A system and method monitoring conditions of a subject's body including a control unit receiving image data and data indicative of an external stimulation applied to the body during collection of the image data therefrom, a memory utility, and a processor utility. The image data is indicative of a sequence of speckle patterns generated by the body according to a certain sampling time pattern. The processor utility performs processing the image data utilizing the data indicative of the applied external field(s), including determining a spatial correlation function between successive speckle patterns in the sequence, and determining a time varying spatial correlation function in the form of a time-varying function of a feature of the correlation function indicative of a change of the speckle pattern over time； selecting a parameter of the time-varying spatial correlation function, and applying a model to the parameter to determine a corresponding body condition； and generating output data indicative of the corresponding body condition.
