C W and pulse Doppler diagnostic system

• US 4,819,652 A
• Filed: 02/08/1985
• Issued: 04/11/1989
• Est. Priority Date: 02/08/1985
• Status: Expired due to Fees

• Current Assignee: University Patents, Inc.
• Original Assignee: University Patents, Inc.
• Inventors: Micco, Alexander J.
• Primary Examiner(s): Jaworski, Francis J.
• Application Number:
  US06/699,676
• Time in Patent Office: 1,523 Days
• Field of Search: 128/660-663, 73/861.25
• US Class Current: 600/455
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: G01S 15/584 with measures taken for suppressing velocity ambiguities, i.e. anti-aliasing
• CPC Class Codes: G01S 15/586 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 15/8979 Combined Doppler and pulse-echo imaging systems

Abstract

In an interlaced pulse-echo and range-gated Doppler system, an ultrasound transmitter generates a train of constant repetition rate echo pulse interlaced with a Doppler pulse train of plural bursts. The time duration between each burst and the preceding range gate opening is held constant while the time to the successive range gate opening is automatically varied to provide a continuously variable PRF tracking of the console range gate depth setting. The power of the transmitted signal is internally varied in the same sense and the cutoff frequency of the receiver low pass tracking filters is varied in the opposite sense to optimize signal-to-noise ratio at various tissue inspection depths. Selectable turnable high pass filters normalized to low velocity roll-off eliminate artifact for peripheral or central vascular probes. The detection system operates in quadrature and includes a synchronous demodulator and a peak detector, and a level detector operative on peak detected signals. Transducer probes interchangeably usable in the system include within each probe a narrow band amplifier critically turned to the respective probe crystal to provide further S/N ratio improvement. The system is operable in CW or pulsed Doppler modes dependent on switch setting on the split crystal probe.

Claims

1. In an ultrasonic diagnostic apparatus including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, and ultrasound transducer means connected to said transmitting means for emitting ultrasound pulses in response to said drive signals and for apply signals to said receiving means in response to ultrasound pulses received in response to said emitted ultrasound pulses, the improvement wherein said transmitting means comprises means for generating a train of Doppler pulse signals each comprised of a burst of a plurality of cycles followed by a receiving cycle, means for generating range gate signal for applying gate signals to said receiving means to enable reception of signals, by said receiving means corresponding to said Doppler pulse signals only during predetermined periods following each Doppler pulse signal, means for applying said Doppler signals to said transducer means as said drive signals, and means for adjusting the time between each Doppler pulse signal and the respective range gate signal while maintaining the time between each Doppler pulse signal and the immediately preceding range gate signal substantially constant and while simultaneously varying the power of emitted ultrasound pulses in the same sense.

2. The ultrasonic diagnostic apparatus of claim 1, wherein said means for generating a range gate signal comprises means for establishing first and second clock signals of opposite phase, and means responsive to substantial coincidence between the leading edge of said range gate signal and one of said first and second clock signals for initiating said range gate signal with the other of said click signals, said one clock signal being that one of said clock signals that initiated the last previous range gate signal.

3. In an ultrasonic diagnostic apparatus including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, and ultrasound transducer means connected to said transmitting means for emitting ultrasound pulses in response to said drive signals and for applying signals to said receiving means in response to ultrasound pulses received in response to said emitted pulses, the improvement wherein said transmitting means comprises means for generating a train of Doppler pulse signals each comprised of a burst of a plurality of cycles followed by a reading cycle, means for generating a range gate signal for applying gate signals to said receiving means to enable reception of signals only during predetermined periods following the emission of each Doppler pulse signal, means for applying said Doppler pulse signals to aid transducer means, sand means for adjusting the time between each Doppler pulse signal and the respective range gate signal and maintaining the time between each Doppler pulse signal and the immediately preceding range gate signal substantially constant while simultaneously varying the pulse repetition rate of said Doppler pulse signals.

4. The ultrasound diagnostic apparatus of claim 3 wherein said means for adjusting comprises means for inhibiting the generation of each Doppler pulse signal until a predetermined minimum delay time following the range gate signal corresponding to the previous Doppler pulse signal.

5. In an ultrasonic diagnostic apparatus including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, and ultrasound transducer means connected to said transmitting means for emitting ultrasound pulses in response to said drive signals and for applying signals to said receiving means in response to ultrasound pulses in response to the emitted ultrasound pulses, the improvement wherein said transmitting means comprises means for generating a train of Doppler pulse signals each comprised of a burst of a plurality of cycles, means for generating a range gate signal for applying gate signals to said receiving means to enable reception of signals corresponding to said Doppler pulse signals only during predetermined periods following each Doppler pulse signal, means for applying said Doppler pulse signals to said transducer means as said drive signals, said receiving means comprising low pass filter means, said apparatus further comprising means for adjusting the time between each Doppler pulse signal and the respective range gate signal while simultaneously decreasing the cutoff frequency of said low pass filter means for increases in said time and increasing said cutoff frequency for decreases in said time.

6. In an ultrasonic diagnostic apparatus including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, and ultrasound transducer means connected to said transmitting means for emitting ultrasound in response to said drive signals and for applying signals to said receiving means in response to ultrasound echoes responsive to said emitted ultrasound, the improvement wherein said transducer means comprises a transducer, means connecting said transmitting means to said transducer, a narrow band amplifier and a transformer having a primary winding connected to said transducer and a secondary winding connected to said narrow band amplifier, said transformer being tuned to the frequency of emission of said ultrasound.

7. The apparatus of claim 6 wherein said transformer comprises a core that saturates when drive signals are applied to said transducer.

8. The apparatus of claim 6 wherein the coupling between said primary and secondary windings is no greater than critical coupling at the frequency of said ultrasound.

9. In an ultrasonic diagnostic apparatus including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, and ultrasound transducer means connected to said transmitting means for emitting ultrasound in response to said drive signals and for applying echo signals responsive to said emitted ultrasound to said receiving means, and wherein said receiving means comprises means for synchronously demodulating received signals to provide first and second signals demodulated at 90 degrees with respect to one another, the improvement wherein said receiving means further comprises means for peak detecting each of said first and second signals to produce peak detected signals, means for level detecting said peak detected signals to substantially eliminate noise perturbations, phase sensitive full wave pulse generating means connected to said level detecting means, and means for integrating the outputs of said pulse generating means for producing said output signals.

10. In the method of diagnostic analysis employing Doppler pulse generation comprising generating Doppler pulse drive signals in the form of bursts of a plurality of cycles, applying said drive signals to an ultrasound transducer for transmitting bursts of ultrasound, receiving echo ultrasound pulses responsive to said transmitted bursts via said transducer and applying them to a receiving means, generating a range gate signal and displaying the output of said receiving means during the occurrence of said range gate signal;

the improvement comprising adjusting the timing between each said burst and the succeeding range gate signal while maintaining the time between each burst and the immediately preceding range gate signal constant and simultaneously adjusting the power of transmitted ultrasound emitted by said transducer in the same sense.

11. In the method of diagnostic analysis employing Doppler pulse generation comprising generating Doppler pulse drive signals in the form of bursts of a plurality of cycles, applying said drive signals to an ultrasound transducer for transmitting bursts of ultrasound, receiving echo ultrasound pulses responsive to said transmitted ultrasound bursts via said transducer and applying them to a receiving means, generating a range gate signal, and displaying the output of said receiving means during the occurrence of said range gate signal;

the improvement comprising adjusting the time between each said burst and the succeeding range gate signal and simultaneously adjusting the pulse repetition rate of said bursts while maintaining the time between each burst and the immediately preceding range gate signal substantially constant.

12. The method of claim 11 wherein said step of adjusting comprises varying the time between each range gate signal and the succeeding burst to be only above a determined minimum timing between said bursts and the following range gate signal.

13. In the method of diagnostic analysis employing Doppler pulse generation comprising generating Doppler pulse drive signals in the form of bursts of a plurality of cycles each, applying aid drive signals to an ultrasound transducer for transmitting ultrasound, receiving echo ultrasound pulses responsive to said transmitted ultrasound via said transducer and applying them to a receiving means, generating a range gate signal, and displaying the output of said receiving means in response to said transmitted ultrasound bursts only during the occurrence of said range gate signal;

the improvement comprising passing said received signals in said receiving means through a low pass filter, and adjusting the time between each said burst and the succeeding range gate signal and simultaneously adjusting the cut off frequency of said low pass filter whereby the cut off frequency is decreased as said time increases and the cutoff frequency is increased as said time decreases.

14. In the method of diagnostic analysis employing Doppler generation comprising generating ultrasound drive signals, applying said drive signals to an ultrasound transducer for transmitting ultrasound, receiving echo ultrasound signals responsive to said transmitted ultrasound via said transducer and applying them to a receiving means, synchronously demodulating the received signals at 90 degrees to produce quadrature signals, and displaying the output of said receiving means during said range gate signal;

the improvement comprising peak detecting said quadrature signals, level detecting the resultant peak detected signals to eliminate noise perturbations, generating pulse signals from said level detected signals in phase sensitive full wave pulse generating means and integrating the full wave generated signals to produce an output signal for diagnostic analysis.

15. In a system for processing continuous signals where said sampling means are provided for sampling said signals at predetermined variable times following a reference time, the sampling means comprising means for producing a gate signal from a leading edge signal that has a timing that is variable with respect to said reference time, the improvement wherein said sampling means comprises means for establishing first and second clock signals of opposite phase for selectively initiating a range gate signal in response to the occurrence of said clock signals, said sampling means comprising means responsive to substantial coincidence between said leading edge and one of said first and second clock signals for initiating said range gate with the other of said clock signals.

16. In an ultrasonic diagnostic apparatus including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, and an ultrasound transducer connected to said transmitting means for emitting ultrasound pulses in response to said drive signals and for applying signals to said receiving means in response to ultrasound pulses received in response to said emitted ultrasound pulses, the improvement wherein said transmitting means comprises means for generating a composite signal comprised of a train of single cycle pulse signals of substantially constant repetition rate each pulse of which is followed by a receiving period and interlaced with a train of Doppler pulse signals, said Doppler pulse signals each being comprised of a plurality of bursts each of a plurality of cycles followed by a receiving period, means for varying the repetition rate of said bursts, and means applying said composite signals as said drive signals to said transducer, and further comprising a narrow-band amplifier connected to said receiving means and means connecting said narrow-band amplifier to said transducer, said narrow-band amplifier having an input impedance critically tuned to reduce Johnson noise and thus provide a substantially improved signal-to-noise ratio at a predetermined frequency.

17. The ultrasonic diagnostic apparatus of claim 16 wherein said connections means comprises a tuned matching transformer having a primary winding coupled to said transducer and a secondary winding coupled to said amplifier.

18. The ultrasonic diagnostic apparatus of claim 17 wherein said transformer has a core that saturates when drive signals are applied to said transducer, the coupling between said primary and secondary windings being no greater than critical at the frequency of said drive signals.

19. In an ultrasonic diagnostic apparatus including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, and an ultrasonic transducer connected to said transmitting means for emitting ultrasonic pulses in response to said drive signals and for applying signals to said receiving means in response to ultrasound pulses received in response to said emitted ultrasound pulses, the improvement wherein said transmitting means comprises means for generating a composite signal comprised of a train of single cycle pulse signals of substantially constant repetition rate each pulse of which is followed by a receiving period and interlaced with a train of Doppler pulse signals, said Doppler pulse signals each being comprised of a plurality of bursts each of a plurality of cycles followed by a receiving period, means for varying the repetition rate of said bursts, and means applying said composite signals as said drive signals to said transducer, said receiving means comprising means for synchronously demodulating received signals to provide first and second signals demodulated at 90 degrees, means for peak detecting each of said first and second signals to produce peak detected signals, means for level detecting said peak detected signals, means for level detecting said peak detected signals to substantially eliminate noise perturbations therefrom, phase-sensitive full-wave pulse generating means connected to said level detecting means, and means for integrating the output of said pulse generating means for producing an output signal.

20. In the method of diagnostic analysis comprising generating drive signals, applying said drive signals to an ultrasound transducer for transmitting ultrasound pulses, receiving echo ultrasound pulses responsive to said transmitted ultrasound pulses via said transducer and applying them to a receiving means, and displaying the output of said receiving means;

the improvement wherein said step of generating drive signals comprises generating a composite drive signal comprised of a train of single cycle pulse signals of constant repetition rate each followed by a receive time and interlaced with a train of Doppler pulse signals, said Doppler pulse signals, each being comprised of a plurality of bursts of a plurality of cycles followed by a receive period, further comprising varying the repetition rate of said bursts, and said step of applying comprises applying said composite drive signal to said transducer, and further comprising the steps of synchronously demodulating received signals at 90 degrees to produce quadrature signals, peak detecting said quadrature signal level detecting the resultant peak detected signals to eliminate noise perturbations, generating pulse signals from said level detected signals in phase-sensitive full-wave pulse generating means, and integrating the generated pulse signals to produce an output signal.

21. In an ultrasonic diagnostic apparatus, including transmitting means for generating drive signals, receiving means for producing output signals for diagnosis, and an ultrasound transducer connected to said transmitting means for emitting ultrasound pulses in response to said drive signals and for applying signals to said receiving means in response to ultrasound pulses received in response to said emitted ultrasound pulses, the improvement wherein said receiving means comprises means for synchronously demodulating received signals to provide first and second signals demodulated at 90°

, means for peak detecting each of said first and second signals to produce peak detected signals, means, and means or integrating the output of said pulse generating means for producing an output signal.

22. In the method of diagnostic analysis comprising generating drive signals, applying said drive signals to an ultrasound transducer for transmitting ultrasound pulses, receiving echo ultrasound pulses responsive to said transmitted ultrasound pulses via said transducer and applying them to a receiving means, and displaying the output of said receiving means, the improvement comprising synchronously demodulating signals received by said receiving means at 90°

to produce quadrature signal, peak detecting said quadrature signals, level detecting the resultant peak detected signals to eliminate noise perturbations, generating pulse signals from said level detected signals in phase-sensitive full-wave pulse generating means, and integrating the generated pulse signals to produce an output signal.

23. In a ultrasonic diagnostic apparatus, including a transmitting means for generating drive signals, a receiving means for producing output signals for diagnosis, an ultrasound transducer means connected to said transmitting means for emitting ultrasound pulses in response to said drive signals and for applying signals to said receiving means in response to ultrasound pulses received in response to said emitted ultrasound pulses, the improvement wherein said transmitting means comprises means for generating a train of Doppler pulse signals, each comprised of a burst of plurality of cycles followed by a receiving cycle, and means for generating a range gate signal for applying gate signals to said receiving means to enable reception of signals by said receiving means corresponding to said Doppler pulse signals only during predetermined periods following each Doppler pulse signal, means for applying said Doppler signals to said transducer means as said drive signals, and means for adjusting the time between each Doppler pulse signal and the respective range gate signal, said means for generating a range gate signal comprising means for establishing first and second clock signals of opposite phase, and means responsive to substantial coincidence between the leading edge of said range gate signal and one of said first and second clock signals for initiating said range gate signal with the other of said clock signals, aid one clock signal being that one of said clock signals that initiated the last previous range gate signal.