JPS6357061B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a two-dimensional display of blood flow distribution based on blood flow velocity information using the ultrasound Doppler method, and an intra-subject ultrasound echo tomogram using the ultrasound reflection method. The present invention relates to an ultrasonic diagnostic device that enables this.

In recent years, it has been known that it is clinically effective to simultaneously observe not only ultrasound echo tomographic images within a subject, particularly tomographic images of the heart, but also the dynamics of blood flowing within the heart.

As a method for detecting blood flow dynamics using ultrasound,
Examples include the pulse modulation Doppler method or the M-sequence modulation Doppler method, which has excellent distance resolution.

Further, a composite device that combines these ultrasonic Doppler methods and an existing electronic scanning ultrasonic diagnostic device is published, for example, in the 31st Japanese Society of Ultrasonics in Medicine, 1977, p. 183 onwards.

However, the above-mentioned apparatus can only observe the blood flow velocity at one arbitrary point, and cannot observe the blood flow velocity distribution in the heart in one or two dimensions.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that eliminates the above-mentioned drawbacks of the conventional technology and is capable of displaying blood flow distribution two-dimensionally and in real time simultaneously with conventional ultrasonic echotomographic images.

An ultrasound diagnostic apparatus according to the present invention includes an electronic scanning ultrasound probe that transmits an ultrasound beam into a subject and receives ultrasound echoes from inside the subject, and receives the ultrasound echo information. The ultrasonic diagnostic apparatus has a means for displaying an ultrasonic echo tomogram inside a subject using a phase detector that detects the phase of the ultrasonic echo information, and a filter that filters the output from the phase detector. By additionally connecting the circuit and a memory circuit that can store the output from this filter circuit in a predetermined sequence and sequentially read out the stored contents, it is possible to simultaneously generate a two-dimensional ultrasound echo tomogram inside the subject. It is characterized by being able to display the state of blood flow distribution.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A sector electronic scanning ultrasonic diagnostic apparatus, which is an embodiment of the present invention, will be described below with reference to the drawings.

In FIGS. 1 and 2, a reference signal generator 1 composed of, for example, a crystal oscillator outputs a signal o having highly stable frequency characteristics to a frequency divider 2.
The frequency divider 2 divides the frequency of the input signal o by N, and supplies the N-divided rate pulse (FIG. 2a) to the delay circuit 3. For example, N=500, reference signal frequency o
= 2.5MHz, the frequency r of the rate pulse input to the delay circuit 3 is 5KHz. The delay circuit 3 is composed of n delay lines 31. Each delay line 31 of the delay circuit 3 is connected to n pulsers 4, and after the rate pulse output from the frequency divider 2 is given a predetermined delay time, it is supplied to the pulser 4, where It is converted into a high voltage vibrator drive pulse. Each pulser 4 is connected to each of the n transducers constituting the ultrasonic transducer array 5,
By applying the drive pulse to each vibrator, each vibrator is energized and excited. Each excited transducer emits an ultrasonic pulse. Therefore, the ultrasonic transducer array 5 transmits an ultrasonic beam into the subject in a direction in which the phases of the emitted ultrasonic pulses are aligned.

The reflected waves of the transmitted ultrasound beam from interfaces with different acoustic impedances within the subject, or the reflected waves that have undergone a Doppler shift within the subject, are returned to the transducers constituting the ultrasound transducer array 5. The waves are received by the

The reflected waves received by the ultrasonic transducer array 5 are subjected to acoustic-to-electrical conversion and are transmitted as reflected signals (Fig. 2b) to the n transducers connected to each transducer constituting the transducer array 5. The signal is supplied to the preamplifier 6, amplified, and then output to a delay circuit 3' constituted by n delay lines 31'. Here, each delay time is delayed by a predetermined time, and the determination and control of this delay time is achieved by the main control circuit 7 including the delay circuit 3 for wave transmission.

Generally, the delay circuit 3 for transmitting waves and the delay circuit 3' for receiving waves are controlled to give the same delay time, so either one is used for the same purpose. In order to improve the filtering accuracy in the filter circuit 17, which will be described later, the ultrasonic beam is transmitted and received multiple times in the same direction.

The reflected signals given a predetermined delay by the delay circuit 3' are added and combined in the adder circuit 8, and then branched and outputted to the detector 9 and the mixer circuit 10.

The reflected signal input to the detector 9 is detected and
The information is supplied to the freeze circuit 11 as tomographic information constituting a mode ultrasound echo tomographic image. Regarding the freeze circuit 11, the electrocardiogram circuit (ECG circuit) 1
2 is frozen as tomographic image display information, and outputs the frozen tomographic image information to one input terminal of the adder 13. Therefore, the adder 13 outputs the video signal to the Z signal input terminal of the first display device 14.

On the other hand, at the same time that the output signal from the adder circuit 8 is input to the mixer circuit 10, the reference pulse signal o from the reference signal generator 1 is also supplied. This mixed output is filtered by being input to the next stage low-pass filter 15, and the phase detection signal (FIG. 2c)
is output as This phase detection signal is a signal containing Doppler shift components at various distances inside the object. Also, since it includes fixed reflections from walls within the heart, etc., it is necessary to remove DC components and frequency components higher than the Doppler shift frequency from this signal component.
The output signal is converted into a digital signal (FIG. 2d) by the A/D converter 16 and then input to the filter circuit 17. Here, fixed reflected signals from the heart wall and the like are removed from the phase detection output.

The filter circuit 17 is composed of adders 18 and 19, a shift register 20, and a multiplier 21. The shift register 20 delays by a time corresponding to one rate pulse interval. Here, if the rate pulse frequency r is 5 KHz, the rate pulse interval time corresponds to 200 μs.

The filter characteristics of the filter circuit 17 are as shown in FIG. 3, for example, and even better filter characteristics can be achieved by providing two stages of the filter circuit 17 shown in FIG. By repeating this for 10 rate pulses (200 μs x 10), the desired filter effect can be obtained.

The filter characteristics in FIG. 3 are expressed with frequency on the horizontal axis and output signal voltage on the vertical axis.

Such a filtering method is an application of MTI (Moving Target Indication) technology in radar.

Output signal from filter circuit 17 (Fig. 2e)
is input into the memory device 22 and then stored, and when read out, is outputted to the D/A converter 23 via the main control circuit 7 in synchronization with a specific phase signal from the electrocardiographic circuit 12. Here, the Doppler shift signal converted from a digital signal to an analog signal is
It is output to the other input terminal of the adder 13, and at the same time, it is output to the Z signal input terminal of the second display device 24.

In this adder 13, the video signal for configuring the frozen ultrasound echo tomogram and this Doppler shift signal are combined and displayed on the first display device 14.
These combined signals are output to the Z signal input terminal of the .

The X and Y signal input terminals of each display device 14 and 24 receive an X-axis sweep signal and a Y-axis sweep signal from a sweep signal generator 25.
An axis sweep signal is provided.

Furthermore, the display method of Doppler blood flow signals will be described in detail below.

If the number of scanning lines for displaying Doppler blood flow signals in the ultrasonic echo tomographic image display area 26 of the display device in FIG. 4 is m, then in order to obtain desired filter characteristics in the filter circuit 17, , As mentioned above, it is necessary to repeat scanning with the ultrasonic beam at the same position 10 times or more.

In that case, when scanning with an ultrasonic beam is performed to obtain information corresponding to the scanning lines 27 from 1 to m, the required time t is as follows: t=1/rate frequency×10×m=10m/r= 10m/500
0 = m/500 (sec) required. In order to observe the video information obtained by this in real time, if the number of frames on the display device is, for example, 30 frames/sec, then 1/30 = m/500, and the number of scanning lines m is about 16. Therefore, in order to display the Doppler blood flow signal in real time, it is necessary to make the field of view narrower than the display area 26.

Therefore, in order to make the visual field width by displaying the Doppler blood flow signal the same as the visual field width of the display area 26,
The scanning area A _{i to p} by the ultrasound beam is sequentially changed in synchronization with the output signal from the electrocardiogram circuit 12, and the Doppler blood flow signal information sequentially obtained according to this scanning is stored in the memory 22, and the cardiac After counting output signals corresponding to several heartbeats from the electric circuit 12, the control is performed such that they are read out from the memory 22 at once.

As described above, by removing the echoes from the walls within the heart, extracting only the Doppler blood flow signal, and superimposing it on a conventional tomographic image and displaying it two-dimensionally in real time, clinically effective results can be obtained. The purpose is to provide an ultrasonic diagnostic device that can supply data.

Furthermore, if you want to display the blood flow direction, add another channel of the circuit configuration after the mixer circuit 10 at the next stage on the output side of the adder circuit 8 in parallel, and connect the inputs of the mixer circuit 10 at 90 degrees from each other. By adding a reference signal o having a phase difference, the forward and reverse flow directions of blood flow may be detected.

In this embodiment, a sector electronic scanning type ultrasonic diagnostic apparatus has been described, but the present invention is also fully applicable to a linear electronic scanning type ultrasonic diagnostic apparatus as well as a mechanical scanning type ultrasonic diagnostic apparatus.

According to the present invention, it is possible to observe the two-dimensional distribution of blood flow simply by bringing an ultrasound probe into contact with a subject to obtain an ultrasound echotomographic image, and it is possible to easily detect areas such as thrombotic sites within blood vessels. can be known. Furthermore, the maximum detectable blood flow velocity can be detected up to the maximum blood flow velocity within a given rate pulse frequency range.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the ultrasonic diagnostic apparatus of the present invention, Fig. 2 is an output waveform diagram of the main component circuits in the embodiment of Fig. 1, and Fig. 3 is a diagram of the filter in the embodiment of Fig. 1. FIGS. 4a and 4b are diagrams showing the filter characteristics of the circuit, and are diagrams showing the scanning range and scanning state of the ultrasonic beam for obtaining Doppler blood flow signals. 1... Reference signal generator, 2... Frequency divider, 3,
3'...Delay circuit, 4...Pulser, 5...Ultrasonic transducer array, 6...Amplifier, 7...Main control circuit, 8
... Addition circuit, 9 ... Detection circuit, 10 ... Mixer circuit, 11 ... Freeb circuit, 12 ... Electrocardiogram circuit, 13 ... Adder, 14, 24 ... Display device,
15...Low pass filter, 16...A/D converter, 17...Filter circuit, 22...Memory, 2
3...D/A converter, 25...Sweep signal generator.

Claims (1)

[Scope of Claims] 1. Ultrasonic beams to be transmitted into the inside of a subject are sequentially 2.
In an ultrasonic diagnostic device that can display in real time an ultrasonic tomographic image obtained by scanning dimensionally and receiving ultrasonic echoes from various parts inside a subject,
A control means for sequentially transmitting the ultrasound beam in the same direction multiple times, and a Doppler shift signal among the ultrasound echoes based on the ultrasound beam transmitted by the control means. means for separating ultrasonic echo signals from interfaces with different acoustic impedances by phase detection, and inputting a plurality of Doppler shift signals based on multiple transmissions in the same direction, and inputting a plurality of Doppler shift signals based on multiple transmissions in the same direction, It is equipped with a filter circuit for removing fixed reflection components and a storage means capable of storing and reading out the filtered Doppler shift signal, and is capable of generating an ultrasound tomographic image inside the subject in real time using the ultrasound echo signal. An ultrasonic diagnostic apparatus characterized in that the hemodynamics inside the subject is displayed two-dimensionally in real time using the Doppler shift signal. 2. In the ultrasonic diagnostic apparatus according to claim 1, readout control from a storage means storing a plurality of sets of the Doppler shift signals is synchronized with an electrocardiogram waveform, and Doppler shift signal groups are sequentially read out. An ultrasonic diagnostic apparatus characterized by synthesizing two-dimensional hemodynamic images by.