Data that informs the state of tissue health and function are the fuel that drives several aspects of biomedical research. DCS suffers from critical limitations that inhibit robust clinical use. DCS like most optical techniques is affected by partial volume effects. Thus, the measured blood flow is more sensitive to superficial tissues such as scalp/skull rather than the brain. Secondly, DCS instruments are often accompanied by a second optical instrument to measure tissue optical properties into a hybrid probe. The result of this hybrid arrangement is 2X increase in cost, and reduced instrument portability. In the past, simple interventions and multi-layered tissue models to account for some of these effects have been suggested but those are not practical for long-term continuous clinical monitoring. An alternative method to use the Diffuse Correlation Spectroscopy (DCS) has been purposed. This method uses readily available laser sources and detectors and can be implemented as an add-on to existing DCS instruments to impart pathlength and depth sensitivity. This approach has superior signal-to-noise ratios compared to devices with similar capabilities, thereby permitting measurements from tissues 3-4 cm below the surface.
A Standard DCS Measurement