JPS6249833A - Ultrasonic blood stream imaging apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ultrasonic blood flow imaging device.

Technical Background of the Invention] Ultrasonic blood flow imaging devices are basically a technology that is an extension of ultrasonic blood flow Doppler devices. The blood flow Doppler device utilizes the fact that ultrasonic echoes undergo a frequency shift due to blood flow, and performs FFT (FastEourier Transf) by adding only one point in the depth direction.
Ormati.

The frequency is analyzed and displayed using MTI (Mo
In a device using a . ving Target Indicator), frequency analysis is performed by adding continuous points in the depth direction. The results are then displayed in colors that correspond to changes in blood flow direction and average velocity. Such a device is
Diagnosis of the circulatory system, especially for its ability to identify abnormal blood flow, has recently attracted attention.

Incidentally, ultrasonic echoes have different amplitudes for various reasons. For example, due to differences in physical properties of ultrasound reflecting objects such as myocardium, blood flow, liver, etc., differences based on location such as depth and direction from the ultrasound probe, etc.
There are differences in the physical performance of the ultrasound probe, such as depth 1 frequency, number of transducers, aperture area, focal length, transmission/reception conversion efficiency, and transmission power.

Conventionally, variations in the amplitude of these ultrasonic echoes were adjusted by the device so that the amplitude was optimal (q. pre
-3TC(Sens 1tivity Time
Ultrasonic echoes from a short distance have been suppressed using technologies such as STC and STC, and the sensitivity of ultrasonic echoes from a long distance has been improved. However, with this method, sensitivity characteristics can only be set artificially, and sensitivity differences due to differences in the physical properties of ultrasound-reflecting objects or differences in the physical performance of ultrasound probes cannot be covered.

These factors have a great influence on ultrasonic blood flow imaging devices. In particular, the influence of the above-mentioned difference in physical properties is remarkable, and the difference in ultrasound echoes between the myocardium, blood vessel wall, and blood flow is very large.

[Problems in the Background Art] Fig. 5 shows an example of the configuration of a conventional ultrasonic blood flow imaging device.
and the first one via the band pass filter 2. The signal is input to the second mixers 3a and 3b, and the first mixer 3a mixes it with the reference signal Fref, and the second mixer 3b mixes it with the reference signal Fref'-90'. Filters 4a, 4b
Enter. And the first. Second low pass filter 4
a.

4b removes high frequency components from these two signals, and the first .4b is controlled by the STC controller 7.
The sensitivity characteristics are corrected by the second STC circuits 5a and 5b,
Rani No. 1. Real signals, stomach signals having a phase of 90° to each other through the second buffer amplifiers 5a and 5b, respectively.
It is sent as an imaginary signal to an A/D converter (not shown).

However, with this device, if you try to sufficiently amplify blood flow echoes, the amplifier etc. will become saturated due to large echo signals from the myocardium, etc., and the operating point will fluctuate by a wide range, and the amplifier will then stop working. be. Also, especially the first one. In the second mixers +J3a and 3b, there is a problem in that when a large-amplitude echo signal is mixed in, the harmonic component becomes large and the output waveform is distorted.

Generally speaking, the A/D converter has a problem in that a large dynamic range and precision are required to extract a blood flow echo signal through a large amplitude echo signal.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it is an object of the present invention to suppress large-amplitude echo signals based on foul echo signals from myocardium, cardiovascular walls, etc., and effectively suppress blood flow echo signals. In addition to improving its resolution, mixers, amplifiers, and
It is an object of the present invention to provide an ultrasonic blood flow imaging device in which each component such as a D converter can maintain normal gluteal function.

[Summary of the Invention] The outline of the present invention for achieving the above object is to obtain a blood flow image of a subject by 1q using the fact that ultrasound echoes from the subject undergo frequency shift due to blood flow. The ultrasonic blood flow imaging device is equipped with a clutter removal circuit capable of removing large (membrane width components) based on echoes reflected from myocardium etc. from echo signals based on ultrasonic echoes from the subject. It is characterized by the following.

[Embodiments of the Invention] A first embodiment of the present invention will be described in detail below with reference to FIG. In addition, in the apparatus shown in the figure, parts having the same functions as those shown in FIG. 5 are given the same reference numerals.
A detailed explanation thereof will be omitted.

The difference between the device shown in FIG. 1 and the device shown in FIG.
bandpass filter 2 and the first . Second mixer 3a, 3b
A clutter removal circuit 8 is connected between the STC
Controller 7 and first and second STC circuits 5a and 5b
This is because it has been omitted.

The clutter removal circuit 8 includes an amplitude amplifier 10 that receives the output of the bandpass filter 2 and amplifies the envelope waveform signal, and an inverter (phase inverter) that inverts the phase of the envelope waveform signal and outputs it as a reference signal. A comparator (11) that compares the echo signal from the band-pass filter 2 with the reference signal from the inverter 11 and sends out a pulse signal if the echo signal from the band-pass filter 2 is larger than the reference signal. Comparator) 12 and
A delay circuit 13 that gives a certain delay time to the echo signal from the band-pass filter 2 is input, and the echo signal from the band-pass filter 2 delayed by the delay circuit 13 is input, and the gate is activated based on the pulse signal. The gate circuit 14 suppresses an echo signal with a large closing amplitude.

The reason why the phase is inverted by the inverter 11 is to lower the reference potential of the next stage comparator 12 when the echo signal has a large amplitude, and to raise the reference potential when the echo signal is weak.

Further, the delay circuit 13 is for correcting the phase delay of the pulse signal sent out from the comparator 12.

Next, the operation of the apparatus having the above configuration will be explained.

The B-mode echo signal is amplified by an amplifier 1 and first inputted to an amplitude detector 10 via a bandpass filter 2. Then, the envelope waveform signal of the echo signal is extracted and increased to a predetermined amplitude.

The signal is then sent to the inverter 11. The inverter 11 performs phase inversion processing on this signal and sends it to the comparator 12 as a reference signal.

A comparator 12 compares the echo signal from the bandpass filter 2 with the reference signal, and when the echo signal is larger than the reference signal, sends a corresponding pulse signal to the gate circuit 14.

On the other hand, the delay circuit 13 applies a certain delay time to the echo signal from the bandpass filter 2 and then sends it to the gate circuit 14 . This delay time is set in advance to be the time required for the comparator 12 to complete the process of comparing the echo signal and the reference signal.

The circuit 14 inputs the echo signal given the delay time 4 and closes the gate during the input period of the pulse signal based on the pulse signal to suppress the amplitude of the echo signal.

As a result, the echo signal with large amplitude based on the echo reflected from the myocardium etc. is transmitted directly to the first signal. Second Miki +73a,
3b, etc., and therefore, generation of waveform distortion due to the mixer and unstable operation of the amplifier as in the conventional device are prevented. Furthermore, a normal A/D converter (not shown) can be used.

FIG. 2 shows a second embodiment of the invention. still,
Components in the apparatus shown in FIG. 1 having the same functions as those shown in FIG. .

The difference between the device shown in FIG. 2 and the device shown in FIG. This method utilizes an echo signal from an amplitude detector in a B-mode receiver provided separately in the diagnostic device.

The device of this second embodiment can also exhibit the same effect as the device shown in FIG.

FIG. 3 shows a third embodiment of the present invention, and in the device of this embodiment, parts having the same functions as those shown in FIG. is omitted.

The difference between this third embodiment device and the one shown in FIG. This is achieved by using a clutter removal circuit 8C configured to increase the cancellation level of the echo signal 6 corresponding to the ultrasonic echo and send to the comparator 12 an attenuation reference signal corresponding to the attenuation characteristics of the ultrasonic wave.

According to the third embodiment, since the pulse signal corresponding to the attenuation reference signal can be sent from the comparator 12 to the gate circuit 14, the large amplitude component suppression effect is more suitable for the attenuation characteristics of the echo signal. can be demonstrated.

It goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made within the scope of the invention.

FIG. 4 shows a modification of the present invention, and in the device shown in the same figure, parts having the same functions as those shown in FIG. Explanation will be omitted.

The device shown in FIG. 4 uses an AGC (Auto Matic) as a clutter removal circuit 8C in which an inverter 11 and a comparator 12 are omitted, and an amplifier and a ring diode attenuator are combined in place of a gate circuit 14.
By using a Ga1n Control) circuit 16 which automatically controls the gain of the echo signal given a predetermined delay time by the delay circuit 13 based on the output signal of the amplitude detector 10, be.

The device shown in FIG. 4 can also perform the same functions as the device of the first embodiment, and in addition, even if there are differences in the sensitivity of the ultrasonic probe, blood flow is always maintained at the optimal gain. It is possible to obtain an echo signal based on the flow.

[Effects of the Invention] According to the present invention described in detail above, it is necessary to expand the dynamic range of other components of this device, such as a mixer, a filter, an amplifier, an A/D converter, etc., in addition to improving cardiovascular walls and myocardium. It is possible to provide an ultrasonic blood flow imaging device that is free from these characteristics and does not cause these characteristic pitfalls.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
FIG. 3 is a block diagram showing a second embodiment of the invention, FIG. 3 is a block diagram showing a third embodiment of the invention, FIG. 4 is a block diagram showing a modification of the invention, and FIG. 1 is a block diagram showing the configuration of a conventional device. 1...Amplifier, 2...Band pass filter, 3a...First mixer, 3b...
- Second mixer, 4a...first low-pass filter, 4b...second low-pass filter, 6a
...First buffer 1 amplifier, 6b...
Second buffer amplifier, 8.8A, 8B, 8C...
...Clutter removal circuit, 10...Amplitude detector,
11...Inverter, 12...Comparator, 13...Delay circuit, 14...
Gate circuit, 15... Adder, 16...
・AGC circuit. Agent Patent Attorney Norio Hijima Norio Ogo

Claims (2)

[Claims] (1) In an ultrasonic blood flow imaging device that obtains a blood flow image of a subject by utilizing the frequency shift of ultrasound echoes from the subject due to blood flow, the ultrasound echoes from the subject are What is claimed is: 1. An ultrasonic blood flow imaging device comprising a clutter removal circuit having a function of removing large amplitude components based on echoes reflected from myocardium or the like from echo signals based on (2) The clutter removal circuit includes an amplitude detector that obtains an envelope waveform signal of the echo signal, an inverter that inverts the phase of this envelope waveform signal and sends it out as a reference signal, and an inverter that converts the reference signal and the echo signal. A comparator that sends out a pulse signal when the echo signal is larger than a reference signal after comparison, and a gate circuit that receives the echo signal at a predetermined timing and closes a gate in response to the pulse signal. The ultrasonic blood flow imaging device according to scope 1.