Coherent hemodynamics spectroscopy (CHS), developed by Tufts professor Sergio Fantini, measures blood flow, blood volume, and oxygen consumption in the brain. The goal is to pinpoint and monitor, real time and non invasively, brain damage from stroke, traumatic injury, or vascular dementia. It can also be used to study how blood flow is regulated in the healthy brain.

CHS uses noninvasive laser diodes that emit near infrared light, delivered to the scalp by fiber optics. Light waves are absorbed by blood vessels in the brain. Remaining light is reflected back to sensors, resulting in optical signals that oscillate with time as a result of the heartbeat, respiration, or other sources of blood pressure variation. Algorithms analyze the light signals, enabling the model to evaluate blood flow and the way the brain regulates it.