-rays, MRI is thought to be completely harmless.

The first MRI scans were available in the 1980s, and there are approximately 22,000 machines at work across the world.

Because of his work, we can now see pictures of the body which give doctors a "snapshot" of the action of the heart Professor Paul Matthews, Oxford University

The technique is particularly useful for looking in detail at images of the brain and spinal cord, although any organ in the body can be imaged in great detail.

Professor Paul Matthews, director of the Centre for Functional MRI at the University of Oxford said: "Professor Mansfield is responsible for many of the major developments that underlie the current use of MRI that has become the single most important medical diagnostic technology.

"Because of his work, we can now see pictures of the body which give doctors a "snapshot" of the action of the heart.

"We can also see the action of the brain which allows scientists to see the dynamics of thought."

Rotating atoms

It works because it can work out the water content of any tissue it scans.

Different types of tissues within organs - including cancer cells - have different water contents, so this gives a detailed impression of the structures beneath the skin.

Water is composed of hydrogen and oxygen atoms - and when exposed to a strong magnetic field, the hydrogen atoms all become aligned in one particular direction.

MRI scans pick out hidden detail of internal organs

A short pulse of radiowave energy sent through the tissue "knocks" the nuclei of these atoms out of alignment, but when the pulse ends, they snap back into place again.

During this "realignment", radiowaves are emitted - it is these that are captured and measured, and which allow computers to determine the water content of each section of tissue scanned.

This is the third year in a row in which Britons have won the Nobel Prize for Medicine.

Professor Colin Blakemore, Chief Executive of the Medical Research Council, said: "Professor Mansfield's work is an excellent example of how high risk research can really pay off.

"When we first funded Sir Peter in the 1970s, we really didn't know if the huge investment in this area would bear fruit.