JPH0213444A - Ultrasonic wave doppler diagnosis device - Google Patents

Abstract

PURPOSE:To make it possible to correctly display a picture image of the state of a motion speed by finally adding doppler signals obtained with each vibration element after orthogonally detected with the signals added while once a phase control is made in each small group. CONSTITUTION:Vibration elements within a vibrator 10b for receiving are divided into plural groups, and orthogonal, detectors 34-1-34-n are connected to each of these vibration element groups via phase control addition circuits 32-1-32n. A phase control addition circuit 32 is composed of e.g., a cross point switch 28 and a delay line 30, and a reflected echo signal is added and outputted after a given delay quantity set to each vibration element group is given. Two highpass filters 36a and 36b are provided to each of an orthogonal detector 34, a low frequency component of the output of the detector 34 is eliminated with the filters 36a and 36b, and the reflected echo signal of a stationary part is removed. An adder 38 is provided behind a highpass filter 36, and a doppler signal obtained from the circuits 32-1-32-n is added.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic Doppler diagnostic device, particularly an ultrasonic Doppler diagnostic device that receives velocity information due to the Doppler effect using continuously outputted ultrasonic waves,
The present invention relates to an ultrasonic Doppler diagnostic device that displays the motion state of a reflective site within a subject on a screen.

[Prior Art] Ultrasonic Doppler diagnostic equipment that continuously emits an ultrasound beam into a subject such as a living body and displays a moving reflector, for example, the state of cardiac blood flow, is well-known. , by receiving reflected echoes from within the subject and detecting the Doppler effect received by the reflected echoes as a shift in the ultrasonic carrier frequency, the velocity state of blood flow, etc. is determined.

FIG. 3 shows a schematic configuration of such a device. When emitting continuous ultrasonic waves, the transducer 10 in the probe is connected to the transmitting transducer 10a and the receiving transducer. 10
Use it separately. The transmitting transducer 10a is provided with a transmitting circuit 12 for emitting continuous ultrasonic waves, and the transmitting circuit 12 outputs an ultrasonic transmitting signal of a predetermined frequency to the transmitting transducer 10a.

Further, the reception transducer 10b is provided with a phase control delay line 14 for receiving reflected echoes in a predetermined direction. In order to obtain this, a delay time proportional to the height of the trapezoidal shape of the phase control delay line 14 is given to the received signal obtained by each vibrating element. and,
The outputs of this phase control delay line 14 are added by an adder 16 to form reflected echo signals from eight points.

The phase control delay line 14 and the adder 16 are actually connected to the cross point I switch 2 as shown in FIG.
8 and a delay line 30. That is, the cross-point switch 28 is connected so that the control lines connected from the points of the delay line 30 having different delay amounts and the control line from the receiving transducer 10b intersect in a matrix, and the cross-point By electrically connecting the (cross points), a predetermined amount of delay can be given to the reflected echoes received by the individual vibration elements. Then, the delay line 30 simultaneously adds echo signals from each vibrating element (current addition) and outputs a received echo signal to the quadrature detector 18.

As shown in FIG. 3, this quadrature detector 18 includes two mixers 20a, 20b and two low-pass filters 22.
a and 22b, and converts the received echo signal into two types of Doppler signals by mixing it with a reference signal (for example, a sine signal and a cosine signal) having a phase different by 90 degrees. This 2
These types of signals are processed through separate routes until they are converted into velocity information.If one is a real part signal and the other is an imaginary part signal, they can be regarded as a complex signal, and the Doppler signal, which is velocity information, can be interpreted as a complex signal. The shift frequency can be determined by the polarization angle of this complex signal.

The low-pass filter 22 removes harmonic components generated in the mixer 20, and the outputs of the low-pass filters 22a and 22b are transferred to the high-pass filters 24a and 24.
b.

This high-pass filter 24 is applied to a stationary part, for example, a heart wall.
It is provided to remove low frequency components (clutter components) such as from blood vessel walls, thereby removing extra signal components unnecessary for Doppler information extraction.

Next, the output of this high-pass filter 24 is supplied to a Doppler signal processing unit 26, where a Doppler shift frequency is determined from the polarization angle of a complex signal, which is a Doppler signal, for example, and from this Doppler shift frequency. Speed can be measured.

[Problems to be Solved by the Invention] However, the adder 16 (in FIG. 4, the delay line 30
), the reflected echo signals from each vibrating element are added together, resulting in a wide range of signal levels, which solves the problem that the continuous wave reflected echo signals, including Doppler signals, become saturated in the dynamic range of conventional devices. was there.

In other words, the echo signal obtained from inside the subject has a considerable difference in intensity depending on the part where it is reflected. For example, the echo signal from muscle (myocardium, etc.) or tissue membrane and the echo signal from pathological blood flow. The amplitude ratio ranges from 60 to 100 decibels. However, conventional devices require a wide dynamic range because they add all signals including those from muscles.

As a solution to this case, it is possible to widen the dynamic range, but there is a problem that the device becomes larger, and there is a situation in which the current dynamic range of the conventional device is at its limit.

Alternatively, a method of adding the Doppler signals after extracting them may be considered, but in this case, the quadrature detector 18 must be provided before the delay line 14 or the adder 16. is required, and this cannot provide a good circuit configuration.

The above problem is particularly problematic in the case of continuous waves, but in the case of pulsed ultrasound, even if the received echo signal is saturated, there is no problem in extracting the Doppler signal component. In other words, when using pulsed ultrasound, received echo signals are extracted for each predetermined region within the subject, and signals from stationary parts such as the heart wall, which are saturated, are not captured.
This is because only the Doppler signal composed of weak signal components needs to be extracted. Therefore, the dynamic range in the case of Doppler signal detection becomes a problem, especially when transmitting and receiving continuous wave ultrasound waves into the subject.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an ultrasound Doppler diagnosis capable of eliminating saturation of received echo signals without expanding the dynamic range and detecting Doppler signals well. The goal is to provide equipment.

[Means for Solving the Problems] In order to achieve the above object, the present invention continuously emits ultrasonic waves into a subject, demodulates the reflected echo signals, and calculates the motion of the reflected site from the Doppler shift frequency. In an ultrasonic Doppler diagnostic device that detects a state, the reflected echoes of the continuous ultrasound waves are phase-controlled, a large number of transducer elements that are received at once are divided into multiple transducer groups, and each transducer group receives a reflected echo signal. a phase control adder circuit that adds up the signals, a quadrature detector connected to each of the phase control adder circuits provided for each vibrating element group, and a high frequency detector that removes low frequency signals from the output of the quadrature detector. It is characterized by comprising a pass filter.

[Operation] According to the above configuration, the reflected echoes of continuous ultrasonic waves reflected from within the subject are once received and summed by the phase control adding circuit for each of the vibrating element groups divided into a plurality of groups. This addition output is supplied to a quadrature detector, and converted into a Doppler signal by the quadrature detector.

The Doppler signal of the quadrature detector is then supplied to a high-pass filter, where the low-frequency signals from the stationary part are removed, so the output of the high-pass filter is shifted to the low frequency region. , and the Doppler signal is at a small level.

Therefore, even if the output of the high-pass filter is finally added as a Doppler signal from a predetermined region, the signal will not be saturated.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a block diagram of a schematic configuration of an ultrasound Doppler diagnostic bag holder according to the present invention, and the circuit of the transmitting section is omitted and only the circuit of the receiving section is shown.

A characteristic feature of the present invention is that in order to eliminate saturation of received echo signals due to continuous ultrasonic waves, the Doppler signals obtained from each transducer are subjected to phase-controlled addition for each small group before being finally summed. This is to perform orthogonal detection.

For this purpose, in the present invention, the vibrating elements in the receiving vibrator 10b are divided into a plurality of groups, and each of the vibrating element groups is provided with a phase control addition circuit 32-1 to 32-n and a quadrature detector 34-n.
Connect 1 to 34-n.

In the embodiment, for example, the receiving vibrator 10b is divided into 4 to 8 vibrating element groups, and if the receiving vibrator 10b has 32 vibrating elements, the vibrating element groups are divided into 8 to 4 vibrating element groups. It will be separated.

In the embodiment, this phase control addition circuit 32 is composed of a cross-point switch 28 and a delay line 30 shown in FIG. It is outputting.

Further, the configuration of the quadrature detector 34 is the same as that of the conventional one, and includes two mixers 2Qa and 20b and two low-pass filters 22a and 22b.

Therefore, in the mixer 20, the reference signal (s in
, cos signals) are multiplied together, and thereby,
The reflected echo signal can be converted to a Doppler signal.

Then, as described above, when the reference signal is multiplied by the reflected echo signal, low frequency components and high frequency components appear, so only the low frequency components that are effective as the Doppler signal to be detected are extracted by the low pass filter 22. That will happen.

Further, each of the quadrature detectors 34 is provided with two high-pass filters 36a and 36b, and the high-pass filters 36 remove low frequency components of the output of the quadrature detector 34, and remove the low frequency components of the output of the quadrature detector 34. This will remove the reflected echo signal. This means that the output of the high-pass filter 36 is shifted to a low frequency region, and at the same time, the signal level is also reduced.

The high-pass filter 36 is provided with an adder 38 that adds the outputs, and the Doppler signals obtained from the plurality of sets of phase control adder circuits 32-1 to 32-n are added here. This means that all the Doppler signals obtained by the receiving transducer 10b are added.

In this case, as described above, since the output of the high-pass filter 36 has a small signal level, the signal level of the output of the adder 38 is significantly lower than in the case of simple addition as in the conventional case. That will happen. Therefore, no distortion occurs due to the limited dynamic range of the device.

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

First, a continuous ultrasonic wave is emitted from the transmitting transducer 10a into the subject, and its reflected echo is received by each transducer element in the receiving transducer 10b. And the output of each vibrating element is
Input processing is performed for each predetermined vibrating element group by n phase control adder circuits 32-1 to 32-n, and addition processing is performed after a predetermined amount of delay is given by the cross point switch 28 and delay line 30. .

The output of the phase control addition circuit 32 is orthogonally detected by a quadrature detector 34 and converted into a Doppler signal, and at the same time, the quadrature detector 34 removes high frequency components generated in the Doppler signal by the mixer 20. This quadrature detector output has low frequency components removed by a high-pass filter 36, and clutter signals in the stationary portion are removed.

As mentioned above, the output of this high-pass filter 36 is
This results in a low-level signal with low frequency components removed.

Note that the output of the quadrature detector 34 is also slightly smaller than the output obtained by simply adding the reflected echo signals obtained by each vibrating element, and the quadrature detector 34 also contributes to a reduction in the signal level. .

Therefore, the adder 38 collects all the reflected echoes (l of M
- When the ply signal is added, the added output becomes extremely low, and the received signal does not become saturated (signal processing within the conventional dynamic range is possible).

The output of this adder 38 is then sent to the Doppler signal processing section 26.
The Doppler shift frequency is analyzed and outputted to the display unit 40 as a speed signal or the like. Therefore, the display unit 40 can display the flow velocity in a predetermined direction in a waveform that changes over time, as shown in FIG. 2, for example.

[Effects of the Invention] As explained below, according to the present invention, after performing quadrature detection by adding each small group while controlling the phase,
Since the Doppler signals obtained from each vibrating element are finally added together, the received signal does not become saturated (there is an advantage that Doppler information can be accurately detected using continuous ultrasound within the conventional dynamic range).

Therefore, it is possible to accurately display an image of the state of movement speed, and it is possible to provide information useful for image diagnosis.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing a schematic configuration of an ultrasonic Doppler diagnostic device according to the present invention, FIG. 2 is a diagram showing an example of speed display by the display device of FIG. 1, and FIG. 3 is a diagram showing a conventional FIG. 4 is a block diagram showing the circuit configuration of the device. FIG. 4 is an explanatory diagram showing another configuration example in place of the phase control delay line and adder in FIG. 3. 10... Oscillator 14... Phase control delay line 16.38... Adder 18.34... Quadrature detector 24.36... High pass filter 26...
Doppler signal processing section 28...Cross point switch 30...Delay line 32...Phase control addition circuit 40...Display device. Self-applicant Aloka Co., Ltd.

Claims (1)

[Claims] (1) In an ultrasonic Doppler diagnostic device that continuously emits ultrasonic waves into a subject, demodulates the reflected echo signals, and detects the motion state of the reflection site from the Doppler shift frequency, the reflected echoes of the continuous ultrasonic waves are a phase control adding circuit that controls the phase of a large number of vibrating elements to divide the large number of vibrating elements received at once into a plurality of vibrating element groups, and adds reflected echo signals for each vibrating element group; An ultrasonic Doppler diagnostic device comprising: a quadrature detector connected to each of the phase control adder circuits; and a high-pass filter that removes low frequency signals from the output of the quadrature detector.