Researchers have developed a method based on speckle contrast optical spectroscopy (SCOS) that can measure a person’s stroke risk non-invasively, akin to a cardiac stress test.
If validated through further tests, the device could transform stroke care, making early detection of increased risk a standard part of medical exams around the world.
The research was carried out at the Keck School of Medicine, University of Southern California and California Institute of Technology (Caltech)
No accessible method to assess stroke risk
Strokes are the leading cause of neurological disability. Close to 90% of them are caused by the reduction or blockage of blood flow to a part of the brain, leading to the death of brain cells.
Currently, there is no widely accessible way to screen patients for physical signs that a stroke is likely to occur. Health care providers rely largely on indirect markers of stroke risk, such as details about a patient’s lifestyle and family history.
“A cardiac stress test allows physicians to counsel patients about their risk for heart disease and to make decisions about treatments. If we can build a brain stress test equivalent that is scalable, affordable and noninvasive, that would make a massive contribution to public health,” said Dr Charles Liu, a professor of clinical neurological surgery, urology and surgery at the Keck School of Medicine and co-senior author of the new research.
Speckle contrast optical spectroscopy measures brain stress
The USC Neurorestoration Center took on that task as part of its larger mission to address critical unmet needs in neurological care. Liu and his colleagues built a device, worn like a headband, that uses a series of lasers and cameras to collect images of the brain through a technique known as speckle contrast optical spectroscopy (SCOS).
In a proof-of-concept study of the new device, funded in part by the National Institutes of Health, the researchers recruited 50 participants to complete a breath-holding ‘stress test’ for the brain while wearing the device, where participants held their breath for as long as they could tolerate. Breath-holding temporarily puts the brain under stress in order to reveal its vulnerabilities, similar to the way running on a treadmill taxes the heart during a cardiac stress test.
The SCOS device was used to collect images from the brains of participants at rest, then again during the stress test. Compared to participants in the low-risk group, those in the high-risk group showed significant differences in blood flow and volume during the stress test, indicating steeper increases in blood pressure. Those findings suggest that the new approach has utility for assessing stroke risk.
Refining the technology for clinical use
The technique transmits lasers through the brain, using cameras to measure how the laser light scatters when it hits an object (in this case, blood cells as they flow through the brain). By measuring blood flow and volume, the researchers can then calculate blood pressure in the brain’s vessels.
More research is needed to refine the test’s parameters and to confirm its utility in a larger population, but it holds the potential to revolutionise stroke care, Liu said.
The device could help providers assess the risks and benefits of various medical treatments, such as whether to prescribe blood thinners, depending on a person’s individual stroke risk. It might ultimately provide more reliable data than existing questionnaires, and it is affordable and portable enough that it could quickly become widespread.
The results were recently published in Biomedical Optics Express.
