JPH08308843A - Ultrasonographic diagnostic device - Google Patents

Abstract

PURPOSE: To shorten time necessary for diagnosis as well as reducing burden to an operator, by detecting a reflection of Doppler spectrum to make a parameter altered automatically, and making the Doppler spectrum without reflection. CONSTITUTION: A PRF/OHz position deciding means 80 has a test region of a specified time Interval, and PRF is decided so that the filled-up range of a frequency axis of a blood flow signal is made X*10% of whole frequency axis in the test region. And zero level is shifted so that the center of the unfilled range is made upper/lower ends of a display region. A probe 11 is excitedly- oscillated by means of a rate pulse outputted from a standard signal generator 20 and the ultrasonic signal is transmitted into a subject body in an electronic scanning part 12. The ultrasonic signal is reflected at each part of the subject body, again received by the probe 11, and is converted into the electric signal corresponding to ultrasonic echo signal by means of the probe 11. A receiving focus can be obtained by means of an adder 24 of the electronic scanning part 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus which utilizes the Doppler effect of ultrasonic waves to diagnose the motion state of moving bodies such as blood.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic pulse Doppler method and an ultrasonic pulse reflection method are used together to obtain a tomographic image (black and white B-mode image) and blood flow information with one ultrasonic probe, and at least the blood flow information. There is known an ultrasonic Doppler diagnostic apparatus that displays the in real time.

An example of this ultrasonic Doppler diagnostic apparatus is shown in FIG.
It will be explained based on. This diagnostic device measures blood flow velocity as blood flow information. The diagnostic device shown in FIG.
Transmitter pulser 202 connected to the ultrasonic transducer 201
And a preamplifier 203 for reception. Preamplifier 2
On the output side of 03, the display device 2 via the mixer 204, the low pulse filter 205, the sample hold circuit 206, the band pass filter 207, and the frequency analyzer 208.
09 is connected.

This ultrasonic Doppler diagnostic apparatus also includes a pulse generation circuit 210 for transmission control and reception control, and a range gate circuit 211 for range gate control. The pulse generation circuit 210 includes a frequency divider circuit, a gate circuit, and the like, and has a clock pulse a of a predetermined frequency (see FIG.
(Refer to FIG. 13), the clock pulse a is supplied to the range gate circuit 211 and the mixer 204, and the rate pulse b (see FIG. 13) corresponding to the ultrasonic wave repetition frequency is generated based on the clock pulse a. The pulse pulse b is applied to the pulser 202 and the range gate circuit 21.
Feed to 1.

The pulsar 202 generates a high-voltage drive voltage pulse based on the supplied rate pulse b, and excites the ultrasonic transducer 201 with the drive voltage pulse. With this excitation, the ultrasonic transducer 201 transmits an ultrasonic pulse signal into the living body P. A part of the transmitted ultrasonic pulse signal is reflected by the blood vessel wall BW in the living body P and the blood flow B (mainly red blood cells) in the blood vessel to become an ultrasonic echo signal. This ultrasonic echo signal is returned to the same ultrasonic transducer 2 again.
01 received, voltage echo signal d (see FIG. 13)
Is converted to.

This voltage echo signal d becomes a reception signal reflecting the Doppler effect of ultrasonic waves. That is, when an ultrasonic pulse is transmitted to the blood flow flowing in the living body P, it is scattered by the flowing blood cells and undergoes the Doppler shift. Therefore, the center frequency fc of the ultrasonic beam changes by fd, and the reception frequency f becomes f = fc + fd. The Doppler shift frequency fd is expressed as follows, as a blood flow velocity v, an angle θ formed by an ultrasonic beam and a blood vessel, and a sound velocity c.

Fd = {(2 · v · cos θ · fc) / c} · fc Therefore, the Doppler shift frequency fd from the received voltage signal fd
Since the blood flow velocity v can be known by detecting the above, the above-described receiving path operates toward this detection.

That is, the preamplifier 203 amplifies the voltage echo signal d and outputs the amplified signal to the mixer 204. The mixer 204 mixes the amplified echo signal d and the clock pulse a, and outputs the mixed signal to the low-pass filter 205 at the next stage. Low-pass filter 205
Removes a high frequency component such as an ultrasonic carrier frequency from the input mixed signal and outputs only a low frequency component centered on the Doppler shift frequency fd to the sample hold circuit 206.

The sample-hold circuit 206 extracts a Doppler shift signal only at the observation position of the velocity of the blood flow B, that is, the position of a range gate (also called sampling point or sampling volume) for the blood flow B on the sampling raster. It is a circuit for doing. In order to perform this signal extraction, the sampling pulse c is supplied from the range gate circuit 211 to the sample hold circuit 206. The range gate circuit 211 is a circuit in which the delay time can be arbitrarily set. The range gate circuit 211 delays the ultrasonic pulse more than the rate pulse b by a time equal to the round-trip propagation between the transducer 201 and the range gate position O, and is set. A sampling pulse c having a different pulse width (see FIG. 13) is formed, and this pulse c is supplied to the sample hold circuit 206. It should be noted that the range gate position O is arbitrarily set by the operator at the position of the blood vessel on the B-mode slice where the blood flow velocity is desired to be obtained with a trackball or a joystick.

The sample and hold circuit 206 has a sampling pulse c corresponding to the range gate position O from the body surface.
The output signal of the low pulse filter 205 is sampled and held by the
Output to 7. The bandpass filter 207 removes the harmonic component generated by the sampling of the sample hold circuit 206, the fixed reflection signal such as blood vessels, and the Doppler shift frequency due to the relatively slow movement in the living body, and the Doppler shift of the blood flow B is removed. Only frequencies are extracted. This extracted signal is sent to the frequency analyzer 208 at the next stage, and the frequency spectrum pattern (Doppler spectrum) of the Doppler shift frequency is calculated by frequency analysis such as fast Fourier transform. This frequency spectrum pattern shows changes in Doppler shift frequency (corresponding to blood flow velocity: vertical axis, intensity of each frequency component is represented by luminance) with the passage of time (horizontal axis). In 209, it is displayed in real time as shown in FIG. 14, for example.

[0011]

However, in the above-mentioned ultrasonic Doppler diagnostic apparatus, when the detected frequency exceeds the repeating frequency (± 1/2 fr), the waveform as if folded back as shown in FIG. Become. As shown in FIG. 15, in order to make it unfolded, the operator must appropriately set the pulse repetition frequency (rate frequency) and 0 level shift according to the blood flow velocity, and the operation time This was a burden on the operator. At the same time, the diagnosis took a very long time.

The present invention has been made in view of the above problems of the prior art, and automatically sets the rate frequency and the 0 level shift by detecting the signal existing area in the detectable frequency range. It is an object of the present invention to provide an ultrasonic Doppler diagnostic apparatus that can reduce the burden on the operator and can significantly shorten the diagnostic time.

[0013]

The ultrasonic Doppler diagnostic apparatus of the present invention is obtained by transmitting / receiving means for transmitting / receiving an ultrasonic beam to / from a diagnostic region including a moving body in a subject, and this transmitting / receiving means. Extraction means for extracting the Doppler signal resulting from the moving body at the position of the desired range gate from the received signal,
Based on the Doppler signal extracted by the extracting unit, a spectrum calculation unit for calculating a Doppler spectrum composed of instantaneous spectra, and a turn-back of the Doppler spectrum are detected to change two parameters of PRF and 0 Hz position, PRF / 0Hz position determining means for forming a Doppler spectrum without folding,
A spectrum display means for displaying a Doppler spectrum without folding is provided.

[0014]

According to the ultrasonic Doppler diagnostic apparatus of the present invention, the turning of the Doppler spectrum is detected and the two parameters of PRF and 0 Hz position are automatically changed to obtain the Doppler spectrum having no turning. , The burden on the operator can be reduced and the diagnosis time can be significantly shortened. There is no troublesome operation and you can observe the spectrum without folding back.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the ultrasonic Doppler diagnostic apparatus according to this embodiment includes an electronic scanning type ultrasonic probe (hereinafter, simply referred to as a probe) 11, and an electronic scanning unit 12 connected to the probe 11. Is equipped with.

The electronic scanning section 12 includes a reference oscillating section 20 for generating a reference clock, a delay line 21 for receiving the reference clock and generating a delayed drive signal (also serving as a delay at the time of reception described later), and the delay line. And a pulser 22 for exciting the array type piezoelectric vibrator group of the probe 11 in response to the delayed drive signal from the probe 21. The electronic scanning unit 12 also has a built-in reception system circuit.
That is, the preamplifier 23 connected to the probe 11,
A delay line 21 for delaying the output signal of the preamplifier 23, an adder 24 for adding the delay signal of the delay line 21, and a detector 25 for subjecting the output signal of the adder 24 to logarithmic amplification and envelope detection. It has and. The delay line 21 and the adder 24 perform phasing addition on the received echo signals, and the electronic signals are subjected to electronic scanning.

The output signal of the detector 25 is supplied to a DSC (digital scan converter) 30 as an image signal of a B-mode tomographic image, and the DSC 30 converts ultrasonic scanning signals into standard TV scanning signals. The converted signal of the DSC 30 is sent via the D / A converter 31 to the display 32 (C
RT).

The output of the adder 24 is also given to the low-pass filter 42 through the mixer 40 for phase detection.
The output of the reference oscillator 20 is directly applied to one channel of the mixer 40 and is connected to the other channel of the mixer 40 via the 90-degree phase shifter 41. Therefore, in addition to receiving echo signals phased and added in the electronic scanning unit 12 is applied to the mixer 40, the reference signal f ₀ having a phase difference of the reference signal f ₀ and 90 degrees from the reference oscillator 20 is of the mixer 40 It is added to each of the two channels. As a result, the mixer 40 causes the Doppler shift signal f _d and “2f ₀
The signal of “+ f _d ” is output to the low-pass filter 42. The low-pass filter 42 removes the high-frequency component of the mixed signal from the mixer 40, and obtains only the Doppler shift signal f _d . This Doppler shift signal f _d is a phase detection output for calculating blood flow information, and is output to the Doppler spectrum calculation unit 50 at the next stage.

The Doppler spectrum calculator 50 includes a range gate circuit 60 for outputting sampling pulses,
A sample hold circuit 61 for inputting the sampling pulse, a band pass filter 62 for filtering the output of the sample hold circuit 61, an A / D converter 63 for digitizing the output of the filter 62, and the A / D conversion. And a frequency analyzer 64 for frequency-analyzing the converted output of the device 63. Sample and hold circuit 6
Although not shown, the 1, the bandpass filter 62, and the A / D converter 63 each have two channels. The output terminal of the frequency analyzer 64 is D through the spectrum averaging circuit 70.
It is connected to SC30.

The sample and hold circuit 61 is intended to extract the Doppler signal of only the blood flow at the desired depth position in the living body. The phase detection output signal of the low pulse filter 42 is the input signal of the sample and hold circuit 61. Has become.

The range gate circuit 60 has a circuit configuration in which a delay time can be arbitrarily set based on a range gate position signal given from an operation panel 82 described later,
The sampling pulse having a set width is delayed from the rate pulse by a time corresponding to the reciprocal movement of the ultrasonic signal between the probe 11 and the position of the desired range gate (also referred to as sampling point or sampling volume). It is supplied to the hold circuit 61. As a result, the sample hold circuit 61 samples and holds the phase detection output signal from the low pass filter 42 with the sampling pulse. The sampled and held phase detection signal then passes through the bandpass filter 62,
The filter 62 removes the harmonic component generated by the sampling in the sample hold circuit 61, the fixed reflection signal from the blood vessel wall, and the component corresponding to the Doppler shift frequency due to the relatively slow movement. Only Doppler signals due to are extracted.

The frequency analyzer 64 has a fast Fourier transform circuit, performs frequency analysis of the Doppler shift frequency input from the bandpass filter 62, and outputs the analysis result, that is, the Doppler spectrum (frequency spectrum pattern), to a spectrum averaging circuit. Output to DSC 30 via 70.
Accordingly, the Doppler spectrum is divided and displayed on the display 32 in parallel with the B-mode tomographic image.

The operation panel 82 is provided with a trackball and a keyboard which can be arbitrarily operated by the operator, and outputs the range gate position signal and the freeze command signal described above through the operation of the panel 82. Further, the operation panel 82 has a switch for turning on / off a function for determining a PRF / 0 Hz position described later.

The PRF / 0 Hz position determining means 80 is for detecting a turn-back and automatically changing two parameters (PRF and 0 Hz position). PRF /
The 0 Hz position determining means 80 sets a certain fixed time as the examination area, and first decides the PRF so that the range in which the frequency axis of the blood flow signal is filled is X% of the entire frequency axis in the examination area. Then, the 0 level is shifted so that the center of the unfilled range is the upper and lower ends of the display area. In this way, the Doppler spectrum is automatically made easier to see.

The controller 90 adjusts the electronic scanning unit 12 according to the operation from the operation panel 82, changes the clock pulse such as the sampling pulse from the reference signal generator 20, and adjusts the range of the Doppler spectrum. Control.

The overall operation of this embodiment will be described below.

When this ultrasonic Doppler diagnostic device is activated,
The electronic scanning unit 12 excites the probe 11 with the rate pulse output from the reference signal generator 20, and transmits an ultrasonic signal into the subject. This ultrasonic signal is reflected by each part of the subject and received again by the probe 11. One of the received signals of the designated raster address outputted from the probe 11 after being converted into an electric signal corresponding to the ultrasonic echo signal and receiving focus being applied by the adder 24 of the electronic scanning unit 12 is sent to the detector 25. It is given, subjected to logarithmic amplification processing and envelope detection processing, and detected and converted into an image signal of a designated raster address. The image signal forming this B-mode tomographic image is supplied to the DSC 30.

One of the received signals output from the adder 24 of the electronic scanning unit 12 is phase-detected by the mixer 40,
A signal having a Doppler shift signal fd and a frequency (2fo + fd) component is obtained, and the high-frequency component is removed by the low pulse filter 42 to obtain only the Doppler shift signal fd. The phase detection output signal for this blood flow information calculation is output to the Doppler spectrum calculation unit 50, and the sample and hold circuit 61 extracts the signal only at the depth position where the blood flow in the living body is flowing. The frequency is analyzed in real time by the conversion and the fast Fourier transform.

In the arithmetic unit 50, the range gate circuit 6
The delay time of 0 can be set arbitrarily. This is probe 1
Sampling point position from 1 (range gate position)
By delaying the round-trip time to the sample hold circuit 61 with a sampling pulse having a width corresponding to the set length, the Doppler signal at the range gate position designated by the operator can be obtained. ing.

The Doppler spectrum obtained by performing the fast Fourier transform in this way is supplied to the DSC 30, and the Doppler spectrum data together with the B mode image data are combined and converted into an image of the standard TV scanning system, and the D / A conversion is performed. It is supplied to the display device 32 via the device 31. As a result, the B-mode tomographic image and the Doppler spectrum of the diagnosis region are displayed on the display 32, for example, in a divided manner.

On the other hand, the Doppler spectrum from the frequency analyzer 64 is also given to the PRF / 0 Hz position determining means 80. In the PRF / 0 Hz position determining means 80, the following 3
In one step, the Doppler spectrum is automatically adjusted to make it easier to see.

In the first step, first, an sMAP is created in which the value of the frequency of power above the threshold value, which is one frequency axis, is 1, and the value of the frequency of power below the threshold value is 0.
For example, when there is a Doppler spectrum as shown in FIG. 2, the Doppler spectrum on the frequency axis at time t ₁ is shown as in FIG. Then, if it is larger than the threshold Th, it is set to 1, and if it is smaller than 0, the sMAP at the time t ₁ as shown in FIG. Such an sMAP is created for all times on the time t axis in FIG.

This is performed on the frequency axis within a fixed time range, and the results (sMAP) are ORed to create SMAP. The region where the SMAP value is 1 is the signal existing region. Here, the ratio of the signal existing region to the detectable frequency range is referred to as the signal existing ratio. For example, in the Doppler spectrum as shown in FIG. 2, since all values of the frequency f exist, O of all sMAPs
When the R operation is performed, the SMAP as shown in FIG. 5 is obtained (of course, the SMAP may be created at once without performing the two-step processing as described above). In this case, the signal existence ratio is 1.

In the second step, the controller 9 adjusts the signal existence ratio to a value within a set fixed range.
The sampling pulse is changed via 0 to change the PRF. If the calculated signal presence ratio exceeds this range, the PRF is changed. That is, if the obtained signal presence ratio exceeds this range, the PRF is increased, and if it falls below this range, the PRF is decreased. For example, this range is set to 0.6 to 0.8 or the like. In the case of FIG. 2, the PRF is increased so that a region where no signal exists, such as the Doppler spectrum of FIG. 6, is formed, and the SMAP shown in FIG. 7 is obtained.

In the third step, when the signal existing ratio is within the set range, the 0 Hz position is moved so that the center of the signal existing area is located at the upper and lower ends of the frequency axis.
This movement of the 0 Hz position is performed by the controller 90 through the D
This is done by controlling the display with SC30 or by controlling the output format from FFT64. For example,
When the Doppler spectrum is displayed so as to be folded back as shown in FIG. 8, the SMAP shown in FIG. 9 is obtained. Then, set 0 so that the center of the area where no signal exists is at both ends.
By moving the Hz position, a Doppler spectrum without folding is displayed as shown in FIG. When there is no folding back, the SMAP as shown in FIG. 11 is obtained. Further, the movement of the position of OH _z may be operated when the center of the signal existing region deviates from the upper and lower ends of the frequency axis by a certain range or more.

As described above, the load on the operator is reduced by automatically setting the rate frequency and the 0 level shift by detecting the signal existing area in the detectable frequency range without the operator's troublesome operation. , The diagnosis time can be significantly shortened. There is no troublesome operation and you can observe the spectrum without folding back.

An ON / OFF switch for this function may be provided. The number of alternating steps may be changed. Further, in this embodiment, the input signal of the PRF / 0 Hz position determining means 80 is the output of the FFT 64, but the output of the DSC 30 may be used. Further, before the first step, means for setting the PRF to the maximum possible value may be added. Then, a marker indicating that the PRF has changed may be displayed when the PRF changes.

[0039]

According to the ultrasonic Doppler diagnostic apparatus of the present invention, the turning of the Doppler spectrum is detected and the two parameters of PRF and 0 Hz position are automatically changed to obtain the Doppler spectrum having no turning. As a result, the burden on the operator can be reduced and the diagnosis time can be significantly shortened. There is no troublesome operation and you can observe the spectrum without folding back.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an ultrasonic Doppler diagnostic apparatus according to an embodiment.

FIG. 2 is a diagram showing an example of a Doppler spectrum.

FIG. 3 is a diagram showing an example of a Doppler spectrum on the frequency axis at time t ₁ in the case of FIG. 2;

FIG. 4 is a diagram showing sMAP at time t ₁ .

FIG. 5 is a diagram showing SMAP in the case of FIG. 2;

FIG. 6 is a diagram showing a Doppler spectrum when the PRF is increased in the case like FIG.

FIG. 7 is a diagram showing SMAP when there is a region where no signal exists.

FIG. 8 is a diagram showing a case where the Doppler spectrum is displayed so as to be folded back.

FIG. 9 is a diagram showing SMAP in the case of FIG. 8;

FIG. 10 is a diagram showing a Doppler spectrum without folding back by moving the 0 Hz position.

FIG. 11 is a diagram showing SMAP without folding back.

FIG. 12 is a diagram showing an example of an ultrasonic Doppler diagnostic apparatus.

13 is a diagram showing a timing chart of the ultrasonic Doppler diagnostic apparatus in FIG.

FIG. 14 is a diagram showing a frequency spectrum pattern.

FIG. 15 is a diagram showing a frequency spectrum pattern.

[Explanation of symbols]

11 probe, 12 electronic scanning unit, 30 DS
C, 31 D / A converter, 32 display device, 40 mixer, 42 low-pass filter, 50 Doppler spectrum calculation unit 80 PRF / 0 Hz position determination means, 82 Operation panel

Claims (1)

[Claims] 1. A transmission / reception unit for transmitting / receiving an ultrasonic beam to / from a diagnostic site including a moving body in a subject, and a moving body at a desired range gate position from a reception signal obtained by the transmitting / receiving unit. Extracting means for extracting the Doppler signal, spectrum calculating means for calculating a Doppler spectrum composed of instantaneous spectrums based on the Doppler signal extracted by the extracting means, and detection of folding of the Doppler spectrum to obtain a PRF
PR for changing the two parameters of 0Hz position and 0Hz position to make a Doppler spectrum without folding
An ultrasonic Doppler diagnostic apparatus comprising F / 0 Hz position determining means and spectrum display means for displaying the Doppler spectrum having no folding back.