JPH08173426A - Ultrasonic doppler diagnostic system - Google Patents

Abstract

PURPOSE: To make it possible to maintain an always adequate device gain by variably setting the parameter of an automatic gain adjusting means according to the conditions of an ultrasonic contrast medium and the sections to be applied to an examinee. CONSTITUTION: Doppler detecting sections 4a, 4b fetch the components subjected to Doppler shift by the blood flow from the reflection echo signals received by a probe 1 and detect the complex blood flow signals from this Doppler shift component. An automatic gain adjusting circuit takes in the output signals from the Doppler detecting sections 4a, 4b and automatically varies the gain by the various heights of the levels of the taken-in signals. The response speed of this gain adjustment is made variable. The parameters for determining the various characteristics of this automatic gain adjusting circuit 12 are changed according to the presence or absence and kinds of the use of the ultrasonic contrast medium and the sections to be applied to the examinee. As a result, the parameters of the automatic gain adjusting means are variably settable according to the conditions of the ultrasonic contrast medium and the sections to be applied to the examinee, by which the always adequate device gain is maintained.

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, the parameters of the automatic gain adjusting means can be variably set according to the conditions of the ultrasonic contrast agent and the application site for the subject, and an appropriate apparatus gain can always be maintained. The present invention relates to an ultrasonic 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 band-pass 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, respectively. 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. . The Doppler detection output is obtained as an output signal from the integrators 9a and 9b. The Doppler detection output 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, when an ultrasonic contrast agent is used for blood flow measurement, the reflected echo from the blood is strengthened, so that it is originally weak. Although the blood flow detection sensitivity is improved for blood flow signals, on the other hand, the blood flow detection sensitivity may be further enhanced and saturated for blood flow signals of originally appropriate strength. Further, since the ultrasonic contrast agent injected into the blood is washed away by the bloodstream, the effect of the contrast agent gradually decreases with time from immediately after the injection,
The intensity of the reflected echo was attenuated with time. This decay time is, for example, on the order of several tens of seconds, although it depends on the application site for the subject. For these, conventionally, only when a contrast agent is used, the gain setting value of the amplifier 3 is lowered and used, or an attenuator for contrast agent (which lowers the gain) is inserted in a part of the apparatus. It corresponded. However, the gain setting of the amplifier 3 and the setting of the attenuator have been manually performed so as to respond while observing the blood flow image displayed on the display unit 6, so that the attenuation characteristic of the temporal echo intensity of the contrast agent is changed. In some cases, it could not follow, the sensitivity became insufficient from the middle, and the reflected echo disappeared. On the other hand, although the automatic gain adjusting means is used, the obtained blood flow signal may be distorted or an obstacle such as masking of a weak signal due to body movement of the subject may occur depending on its response characteristic. There was an occasion.

Therefore, the present invention addresses such a problem, and the parameters of the automatic gain adjusting means can be variably set according to the conditions of the ultrasonic contrast agent and the application site for the subject, and an appropriate device gain can always be maintained. An object is to provide an ultrasonic Doppler diagnostic device.

[0006]

In order to achieve the above object, an ultrasonic Doppler diagnostic apparatus according to the present invention uses a complex blood component of a component which has undergone Doppler shift due to blood flow from a reflection echo signal from the inside of a subject. A Doppler detector that detects the current signal,
An ultrasonic Doppler diagnostic apparatus comprising a frequency analysis unit for frequency-analyzing the blood flow signal detected by the Doppler detection unit and a display unit for displaying analysis data from the frequency analysis unit as a spectrum of blood flow velocity. In the above, the output signal from the Doppler detection unit is taken in, and the gain is automatically made variable according to the level of the taken-in signal, and an automatic gain adjusting means is provided in which the response speed of this gain adjustment is made variable. The parameters that determine the various characteristics of the gain adjusting means are changed according to the presence / absence and type of the ultrasonic contrast agent and the application site for the subject.

Further, the parameters for determining the various characteristics of the automatic gain adjusting means are stored in a table stored in advance as a numerical value group that changes depending on the presence or absence and type of use of the ultrasonic contrast agent and the application site for the subject. Alternatively, a numerical value may be selected from this table and determined.

[0008]

In the ultrasonic Doppler diagnostic apparatus configured as described above, the gain is adjusted by the level of the signal fetched from the Doppler detecting section by the automatic gain adjusting means provided so as to fetch the output signal from the Doppler detecting section. And the response speed of this gain adjustment is made variable, and the parameters that determine the various characteristics of the automatic gain adjustment means are set according to whether or not the ultrasonic contrast agent is used and the type and the application site for the subject. Works to change. Thus, the parameters of the automatic gain adjusting means can be variably set according to the conditions of the ultrasonic contrast agent and the application site for the subject, and an appropriate device gain can always be maintained.

[0009]

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. , And a display unit 6, and further includes an automatic gain adjustment circuit 12.
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, an automatic gain adjustment circuit 12 is provided between the Doppler detection units 4a and 4b and the frequency analysis unit 5. The automatic gain adjusting circuit 12 serves as means for taking in the output signals from the Doppler detecting units 4a and 4b, and automatically changing the gain according to the level of the taken-in signal, and the response speed of the gain adjusting is The parameter that is variable and that determines various characteristics of the automatic gain adjustment circuit 12 is changed according to whether or not the ultrasonic contrast agent is used, the type, and the application site for the subject. That is,
In the gain adjustment, the gain is automatically changed so that the gain is lowered when the level of the input signal from the Doppler detectors 4a and 4b is high and the gain is increased when the level of the input signal is low. ing.

As shown in FIG. 1, the internal configuration of the automatic gain adjusting circuit 12 is a ROM for determining the gain value by inputting the blood flow signals output from the Doppler detectors 4a and 4b.
13, gain controllers 14a and 14b for each system that similarly inputs blood flow signals from the Doppler detection units 4a and 4b and multiplies the gain values, and an addition that constitutes an infinite impulse response type low-pass filter (digital filter). It comprises a multiplier 15, multipliers 16 and 17, and a delay register 18. The ROM 13 includes the Doppler detection unit 4
A table for deciding the gain value is stored so that the gain is lowered when the absolute value level of the input signals from a and 4b is high, and the gain is increased when the absolute value level of the input signal is low. In addition, the automatic gain adjustment circuit 12 includes a parameter control circuit 1 for changing circuit parameters.
9, a parameter control circuit 19 is connected to a console 20 for inputting to change and set the circuit parameters.

Next, the operation of the ultrasonic Doppler diagnostic apparatus thus constructed will be described. Here, the probe 1 to the wall filter 10 of each Doppler detection unit 4a, 4b is used.
The operations up to a and 10b are the same as in the conventional example shown in FIG. First, the complex blood flow signals output from the Doppler detection units 4a and 4b are input to the ROM 13 in the automatic gain adjustment circuit 12 and the two gain controllers 14a and 14b. The ROM 13 reads the stored table from the magnitude of the absolute value of the input complex blood flow signal, and the gain controller 14
The gain value applied to a and 14b is determined. That is,
If the level of the absolute value of the input signal is high, the gain is lowered, and if the level of the absolute value of the input signal is low, the table created so as to increase the gain is read, and the read gain value is output.

Next, the gain value output from the ROM 13 is input to the adder 15. The adder 15 constitutes an infinite impulse response low pass filter together with the two multipliers 16 and 17 and the delay register 18.
The gain value input to the adder 15 passes through this low-pass filter, and two gain controllers 14a, 1
It is output to 4b. At this time, the parameters Pa and Pb of the low-pass filter are set to the parameter control circuit 1
9 is input, and the cutoff frequency of the low-pass filter is determined by the parameters Pa and Pb. Therefore, the response speed of the automatic gain adjustment circuit 12 is controlled by the parameters Pa and Pb. It should be noted that the operator inputs in advance from the console 20 the input of the parameter control circuit 19 whether or not the ultrasonic contrast agent is used, the type of the ultrasonic contrast agent, and the information D _{1 of the} application site for the subject. . In this way, the response speed is controlled by the low-pass filter, and the blood flow signals output from the Doppler detectors 4a and 4b are multiplied by the gain values read from the ROM 13 by the gain controllers 14a and 14b. As a result, the blood flow signal is output after being multiplied by a gain value in which the gain is automatically changed according to the level of the signal.

The blood flow signal output from the automatic gain adjustment circuit 12 in this manner is input to the next frequency analysis unit, where the power spectrum is calculated. afterwards,
This power spectrum data is input to the display unit 6 and is displayed as a spectrum of the blood flow velocity in real time.
Is displayed on the screen.

Another embodiment of the ultrasonic Doppler diagnostic apparatus having the above-mentioned configuration and operation is an automatic gain adjustment circuit 12
As a parameter for determining various characteristics of the above, a table stored in advance as a numerical value group that changes according to the presence or absence and type of use of an ultrasonic contrast agent and an application site for a subject is held, and numerical values are selected from this table. There are things that I decided to make. That is, the parameters Pa, Pb,
Pc is a table in which information on the presence / absence of use of the ultrasonic contrast agent, the type of the ultrasonic contrast agent, and the information of the application site for the subject is stored in advance in a memory (not shown) provided in the parameter control circuit 19. It comes to be asked from. The contents of this table are such that when the ultrasonic contrast agent is not used, the blood flow signal is passed through without being operated by the automatic gain adjustment circuit 12 by the parameter Pc, and when the ultrasonic contrast agent is used, the above automatic Gain adjustment circuit 1
2 is set to operate.

If the ultrasonic contrast agent applied to the subject is a circulatory organ, the blood flow velocity is high and the contrast agent can be quickly washed away. Therefore, the response speed of the automatic gain adjustment circuit 12 is set to the parameter control circuit. It is set quickly by parameters Pa and Pb from 19. On the other hand, when the application site to the subject is the abdomen, the contrast agent is not washed out very quickly, so the response speed of the automatic gain adjustment circuit 12 is similarly set to be slow by the parameters Pa and Pb.
In this way, the table is such that the automatic gain adjustment circuit 12 is operated. It should be noted that the intensity and duration of the reflected echo enhancement effect generally vary depending on the type of the ultrasonic contrast agent, and the parameters Pa and Pb can be set depending on the type of the ultrasonic contrast agent. A table has been created in. Further, the contents of the table can be rewritten by an input operation from the console 20 as needed.

In FIG. 1, the automatic gain adjusting circuit 12 is provided between the Doppler detecting units 4a and 4b and the frequency analyzing unit 5, but the present invention is not limited to this, and the automatic gain adjusting circuit is not limited to this. 12 receives the output signals from the wall filters 10a and 10b of the Doppler detection units 4a and 4b, and the gain controllers 14a and 14a after the gain adjustment processing.
The output signal from 14b is returned to the amplifier 3, and this amplifier 3
May be a variable gain amplifier.

[0020]

Since the present invention is constructed as described above,
By the automatic gain adjusting means provided to capture the output signal from the Doppler detection unit, the gain is automatically varied depending on the level of the signal captured from the Doppler detection unit and the response speed of this gain adjustment is varied. age,
The parameters that determine the characteristics of the automatic gain adjusting means can be changed according to the presence or absence of the ultrasonic contrast agent, the type, and the application site for the subject. Thus, the parameters of the automatic gain adjusting means can be variably set according to the conditions of the ultrasonic contrast agent and the application site for the subject, and an appropriate device gain can always be maintained. Therefore, it is possible to eliminate the distortion of the blood flow signal by the automatic gain adjusting means and the occurrence of obstacles such as masking of a weak signal due to the body movement of the subject. In addition, unlike the conventional method, the gain setting of the device and the setting of the attenuator are not performed manually during the inspection, but are automatically set, so that it is possible to follow the time-dependent attenuation characteristic of the reflected echo intensity of the contrast agent. It is possible to perform a stable inspection over time from the initial injection of the agent.

[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 ... Automatic gain adjustment circuit 19 ... Parameter control circuit 20 ... Console

Claims (2)

[Claims] 1. A Doppler detection unit for detecting a component subjected to Doppler shift due to blood flow from a reflected echo signal from the inside of a subject as a complex blood flow signal, and a blood flow signal detected by this Doppler detection unit. In an ultrasonic Doppler diagnostic device comprising a frequency analysis unit for frequency analysis and a display unit for displaying analysis data from the frequency analysis unit as a spectrum of blood flow velocity, the output signal from the Doppler detection unit is captured. The gain is automatically varied depending on the level of the captured signal, and the automatic gain adjustment means is provided in which the response speed of the gain adjustment is variable, and parameters for determining various characteristics of the automatic gain adjustment means are set, An ultrasonic Doppler diagnostic apparatus, wherein the ultrasonic Doppler diagnostic device is configured to be changed according to whether or not an ultrasonic contrast agent is used and the type thereof and an application site for a subject. 2. The parameter for determining various characteristics of the automatic gain adjusting means holds a table stored in advance as a numerical value group that changes depending on the presence / absence and type of use of an ultrasonic contrast agent and an application site for a subject. The ultrasonic Doppler diagnostic apparatus according to claim 1, wherein a numerical value is selected from this table for determination.