JPH0659283B2 - Ultrasonic diagnostic equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to a blood flow in a living body based on a reflection signal obtained in the living body by emitting an ultrasonic beam into the living body. The present invention relates to an ultrasonic diagnostic apparatus that displays information.

[Conventional technology]

In the ultrasonic diagnostic apparatus used in the medical field, for example, the tomographic data of the heart is displayed on a monitor in real time, or the blood flow velocity at a specific site is measured by the pulse Doppler method, and this distribution is displayed on the monitor as described above. Is commonly done. Further, there is a device in which the tomographic data is displayed on a monitor and the blood flow velocity at a specific site is displayed side by side on the monitor on which the tomographic data is displayed.

Also, recently, in order to grasp the blood flow velocity two-dimensionally, 2
The three-dimensional blood flow tomography method is adopted. This expresses the blood flow velocity in two dimensions in real time by combining the blood flow velocity with the tomographic data. That is, the tomographic information and the blood flow information are digitized and synthesized respectively, R,
The blood flow velocity is converted into G and B television signals and displayed on the normal tomographic image, and the average velocity profile of the detected blood flow is displayed in color.
Flow mapping).

In such an ultrasonic diagnostic apparatus, the obtained blood flow data contains a random noise component, which is particularly caused by a gradual movement of an abdominal organ or a circuit system. In order to remove these noise components, conventionally, MTI (Moving
(Target Indication) Filter and power limiter circuit are provided. The MTI filter is a high-pass filter and is for removing noise components by removing low-frequency components. The power limiter circuit is for removing random noise components by removing low power components.

[Problems to be Solved by the Invention]

The conventional ultrasonic diagnostic apparatus has a problem that the MTI filter cannot remove this noise component only by the power limiter circuit, especially when only a gentle movement of the abdominal organ is input.

That is, the signal component due to the gentle movement of the abdominal organ is
Since the speed is slow, its power can be kept low by the MTI filter, but the power of this signal component is so large that it cannot be kept sufficiently low by the MTI filter. Therefore, many signal components that exceed the limiter value of the power limiter circuit remain,
This becomes noise.

An object of the present invention is to provide an ultrasonic diagnostic apparatus that can remove noise components due to movement of abdominal organs and can improve the S / N ratio.

[Means for Solving the Problems]

An ultrasonic diagnostic apparatus according to the present invention, a blood flow data processing unit,
A power limit value generation circuit and a power limiter circuit are provided. The blood flow data processing unit is for obtaining blood flow data in the living body based on a reflection signal obtained from the living body. The power limit value generation circuit is a circuit that generates a predetermined power limit value according to the blood flow velocity obtained by the blood flow data processing unit. The power limiter circuit is a circuit that shuts off the output signal from the blood flow data processing unit when the strength of the blood flow signal obtained by the blood flow data processing unit is smaller than the power limit value.

[Action]

In the ultrasonic diagnostic apparatus according to the present invention, the blood flow data processing unit obtains blood flow data in the living body based on the reflection signal obtained from the living body. The power limit value generation circuit
A predetermined power limit value is generated according to the blood flow velocity obtained by the blood flow data processing unit. The power limiter circuit cuts off the output signal of the blood flow data processing unit when the strength of the blood flow signal obtained by the blood flow data processing unit is lower than the power limit value.

For example, by setting the power limit value by the power limit value generation circuit so that it becomes higher as the blood flow velocity becomes smaller, it is possible to remove low-speed, high-power noise components caused by slow movements of the abdominal organs. You can Thereby, the S / N ratio can be improved.

〔Example〕

FIG. 3 shows a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

In FIG. 3, the probe 1 is composed of a plurality of micro-vibrators and is connected to the transmission / reception circuit 2. The transmission / reception circuit 2 includes a high frequency pulse oscillator for transmitting an ultrasonic beam, a receiver for receiving and processing reflected echoes, a delay circuit for performing electronic scanning, a delay amount selection circuit, and the like. The output of the transmission / reception circuit 2 is the tomographic data processing system 3
And the blood flow data processing system 4.

The tomographic data processing system 3 is a circuit for obtaining tomographic data of a living body. The tomographic data processing system 3 includes a wave shaping circuit 5 that performs a waveform shaping process on a received signal, and an A / D converter 6 connected to the wave shaping circuit 5. The output of the A / D converter 6 is the display signal generation circuit 11 including a DSC (digital scan converter).
It is connected to the.

The blood flow data processing system 4 is a circuit for obtaining blood flow data of the living body based on the Doppler shift frequency. The blood flow data processing system 4 includes a wave shaping and detection circuit 7 that performs wave shaping and detection, and an A / D converter 8 connected to the wave shaping and detection circuit 7.
And a color flow information calculation circuit 9 and a Doppler mode calculation circuit 10 connected to the A / D converter 8. The color flow information calculation circuit 9 is a circuit that performs calculation processing such as color classification processing according to the blood flow velocity. The Doppler mode calculation circuit 10 is a circuit for calculating a change in blood flow velocity at a specific site. Then, the color flow information calculation circuit 9 and the Doppler mode calculation circuit 1
The output of 0 is connected to the display signal generation circuit 11.
Further, the output of the display signal generation circuit 11 is connected to a display 12 composed of a CRT.

The configuration of the color flow information calculation circuit 9 is shown in FIG. The MTI filter 21 shown in FIG. 4 is connected to the output of the A / D converter 8. The MTI filter 21
It is a digital high-pass filter that suppresses the power of low-speed components. MTI filter 21
The frequency calculation circuit 22 is connected to the output of the. The output of the frequency calculation circuit 22 is connected to the speed / power / dispersion calculation circuit 23. The velocity / power / dispersion calculation circuit 23 is a circuit for calculating the blood flow velocity and the power / dispersion of the blood flow signal. Each output of the speed / power / dispersion calculation circuit 23 is connected to a power limiter circuit 24 as shown in FIG.

In FIG. 1, the power limiter circuit 24 is a power limit value generation circuit 30 to which the velocity component of the blood flow signal is input.
And the comparator 31 to which the power component of the blood flow signal and the output of the power limit value generation circuit 30 are input, and the power component, the velocity component, and the dispersion component of the blood flow signal are input to the output from the comparator 31. A gate 32 which is controlled to be switched according to
And have. The power limit value generation circuit 30 is RA
Have M. A table of each velocity component of the blood flow signal and the corresponding power limit value is written in this RAM. Further, the comparator 31 includes an input B from the power limit value generation circuit 30 and a power component A of the blood flow signal.
When the relationship is A ≧ B, “1” is output. The gate 32 is configured to be "open" upon receiving the output "1" from the comparator 32.

Next, the operation will be described.

First, the high frequency pulse oscillator of the transmitter / receiver circuit 2 is driven,
It is applied to the high frequency pulse probe 1. Thereby, the ultrasonic beam is transmitted from the probe 1 into the living body. The reflected echo reflected in the living body is received by the probe 1 and input to the transmission / reception circuit 2. The reflected echo signal which has been subjected to the predetermined processing by the transmission / reception circuit 2 is input to the tomographic data processing system 3 and the blood flow data processing system 4. The reflected echo signal input to the tomographic data processing system 3 is subjected to signal processing such as amplification, waveform shaping, and filter processing by the wave reception shaping circuit 5. And
After being converted into digital data by the A / D converter 6,
It is input to the display signal generation circuit 11. The reflected echo signal input to the blood flow data processing system 4 is subjected to signal processing such as amplification, waveform shaping, and detection processing by the back shaping and detection shaping circuit 7. Then, it is converted into digital data by the A / D converter 8. This digital data is used as a color flow information calculation circuit 9 and a Doppler mode calculation circuit 1.
Input to 0 respectively.

The digital data input to the color flow information calculation circuit 19 is first suppressed by the MTI filter 21 in its low-speed component power. The frequency calculation circuit 22 calculates the frequency, and the speed / power / dispersion calculation circuit 23 performs the calculation process. Each output of the speed / power / dispersion calculation circuit 23 is input to the power limiter circuit 24.

In the power limiter circuit 24, the velocity component of the blood flow signal is input to the power limit value generation circuit 30. In the power limit value generation circuit 30, referring to the table,
Outputs the power limit value according to the input speed component. This output is input to the B input of the comparator 31. Further, the power component of the blood flow signal is input to the A input of the comparator 31. The comparator 31 compares the input A with the input B, outputs “1” when A ≧ B, and outputs “0” when A <B. The output of the comparator 31 is the gate 32.
Entered in.

On the other hand, the power, velocity, and dispersion components of the blood flow signal are input to the gate 32. The gate 32 becomes "open" only when receiving the output "1" from the comparator 31. As a result, each component of the blood flow signal passes through the gate 32.

For example, the velocity component, that is, the frequency component f and the blood flow intensity p
It is assumed that the relationship with and is set as the curve 42 in FIG.
In the figure, reference numeral 40 is a blood flow signal, and 41 is a noise component resulting from the gradual movement of the abdominal organ. In this case, the comparator 31 cuts the signal in the lower portion (hatched portion) of the curve 42, and the signal in the upper portion of the curve 42 passes through the gate 32. As a result, the noise component coming from the abdominal organ can be removed and the S / N ratio can be improved.

Each component that has passed through the gate 32 is displayed by the display signal generation circuit 11
Entered in. In addition, the Doppler mode calculation circuit 10 performs a calculation process such as a change in blood flow velocity on the digital signal output from the A / D converter 8. The output of the Doppler mode calculation circuit 10 is similarly input to the display signal generation circuit 11.

In the display signal generation circuit 11, the A / D converter 6, the color flow information calculation circuit 9 and the Doppler mode calculation circuit 1
Each output of 0 is processed into a signal that can be displayed on the CRT of the display 12, and the display signal is output. The display 12 receives the display signal and displays the tomographic data and the blood flow data on the CRT.

[Other Examples]

In the above embodiment, the power limit value is generated according to the velocity component of the blood flow signal, but the application of the present invention is not limited to this. For example, the power limit value may be changed in consideration of not only the velocity component but also the depth of field, the sampling frequency, or the region of interest. This makes it possible to remove the noise component more finely.

〔The invention's effect〕

According to the ultrasonic diagnostic apparatus of the present invention, since the power limit value generating circuit for generating a predetermined power limit value according to the blood flow velocity is provided, the power is reduced at a low speed such as a gentle movement of the abdominal organ. The noise component having a large number can be reliably removed, and thus the S / N ratio can be improved.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a power limiter circuit used in an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing a relationship between a power limit value and a blood flow signal or noise component. FIG. 4 is a schematic block diagram of the apparatus of the above embodiment, FIG.
The figure is a schematic block diagram of a color flow information calculation circuit. 1 ... Probe, 2 ... Transceiver circuit, 4 ... Blood flow data processing system, 9 ... Color flow information calculation circuit, 24 ... Power limiter circuit, 30 ... Power limit value generation circuit,
31 ... Comparator, 32 ... Gate.

Claims (1)

[Claims] 1. A blood flow data processing unit for obtaining blood flow data in a living body based on an ultrasonic reflection signal obtained from a living body, and a blood flow velocity obtained by the blood flow data processing unit. A power limit value generation circuit for generating a predetermined power limit value, and an output signal from the blood flow data processing unit when the strength of the blood flow signal obtained by the blood flow data processing unit is smaller than the power limit value. An ultrasonic diagnostic device equipped with a power limiter circuit for shutting off.