Wearable Brain-Imaging Offers Alternative to 'Gold Standard' Method

Researchers at Washington University in St. Louis are developing an alternative to the current gold standard of brain imaging, functional magnetic resonance imaging (fMRI). The researchers’ technology would allow subjects to move freely while high-resolution images of the brain are generated using light-based technology.

Through a small business technology transfer grant from the National Institutes of Health awarded to EsperImage, a Washington University startup founded by Washington University radiology professors Joseph P. Culver and Adam Eggebrecht, along with Jason Trobaugh and Ed Richter, both professors of practice in electrical and systems engineering, the effort centers on diffuse optical tomography (HD-DOT) technology.

In contrast to fMRI, which is loud and constraining, wearable brain-imaging tech would enable the study of how brain areas work together to solve specific tasks and govern behavior under naturalistic conditions, said Culver, the Sherwood Moore Professor of Radiology at the Mallinckrodt Institute of Radiology and the primary inventor of the technology.

Wearable brain-imaging tech aims to reveal how the brain works in natural, realistic situations. Washington University in St. Louis faculty members (from left) Joseph P. Culver (holding a piece of a prototype imaging device), Jason Trobaugh, Ed Richter, and Adam Eggebrecht (not pictured) have received a grant from the NIH to develop and commercialize a brain-imaging cap that uses LED light to gauge brain activity. Courtesy of Elizabethe Holland Durando/Washington University in St. Louis.

Culver started designing the HD-DOT instrument for imaging the brain in 2005. The technique uses LED sources that beam in infrared light from outside the head, paired with detectors that measure the light coming back out. The signals collected by each source-detector pair contain information about local brain blood flow. By placing many sources and detectors in an interlaced high-density array all around the head, the researchers can map blood dynamics — a proxy for brain activity — all over the brain. Recently, Culver and colleagues demonstrated that they could use an HD-DOT cap to detect brain signals and then decode them to figure out what a person sees.

The researchers envision the cap as a research tool for cognitive neuroscientists. Such scientists study how brain activity, as measured by neuroimaging systems, relates to the complex cognitive functioning of the brain. For example, scientists could use such a cap to image the brains of children as they freely talk and interact with their caretakers. This would aid discovery about how language networks in the brain develop and contribute to normal or abnormal language acquisition.

The team intends to get the cap down to 4 lb, about the weight of a football helmet. The current prototype is 8 lb, plus a power source that fits inside a backpack. This is a significant reduction in weight compared to the first-generation HD-DOT devices, which weigh hundreds of pounds. Users had to sit in a fixed chair and wear a headset tethered to a bank of electronics the size of a chest of drawers.

The working design calls for a cap studded with 288 optical sensors, known as optodes, in the form of small copper-colored boxes about the size of an adult’s thumb. Each optode contains a light source, a detector, and eight tiny circuit boards that function together as a miniscule computer. In total, 72 minicomputers are connected to a digital network through the cap and their collective data are beamed by Wi-Fi to a central computer that acquires, analyzes, and displays the data.

According to Trobaugh, co-founder and CEO of EsperImage, the cap that the team is using in its current work took about five months to build. The challenge now, he said, is to advance the lab prototype to a commercial system that can be mass-produced and disseminated.