Laser headband non-invasively IDs stroke risk in real time
by Bronwyn Thompson · New AtlasA laser-driven device that offers instant feedback on a patient's stroke risk could revolutionize current difficult methods of accurate assessment and provide a portable, affordable and non-invasive way for clinicians to make life-saving interventions.
Researchers from the California Institute of Technology (Caltech) and the Keck School of Medicine of University of Southern California (USC) have developed a wearable laser-based device that monitors brain blood flow changes and volume when a patient holds their breath. Analysis of this test in real time can provide instant feedback as to the patient's stroke risk.
"With this device, for the first time, we are going to have a way of knowing if the risk of someone having a stroke in the future is significant or not based on a physiological measurement," said the study's co-lead author Simon Mahler, a postdoctoral scholar at Caltech. "We think this can really revolutionize the way stroke risk is assessed and will eventually help doctors determine if a patient's risk is stable or worsening."
The device shines an infrared laser light through the skull and into the brain, while an adjacent camera collects data measuring light bouncing back after being 'scattered' by the blood flow within blood vessels. This method, known as speckle contrast optical spectroscopy (SCOS), essentially shows the rate of blood flow by how quickly the scattering changes.
In the study, the team recruited 50 participants who were then split into two groups – high and low risk – after completing a questionnaire based on the Cleveland Stroke Risk Calculator. Fitted with the device, each participants had their brain's blood flow rate and volume analyzed for three minutes, and were required to hold their breath at the one-minute mark.
Holding one's breath creates stress on the brain as it's deprived of oxygen, which causes the rest of the body to respond by pumping more blood to the organ. Blood flow then returns to baseline – or 'normal' – levels once regular breathing restarts. Through this process, the device's SCOS analysis picked up key differences between the low risk and high risk group.
"As people age their blood vessels get stiffer, making them more prone to stroke," said Changhuei Yang, a professor at Caltech. "By asking a person to hold their breath, we can use SCOS to measure how much the blood vessels expand and how much faster blood is flowing within the vessels in response. These reactive measurements are indicative of vessel stiffness, and such measurement capabilities are unique to transcranial optical methods.
"Our technology makes it possible to make these type of measurements non-invasively for the first time," he added.
The researchers are now looking at adding machine learning in analyzing the collected data, and conducting a clinical trial to track patients for more than two years. What's more, they hope that as this technology develops, it will eventually do more than analyze risk but be able to detect just where in the brain a stroke has already occurred.
Nearly 800,000 Americans, and 15 million people worldwide, are affected by stroke every year and it remains the leading cause of serious, enduring disability in the US.
"This approach could one day be incorporated into the regular testing performed during annual physical examinations, providing physicians with crucial information about the patient's health," said Charles Liu from USC. "It could be particularly beneficial for communities with limited access to advanced medical facilities and has the potential to lead to personalized strategies for reducing stroke risk."
The study was published in the journal Biomedical Optics Express.