Born in Philadelphia, Kety received his MD from the University of Pennsylvania, but his interest in science burgeoned at the age of 10 when an aunt bought him a chemistry set. Chemistry became his hobby, and during college Kety obtained a job with a toxicologist who was a consultant to several lead companies. He had Kety analyze the urine of the workers at those companies. The standard procedure was to precipitate the lead as an insoluble salt, and then redissolve it with sodium citrate, which formed a chelate with the lead. On the basis of this experience he assumed that one could treat lead poisoning by administering sodium citrate to increase the excretion of lead, a hypothesis he later confirmed while a medical student, and then published in 1942.
He obtained a fellowship at Harvard with Joseph Aub, a world authority on lead poisoning, but World War II had broken out, and Aub had begun working on traumatic shock. Kety quickly became interested in shock, and recognized that the reflexes triggered in shock preserved the circulation of the blood in the brain and the heart at the expense of the circulation in other organs. His interest then turned to cerebral circulation and, after completing his fellowship with Aub, he returned to Penn to work on cerebral circulation in Carl Schmidt's laboratory. There he developed a very original technique for quantitative measurements of blood flow and energy metabolism in the human brain. The technique was based on his insight that the brain would absorb an inert diffusible gas from arterial blood, and its accumulation should be independent of the brain's metabolic activity and dependent only on physical parameters such as diffusion, solubility and perfusion. In a classic paper published in 1951, he presented his mathematical treatment of the exchange of diffusible substances between capillaries and tissue in the lung and other organs, and opened a new chapter in physiology and medicine. He examined these processes in essential hypertension, diabetic acidosis, schizophrenia, normal sleep and anesthesia, and elucidated many of the underlying physiological processes. By combining his equations with autoradiography, he could measure the circulation in different regions of the brain. When used with positron emission tomography, his principles made possible the measurement of local blood flow and the visualization of functional activity throughout the brain. The field of functional brain imaging was thus ushered in, revolutionizing the study of mental, cognitive and emotional processes.
