Ultrasound imaging system employing phase inversion subtraction to enhance the image

A method for generating an ultrasound image that enhances regions occupied by non linear scattering media. The method utilizes first and second ultrasound pulses that are alternatively transmitted into the specimen being imaged. The first and second ultrasound pulses are amplitude modulated harmonic signals, the first ultrasound pulse differing from the second ultrasound pulse by the phase of the harmonic signal. The echo signals generated by these pulses are measured and combined. In one embodiment of the present invention, the first and second ultrasound signals differ by 180 degrees and the echo signals are combined by adding the echo signals generated by each of the ultrasound pulses.