JPH0426417A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To obtain the ultrasonic diagnostic device which can raise a dynamic range for the reflected echoes from blood flow by providing an arithmetic means for subtracting the echo information accumulated in a memory means from the reflected ultrasonic echoes. CONSTITUTION:The echo data obtd. by the 1st time of the reflected echo is read out of a memory 13 for the echoes from the 2nd to the 8th time. This data is converted to an analog signal by a D/A converting circuit 14. The echo data accumulated in this memory 13 is subtracted from the reflected echo in a subtraction circuit 11. The output of the subtraction circuit 11 of the 2nd and subsequent time is, therefore, the signal of only the blood flow component from which a clatter component is removed. The gain of a variable gain amplifier 15 can be increased to the extent of not saturating a phase matching addition circuit 16 in this case. The dynamic range is, therefore, raised for the reflected echoes from the blood.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic diagnostic device, and in particular, it emits ultrasonic pulses multiple times in one direction in order to obtain blood flow data, and collects the reflected ultrasonic echoes from these ultrasonic pulses. The present invention relates to a device for obtaining biological information.

[Conventional technology]

Ultrasonic diagnostic equipment used in the medical field, for example, displays tomographic data of the heart on a monitor in real time, or measures blood flow velocity in a specific area using the pulsed Doppler method, and displays this distribution on a monitor in the same way as above. things are being done. In such an ultrasonic diagnostic apparatus, a two-dimensional blood flow tomography method is employed in order to two-dimensionally understand the blood flow velocity. This two-dimensional blood flow tomography method combines blood flow velocity with tomographic data and expresses blood flow velocity two-dimensionally and in real time. That is, the tomographic information and blood flow information are each digitized and synthesized, and R
, G, and B television signals, and the blood flow velocity is displayed superimposed on a normal tomographic image. Additionally, the average velocity profile of the detected blood flow is displayed in color.

Conventional devices employing the two-dimensional blood flow tomography method use digital filters to remove strong reflected echo signals from living tissue (clutter). This digital filter is provided after the Doppler signal detection circuit, and is configured to input a digital signal obtained by A/D conversion after detecting the reflected echo signal at 90 degrees.

[Problem to be solved by the invention]

In general, in order to improve the S/N ratio of a signal, amplification is performed before signal processing. However, in conventional ultrasound diagnostic equipment, some of the reflected echoes received by each transducer element include clutter Since the signal contains a strong echo component, if amplification is performed before signal processing, the signal will be distorted by the clutter. Therefore, it is not possible to amplify with a very large gain, and there is a problem that the dynamic range of especially weak blood flow echo signals is restricted by the rack as described above.

An object of the present invention is to provide an ultrasonic diagnostic apparatus that can increase the dynamic range of reflected echoes from blood flow.

[Means to solve the problem]

The ultrasonic diagnostic apparatus according to the present invention emits a plurality of ultrasonic pulses in one direction from each transducer constituting a probe, and obtains biological information from reflected ultrasonic echoes from within a living body. It also includes storage means and calculation means.

The storage means stores echo information of one of a plurality of reflected ultrasound echoes in one direction obtained from each transducer. Further, the calculation means is for subtracting the echo information stored in the storage means from the reflected ultrasound echo.

[Function] In an ultrasonic diagnostic device that uses a two-dimensional blood flow tomography method, 1
Emit ultrasound pulses multiple times in one beam direction. Therefore, for example, the reflected echo obtained by the first ultrasonic pulse is stored in a storage means, and then the second
The echo information stored in the storage means is subtracted from the reflected echoes obtained by the ultrasonic pulses after the first ultrasound pulse. This removes strong echo components that do not move, such as living tissue.

In this way, strong echo components obtained from biological tissues and the like are removed, so that they can be amplified with a large gain, and the dynamic range can be increased with respect to the reflected echo components from blood flow.

〔Example〕

FIG. 3 is an overall schematic configuration diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

The ultrasonic diagnostic apparatus is comprised of an apparatus main body 1 and a probe 2 connected to this apparatus main body 1. probe 2
is composed of multiple micro oscillators. Device main body
has a transmitting system and a receiving system. The transmission system includes a wave transmitting section 3 that is controlled by a system control section (not shown). The wave transmitting unit 3 includes a high-frequency pulse oscillator for transmitting an ultrasonic beam, a delay circuit for performing electronic scanning, a delay amount control circuit, and the like.

The receiving system includes a wave receiving unit 4, a tomographic data processing circuit 5 for obtaining tomographic data such as a B-mode image, a Doppler signal detection circuit 6 and a blood flow velocity calculation circuit 7 for obtaining blood flow data.
and DSC8.

The tomographic data processing circuit 5 includes a logarithmic amplifier circuit, a detection circuit, a low-pass filter, an A/D conversion circuit, and the like. Further, the Doppler signal detection circuit 6 includes a 90° phase shifter, a mixer, an A/D conversion circuit, and the like. The blood flow velocity calculation circuit 7 is a circuit for calculating the average flow velocity of blood flow by performing MTl filter processing, fast Fourier transform calculation, or autocorrelation calculation. The outputs of the tomographic data processing circuit 5 and blood flow velocity calculation circuit 7 are input to a DSC (digital scan converter) 8. The DSC8 is composed of an image memory, a D/A conversion circuit, etc.
A CRT monitor 9 is connected to the rear stage.

FIG. 1 is a block diagram showing details of the wave receiving section 4. As shown in FIG.

The delivery section 4 receives each vibrator 2a, 2b that constitutes the probe 2.
,... Preamplifiers connected to each of...
It has O. An output terminal of the preamplifier 10 is connected to a child terminal of a subtraction circuit 11 and an A/D conversion circuit 12. A memory 13 and a D/D converter circuit 12 are connected to the output side of the A/D converter circuit 12.
An A conversion circuit 14 is connected, and a D/A conversion circuit 14
The output terminal of is connected to one terminal of the subtraction circuit 11. Further, the output terminal of the subtraction circuit 11 is connected to the variable gain amplifier 1
5 to the phasing/summing circuit 16. The gain of the variable gain amplifier 15 can be controlled by a gain control signal from a system control circuit (not shown).

Next, the operation will be explained.

First, the probe 2 is driven by the wave transmitting unit 3, and each transducer emits an ultrasonic beam in one direction a plurality of times (eight times in this case). The reflected echoes from inside the living body for each of the ultrasound beams are inputted to the wave receiving unit 4 via the probe 2 again.

In the delivery section 4, a reflected echo signal corresponding to the first emitted ultrasonic pulse is input to the subtraction circuit 11 and also to the A/D conversion circuit 12. The reflected echo data converted into digital data by the A/D conversion circuit 12 is stored in the memory 13. This first reflected echo signal is sent to the variable gain amplifier 15 without being subjected to power reduction processing. Therefore, as shown in FIG. 2, the first reflected echo signal has a large signal strength due to the clutter component. In this case, the gain of the variable gain amplifier 15 is 0.
Alternatively, the value is set to a small value such that saturation does not occur in the phasing and adding circuit 16 at the subsequent stage.

The outputs of the variable gain amplifiers 15 corresponding to the respective vibrators 2a, 2b, . The output of the phasing and addition circuit 16 is input to the tomographic data processing circuit 5 and the Doppler signal detection circuit 6. As mentioned above, the first data contains clutter components and the signal strength of the blood flow component is small, so the tomographic data processing circuit 5 is used only for processing tomographic data and not for detecting Doppler signals. Then, the signal is subjected to processing such as amplification and detection, and is stored in the DSC 8 after being A/D converted. This tomographic data is then converted into a television signal and displayed on the monitor 9.

Next, processing of reflected echoes for the second and subsequent ultrasound pulses will be described. For the second to eighth echoes, the echo data obtained by the first reflected echo is read out from the memory 13, converted into an analog signal by the D/A conversion circuit 14, and reflected by the subtraction circuit 11. The echo data stored in this memory 13 is subtracted from the echo.

Therefore, the output of the subtraction circuit 11 from the second time onwards is the second
As shown in the figure, the signal contains only blood flow components from which clutter components have been removed. In this case, the gain of the variable gain amplifier 15 can be made large enough to prevent the phasing and addition circuit 16 from being saturated.

The phased addition output signal from which these clutter components have been removed is input to the Doppler signal detection circuit 6.

The Doppler signal detection circuit 6 performs detection and filter processing to obtain a Doppler signal. The Doppler signal obtained by this Doppler signal detection circuit 6 is subjected to arithmetic processing in a blood flow velocity detection circuit 7, thereby obtaining an average blood flow velocity. After this data is sent to the DSC 8, it is converted into a television signal and displayed on the monitor 9.

In such an embodiment, large amplification can be performed before the signal processing circuit, and the dynamic range can be increased for reflected echoes from blood flow.

[Other Examples]

In the embodiment described above, the first reflected echo of an ultrasonic pulse emitted multiple times is stored in the memory 13, and the clutter component is removed based on this data. The reflected echoes obtained by subsequent ultrasonic pulses may be sequentially stored in the memory 13, and the crank component may be removed based on the updated data.

〔Effect of the invention〕

As described above, in the present invention, since a circuit for subtracting strong reflected echo components such as clutter components is provided in the input stage before the signal processing circuit, it is possible to increase the dynamic range for reflected echoes from blood flow. can.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a wave receiving section of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining its operation, and FIG. 3 is a schematic diagram of the ultrasonic diagnostic apparatus. FIG. 2 is a block configuration diagram. 4... Receiving section, 11... Subtraction circuit, 13... Memory, 15... Variable gain amplifier, 16... Phase-setting and addition circuit. Patent applicant Shimadzu Corporation Representative Patent attorney Yukio Ono

Claims (1)

[Claims] (1) In an ultrasonic diagnostic device that emits multiple ultrasound pulses in one direction from each transducer that makes up the probe and obtains biological information from reflected ultrasound echoes from inside the living body, one direction is obtained from each transducer. An ultrasonic diagnostic apparatus comprising: storage means for storing echo information of one of a plurality of reflected ultrasound echoes for .