JPH08224237A - Ultrasonic doppler diagnosing device - Google Patents

Abstract

PURPOSE: To accurately measure bloodstream speed even in a slow speed bloodstream by eliminating a relative speed-component between an examinee and a probe in an ultrasonic Doppler diagnosing device. CONSTITUTION: A relative speed estimating part 12 as a means to estimate by calculating the relative speed of the examinee and the probe 1 by fetching complex signals S1 , S2 obtained in Doppler detecting parts 4a, 4b is provided. Also, a complex multiplier 13 is provided as a means to eliminate the relative speed component of the examinee and the probe 1 from the frequency spectrum of a Doppler detection signal by inputting the estimated value of the relative speed from the relative speed estimating part 12 and inputting the Doppler detection signal obtained in the Doppler detecting parts 4a, 4b. In this way, it is possible to accurately measure the bloodstream speed even in the slow speed bloodstream by eliminating the relative speed component of the examinee and the probe 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transmits and receives ultrasonic waves to and from a diagnostic region of a subject, detects a frequency signal subjected to Doppler shift due to blood flow from the obtained reflection echo signal, and detects the subject. The present invention relates to an ultrasonic Doppler diagnostic apparatus for measuring a complex blood flow signal, and in particular, it is capable of measuring an accurate blood flow velocity even in low-speed blood flow by removing a relative velocity component between a subject and a probe. An acoustic Doppler diagnostic device.

[0002]

2. Description of the Related Art A conventional ultrasonic Doppler diagnostic apparatus of this type, as shown in FIG. 2, supplies a probe 1 for transmitting and receiving ultrasonic waves to the inside of a subject and a transmission pulse for the probe 1. Pulser 2, an amplifier 3 that amplifies the reflected echo signal received by the probe 1, and a component that has undergone Doppler shift due to the blood flow from the reflected echo signal from this amplifier 3 is detected as a complex blood flow signal. Doppler detection units 4a and 4b, a frequency analysis unit 5 that frequency-analyzes blood flow signals detected by the Doppler detection units 4a and 4b, and analysis data from the frequency analysis unit 5 is displayed as a spectrum of blood flow velocity. The display unit 6 has a display. The Doppler detectors 4a and 4b
Are multipliers 7a and 7b and a sample gate 8 respectively.
a, 8b, integrators 9a, 9b, and wall filter 1
It consists of 0a and 10b. Reference numeral 11 indicates a bandpass filter.

In the conventional ultrasonic Doppler diagnostic apparatus constructed as described above, the transmission pulse generated by the pulsar 2 and having a constant repetition frequency is applied to the probe 1.
The probe 1 transmits ultrasonic waves into the subject. The reflected echo signal from the inside of the subject is received by the probe 1, the received signal is input to the amplifier 3, amplified in accordance with the set gain value, and then passes through the bandpass filter 11. The received signal that has passed through the bandpass filter 11 is sent to the Doppler detectors 4a and 4b, and is multiplied by the sin wave component and the cos wave component as reference waves in the multipliers 7a and 7b. The complex baseband signal thus obtained passes through the sample gates 8a and 8b which pass the signal only in the sections of the delay time and the time width corresponding to the predetermined depth and width, respectively, and is input to the integrators 9a and 9b. . Doppler detection signals are obtained as output signals from the integrators 9a and 9b. This Doppler detection signal is input to the wall filters (high-pass filters) 10a and 10b, and the high-level DC signal from the living tissue contained in the reflected echo signal is removed,
Only the blood flow signal having the Doppler shift component is extracted. Thereafter, the blood flow signal detected in this way is input to the frequency analysis unit 5 and frequency analyzed to calculate the power spectrum. Then, the calculated power spectrum is input to the display unit 6 and displayed as a spectrum of the blood flow velocity in real time.

[0004]

However, in such a conventional ultrasonic Doppler diagnostic apparatus, the Doppler detector 4 is used.
The blood flow velocity values obtained by a and 4b are blood flow velocities with the probe 1 as a reference, and the true blood flow velocity with respect to the subject tissue cannot be measured. That is, in order to measure the blood flow velocity at the diagnostic site in the subject, the probe 1 is pressed against the body surface of the subject to transmit and receive an ultrasonic beam, but since the tissue of the subject is not solid, The probe 1 may move in the front-back direction due to the pressing force, and the subject itself may also move. Therefore,
The positional relation between the probe 1 and the blood flow portion of the diagnosis site in the subject is not constant, and relative velocity is generated by mutual movement. In this way, when the relative velocity is generated between the subject and the probe 1, the blood flow velocity obtained as described above is the true blood flow velocity based on the subject and It was detected as the sum of the relative velocity of the probe 1 with respect to the sample, and was different from the true blood flow velocity. In particular, in measurement of low-speed blood flow, the component of the relative velocity between the subject and the probe 1 that is added to the true blood flow velocity cannot be ignored, and accurate blood flow velocity may not be measured. It was This means that when the Doppler blood flow measurement method is applied to the abdomen where the measurement of low-speed blood flow is relatively large, the effect cannot be ignored.

Therefore, the present invention addresses such a problem and removes the relative velocity component between the subject and the probe to accurately measure the blood flow velocity even in low-speed blood flow. An object is to provide a sonic Doppler diagnostic device.

[0006]

In order to achieve the above object, an ultrasonic Doppler diagnostic apparatus according to the present invention includes a probe for transmitting and receiving ultrasonic waves in a subject, and a transmission pulse for the probe. A pulsar to be supplied, an amplifier that amplifies the reflected echo signal received by the probe, and a Doppler detection that detects a component that has undergone Doppler shift due to the blood flow from the reflected echo signal from this amplifier as a complex blood flow signal. Section, a frequency analysis section that frequency-analyzes the blood flow signal detected by the Doppler detection section, and a display section that displays analysis data from the frequency analysis section as a spectrum of blood flow velocity. In the Doppler diagnostic apparatus, means for calculating and estimating the relative velocity between the subject and the probe by taking in the complex signal obtained in the Doppler detection unit is provided, and the estimated value of the relative velocity from this estimating unit. Along with the input, the Doppler detection signal obtained in the Doppler detection unit is input, and the relative velocity component between the subject and the probe is removed by subtracting the estimated value of the relative velocity from the frequency spectrum of this Doppler detection signal. The means for doing so is provided.

[0007]

In the ultrasonic Doppler diagnostic apparatus thus constructed, the relative velocity estimating means newly added captures the complex signal obtained in the Doppler detecting section to determine the relative velocity between the subject and the probe. The frequency spectrum of the Doppler detection signal is calculated by estimating and calculating the relative velocity component and inputting the estimated value of the relative velocity from the estimation unit and the Doppler detection signal obtained in the Doppler detection unit. By subtracting the estimated value of the relative velocity from the above, the relative velocity component between the subject and the probe is removed. As a result, the relative velocity component between the subject and the probe can be removed and an accurate blood velocity can be measured even in low-speed blood flow.

[0008]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of an ultrasonic Doppler diagnostic apparatus according to the present invention. This ultrasonic Doppler diagnostic apparatus transmits and receives ultrasonic waves to and from a diagnostic region of a subject, detects a frequency signal that is Doppler-shifted by blood flow from the obtained reflected echo signal, and detects the complex signal of the subject. A blood flow signal is measured and a blood flow image is displayed. As shown in FIG. 1, a probe 1, a pulser 2, an amplifier 3, Doppler detectors 4a and 4b, and a frequency analyzer 5 are provided. , A display unit 6, a relative speed estimation unit 12, and a complex multiplier 13
And. Note that reference numeral 11 indicates a bandpass filter provided in the subsequent stage of the amplifier 3.

The probe 1 transmits / receives ultrasonic waves to / from a diagnostic region in the subject. Although not shown, the transducer 1 is a source of ultrasonic waves and a vibrator for receiving reflected waves. have. The pulsar 2 supplies a transmission pulse to the probe 1, and is configured to generate a transmission pulse having a constant repetition frequency. Amplifier 3
Is for amplifying a reflected echo signal from the inside of the subject received by the probe 1, and a required gain value for signal amplification is set. The band-pass filter 11 inputs the reception signal after being amplified by the amplifier 3, removes unnecessary frequency components, and passes other components.

The Doppler detectors 4a and 4b take out the component which has undergone the Doppler shift due to the blood flow from the reflected echo signal after passing through the bandpass filter 11 and detect the complex blood flow signal from the Doppler shift component. It comprises multipliers 7a and 7b, sample gates 8a and 8b, integrators 9a and 9b, and wall filters 10a and 10b, respectively. The frequency analysis unit 5 frequency-analyzes the blood flow signals detected by the Doppler detection units 4a and 4b to calculate a power spectrum. Further, the display unit 6 receives the analysis data output from the frequency analysis unit 5, converts it into an analog signal, and displays it on the screen as a spectrum of blood flow velocity, and is composed of, for example, a television monitor.

Here, in the present invention, the relative speed estimation unit 12 and the complex multiplier 13 are added to the above-mentioned configuration. The relative velocity estimating section 12 is a means for taking in the complex signals obtained in the Doppler detecting sections 4a and 4b to calculate and estimate the relative velocity between the object and the probe 1, and the Doppler detecting section The complex baseband signals obtained by multiplying the sin wave component and the cos wave component as the reference waves by the multipliers 7a and 7b provided in the units 4a and 4b respectively are input, and the signals of the estimated values after the calculation are input. The signal is output to the complex multiplier 13 inserted in the middle of the Doppler detection units 4a and 4b.

As shown in FIG. 1, an example of the internal structure of the relative speed estimating section 12 is such that the complex baseband signals output from the multipliers 7a and 7b in the Doppler detecting sections 4a and 4b are input, respectively. Three sets of gate circuits 14a, 14b, 14c and 14d, 14 corresponding to, for example, three positions in the depth direction in the subject obtained by dividing the pulse repetition period at equal intervals.
e, 14f and the gate circuit 1 of each corresponding depth
Four ROMs 4a, 14d; 14b, 14e; 14c, 14f, three ROMs 15 storing an arc tan table for obtaining the phase angle of fluctuations of the complex baseband signals.
a, 15b, 15c and ROM 1 corresponding to each depth
Delay register 1 for temporarily storing phase angle signals output from 5a, 15b, and 15c and giving a predetermined delay time
6a, 16b, 16c and the delay registers 16a, 1
A subtractor for calculating the difference (change amount) between the phase angles by synchronously inputting the previous phase angle signals read from 6b and 16c and the current phase angle signals output from the ROMs 15a, 15b and 15c. 17a, 17b, 17c and an average calculator 18 for averaging the amount of change in the phase angle at each depth output from each of the subtractors 17a, 17b, 17c.
, Adder 19, delay register 20, sin table and c
It is composed of a ROM 21 which stores an os table and a complex generator which oscillates at the same frequency as the Doppler shift frequency output from the average calculator 18.

The complex multiplier 13 receives the estimated value of the relative speed from the relative speed estimation unit 12 and the Doppler detection signals obtained in the Doppler detection units 4a and 4b, and receives the Doppler detection signal. It is a means for removing the relative velocity component between the subject and the probe 1 by subtracting the estimated value of the relative velocity from the frequency spectrum of the signal.
An integrator 9 provided in the Doppler detectors 4a and 4b
It is provided so that the Doppler detection signals obtained at a and 9b are input and the calculation results are sent to the wall filters 10a and 10b provided in the Doppler detection units 4a and 4b. The calculation by the complex multiplier 13 is performed so that the sign of the Doppler shift frequency due to the relative speed between the subject and the probe 1 causes a frequency shift with the opposite sign.

Next, the operation of the ultrasonic Doppler diagnostic apparatus thus constructed will be described. Here, the operation from the probe 1 to the complex baseband signals S ₁ and S ₂ by the multipliers 7a and 7b in the Doppler detection units 4a and 4b is as shown in FIG.
Since it is the same as the conventional example shown in FIG. First, the complex baseband signal S ₁ , obtained by the multipliers 7a and 7b,
S ₂ is the sample gates 8a, 8a provided in the subsequent stage.
In addition to being sent to b, it is sent to the relative speed estimation unit 12.
The complex baseband signals S ₁ and S ₂ sent to the relative velocity estimation unit 12 include three sets of gate circuits 14a, 14b, 1 provided corresponding to, for example, three positions in the depth direction in the subject.
4c and 14d, 14e and 14f, respectively, and complex baseband signals S ₁ and S ₂ from the corresponding depths are taken in by the set gates.

Next, the complex baseband signals S ₁ and S ₂ fetched are the signals from the first set of gate circuits 14a and 14b for each set corresponding to each depth.
, The signals from the second set of gate circuits 14b and 14e are sent to the second ROM 15b, and the signals from the third set of gate circuits 14c and 14f are sent to the third ROM 15c. The tan table determines the phase angle of fluctuation. Then, the phase angle signals output from the ROMs 15a to 15c are temporarily stored in the corresponding delay registers 16a, 16b, and 16c, and given a predetermined delay time. Next, each ROM 15a
15c and the signal of the current phase angle output from each of the delay registers 16a to 16c are synchronized with the corresponding subtractor 17 respectively.
a, 17b, 17c, and the difference in phase angle within a predetermined time is calculated. The Doppler shift frequency is obtained from the amount of change in the phase angle within this predetermined time. Then, this Doppler shift frequency gives data of the relative velocity between the subject and the probe 1 at the corresponding depths.

Next, the amount of change in the phase angle at each depth output from each of the subtractors 17a to 17c is input to the average calculator 18. In this average calculator 18, each subtractor 1
The relative velocity of the probe 1 with respect to all depths set in the depth direction in the subject is calculated by simply averaging the amount of change in phase angle input from 7a to 17c. Thereby, the relative speed of the probe 1 with respect to the entire subject can be estimated. Next, the estimated value of the relative speed output from the average calculator 18 is input to the complex generator, integrated by the adder 19 and the delay register 20, and the ROM into which the integrated value is input.
The sin and cos tables in 21 determine the sin and cos components of the Doppler shift frequency. And
The sin component and the cos component of the estimated value of the relative speed are sent to the complex multiplier 13.

On the other hand, in the Doppler detectors 4a and 4b, the complex baseband signals S ₁ and S ₂ obtained by the multipliers 7a and 7b are only the signals having a predetermined depth and width at the sample gates 8a and 8b. Is passed and integrated by integrators 9a and 9b to output a Doppler detection signal. Then, the output Doppler detection signal is input to the complex multiplier 13. At this time, the sin and cos components of the estimated value of the relative speed obtained by the relative speed estimation unit 12 are also input to the complex multiplier 13. Next, the complex multiplier 13 uses the input Doppler detection signal and the estimated value of the relative velocity to subtract the estimated value of the relative velocity from the frequency spectrum of the Doppler detection signal to detect the object and the object. The velocity component relative to the tentacle 1 is removed. As a result, only the blood flow velocity component is output from the complex multiplier 13.

Next, the blood flow velocity signal output from the complex multiplier 13 is input to the wall filters 10a and 10b, and only the blood flow signal having the Doppler shift component is extracted. Thereafter, the blood flow signal detected in this way is input to the frequency analysis unit 5 and frequency analyzed to calculate the power spectrum. Then, the calculated power spectrum is input to the display unit 6 and displayed as a spectrum of the blood flow velocity in real time. At this time, since the complex multiplier 13 is arranged in front of the wall filters 10a and 10b, the Doppler shift frequency due to the relative speed between the object and the probe 1 is the wall filters 10a and 1b.
Even when the cut-off frequency of 0b is exceeded, the strong reflected echo signal from the subject tissue does not cause saturation in the signal processing in the subsequent stage.

In the above description, the complex baseband signals S ₁ and S ₂ from three depths, which are set at equal intervals in the depth direction inside the subject, are taken in and the subject and the probe 1 are taken. It was supposed to estimate the relative speed with
The present invention is not limited to this, and although the accuracy of the relative velocity estimation is high or low, the complex baseband signals S ₁ and S ₂ from one or four or more depths in the depth direction may be fetched. . Further, the function of the relative speed estimation unit 12 shown in FIG. 1 may be realized by software by a digital signal processor (DSP) or the like.

[0020]

Since the present invention is constructed as described above,
By the newly added relative velocity estimating means, the complex velocity obtained in the Doppler detector is taken in to calculate and estimate the relative velocity between the object and the probe, and the relative velocity component removing means estimates the above. By inputting the estimated value of the relative velocity from the means and the Doppler detection signal obtained in the Doppler detection unit, and by subtracting the estimated value of the relative velocity from the frequency spectrum of the Doppler detection signal It is possible to remove the relative velocity component with respect to the probe.
As a result, the relative velocity component between the subject and the probe can be removed and an accurate blood velocity can be measured even in low-speed blood flow. Therefore, even if the Doppler blood flow measuring method is applied to the abdomen where the measurement of low-speed blood flow is relatively large, highly accurate measurement can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an ultrasonic Doppler diagnostic apparatus according to the present invention.

FIG. 2 is a block diagram showing a conventional ultrasonic Doppler diagnostic apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Probe 2 ... Pulsar 3 ... Amplifier 4a, 4b ... Doppler detection part 5 ... Frequency analysis part 6 ... Display part 11 ... Band filter 12 ... Relative speed estimation part 13 ... Complex multiplier 14a-14f ... Gate circuit 15a-. 15c ... ROM 16a-16c ... Delay register 17a-17c ... Subtractor 18 ... Average calculator 19 ... Adder 20 ... Delay register 21 ... ROM

Claims (1)

[Claims] 1. A probe for transmitting and receiving ultrasonic waves to and from a subject, a pulser for supplying a transmission pulse to the probe, an amplifier for amplifying a reflected echo signal received by the probe, A Doppler detection unit that detects a component that has undergone Doppler shift due to blood flow from the reflected echo signal from the amplifier as a complex blood flow signal, and a frequency analysis unit that analyzes the frequency of the blood flow signal detected by this Doppler detection unit. In an ultrasonic Doppler diagnostic apparatus having a display unit for displaying the analysis data from the frequency analysis unit as a spectrum of blood flow velocity, the complex signal obtained in the Doppler detection unit is captured and the object to be detected is detected. A means for calculating and estimating the relative velocity with respect to the tentacle is provided, and the estimated value of the relative velocity from this estimating means is input, and the Doppler detection signal obtained in the Doppler detection unit is also input. An ultrasonic Doppler diagnostic apparatus comprising means for removing a relative velocity component between a subject and a probe by subtracting the estimated value of the relative velocity from the frequency spectrum of a detection signal.