Paul Lauterbur and the Invention of MRI

7. The Worldwide Laboratory

7 The Worldwide Laboratory Discovery consists of seeing what everybody has seen and thinking what nobody has thought. —Albert von Szent-Györgyi There never was an old theory of MRI; it was born whole. Paul once gave a talk titled “Magnetic Resonance Imaging: Why It Takes So Long to Understand Simple Things.” From 1946, once the phenomenon of NMR was understood any knowledgeable person could have invented MRI, but until Paul no one had the clarity of mind or the creativity to realize its beauty. Even so, everything new has precedents. All of the efforts to use projection reconstruction techniques for various purposes were mathematical precedents to Paul’s image reconstruction methods, although he was unaware of them and wound up reinventing them. A different case is that of the late Herman Carr, a professor of physics at Rutgers University, who in 1951 made what in current MRI would be called a “phantom,” three pieces of rubber of volumes 3:2:1, which were placed in a one-dimensional magnetic field gradient to simulate the chemical shifts of ethanol. The signals obtained from this phantom agreed with those from liquid ethanol itself, providing what may be the first one-dimensional NMR image ever recorded. This was twenty years before Paul had the idea of deliberately applying controlled field gradients to obtain multidimensional spatial images. Herman Carr wrote letters and articles to Physics Today and other publications complaining that his early work was overlooked. Dr. Carr was not alone in using field gradients for specific purposes. Unknown to Paul at the time, and perhaps to Dr. Carr, several people were using field gradients to identify separate physical positions of chemicals, 108 Chapter 7 and in unpublished work at the National Institutes of Health, Vsevolod Kudravcev (“Kud”) recognized that field gradients could be used to localize a volume of interest. All of these applications depended on the spatial variation of the NMR signal. Paul explained,“All of these were important precedents, but each was very specific to the [particular experiment] and with no intimation of generality in the process.” The important difference was that unlike earlier scientists, Paul was from the very beginning thinking of a general process. Although the citations often refer to two-dimensional imaging, that was a more practical way than the natural three-dimensional procedure, which was not as easy to implement both technically and mathematically. Two-dimensional imaging, Paul said, “was really a stopgap solution.” Or, as David Hoult succinctly declared, “You need three dimensions to win a Nobel Prize.” Other things are erroneously believed to be precedents to MRI. Advances in computer technology have made MRI clinically practical, but the concept of MRI did not involve computers. The first images were actually drawn by hand. It was the other way around: the advent of MRI, along with other imaging methods such as positron emission tomography and computed tomography (CT), led to the belief for the first time that computers might have an important role to play in medical imaging. Superconducting magnets, now used in clinical imaging, are these days usually believed to be precedents and requirements for MRI. Not true: all of the early development of imaging was done using iron core magnets or ordinary electromagnets. In the early days there was a widespread belief that the high fields generated by superconducting magnets would actually degrade images. And then there is Raymond Damadian, at that time of the SUNY Downstate Medical Center in Brooklyn, who became a phenomenon not often seen in science. Dr. Damadian campaigned heavily for his priority in MRI through the press, and even forced a congressional hearing about supposed bias against him at the National Institutes of Health. As a result of this behavior he managed to share honors with Paul on three occasions , including induction into the Long Island Technology Hall of Fame and the National Inventors Hall of Fame, and receiving the National Medal of Technology. The issue really should have been put to rest by now since only two Nobel Prizes were awarded for MRI. There could have been three, and Damadian was not included. The Worldwide Laboratory 109 Dr. Damadian made an important contribution, which was to show that tissue water relaxation time, an important source of contrast in MRI, is longer in cancerous than in normal tissues. From very early days, even in the laboratories of Felix Bloch and Edward Purcell, people looked at...