A team of researchers at Washington University School of Medicine, St. Louis, MO, have developed a brain-scanning technology that tracks what the brain is actively doing by shining dozens of tiny LED lights on the head. This new generation of neuroimaging, they say, compares favorably to other approaches but avoids the radiation exposure and bulky magnets that other methods others require.
This new technology is called diffuse optical tomography (DOT). While under development for more than 10 years, the method had previously been limited to small regions of the brain. The new DOT instrument covers two-thirds of the head and, for the first time, can image brain processes taking place in multiple regions and brain networks such as those involved in language processing as well as daydreaming.
During DOT scans, the subject wears a cap composed of many light sources and sensors connected to cables. The full-scale DOT unit takes up an area slightly larger than an old-fashioned phone booth, but Culver and his colleagues have built versions of the scanner mounted on wheeled carts. The technology is designed to be portable, so it could be used at a patient’s bedside or in the operating room.
While the magnetic fields in magnetic resonance imaging often disrupt the function or safety of implanted electrical devices, there is no interference with the optical technique, making it safe and effective for children and for patients with electronic implants, such as pacemakers, cochlear implants, and deep brain stimulators.
The technique works by detecting light transmitted through the head and capturing the dynamic changes in the colors of the brain tissue. They say that DOT technology could be helpful in many medical scenarios as a surrogate for functional MRI, the most commonly used imaging method for mapping human brain function. Functional MRI also tracks activity in the brain via changes in blood flow. In addition to greatly adding to our understanding of the human brain, fMRI is used to diagnose and monitor brain disease and therapy.
While DOT doesn’t let scientists peer very deeply into the brain, researchers can get reliable data to a depth of about one centimeter of tissue. That centimeter contains some of the brain’s most important and interesting areas with many higher brain functions, such as memory, language, and self-awareness, represented.