Abstract: Apparatus and methods are provided including directing acoustic radiation toward a region of interest within a subject's body. Light is transmitted from a light emitter to a light detector such that a first light portion is transmitted without passing through the subject's tissue, and a second light portion is transmitted via the region of interest. Scattered light of the second light portion contains a tagged component corresponding to photons tagged by the acoustic radiation, and an untagged component corresponding to photons untagged by the acoustic radiation. Light of the first light portion undergoes an interaction with light of the second light portion at the light detector. A property of tissue of the region of interest is determined, by decoupling from each other the tagged and untagged components of the second light portion, based upon the interaction between the light of the first and second light portions.

Abstract: A fluid flow monitoring system is provided that has a processor utility which is connectable to an acoustic generator associated with acoustic ports and is operable for generating signals S0 to activate the acoustic ports for irradiating a region of interest with acoustic radiation of a certain frequency range centered at a frequency F0 and is connectable to at least one light output port associated with one or more light detectors for receiving light of at least one wavelength ? from the region of interest including light tagged by said acoustic radiation. The processor utility may be configured for analyzing the generated signals S0 and data indicative of the received light including light tagged by the corresponding acoustic radiation and determining correlation between the signals S0 and the data indicative of the received light, the correlation being informative of a measure of fluid flow in a turbid medium.