The present invention provides methods and systems for generating ultrasound images of a plurality of scatterers disposed in a target region. More particularly, a method of the invention derives model response functions for each of a plurality of transducers for a given distribution of scattering media. The interrogation pattern can be selected to include a set of unfocused ultrasound waves generated by one or more of the transducers. The interrogation pattern is transmitted into the target region, and the transducers are utilized to detect echoes generated by the scatterers in the target region in response to the interrogation pattern. The methods and systems of the invention advantageously allow obtaining ultrasound images of a target region without employing beamforming either in transmission of ultrasound waves into the region or in detection of echoes generated by scatterers in the target region in response to the transmitted waves.