Cerebral blood flow imaging in humans using fiber-based speckle contrast optical spectroscopy

Speckle contrast optical spectroscopy/tomography (SCOS/T) offers a noninvasive, lower-cost alternative for continuous bedside monitoring of cerebral blood flow. Here, we present a single-source, single-detector, fiber-based SCOS system that improves SNR through pixel-level averaging with camera-based detection. In human measurements, we observe high-SNR pulsatile hemodynamic signals through hair. We show that SNR scales approximately with the square root of the number of averaged pixels, enabling detection of stimulus-evoked responses. These results demonstrate that averaging over more fibers in the fiber bundle improves SNR in SCOS, motivating the use of SCOS/T for functional brain monitoring.