Wearable laser measures brain-blood flow to predict stroke risk
A portable, non-invasive, speckle-contrast optical spectroscopy (SCOS) device assesses stroke risk by calculating changes in brain-blood flow and volume.
A SCOS device, developed by researchers from the University of Southern California and California Institute of Technology (both CA, USA), has successfully differentiated between groups with low and high risk of stroke by measuring changes in blood flow during a brain-stress test involving a breath-holding exercise. The technology has the potential to advance prevention and intervention approaches for effective stroke risk assessment.
With stroke affecting approximately 15 million people worldwide each year, monitoring the early physiological signs of the condition could improve patient outcomes and potentially prevent neurological disability for many individuals.
Existing tools to monitor changes in blood flow including PET, SPECT and CT are expensive and difficult to use in clinics or community settings.
The SCOS device comprises two parts that are placed on the head: a laser diode and a complementary metal-oxide-semiconductor-based camera. The device shines an infrared laser onto the brain, which penetrates the skull and scatters in a pattern that depends on the blood flow and tissue oxygenation. When the wearer takes a breath in, their blood vessels expand and increase blood flow. The stiffer their blood vessels, the smaller the increase in blood flow rate. The laser speckle’s scatter fluctuates quicker with faster blood flow.
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The team tested 50 people who were split evenly into low- and high-risk stroke groups based on the Cleveland Stroke Risk Calculator. They demonstrated that the blood flow and volume fluctuation recorded during breath intake were substantially different for the two groups.
Charles Liu (University of Southern California), study author commented, “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. 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 next steps for the research include a larger clinical trial, with progress tracked over 2 or more years to investigate how changes in stress test scores could correlate with real-world outcomes.
