JPH0234156A - Ultrasonic doppler device - Google Patents

Abstract

PURPOSE:To execute normal tracking action by passing an echo signal through a narrow band amplifier and, thereafter, inputting it to a tracking means. CONSTITUTION:An ultrasonic Doppler device is composed of an ultrasonic B/M mode image videoizing device 1, a Doppler unit 2, an echo tracking circuit 3 and a narrow band amplifier 4. The echo signal to contain a wide band frequency is outputted as the echo signal close to a single frequency by the narrow band amplifier 4 and supplied to the echo tracking circuit 3. Thus, the influence of a speckle, etc., is suppressed, and the normal echo tracking action is executed.

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasound Doppler device used in ultrasound diagnosis and provided with echo tracking means. (Prior Art) Conventionally, an ultrasonic Doppler apparatus measures, for example, blood flow information in a blood vessel of a subject to obtain diagnostic information. Only 1.2,
In the pulsed Doppler method used in this ultrasonic Doppler device, the sample position is fixed at a certain depth, so the sample cannot be kept in a fluctuating blood vessel, and blood flow information cannot be obtained continuously. I couldn't do it. The echo tracking method is a solution to this problem. In this echo tracking method, the obtained echo signal is constantly followed, or tracked, and the blood vessel wall is connected to a PLL circuit (Phase I, locked loop).
), the sample position is kept at a constant distance from the tracking point, and the sample position is maintained within the bloodstream. FIG. 3 is a diagram showing a timing chart for explaining the echo tracking method. The rate pulse a is a pulse generated at the period of transmitting an ultrasonic pulse, and the transmission pulse is generated at the trailing edge of the rate pulse a. Rate pulse This interval is, for example, 250 μs (ultrasonic repetition frequency 4 KHz). The received echo signal is a signal obtained from a blood vessel, and includes echoes of the front and back walls of the blood vessel, and weak echoes due to blood flow within the blood vessel. Tracking pulse C uses a PLL circuit etc. to track the back wall of the blood vessel (or the front wall of the blood vessel) (PL, P2 in the figure)
By applying tracking pulses TPL, TP
2. This tracking pulse TP
is designed to move following the movement of the rear wall of the blood vessel. The sample position d is adjusted so that it is located at a certain distance from the tracking pulse of a certain rate and within the blood vessel of the next rate. Therefore, the sample position can always be located within the blood vessel. On the other hand, in addition to the above method, there is a method of synchronizing the phase of the reference signal of the quadrature phase detection circuit with the movement of the tracking pulse (following type reference signal e). In this method, as shown in the figure, oscillation of the reference signal is started from the leading edge of a certain tracking pulse and stopped at the trailing edge of the sample position pulse of the next rate. In other words, this method generates Doppler components due to the movement of blood vessels.

[2. Since this Doppler component is added to the blood flow signal, it is provided to remove this influence. In this way, in the echo tracking method, the sample position is always located within the oscillating blood vessel, and the reference tracking method is used to remove the Doppler component due to the oscillating blood vessel. Next, the echo tracking method will be explained with reference to FIGS. 4 and 5. FIG. 4 is a diagram showing a timing chart for explaining the operation of the above method, and FIG. 5 is a diagram showing details of the echo tracking circuit 3 consisting of a tracking circuit main body 30 and a tracking type sample position generator 31. It is. That is, the time axis of the wall echo portion of the received echo b for the rate pulse a is displayed in an enlarged manner. First, the waveform of the received echo B is shaped by the waveform shaping circuit 30a to obtain a shaped wave C converted into a digital signal. It is assumed that tracking is performed at point α1 of the shaped wave C, and the width of the tracking pulse J is half the wavelength of the received echo b. The shaped wave C and a tracking pulse from the tracking pulse generator 30j,
are the pulse D1 generation/hold circuits 30b, respectively. It is input to the pulse 01 generation/hold circuit 30c. As a result, the area to the left of the point α1 is C1 ((-) value) of e, and the area to the right is Dl ((+) value) of e. Then, the adder 30d adds the sum c1. +D1 is required. In pulsed Al, IcI l<IDI
Since it is +, it becomes a (+) value. This tracking pulse d is controlled to always move so that it becomes Ci+D i-0. f is a diagram showing the state of the control, in which the value of Ci + Di is held by the C1+Di value hold circuit 30e, and the integral curve F is obtained by the integrating circuit 30)1 (((
+) value increases. (-) value decreases). Then, the integral waveform and the sawtooth wave Ei+1 from the sawtooth wave Ei generator 30i are input to the tracking pulse generator 30j. Then, a tracking pulse Ai+1 is generated at the intersection of the integral waveform and the sawtooth wave Ei+1. In the case of FIG. 4, since CI IDI is (+), F increases and a tracking pulse A2 is generated from the intersection point 02 with E2. The tracking pulse is then input to the follow-up sample position generator 31, and a sample position is generated at the echo position corresponding to the inside of the blood vessel. The tracking pulse is also input to a follow-up reference signal generator (not shown) (numeral 23 in FIG. 1) to generate a reference signal whose phase is synchronized with the tracking pulse. The tracking circuit 3 includes a tracking circuit main body 30 including a tracking 0N10FF switch 30g and a switching device 30 for switching on and off the signal lines between the Ci+Di value hold circuit 30e and the integration circuit 30h in response to the tracking 0N10FF switch 30g.
f, and the tracking operation can be started/stopped as desired by the operator. (Problems to be Solved by the Invention) The conventional ultrasonic Doppler apparatus described above has the following problems. In other words, regarding the tracking operation, since the received echo b shown in FIG.
The tracking pulse d obtained from j also operates normally as described above. However, there is a problem in that if the phase of the echo signal being tracked is disturbed due to speckles, noise, etc., the waveform becomes a shaped waveform with a distorted phase, making tracking impossible. SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic Doppler apparatus that can perform a tracking operation even when the phase of an echo signal is disturbed due to speckles, noise, or the like. [Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following means are taken to solve the above problems and achieve the objects. That is, the present invention transmits ultrasonic waves to the blood flow in the in-vivo circulatory tissue of a subject, and when discriminating Doppler components shifted by the blood flow from the echo signals obtained thereby, In an ultrasound Doppler apparatus, the ultrasound Doppler apparatus is equipped with an echo tracking means that increases the accuracy of the discrimination by determining a certain point for the echo signal and making this point track the echo signal for each ultrasound transmission rate. The signal is characterized in that the signal is input to the tracking means after being passed through a band amplifier. (Function) By taking such measures, even if the received echo is out of phase, the signal (received echo) after passing through the narrowband amplifier will be free of phase disturbance, allowing normal tracking. The action begins to take place. (Example) An example of the ultrasonic Doppler apparatus according to the present invention will be described below as a first example.
This will be explained with reference to the figures. The ultrasonic Doppler apparatus of this embodiment includes an ultrasonic B/M mode image visualization apparatus 1, a Doppler unit 2, an echo tracking circuit 3, and a narrowband amplifier 4. The device of this embodiment is characterized by providing a narrow band amplifier 4 at the front stage of the echo tracking circuit 3, and receiving echoes obtained from the ultrasonic B/M mode image visualization device 1 are shown in FIG. 2, for example. The configuration is such that the signal is applied to the echo tracking circuit 3 after being amplified according to the frequency characteristics. In other words, the configuration of the conventional ultrasound Doppler apparatus is such that the narrowband amplifier 4 is removed. The ultrasound B/M mode image visualization device 1 is an array-type ultrasound system that transmits an ultrasound beam toward a blood vessel BV inside the subject P and sends received echo signals to a preamplifier 14, which will be described later. What do you do with probe UP? Ultrasonic B/M mode image visualization device 1. is a balsa 10. which gives, for example, a burst signal to this probe UP. Balsa driver that drives this balsa 10]1. A transmission delay device 12 which provides a delayed signal for each transducer to be transmitted to the balsa driver 11. The ultrasonic transmission system includes a rate pulse generator 13 that receives a reference signal from a reference signal generator 21 (described later), divides the frequency of the reference signal, and generates a rate pulse signal. The ultrasound B/M mode image visualization apparatus 1 includes a preamplifier 14 that amplifies the echo signal from the probe UP, and a reception delay device 15 that delays reception of the echo signal output from the preamplifier 14 for each transducer. It has an ultrasonic receiving system including an adder 16 that adds the signals of each transducer output from the receiving delay device 15. The ultrasonic B/M mode image visualization device 1 includes a B/M mode image detection unit 17 that performs envelope detection on the added echo signal from the ultrasonic receiving system, for example, in detecting a B mode image, and A synthesis section 18 consisting of a digital scan converter that synthesizes the B/M mode image output from the /M mode image detection section 17 and Doppler information output from the Doppler Uni-Soto 2, and the output of this synthesis section 18 is displayed. Display section 19
It is composed of. The Doppler processing unit 2 is configured as follows. The quadrature phase detector 20 includes a mixer 20a which inputs the echo signal from the adder 16 and inputs and mixes a signal from a reference signal generator 2 or a follow-up reference signal generator 23, which will be described later. LPF (
low pass filter) 20b. When fixing the phase of the reference signal, the reference signal from the reference signal generator 21 is transferred to 1. When inputting the reference signal to the mixer 20a and synchronizing the phase of the reference signal with the tracking pulse, the reference signal from the follow-up reference signal generator 23 is inputted to the mixer 20a via the switch 22. The sample circuit 24 converts the signal from the LPF 20b into a blood flow echo using a fixed sample position generator 26 (described later) or a sampling pulse from a pull position generator 31 (described later). Sample the corresponding parts, integrate and
The hold device 27 integrates the sampled signal by the width of the sampling pulse, and 1. The rate is held. BPF (band pass filter)
28 removes Doppler shift (clutter) due to high frequency components and unnecessary movements of blood vessel walls, etc., and an FFT (fast Fourier transform) calculation circuit 29 performs frequency analysis on the output signal of the BPF 28 using the FFT (fast Fourier transform) method. ing. The echo tracking circuit 3 is configured as follows. That is, the tracking circuit main body 30 inputs the echo signal from the adder 6 of the ultrasonic receiving system, passes it through the narrowband amplifier 4, shapes the waveform, and converts it into a digital signal (7
, a tracking pulse is generated. Using this tracking pulse, the tracking reference signal generator 23
A reference signal whose phase is synchronized with the tracking pulse is generated by the tracking sample position generator 31.
generates a sampling pulse that tracks inside the blood vessel. Note that the details are the same as those shown in FIGS. 3 to 5. Next, the operation of the embodiment configured as described above will be explained. That is, the ultrasonic pulse transmitted to the subject P is reflected by the blood vessel BV and received by the probe UP, and the echo signal is sent to the preamplifier 14° reception delay circuit 15. The signal is outputted through an ultrasonic reception system consisting of an adder 6 to a B/M mode image detection section 17 , a Doppler unit 2 , and a narrowband amplifier 4 provided before the echo tracking circuit 3 . Here, it is assumed that the echo signals do not have a uniform phase as shown in FIG. 4, but have a phase disordered due to speckles, toy particles, or the like. In such a case, the incoming J-signal containing broadband frequencies is processed by the narrowband amplifier 4.
The echo signal is output as an echo signal close to a single frequency and given to the echo tracking circuit 3. As a result, the influence of speckles and the like is suppressed, and the normal echo tracking operation shown in FIGS. 3 to 5 is performed. That is, a tracking pulse d is generated and this tracking pulse d drives the follow-up reference signal generator 23. This reference signal is
is input to mixer 20a via. Then, the echo signal is mixed with the tracking reference signal by the mikina 20a, low-pass filtered by the LPF 20b, and subjected to quadrature phase detection. This transverse wave output is sampled by the sample circuit 24, and the integration/hold circuit 2
7, high frequency components and clutter are removed by the BPF 28, and the frequency is further analyzed by the FFT calculation circuit 29 to obtain blood flow information. As described above, according to this embodiment, since the narrowband amplifier 4 is provided before the echo tracking circuit 3, the echo signal containing speckles and noise has a waveform close to a single frequency. Therefore, even if an echo signal containing speckles or noise is output from the ultrasonic receiving system, the tracking circuit 3 performs the same echo tracking as when R and F waveforms without speckles are input. will be carried out. Therefore, it is possible to perform highly reliable ultrasonic diagnosis without becoming unable to track. Note that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention. [Effects of the Invention] As described above, in the present invention, the echo signal is passed through a narrowband amplifier and then inputted to the tracking means. The signal (received echo) after passing through the amplifier has no phase disturbance, and a normal tracking operation can be performed. Therefore, according to the present invention, it is possible to provide an ultrasonic Doppler apparatus that can perform a tracking operation even when the phase of an echo signal is disturbed due to speckles, noise, or the like.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the ultrasonic Doppler apparatus according to the present invention, Fig. 2 is a diagram showing the narrowband amplifier and the band characteristics of the echo signal in the same embodiment, and Fig. 3 is a diagram showing the echo tracking method. FIG. 4 is a diagram showing the generation of tracking pulses, and FIG. 5 is a diagram showing an echo tracking circuit. UP...Ultrasonic array probe, 1...Ultrasonic B/
M-mode image visualization device, 2... Doppler unit, 3.
. . . echo tracking circuit, 30 . . . dragging circuit main body, 3 1 . . . tracking type sample position generator, 4 . . . narrowband amplifier. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] When transmitting ultrasonic waves to the blood flow in the in-vivo circulatory tissue of a subject and discriminating Doppler components shifted by the blood flow from the echo signals obtained thereby, In an ultrasound Doppler apparatus equipped with an echo tracking means that increases the accuracy of the discrimination by determining a certain point and making this point follow the echo signal for each ultrasound transmission rate, after passing the echo signal through a narrowband amplifier, An ultrasonic Doppler apparatus characterized in that the ultrasound Doppler apparatus is configured to input data to the tracking means.