Knowledge of history once againproves vital to imaging practice

Discussion has always been lively on the value of reviewing history in the pursuit of new developments in technology. Sir Isaac Newton, for example, is credited with making the statement: "If I have seen further it is by standing on the shoulders of giants."¹ Henry Ford, on the other hand, has been quoted as saying "History is more or less bunk." Ford also went on to say that "the only history that is worth a tinker's damn is the history that we make today."²

It is interesting to look at developments in medical imaging technology and radiological techniques and see how much they have relied on previous work, ideas, or concepts. I have always been fascinated by how future developments in imaging and therapy can be linked back to Roentgen's original and momentous discovery of x-rays.

One of my favorite historical clinical images is that of an amputated hand that had been injected with Teichmann's mixture in January 1896, and on which the digital and interosseous arteries and their anastomoses were clearly recognized.² Teichmann's mixture was a curious combination of petroleum, cinnabar, and chalk. The contrast results from the calcium in the chalk-usually made up of compounds of calcium sulphate or calcium carbonate-and the mercury in cinnabar, which is mercury sulphide or painter's vermilion.

Inte restingly, as early as 1907, M.K. Kassabian of Philadelphia was drawing on his experience of angiocardiography to recommend that "the injection must be done carefully and slowly."² Others took up the challenge of imaging the body's circulation on cadavers and in vivo. One of the most fascinating stories concerns the German physician Werner Forssmann, who catheterized his own heart using "a well-oiled urethral catheter."² This experimental procedure, involving a 65-cm catheter fed from his left elbow, marked the beginning of cardiac catheterization. To check the cathe ter's positi on on the primitive fluoroscopy system, Forssmann asked a nurse to hold a mirror in front of the screen.

Forssmann's reward for his initiative and courage was the sack and subsequent restriction from further hospital positions. He served as a medical officer during World War II until he was imprisoned. Forssmann's paper describing the catheterization technique was read by André Frédéric Cournand and Dickinson W. Richards while he was being held as a prisoner of war. The pair then developed ways of applying his technique to the diagnosis of heart disease and research. This work was rewarded in 1956 when the Nobel Prize in Physiology or Medicine was awarded jointly to Cournand, Richards, and Forssmann. Cournand acknowledged Forssmann in his speech at the Nobel banquet as the man who "in a single brilliant experiment offered us the key to the solution of that riddle propounded by William Harvey more than three centuries ago-the measurement of the passage of blood into and out of the human heart."³

It is easy to see from these examples how history has played an important role in such a vital part of today's healthcare. We are all aware of the early work conducted by Marie and Pierre Curie⁴ and by Henri Becquerel, and their impact on radiation medicine. Another prime example of early research and subsequent medical imaging benefits concerns William Henry Bragg and his son Lawrence.

William Bragg was working as a professor of physics and mathematics at the University of Adelaide in Australia when Roentgen discovered x-rays.⁵ The pair worked together on x-ray crystallography techniques to determine the structure of crystals. This work was continued when William Bragg returned to England to take up another academic position at Leeds. The Braggs were subsequently awarded the 1915 Nobel Prize for Physics.

Francis Watson and James Crick were personally encouraged and supported by Sir Lawrence Bragg in their quest to find the structure of DNA. In 1962, Crick and Watson received the Nobel Prize for their discovery that DNA had a double helix structure, together with Maurice Wilkins, who was included specifically for his work in xray crystallography.^1,6

The work of the Braggs, Crick, Watson, and Wilkins laid the foundations for a new discipline of molecular science and biology, through which we can link to more recent pioneers in medical imaging. Prof. Michael Phelps, chair of molecular and medical pharmacology and director of the Crump Institute for Molecular at the University of California, Los Angeles, is one such pioneer. He is recognized as the inventor of the PET scanner developed in 1973 at Washington State University.

Watson is reputed to have said, during an interview, "Bragg was not a chemist, but Bragg's Law was the basis of understanding in solving the molecular structure. So we were standing on the shoulders of Bragg and then [Linus] Pauling."¹

I am sure that the many Nobel Laureates we are so proud of in medical imaging-Sir Godfrey Hounsfield, Allan Cormack, Paul Lauterbur, and Sir Peter Mans field, and Phelps - would readily agree that their work was also in no small way the result of those who went before. In the words of Dr. James Thrall, radiologist - in - chief at Massachusetts General Hospital in Boston, U.S., "This is a race without a finish line. It is never complete. Every discovery suggests new directions."⁷