Portable device for quantitative measurement of tissue autoregulation and neurovascular coupling using EEG, metabolism, and blood flow diagnostics

A method of determining an absolute value of cerebral metabolic rate of oxygen (CMRO2) using a volumetric calibration, the method comprising:

• a. positioning one or more light sources and two or more detectors in proximity to a head of a subject;
• b. emitting a coherent light signal from one or more of the light sources into the head, such that one or more backscattered light signals are generated;
• c. detecting one or more of the backscattered light signals via the two or more detectors, wherein the detected signals correspond to an optically measured volume of tissue;
• d. calculating a tissue absorption coefficient and a tissue scattering coefficient from the detected signals;
• e. calculating a calibrated perfusion metric representing perfusion over an area of the volume of tissue from the detected signals;
• f. calculating a deoxygenated hemoglobin concentration (ctHb) in the volume of tissue from the tissue absorption coefficient;
• g. calculating a mean penetration depth of the detected signals, using the tissue absorption coefficient and tissue scattering coefficient;
• and
• h. calculating an absolute value of CMRO2 from the deoxygenated hemoglobin concentration, the calibrated perfusion metric, and the mean penetration depth.