He was 77 and had been suffering from kidney disease.
FOR THE RECORD:
Lauterbur obituary: The obituary of Nobel laureate Paul C. Lauterbur in Wednesday's California section identified him as a physicist. He was a chemist. —
Lauterbur played a key role in the development of magnetic resonance imaging, or MRI, which produces highly detailed images of soft tissues and organs without using X-rays.
Although the first MRI instruments did not become available until the early 1980s, their use has exploded to the point that more than 60 million MRI examinations are 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.
"Paul's influence is felt around the world every day, every time an MRI saves the life of a daughter or a son, a mother or a father," Richard Herman, chancellor of the University of Illinois at Urbana-Champaign, where Lauterbur was a professor, said in a statement. "He will be greatly missed."
MRI relies on the magnetic properties of the hydrogen in water, which accounts for about two-thirds of the human body. When the hydrogen atoms are placed in a powerful magnetic field and bombarded with radio waves, they emit radio signals that provide information about their local environment.
Before Lauterbur's work at the State University of New York at Stony Brook, chemists used this technique, called nuclear magnetic resonance, to help determine the structure of organic molecules. But nobody thought of using it for imaging because they didn't know how it could be done.
Lauterbur's inspiration — conceived at a restaurant table and sketched out on a napkin — was to establish a gradient in the field, varying its intensity at different points in the sample. That made it possible to determine where each atom was in relation to the others.
His thought processes were unique, said Caltech chemist John D. Baldeschwieler. "For years, everyone in the field was trying to get the most homogeneous field in order to get the highest possible resolution," he said. "Lauterbur thought about the problem in a completely inverse way. If you didn't have a homogeneous field, but a gradient, then the frequency would indicate position in space."
Assembling his apparatus, he placed a test tube inside it and startled his colleagues with a faint picture. His first living subject was a clam taken from the nearby Long Island Sound.
In his original publication in the journal Nature, he called the new technique zeugmatography — from the Greek zeugma, or yoke — because it yoked together two different types of radiation, magnetic and radiofrequency.
Fortunately, that name did not last. Marketers also removed the "nuclear" from the name for fear it would invoke images of lethal radiation.
British physicist Sir Peter Mansfield of the University of Nottingham, who shared the 2003 Nobel Prize with Lauterbur, devised techniques for sequentially altering the magnetic gradient so 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's university decided 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 in 2003. "That turned out not to be a spectacularly good decision."
The University of Nottingham did file patents, however, and Mansfield became wealthy enough to donate a new MRI center to the university.
Lauterbur tried for years to get the federal government, particularly the National Institutes of Health, to fund a prototype of the instrument to image people, Baldeschwieler said. "It was an extraordinarily bold step. Nobody thought such a thing would be possible," he said.