2 Scientists Win Nobel for MRI Technology

American chemist Paul C. Lauterbur and British physicist Sir Peter Mansfield, who converted a chemist’s laboratory tool into a “revolutionary breakthrough” in medical imaging, were awarded the 2003 Nobel Prize in Physiology or Medicine on Monday.

Lauterbur, 74, of the University of Illinois at Urbana, and Mansfield, 69, of the University of Nottingham, share the $1.3-million prize for the development of magnetic resonance imaging, or MRI, which provides detailed images of the interior of the human body without the harmful radiation of X-rays and computed tomography, or CT, scans.

The first MRI instruments for medicine did not become available until the early 1980s, but their use has exploded since then. More than 60 million MRI examinations are now performed every year. The technique is particularly valuable for imaging the brain and spinal cord, monitoring the progress of diseases such as multiple sclerosis, and assessing damage to knees and other joints.

The pair’s work “really had an enormous impact on real people,” said medical physicist Paul Bottomley of Johns Hopkins University. “It’s an innovation that works and that has real value.”

Lauterbur learned of the award at 3:30 a.m. Monday in a phone call from Sweden. “Then the telephone calls and visits started,” he said. “It was a couple of hours later before I finally got a cup of coffee. I was surprised and very gratified.... People have been talking about a Nobel, but a lot of people do very good work and never have this experience.”

Mansfield’s wife took his call from the Nobel Foundation and at first he thought she was joking, he told Associated Press. “I’d given up all hopes and ideas of receiving anything in the way of an accolade of this type.”

But experts agreed that the award was overdue because of the importance of their work.

“It’s so significant that I thought these guys had won it earlier,” said Dr. Howard Marx of City of Hope National Medical Center in Duarte, Calif. “It has such a robust spectrum of use in medicine. That’s what’s really nice about it.”

The award marks the second time in the 102-year history of the medicine-category Nobel that it has been awarded for an imaging technology. In 1979, the prize was given to American Allan M. Cormack and Briton Godfrey N. Hounsfield for the development of CT scans.

MRI relies on the magnetic properties of the hydrogen in water, which accounts for two-thirds of the human body. When the hydrogen atoms are in a powerful magnetic field and are bombarded with radio waves, they emit radio signals that provide information about their local environment.

Before Lauterbur’s work, chemists used this technique, called nuclear magnetic resonance, or NMR, to deduce the structure of organic molecules. But no one had thought of using it for imaging, Bottomley said.

Lauterbur’s idea was to establish a gradient in the magnetic field -- varying its intensity at different points in the sample -- so that it was possible to determine where each hydrogen atom was in relation to the others. “Overnight, there was no imaging method and then there was,” Bottomley said.

Mansfield devised techniques for sequentially altering the magnetic gradient so that the device could produce an image of a two-dimensional slice of the human body. He also perfected techniques to speed up the process, cutting the required time for producing an image from hours to seconds.

Lauterbur was working at State University of New York at Stony Brook at the time of his discovery, and the university chose not to file patent applications based on his work. “The company that was in charge of such applications decided that it would not repay the expense of getting a patent,” Lauterbur said. “That turned out not to be a spectacularly good decision.”

The University of Nottingham did file patents, however, and Mansfield has profited handsomely. He now works in the Sir Peter Mansfield Magnetic Resonance Center, a building he recently donated to the university.

MRI has been so successful that the original technique has spawned numerous offspring. Functional MRI, for example, measures brain activity by detecting oxygen levels in specific areas. Diffusion MRI can detect strokes by measuring movement of water at microscopic distances in the brain. MRI angio- graphy diagnoses heart disorders by taking pictures of blood vessels. Low-field MRI offers the prospect of cheaper and more portable imaging equipment.