Early Detection for Brain Injuries

New York Times | By Anne Eisenberg

Football teams of the future — even high school squads on limited budgets — may someday have a new tool to check players for brain injuries. It’s a special form of headgear, packed with sensors that read the brain waves of athletes after they come off the field, thus detecting changes caused by the trauma of hard knocks.

The compact, portable sensors decipher neural activity by measuring changes in the brain’s tiny magnetic field. These small magnetometers — still in the laboratory and in prototype — have yet to be tried on athletes. But their potential is enormous for brain imaging and for inexpensive monitoring of brain diseases, as well as for many other applications like the control of prosthetics, said Dr. José Luis Contreras–Vidal, a professor of electrical and computer engineering at the University of Houston. Dr. Contreras-Vidal’s research includes work on a system that will use brain signals to control prosthetic legs.

“This is a transformative technology” that could make brain interfaces available at a small cost, he said. “We could potentially use these devices to record in real time brain waves that could be analyzed for specific diseases such as Alzheimer’s, or the progression of these diseases.”

The research is occurring at a time of growing concern about collisions and subsequent brain injuries in sports — and the dire effects that may show up only many years later. But an inexpensive system for spotting changes in brain behavior could play an important safety role one day in boxing, football and many other sports.

The magnetic sensors, part of a field called optical or atomic magnetometry, were created at the Commerce Department’s National Institute of Standards and Technology in Boulder, Colo., by Svenja Knappe and colleagues.

“We are trying to make them small and inexpensive,” Dr. Knappe said of the devices, each roughly the size of a sugar cube. The sensors are designed to be mass-produced in the future, so that several hundred of them might one day line the inside of the special headgear that detects brain changes. She and her colleagues are also trying to improve the sensors’ performance.

Instruments that measure magnetic fields are not new, said Dr. Dmitry Budker, a physics professor at the University of California, Berkeley, and an editor of “Optical Magnetometry,” a coming book.

But the sensors under development at the National Institute of Standards and Technology and other labs may someday offer portability, compactness and flexibility that isn’t possible with conventional magnetometers called superconducting quantum interference devices, or Squids. Those superconducting devices are highly sensitive detectors for brain signals, said Matti S. Hamalainen, a neuroscientist who specializes in functional brain imaging at Massachusetts General Hospital and Harvard Medical School. But they require cryogenic cooling, and patients must be protected from the extremely low temperatures with a heavy, insulated housing.

Installing Squid systems can cost $1 million to $3 million, Dr. Hamalainen said. So they won’t be found on a high school football field soon.

He said the compact sensors have advantages. Unlike those in superconducting devices, they could be used at room temperature, and in helmets that could match the size of the head.

“It would be nice to be able to use a portable, adjustable sensor” that could be fitted closer to the skulls of smaller adults and children, he said. “The closer you are to the sources of the signals, the better the information you can get.”

The magnetic sensors may also help to interpret neural signals in other applications, Dr. Contreras-Vidal said. One standard, noninvasive way to read the complex snap, crackle and pop of neurons is by electroencephalography, or EEG. A cap of electrodes is placed on the skull to eavesdrop on the signal.

“But there are many artifacts when you record electrical brain waves with EEG,” he said. “You get a fuzzy, blurry picture of what’s going on inside. Some of these problems do not occur when you are using magnetic recordings.”

AT the University of Wisconsin, Madison, Thad G. Walker, an atomic physicist, uses optical magnetometry to monitor the magnetic fields of the beating heart rather than the brain. Professor Walker and his group have created small magnetometers that are an inexpensive alternative to superconducting devices now used to spot various heart abnormalities in a fetus. The technology is sensitive enough to measure different features of the heart signal of a 20-week-old fetus, he said.

Research groups at many institutions are trying to find practical and economical ways to commercialize optical magnetometry, said Dr. Michael Romalis, a physics professor at Princeton University and a prominent researcher in the field.

“My guess is that it will take a few years for these efforts to mature,” he said.

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