JPH0767449B2 - Ultrasonic Doppler diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention detects an ultrasonic Doppler diagnostic apparatus, in particular, the velocity of a motion reflector in a subject, and detects, for example, a motion state of a wall, a valve, a blood flow, etc. in the heart. The present invention relates to an ultrasonic Doppler diagnostic apparatus that displays images.

[Prior Art] Ultrasonic Doppler that radiates ultrasonic waves into a subject such as a living body, receives reflected echoes thereof and displays a tomographic image as an image, and also displays velocity (Doppler) information such as cardiac blood flow as an image. Diagnostic devices are well known.

In this type of device, first, a pulsed ultrasonic wave or a continuous ultrasonic wave is radiated into the subject, its reflected echo is received, the received wave is multiplied by a reference wave, and the signal is subjected to the Doppler effect. Extract the Doppler signal. Then, the Doppler shift frequency is obtained by performing velocity calculation processing based on this Doppler signal, and this Doppler shift frequency is displayed as an image as velocity information.

In this case, since only the Doppler shift signal based on the reflection from the blood flow that is the target of image display is detected, low speed information (low frequency signal) that is a signal from a fixed reflector or a very slowly moving reflector is detected. Remove using a wall motion filter. Therefore, the velocity information is accurately calculated only in the blood flow in a state where the low velocity information such as the heart wall is removed, and the velocity information is displayed by being superimposed on the B-mode tomographic image or the velocity in a predetermined direction. The profile is displayed together with the tomographic image.

[Problems to be Solved by the Invention] By the way, in recent years, it has been attempted to display motion information of structures such as a wall of a heart and a valve as an image and observe it together with blood flow information. Device has been proposed.

First, since the M mode display (black and white) for displaying the movement change of the structure in the ultrasonic beam direction on the time axis has been conventionally performed, the displacement / time gradient of the curve displayed in the M mode is used. This is to find the moving speed of the structure.

FIG. 5 shows a display state of a conventional ultrasonic image. FIG. 5A shows a tomographic image of the heart, and the heart repeats expansion shown by a solid line and contraction shown by a broken line in a predetermined cycle. There is.
When the portion selected by the cursor line 100 of the heart is displayed in the M mode, it becomes as shown in FIG. 7B, and the change of the heart wall is displayed as a curve 200. Therefore, the inclination is detected by the displacement dy / dt within the predetermined time on the curve 200, and the motion velocity of the heart wall or the like is obtained from this.

Second, a conventional pulse Doppler device that displays velocity information in a range gate on a B-mode tomographic image is used to find the motion velocity information of the structure by matching the range gate to the structure such as the heart wall.

However, in either the first or the second device, there is a problem that the calculation process is troublesome, and in particular, the real time display is difficult in the first device, and in the case of the second device, the target part There is a risk of displaying an image of a region different from that.

That is, in the second case, for example, even if the specific point 101 of the heart wall is designated, the heart wall does not exist at the specific point at the next moment, and the motion velocity information becomes inaccurate.

OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an ultrasonic Doppler system capable of accurately displaying even low-speed information such as a heart wall and a valve. To provide a diagnostic device.

[Means for Solving the Problem] In order to achieve the above object, the invention according to the first aspect radiates an ultrasonic wave into a subject, receives a reflected echo thereof, and receives the received wave and a reference wave. Extract the Doppler signal by comparing the, in the ultrasonic Doppler diagnostic device that displays the motion state image by calculating the Doppler displacement frequency from the motion reflector based on this Doppler signal, in a predetermined frequency band in the Doppler signal A predetermined bandpass filter for extracting only a signal, a difference calculator for calculating a difference between an input signal and an output signal of the filter, and a switcher for switching and outputting any one of the filter output and the difference calculator output. The low speed information and the high speed information are selectively obtained.

According to a second aspect of the present invention, a high-pass filter that extracts only a signal in a high frequency band from a Doppler signal, a low-pass filter that extracts only a signal from a low frequency band in a Doppler signal, and the outputs of both filters are provided. And a switching device for switching and outputting any one of them, and the low speed information and the high speed information are selectively obtained.

The invention according to claim 3 is characterized in that the speed of the low-speed motion reflector toward the probe is expressed in red, the speed of moving away from it is expressed in blue, the magnitude of the speed is expressed in luminance, and the motion information is displayed two-dimensionally. And

The invention according to claim 4 is characterized in that a plurality of hues are changed and displayed in accordance with the magnitude of the velocity of the low velocity motion reflector.

The invention according to claim 5 is characterized in that a cursor line is displayed on the B-mode screen and a speed change of the low-speed motion reflector designated by the cursor line is displayed in a graph.

[Operation] According to the first claim, if the high-pass filter is used as the predetermined band-pass filter, only the signal in the high-frequency band of the Doppler signal is taken out, while the difference calculator operates the high-pass filter. The difference between the input signal and the output signal is calculated. Therefore, the high-pass information is output from the high-pass filter, and the low-speed information is output from the difference calculator. The low-velocity information displays the motion state of the heart wall and the valve.

According to the second aspect of the invention, only the high frequency band signal of the Doppler signal is extracted by the high pass filter, and only the low frequency band signal of the Doppler signal is extracted by the low pass filter. Therefore, low speed information is output from the low pass filter.

Further, according to the inventions of the third to fifth aspects, it is possible to display an image in which low-speed information is easily observed.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a circuit configuration of the ultrasonic Doppler diagnostic apparatus according to the first embodiment, in which a transducer 10 is provided at a tip portion thereof and a probe 10 that abuts a subject and emits ultrasonic waves is provided. The transmitter 12
And the receiving unit 14 is connected. The transmitter 12 supplies an excitation signal to the transducer inside the probe 10, and the probe 10 can radiate pulse ultrasonic waves or continuous ultrasonic waves into the subject.

On the other hand, the receiving unit 14 receives the reflected echo from the inside of the subject that has reached the probe 10 and amplifies this received signal. In the embodiment, not only the Doppler information is obtained, but also ultrasonic wave transmission / reception for displaying the tomographic image in the subject in the B mode is performed, and the reception signals of both are received by time division control or the like.

Further, the quadrature detection unit 16 connected to the receiving unit 14
Quadrature detection is performed to obtain the Doppler signal, and the received signal is multiplied by the reference signals that are different from each other by 90 degrees.
Therefore, the Doppler signal after quadrature detection has two parts, a real part and an imaginary part.
It can be regarded as a complex signal composed of individual signals, and the Doppler frequency shift can be specified from the argument of this complex signal. The signals of the real number part and the imaginary number part output from the quadrature detection unit 16 are separately converted into digital signals by the A / D converters 18a and 18b.

A characteristic of the present invention is that low speed information is extracted. For this reason, in the first embodiment, high-pass filters 20a, 20b are provided as predetermined band-pass filters, and the high-pass filters are provided. Delay lines 22a, 22b that delay the filter 20 by the time required for the Doppler signal to pass.
And subtractors 24a and 24b are provided as difference calculators.

FIG. 3 shows the relationship between the Doppler signal and the filter characteristics. A in the figure shows a low-speed Doppler signal (so-called clutter component) from a fixed reflector or a slowly moving reflector such as the heart wall or valve. And B in the figure is a Doppler signal from a high-speed reflector that moves relatively fast such as blood flow. The amplitude ratio between the low-speed Doppler signal and the high-speed Doppler signal is about 100 times.

Since the characteristic of the high-pass filter 20 is as shown by the alternate long and short dash line 300, only the high-speed Doppler signal B can be passed, and the subtractor 24 changes the original Doppler signal to the high-speed Doppler signal B. Low-speed Doppler signal A without
Will only output. Then, a switch 26 for selectively outputting the both Doppler signals is provided,
One of the Doppler signals is output at every predetermined timing.

Further, a speed calculator 28 for calculating the speed from the Doppler signal is provided, and the speed calculator 28 calculates the declination of the complex signal of the real part and the imaginary part to obtain the Doppler frequency shift. An autocorrelation calculating circuit disclosed in Japanese Patent Publication No. 62-44494 can be used as the velocity calculating unit 28, and the velocity of the moving reflector can be calculated by obtaining a complex conjugate product between complex signals that are shifted by one period. It can be detected accurately.

A digital scan converter (DSC) 30 for image-processing the speed information of the speed calculation unit 28 is provided, and a display unit 32 is connected to the subsequent stage of the DSC 30.

As described above, in the embodiment, the tomographic image in the specimen is also displayed in black and white, so the detector 34 for obtaining the tomographic image signal is connected between the receiving unit 14 and the DSC 30.

The first embodiment has the above configuration, and its operation will be described below.

First, ultrasonic waves are radiated from the probe 10 to, for example, the heart region in the subject, and reflected echoes from the heart region are received again by the probe 10, and the received signal obtained by the receiving unit 14 is The quadrature detection unit 16 extracts the frequency component and forms a Doppler signal as a complex signal. This Doppler complex signal is divided into two signals, a real number part and an imaginary number part, each of which is A / D converter 18a, 18b
Is converted into a digital signal by.

The outputs of the A / D converters 18a and 18b are supplied to the high pass filters 20a and 20b and the delay lines 22a and 22b, and only the high speed Doppler signal is extracted from the high pass filter 20. The delay line 22 delays the Doppler signal by the passage time of the high-pass filter 20 and supplies the delayed signal to the subtractor 24. The subtracter 24 subtracts the filter output from the delay line output to extract only low-speed information. Be done.

The high speed information and the low speed information are selected by the interlocking switch.
26a, 26b, and when this switch 26 is switched to the terminals A, A'side, the cardiac blood flow is superimposed on the tomographic image of the heart as in the conventional device, and a two-dimensional image is obtained. Is displayed.

Then, when observing the motion state of the heart wall or the valve in this state, the switching devices 26a and 26b are switched from the terminals A and A'to the terminals B and B'based on the switching signal from the operating section. ,
The low speed Doppler signal is supplied to the speed calculator 28.

Then, the velocity calculator 28 calculates the declination of the low-speed Doppler signal (complex signal) to obtain the Doppler frequency shift, and the Doppler frequency shift information is supplied to the DSC 30.
In this way, the display unit 32 displays the velocity information of the heart wall, the valve, and the like.

The image display of the low speed information on the display unit 32 can be performed in the following various formats.

First, similar to the conventional two-dimensional display overlaid on a tomographic image, for example, the velocity of the heart wall or valve toward the probe is represented by red, the velocity of leaving the probe is represented by blue, and the velocity magnitude is represented by luminance. is there. According to this, there is an advantage that the motion direction can be easily identified by different hues.

Secondly, since the movements of the heart wall and valves can be confirmed in the tomographic image (black and white display) displayed in the B mode, the direction of the velocity is determined by the tomographic image, and only the magnitude of the velocity is different in hue. For example, the lowest level of speed is white, and yellow, orange, and red are changed as the speed increases.
This has the advantage that changes in speed can be easily observed.

Third, as shown in FIG. 4 (a), a cursor line 100 is displayed on the B mode screen, and changes in the velocity of the heart wall or valve designated by the cursor line 100 are shown in FIG. 4 (b). ), The position is plotted on the vertical axis, and the positive and negative of the speed are divided and displayed in a graph. According to this, it is possible to observe detailed velocity information of a specific point, and it is possible to favorably apply the observation of not only the heart but also the movement of the fetus.

Although the high-pass filter 20 is used as the predetermined band-pass filter in the description of the embodiment, the same effect can be obtained by using a low-pass filter for this.

Next, a second embodiment of the present invention will be described with reference to FIG.

In FIG. 2, the use of high-pass filters (HPF) 20a, 20b for extracting the high-speed information is the same as in the first embodiment, but a low-pass filter (HPF) for extracting the low-speed information ( LPF) 36a and 36b are connected. The operating characteristic of the low-pass filter 36 in this case is shown by a broken line 301 in FIG. 3, and allows only the low-speed Doppler signal A to pass.

Then, the low-pass filter 36 of this high-pass filter 20.
Is performed by the changeover devices 38a and 38b, and either the high speed information or the low speed information can be selected by the changeover signal of the operation unit as in the case of the first embodiment. The same effect can be obtained.

[Effects of the Invention] As described above, according to the present invention, the predetermined bandpass filter is used to extract the high speed information as well as the low speed information. Therefore, the motion state of the organs such as the heart wall and the valve. Can be displayed on the screen, and low-speed motion information useful for observing the heart function and fetus can be provided.

Particularly, according to the first claim, since the difference between the input and the output of the filter is calculated, there is an advantage that the low speed information can be easily obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of the ultrasonic Doppler diagnostic apparatus according to the first embodiment, FIG. 2 is a block diagram showing a circuit configuration of the second embodiment, and FIG. 3 is a filter characteristic and Doppler of the embodiment. FIG. 4 is a graph showing the relationship between signals, FIG. 4 is an explanatory view showing an example of a display format of low-speed information, and FIG. 5 is a tomographic image displayed by a conventional device (FIG. A).
It is explanatory drawing which shows and M mode image (FIG. B). 10 …… Probe 16 …… Quadrature detector 20a, 20b …… High-pass filter (HPF) 22a, 22b …… Delay line 24a, 24b …… Subtractor 26,38 …… Switcher 28 …… Speed calculator Part 36 ... Low-pass filter.

Claims (5)

[Claims] 1. An ultrasonic wave is radiated into a subject, a reflected echo thereof is received, a Doppler signal is extracted by comparing the received wave with a reference wave, and a Doppler signal from a moving reflector is based on the Doppler signal. In an ultrasonic Doppler diagnostic apparatus for calculating a shift frequency and displaying a motion state as an image, a predetermined bandpass filter for extracting only a signal of a predetermined frequency band in the Doppler signal, and a difference between an input signal and an output signal of this filter. And a switch for switching and outputting any one of the filter output and the difference calculator output, and the low speed information and the high speed information are selectively obtained. Ultrasonic Doppler diagnostic device. 2. An ultrasonic pulse beam is radiated into a subject to receive its reflection echo, the received wave is compared with a reference wave to extract a Doppler signal, and the Doppler signal is extracted from the motion reflector based on the Doppler signal. In an ultrasonic Doppler diagnostic device for calculating a Doppler shift frequency and displaying a motion state as an image, a high-pass filter for extracting only a high frequency band signal of the Doppler signal and only a low frequency band signal of the Doppler signal An ultrasonic Doppler characterized by comprising: a low-pass filter for taking out the signal and a switcher for switching and outputting either of the outputs of the both filters, and selectively obtaining low speed information and high speed information. Diagnostic device. 3. The apparatus according to claim 1, wherein the velocity of the low-velocity motion reflector toward the probe is represented by red, the velocity of moving away from the probe is represented by blue, and the magnitude of velocity is represented by luminance. , An ultrasonic Doppler diagnostic apparatus characterized by displaying motion information in two dimensions. 4. The ultrasonic Doppler diagnosis according to claim 1, wherein a plurality of hues are changed and displayed according to the magnitude of the velocity of the low velocity motion reflector. apparatus. 5. The apparatus according to claim 1 or 2, wherein a cursor line is displayed on the B mode screen, and a speed change of the low speed motion reflector designated by the cursor line is displayed graphically. A characteristic ultrasonic Doppler diagnostic device.