7 Paul Lauterbur and Peter Mansfield 7distortions could be used to create two-dimensional
images of a sample’s internal structure. While at Stony
Brook, he worked evenings developing his idea, using an
NMR unit borrowed from campus chemists. His discovery
laid the groundwork for the development of MRI as
Mansfield transformed Lauterbur’s work into a practical
medical tool.
Peter Mansfield
Peter Mansfield received a Ph.D. in physics from the
University of London in 1962. Following two years as a
research associate in the United States, he joined the
faculty of the University of Nottingham, where he became
professor in 1979. Mansfield was knighted in 1993.
Mansfield’s prize-winning work expanded upon
Lauterbur’s earlier discoveries regarding NMR. MRI
imaging succeeds because the human body is about two-
thirds water, whose molecules are made of hydrogen and
oxygen atoms. There are differences in the amount of
water present in different organs and tissues. In addition,
the amount of water often changes when body structures
become injured or diseased; those variations show up in
MRI images. When the body is exposed to MRI’s magnetic
field and its pulses of radio waves, the nucleus of each
hydrogen atom in water absorbs energy; it then emits the
energy in the form of radio waves, or resonance signals, as
it returns to its previous energy level. Electronic devices
detect the myriad resonance signals from all the hydrogen
nuclei in the tissue being examined, and computer pro-
cessing builds cross-sectional images of internal body
structures, based on differences in water content and
movements of water molecules. Computer processing
also can stack the cross sections in sequence to create
three-dimensional, solid images. Because MRI does not