Nonlinear imaging using orthogonal transmit and receive codes

A method for imaging ultrasound scatterers, comprising the steps of:

• producing a first coded wavelet which is a function of a first transmit code convolved with a base wavelet and a second coded wavelet which is a function of a second transmit code convolved with said base wavelet;
• driving transducer elements with said first coded wavelet during a first transmit firing and with said second coded wavelet during a second transmit firing, said first and second transmit firings being focused at a transmit focal position;
• receiving first and second sets of echo signals from transducer elements subsequent to said first and second transmit firings respectively;
• forming first and second beamsummed receive signals derived from said first and second sets of echo signals respectively;
• correlating said first beamsummed receive signal with a first receive code to form a first filtered signal;
• correlating said second beamsummed receive signal with a second receive code to form a second filtered signal;
• vector summing said first and second filtered signals to produce a summed signal;
• processing said summed signal to form an image signal;
• and
• displaying an image which is a function of said image signal,
• wherein the correlation of said first transmit code with said first receive code summed with the correlation of said second transmit code with said second receive code equals zero.

A system for nonlinear imaging of ultrasound scatterers, comprising:

• an ultrasound transducer array comprising a multiplicity of transducer elements;
• a transmitter coupled to said transducer array for pulsing said transducer elements with a first coded wavelet during a first transmit firing and with a second coded wavelet during a second transmit firing, said first coded wavelet being derived by coding a base wavelet with a first transmit code and said second coded wavelet being derived by coding said base wavelet with a second transmit code;
• a receiver coupled to said transducer array for receiving a first set of signals from said transducer following said first transmit firing and a second set of signals from said transducer elements following said second transmit firing;
• a beamformer for forming first and second beamsummed receive signals from said first and second sets of signals respectively;
• a filter arranged to correlate said first beamsummed receive signal with a first receive code to form a first filtered signal and correlates said second beamsummed receive signal with a second receive code to form a second filtered signal;
• a vector summer for summing said first and second filtered signals to produce a summed signal;
• a processor programmed to form an image signal from said summed signal;
• and
• means for displaying an image which is a function of said image signal,
• wherein the correlation of said first transmit code with said first receive code summed with the correlation of said second transmit code with said second receive code equals zero.

A system for nonlinear imaging of ultrasound scatterers, comprising:

• an ultrasound transducer array comprising a multiplicity of transducer elements;
• transmit means coupled to said transducer array for pulsing a set of selected transducer elements which form a transmit aperture with a first coded wavelet during a first transmit firing and with a second coded wavelet during a second transmit firing, said first coded wavelet being derived by coding a base wavelet with a first transmit code and said second coded wavelet being derived by coding said base wavelet with a second transmit code;
• acquisition means coupled to said transducer array for acquiring first and second beamsummed receive signals subsequent to said first and second transmit firings respectively;
• demodulation means for demodulating said first and second beamsummed receive signals to form first and second demodulated signals respectively;
• a filter for correlating said first demodulated signal with a first receive code to form a first filtered signal and correlating said second demodulated signal with a second receive code to form a second filtered signal;
• means for vector summing said first and second filtered signals to produce a summed signal;
• a processor programmed to form an image signal from said summed signal;
• and
• means for displaying an image which is a function of said image signal,
• wherein the correlation of a demodulated version of said first transmit code with said first receive code summed with the correlation of a demodulated version of said second transmit code with said second receive code equals zero.

A method for imaging ultrasound scatterers, comprising the steps of:

• producing a first coded wavelet which is a function of a first transmit code convolved with a base wavelet and a second coded wavelet which is a function of a second transmit code convolved with said base wavelet;
• driving transducer elements with said first coded wavelet during a first transmit firing and with said second coded wavelet during a second transmit firing, said first and second transmit firings being focused at a transmit focal position;
• receiving first and second sets of echo signals from transducer elements subsequent to said first and second transmit firings respectively;
• forming first and second beamsummed receive signals derived from said first and second sets of echo signals respectively;
• demodulating said first and second beamsummed receive signals to form first and second demodulated signals respectively;
• correlating said first demodulated signal with a first receive code to form a first filtered signal;
• correlating said second demodulated signal with a second receive code to form a second filtered signal;
• vector summing said first and second filtered signals to produce a summed signal;
• processing said summed signal to form an image signal;
• and
• displaying an image which is a function of said image signal,
• wherein the correlation of a demodulated version of said first transmit code with said first receive code summed with the correlation of a demodulated version of said second transmit code with said second receive code equals zero.