Sample light is delivered into the anatomical structure having a target voxel, whereby a portion of the sample light passing through the target voxel is scattered by the anatomical structure as signal light, and another portion of the sample light not passing through the target voxel is scattered by the anatomical structure as background light that is combined with the signal light to create a sample light pattern. Reference light is combined with the sample light pattern to generate an interference light pattern, such that the signal light and the reference light are combined in a heterodyne manner. Ultrasound is delivered into the target voxel, such that the signal light is frequency shifted by the ultrasound. The ultrasound and the sample light are pulsed in synchrony at the target voxel, such that at least one pulse of the sample light has a combined duration less than a pulse width of the ultrasound.
