FoundationalConceptsNeuroscience

sible to focus on measuring the spin properties of hydrogen atoms
in the water molecules within the body. Different kinds of tissue will
form differing chemical environments for the water. Thus, the spatial
pattern of different resonant energies may be used to construct an
image of the interior of the organism. This is possible because both
magnetic fields and radio waves easily penetrate living organisms, like
the human body.
It was not an easy step from the first NMR devices in the 1940s to
the devices capable of imaging parts of the human body in the 1970s.
You can’t just stick a person inside an NMR spectrometer and start
collecting data. Sophisticated design innovations involving configu-
rations of magnetic fields that varied in precise ways over space and
time were necessary before the construction of three-dimensional
images became possible. As with CT, computers are needed to manip-
ulate the large quantity of data gathered.
The result is NMR imaging. By the 1980s, NMR imaging was being
introduced into hospitals to expand the imaging capacity beyond
that of CT. In addition, NMR imaging does not involve exposure to
knowingly toxic x-rays. While the impact of exposure to very strong
magnetic fields is generally accepted as safe, the jury is still out on
that one. However, even if there is some toxicity associated with brief
exposures to very strong magnetic fields, it is likely to be far less prob-
lematic than exposure to x-rays.
Soon after NMR imaging devices began to be installed in hospitals,
the name began to come under criticism; some people were bothered
by the N in NMR. While the N simply refers to the atomic nucleus
(and its associated spin), some folks heard “nuclear” and inferred an
association with nuclear radiation (radioactivity, a generally toxic
phenomena) and even nuclear weapons. When a local hospital an-
nounced it was installing a modern NMR imaging device to improve