Ultrasonic diagnostic imaging with nonlinearly intermodulated frequency components

An ultrasonic imaging method for performing sum or difference frequency imaging with an ultrasound system having an array transducer, a transmitter, and an ultrasound signal processor comprising:

• transmitting a ultrasonic beam from the array transducer into a region to be imaged, the beam containing at least two different frequency components exhibiting different lateral beam profiles;
• receiving echo signals in response to the transmitted waves which contain intermodulated signal components produced by nonlinear effects of materials in the region to be imaged which exhibit a beam profile which is laterally narrower than the widest of the two different lateral beam profiles of the components of the transmitted beam;
• and
• producing a two or three dimensional ultrasonic image utilizing the intermodulated signal components.

An ultrasonic imaging method for performing sum or difference frequency imaging with an ultrasound system having an array transducer, a transmitter, and an ultrasound signal processor comprising:

• transmitting a ultrasonic beam from the array transducer into a region to be imaged, the beam containing at least two different frequency components exhibiting beam profiles with different signal to noise ratios;
• receiving echo signals in response to the transmitted waves which contain intermodulated signal components produced by nonlinear effects of materials in the region to be imaged which exhibit a beam profile with a signal to clutter ratio which is greater than the lesser signal to clutter ratio of the beam profiles of the components of the transmitted beam;
• and
• producing a two or three dimensional ultrasonic image utilizing the intermodulated signal components.

An ultrasonic diagnostic imaging system comprising:

• a transducer array exhibiting a passband encompassing the frequencies of two different transmit frequency components located remote from the center of the passband, and the frequency of an intermodulation product of the two different transmit frequency components located closer to the center of the passband than either of the frequencies of the two different transmit frequency components;
• a transmitter, coupled to the transducer array which actuates the transducer array to transmit a beam containing the two different transmit frequency components;
• a receiver coupled to the transducer array which produces coherent echo signals of an intermodulation product of the two different transmit frequency components;
• an image processor, coupled to the receiver, which produces ultrasonic image signals from the signals produced by the receiver;
• and
• a display.