In a 1987 expedition, neurologist Marcus Raichle, MD, climbed 18,000 feet above sea level, scaling the icy Karakoram Mountains of Pakistan. There, amidst heavy snow and high winds, Raichle and 18 researchers injected themselves with radioactive xenon.
A crude scanner measured the gas as it diffused through their bodies, accurately recording blood flow in the mountaineers’ brains. Their objective was to better understand acute mountain sickness, a syndrome affecting climbers that causes headaches, vomiting, cerebral and pulmonary edema and, occasionally, death.
The British expeditionists’ earlier treks already had linked the syndrome to the brain’s uptake of oxygen. On this journey, they invited Raichle, an experienced mountaineer and physician highly regarded for his expertise in mapping brain blood flow.
Thirty years later, Raichle is still unraveling clues to the brain by studying its blood flow and oxygen use. This blood flow — laden with oxygen and nutrients — fuels the brain, with the busiest areas burning through fuel the fastest.
Raichle, now 81, the Edith L. Wolff Distinguished Professor of medicine and a professor of radiology, neurology, neurobiology and biomedical engineering at Washington University in St. Louis, is a central figure in the history and science of brain imaging. He is noted for developing positron emission tomography (PET) techniques, explaining principles underlying functional magnetic resonance imaging (fMRI) and capturing some of the first snapshots of the brain at work.
He tells a thrilling tale of scientific mysteries and their startling solutions, which have transformed how we understand ourselves.
New imaging techniques
“If you were to write a history of brain imaging, there’d be a pop-out box about Marc Raichle at multiple spots,” said Steven Petersen, the James S. McDonnell Professor of Cognitive Neuroscience in Neurology and longtime collaborator. “Every five or 10 years, he’s done something seminal.”
Raichle joined the School of Medicine faculty in 1971, just before the science of brain imaging took off. Michel Ter-Pogossian — a physicist who would develop the PET scan a few years later — recruited him. They met at a scientific conference in London. Raichle had studied brain blood flow as a postdoctoral researcher, and a clerical error had resulted in a conference invitation being issued to him instead of his adviser.
At the time, Raichle was serving as a major and flight surgeon at the U.S. Air Force School of Aerospace Medicine in Texas, pursuing his interest in brain blood flow and screening pilots who had experienced medical problems impairing their ability to fly. Never one to turn down an opportunity, he hopped a military plane and attended the conference.
Read the full profile in Outlook magazine.