ABSTRACT
Acousto-optic measurements are based on locally modulating light with a localized low power ultrasound beam. The use of non-invasive, acousto-optic monitoring of cerebral oxygen saturation was recently demonstrated in clinical settings. A new acousto-optic cerebral blood flow monitor enables continuous monitoring of changes in microvascular blood flow in cerebral tissue. Near-infrared light is commonly used to monitor, and even image, hemodynamic, metabolic, and physiological changes within cerebral tissue. The induction of acousto-optically modulated light within cerebral tissue suffers from the high attenuation of the ultrasound wave that propagates through the skull bone. The molar extinction coefficients and the concentrations of both absorbing chromophores and scattering centers control the attenuation of light as it propagates a distance in the tissue. Optical measurements, which provide non-invasive, simple to use readings of both spectral and temporal characteristics of the tissue’s vasculature, with a high temporal resolution, can provide such necessary clinical information.
