Experimental Evaluation of Laser SCOS for Monitoring Brain Blood Flow

Non-invasive measurement of cerebral blood flow remains challenging due to the barriers posed by the scalp and skull. These superficial layers not only attenuate the signal but also have hemodynamic activity that corrupts brain-specific signals. We developed a seven-channel laser speckle contrast optical spectroscopy (SCOS) system designed to non-invasively probe blood flow and blood volume at varying tissue depths such as the scalp and brain layers. Each channel employed a unique source-detector separation, allowing to tune the ratio between superficial and deeper blood flow contributions.

To test a seven-channel SCOS system, the Speckle Imaging Lab temporarily occluded the superficial temporal artery (STA), which perfuses only the scalp. Measurements in 20 healthy adult subjects showed that scalp-sensitive channels exhibited significant decreases in blood flow and volume signals during STA occlusion, while brain-sensitive channels remained largely unaffected. These findings confirm that SCOS measurements are depth-dependent and that scalp and brain signals can be distinguished.

About the presenter
Simon Mahler, Ph.D., is an assistant professor in the Department of Biomedical Engineering at Stevens Institute of Technology, New Jersey. His speckle imaging lab focuses on the intersection of biophotonics, device engineering, cardiovascular research, and optical measurement.

Mahler’s recent research focuses on developing laser speckle imaging techniques for visualizing blood flow in applications spanning neuroscience, embryology, and applied biomedical research. He earned his bachelor and master’s degrees from University of Paris-Saclay, France. He earned his doctorate in optical physics and complex systems from the Weizmann Institute of Science and previously held a postdoctoral appointment in biophotonics (Prof. Changhuei Yang) at the California Institute of Technology.