Friday, May 1, 2009

Paul Lauterbur

This week we celebrate the 80 anniversary of the birth of Paul Lauterbur (May 6, 1929 - March 27, 2007), co-winner with Peter Mansfield of the 2003 Nobel Prize in Physiology or Medicine "for their discoveries concerning magnetic resonance imaging". Lauterbur's contribution was the introduction of magnetic field gradients, so that differences in frequency could be used to localize the spins. In Sec. 18.9 of the 4th Edition of Intermediate Physics for Medicine and Biology, Russ Hobbie and I describe this technique.
"Creation of the [magnetic resonance] images requires the application of gradients in the static magnetic field Bz which cause the Larmor frequency to vary with position. The first gradient is applied in the z direction [the same direction as the static magnetic field] during the pi/2 pulse so that only the spins in a slice in the patient are selected (nutated into the xy plane). Slice selection is followed by gradients of Bz in the x and y directions. These also change the Larmor frequency. If the gradient is applied during the readout, the Larmor frequency of the signal varies as Bz varies with position. If the gradient is applied before the readout, it causes a position-dependent phase shift in the signal which can be detected."
Lauterbur grew up in Sidney, Ohio. He attended college at Case Institute of Technology, now part of Case Western Reserve University in Cleveland, where he majored in chemistry. He obtained his PhD in Chemistry in 1962 from the University of Pittsburgh. He was a Professor at the State University of New York at Stony Brook from 1969-1985, during which time he published his landmark paper Image Formation by Induced Local Interactions: Examples Employing Nuclear Magnetic Resonance, (Nature, 242:190-191, 1973). In an interesting story, Lauterbur came up with the idea of using gradients to do magnetic resonance imaging while eating a hamburger in a Big Boy restaurant.

You can learn more about magnetic resonance imaging by reading Lauterbur's book (with Zhi-Pei Liang)
Principles of Magnetic Resonance Imaging: A Signal Processing Perspective. If looking for a briefer introduction, consult Chapter 18 of Intermediate Physics for Medicine and Biology. Be sure to use the 4th Edition if you want to learn about recent developments, such as functional MRI and diffusion tensor imaging.

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