Ultrasonic spectral contrast imaging

Claim 2

An ultrasonic imaging method for ultrasonic imaging of tissues located in a tissue image region including a contrast agent in at least a portion of said tissue image region, said method comprising the steps of: (a) projecting an ultrasound beam into said tissue image region; (b) receiving ultrasound reflections from said tissue image region and transducing said reflections into corresponding electrical echo signals; (c) first processing said electrical echo signals to derive a plurality of frequency component signals, each frequency component signal representing an electrical echo signal parameter associated with a pre-determined frequency component of said electrical echo signals; (d) second processing said plural frequency component signals to combine them into a single enhanced contrast image data signal; (e) repeating steps (a) through (d) to derive an ordered array of enhanced contrast image data signals representing an image of said tissue image region; and (f) displaying said ordered array of enhanced contrast image data signals as a visual image of said tissue image region.

Claim 3

An ultrasonic imaging method as in claim 1 wherein said predetermined frequency components are located within the 6 dB amplitude bandwidths of electrical echo signals produced by said tissue with and without said contrast agent being present.

Claim 4

An ultrasonic imaging method as in claim 2 wherein said predetermined frequency components include the peak resonant frequency component of one of (i) said tissue with contrast agent or (ii) said tissue without contrast agent.

Claim 5

An ultrasonic imaging method as in claim 1 wherein, said first and second processing steps include the processing of digital signals.

Claim 6

An ultrasonic imaging method as in claim 1 wherein said first and second processing steps include the processing of analog signals.

Claim 7

An ultrasonic imaging method as in claim 1 wherein said first processing step includes passing said electrical echo signals in parallel through frequency bandpass filters.

Claim 8

An ultrasonic imaging method as in claim 1 wherein said first processing step includes converting said electrical echo signals to digital format and subjecting resulting digital signals to digital Fourier analysis, chirp-Z, short-time Fourier or wavelet transformation, or split-spectrum processing.

Claim 9

A device for processing of ultrasound echoes reflected from tissue containing contrast agent as radiofrequency signals by the method of claim 1, characterized in that it comprises: elements for separating the received response signal into at least two independent channels with pass-bands which can be tuned independently to pre-determined frequencies, and at least two radiofrequency demodulators, one for each said channel.

Claim 10

The device of claim 8 including elements for separating the response signal into at least three independent channels.

Claim 11

A realtime method of ultrasonic imaging of organs and tissue by detection of ultrasound backscatter of a region containing a contrast agent, the method comprising: projecting an ultrasound beam to a zone of tissue to be imaged, receiving the echo reflected from the tissue as a radiofrequency response signal, processing the radiofrequency response signal into a video output by (a) passing the response signal to at least two independent channels with frequency pass-bands respectively tuned to one of at least two selected frequencies in a range lying between the lower and upper bounds of (i) the 6 dB bandwidth of the contrast agent response and (ii) the 6 dB bandwidth of the tissue response, and (b) demodulating signals passing each of said independent channels and processing the resulting demodulated signals to combine them into a single output signal wherein the echoes reflected by tissues containing contrast agent are significantly enhanced in comparison to those echoes reflected by tissue without contrast agent, storing the output in a video scan converter, and scanning the tissue to produce a video image of a region under investigation.

Claim 12

A realtime method of ultrasonic imaging of organs and tissue by detection of ultrasound backscatter of a region containing a contrast agent, the method comprising: projecting an ultrasound beam to a zone of tissue to be imaged, receiving the echo reflected from the tissue as a radiofrequency response signal, processing the radiofrequency response signal into a video output by (a) passing the response signal to at least two independent channels with frequency pass-bands respectively tuned to one of at least two selected frequencies in a range lying between the lower and upper bounds of (i) the 6 dB bandwidth of the contrast agent response and (ii) the 6 dB bandwidth of the tissue response, and (b) demodulating signals passing each of said independent channels and processing the resulting demodulated signals to combine them into a single output signal wherein the echoes reflected by tissues containing contrast agent are significantly enhanced in comparison to those echoes reflected by tissue without contrast agent, storing the output in a video scan converter, and scanning the tissue to produce a video image of a region under investigation.

Claim 13

The method of claim 10 wherein said frequencies are selected so that the difference of echo amplitude reflected from tissue containing contrast agent and that reflected by tissue without contrast agent, or their ratio, is maximal.

Claim 14

The method of claim 10 wherein the response signal is passed through at least three respectively corresponding independent channels.

Claim 15

The method of claim 10 wherein one of the selected frequencies is the resonant frequency of the contrast agent.

Claim 16

The method of claim 10 wherein the values of the selected frequencies are a function of time-of-arrival of the reflected echoes.

Claim 17

The method of claim 10 wherein the demodulated channel signals are processed by division, subtraction, addition or a combination thereof.

Claim 18

An ultrasonic imaging system for ultrasonic imaging of tissues located in a tissue image region including a contrast agent in at least a portion of said tissue image region, said system comprising: (a) means for projecting an ultrasound beam into said tissue image region; (b) means for receiving ultrasound reflections from said tissue image region and transducing said reflections into corresponding electrical echo signals; (c) means for first processing said electrical echo signals to derive a plurality of frequency component signals, each frequency component signal representing an electrical echo signal parameter associated with a pre-determined frequency component of said electrical echo signals; (d) means for second processing said plural frequency component signals to combine them into a single enhanced contrast image data signal; (e) means for repeatedly operating means (a) through (d) to derive an ordered array of enhanced contrast image data signals representing an image of said tissue image region; and (f) means for displaying said ordered array of enhanced contrast image data signals as a visual image of said tissue image region.

Claim 19

An ultrasonic imaging system for ultrasonic imaging of tissues located in a tissue image region including a contrast agent in at least a portion of said tissue image region, said system comprising: (a) means for projecting an ultrasound beam into said tissue image region; (b) means for receiving ultrasound reflections from said tissue image region and transducing said reflections into corresponding electrical echo signals; (c) means for first processing said electrical echo signals to derive a plurality of frequency component signals, each frequency component signal representing an electrical echo signal parameter associated with a pre-determined frequency component of said electrical echo signals; (d) means for second processing said plural frequency component signals to combine them into a single enhanced contrast image data signal; (e) means for repeatedly operating means (a) through (d) to derive an ordered array of enhanced contrast image data signals representing an image of said tissue image region; and (f) means for displaying said ordered array of enhanced contrast image data signals as a visual image of said tissue image region.

Claim 20

An ultrasonic imaging system as in claim 16 wherein said predetermined frequency components are located within the 6 dB amplitude bandwidths of electrical echo signals produced by said tissue with and without said contrast agent being present.

Claim 21

An ultrasonic imaging system as in claim 17 wherein said predetermined frequency components include the peak resonant frequency component of one of (i) said tissue with contrast agent or (ii) said tissue without contrast agent.

Claim 22

An ultrasonic imaging system as in claim 16 wherein, said means for first and second processing include means for processing of digital signals.

Claim 23

An ultrasonic imaging system as in claim 16 wherein said means for first and second processing include means for processing of analog signals.

Claim 24

An ultrasonic imaging system as in claim 16 wherein said means for first processing includes plural frequency bandpass filters.

Claim 25

An ultrasonic imaging system as in claim 16 wherein said means for first processing includes means for converting said electrical echo signals to digital format and subjecting resulting digital signals to digital Fourier analysis, chirp-Z, short-time Fourier or wavelet transformation, or split-spectrum processing.

Claim 28

The system of claim 23 wherein in the means for separating the received ultrasonic signal includes means for separating it into at least three independent channels.

Claim 29

The system of claim 23 including variable bandpass filters or a spectrum analyzer for separating the received ultrasonic signals into said independent channels.

Claim 30

The system of claim 25 where spectral Fourier analysis of the returning echoes is applied within a sliding time window on the returning echoes.

Claim 31

The system of claim 23 wherein the pre-selected frequencies are functions of time-of-arrival of the reflected echoes.

Claim 32

The system of claim 23 wherein the system further comprises a receiving amplifier with a time-gain function connected to supply the received ultrasonic signals to the signal separation elements and non-linear amplifiers connected to process the demodulator outputs.

Claim 33

The system of claim 23 wherein the processing means includes at least one analog subtract/divide amplifier for processing the output signal.

Claim 34

The system of claim 23 wherein the system includes a video scan converter.

Claim 35

The system of claim 23 wherein said signal processing means includes digital electronic circuits operating on data obtained by analog-to-digital conversion of the received ultrasound echo signals.

Claim 36

The system of claim 23 where the signal processing means includes means for coding the amplitude of processed output signals by different video colors superimposed on an otherwise conventional grey-scale video image obtained by processing in B-mode imaging.

Claim 37

The system of claim 23 wherein said signal processing means are part of a receiver of a pulsed-Doppler ultrasound system.

Claim 38

The system of claim 33 wherein the pulsed-Doppler ultrasound system incorporates an audible signal output by means of a loudspeaker.

Claim 39

The system of claim 33 wherein the pulsed-Doppler ultrasound system incorporates a spectral video output representing a spectrum of velocity distribution.

Claim 40

The system of claim 33 wherein the pulsed-Doppler ultrasound system incorporates a two-dimensional map of velocity distribution.

Claim 41

The system of claim 36 wherein the two-dimensional map of velocity distribution is color coded.

Claim 42

The system of claim 33 wherein the pulsed-Doppler ultrasound system incorporates a two-dimensional map of echo-amplitude or energy derived from Doppler echo components from moving targets.

Claim 43

The system of claim 33 wherein the pulsed-Doppler ultrasound system incorporates a two-dimensional map of Doppler echo components from targets moving with a velocity inferior to a predetermined threshold.

Claim 44

The system of claim 33 wherein the pulsed-Doppler ultrasound system incorporates a two-dimensional map of Doppler echo components from targets moving with a velocity superior to a predetermined threshold.

Claim 45

Use of the ultrasonic system of claim 23 for imaging of tissue or organs of human and animal patients.

Claim 46

Use of the ultrasonic system of claim 23 for imaging of a cardio-vascular system of human and animal patients.