JPH0234157A - Ultrasonic doppler device - Google Patents

Abstract

PURPOSE:To execute a correct blood flow diagnosis even when an echo signal is made extremely small by stopping echo tracking action when the echo signal is decides as abnormal. CONSTITUTION:An ultrasonic Doppler device is composed of an ultrasonic B/M mode videoizing device 1, a Doppler unit 2, an echo tracking circuit 3, an abnormal echo detecting circuit 4 and a tracking stopping circuit 5. When the abnormality of the echo signal is detected based on an output, in which the echo signal is envelope-detected, by the abnormal echo detecting circuit, the tracking stopping circuit 5 stops the tracking action by the echo tracking circuit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an ultrasonic Doppler apparatus used in ultrasonic 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. However, in the pulsed Doppler method used in this ultrasound Doppler device, the sample position is fixed at a certain depth, so it cannot be placed permanently inside the fluctuating blood vessel, and blood flow information is continuously obtained. I couldn't. The echo tracking method is a solution to this problem. This echo tracking method constantly follows the obtained echo signal, that is, tracks the blood vessel wall.
L circuit (Phase Locked Loop) 1.
The sample position is kept at a constant distance from the tracking point so that the sample is always present in the bloodstream.

FIG. 4 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.

The interval between the rate pulses a is, for example, 250 l1s (ultrasonic repetition 17 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 TPI, 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 in which the phase of the reference signal of the quadrature phase detection circuit is synchronized with the movement of the tracking pulse (following reference signal e). The oscillation of the signal is started and stopped at the trailing edge of the next sample position pulse.

That is, in this method, a Doppler component is generated due to the oscillation of the blood vessel, and this Doppler component is added to the blood flow signal, so this method is provided to eliminate 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. 5 and 6. FIG. 5 is a diagram showing a timing chart for explaining the operation of the above method, and FIG. 6 is a diagram showing details of the echo tracking circuit 3 consisting of a tracking circuit main body 30 and a follow-up 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 received echo b is waveform-shaped by the waveform shaping circuit 30a, and a shaped wave C converted into a digital signal is obtained. It is assumed that tracking is performed at point α1 of the shaped wave C, and the width of the tracking pulse d is half the wavelength of the received echo b. The shaped wave C and the tracking pulse from the tracking pulse generator 30j are each sent to a pulse Di generation/hold circuit 30b.

The pulse Ci is generated manually by the Hall 1 circuit 30c.

As a result, the area to the left of the point αl becomes C1 ((-) value) of e, and the area to the right of e becomes Dl ((+) value). Then, the sum C1IDI is obtained by the adder 30d. In pulsed Al, IcI l<IDI
Since it is +, it becomes a (+) value. This tracking pulse d is controlled to always move to C++DimO.

f is a diagram showing the state of the control, 'Ci +D
The value of Ci +D i is held by the i value holding circuit 30e, and the integral curve F is obtained by the integrating circuit 30h (if the value is (+), it increases; if the value is (=), it 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, at the intersection of the integral waveform and the sawtooth wave Ei+1, the tracking pulse A i +1
occurs. In the case of Figure 5, CI IDI is (+)
Therefore, F increases and tracking pulse A2 is generated from the 62nd point of intersection 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. Also, a tracking reference signal generator (reference numeral 23 in Fig. 1) with no tracking pulse (not shown)
A reference signal whose phase is synchronized with the tracking pulse is generated.

The tracking circuit 3 includes a tracking 0N10FF switch 30g and a Ci+D i value hold circuit 30e in its tracking circuit main body 30.
It has a switch 30f for switching on and off the signal line between the servo controller and the integrating circuit 30h, so that the tracking operation can be started/stopped as desired by the operator.

(Problem to be solved by the invention) However, in the conventional ultrasonic Doppler device described above,
There are the following problems. In other words, regarding the tracking operation, since the received echo b shown in FIG. 5 has no phase disturbance, the shaped waveform C and the tracking pulse d obtained from the shaped waveform C also perform normal operations as described above. be exposed.

However, for some reason, the amplitude of the echo signal of the blood vessel being tracked may become extremely small.

In such a case, speckles and the like may occur and the phase may be disturbed. If this happens, tracking will be lost, the tracking pulse will shift by several wavelengths, and the sample position will deviate from within the oscillating blood vessel. Furthermore, the tracking type reference signal also shifts in phase due to the loss of tracking. In such cases, the detected information is
There was a problem in that accurate diagnosis could not be made because the blood flow information within the fluctuating blood vessels was not accurately captured.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ultrasonic Doppler apparatus that allows accurate blood flow diagnosis even when the echo signal of a blood vessel being tracked becomes extremely small.

[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 ultrasonic Doppler apparatus equipped with an echo tracking means that increases the accuracy of the discrimination by determining a certain point with respect to the echo signal and making this point follow the echo signal for each ultrasound transmission rate,
The apparatus is characterized by comprising means for stopping the operation of the tracking means when it is determined that the echo signal is abnormal based on the output of envelope line detection of the echo signal.

(Function) By taking such measures, even if the echo signal of the blood vessel being tracked becomes extremely small, the tracking operation is stopped when a received echo that causes tracking to be lost is received. Therefore, erroneous information will not be presented, making it possible to perform accurate diagnosis.

(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, an abnormal echo detection circuit 4, and a tracking stop circuit 5. There is.

The device of this embodiment is characterized in that the abnormal echo detection circuit 4 receives the envelope detection output of the received echo from the B/M mode image detection unit 17 of the ultrasonic B/M mode image visualization device 1. If it is determined that the amplitude of the received echo is so small that tracking is lost, a command is given to the tracking stop circuit 5, and the tracking stop circuit 5 sends a signal to the echo tracking circuit 3 to stop the operation (e.g. Tracking 0N10F in Figure 6
A command for F switch 30g) is issued.

The ultrasonic B/M mode image visualization device 1 transmits an ultrasonic beam toward a blood vessel BV inside the subject P, and receives 1. It has an array-type ultrasonic probe UP that sends out echo signals to a preamplifier 14, which will be described later.

Ultrasonic B,/M mode image visualization device 1. is a balsa 1,0 that gives a burst signal to this probe UP, for example.
．． A balsa driver 11 that drives this balsa 1o, a transmission delay device 12 that provides a delay signal for each transducer to be transmitted to this 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.

Ultrasonic B/M mode image visualization device], is the probe UP
a preamplifier 14 that amplifies the echo signal from the preamplifier 14, and a reception delay device 15 that delays the 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; Between the B/M mode image detection and detection sections 7 is a synthesis section 18 consisting of a digital scan converter that synthesizes the output B/M mode image and the Doppler information output from the Doppler unit 2, and the output of this synthesis section 18. Display section 19 that displays
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 No. 13 from the adder 16 and also inputs and mixes a signal from a reference signal generator 21 or tracking reference signal generator 23, which will be described later. LPF (
low bus filter) 20b. When the phase of the reference signal is fixed, the reference signal from the reference signal generator 21 is input to the mixer 20a via the switch 22, and when the phase of the reference signal is synchronized with the tracking pulse, a follow-up reference signal generator is used. The reference signal of the mixer 23 is input to the mixer 20a via the switch 22.

The sample circuit 24 receives the signal from the LPF 20b via a switch 25 and uses sampling pulses from a fixed sample position generator 26 (described later) or a follow-up sample position generator 31 of the echo tracking circuit 3 to detect a portion corresponding to a blood flow echo. The integrator and hold device 27 integrates the sampled signal by the width of the sampling pulse and holds the sampled signal by the width of the sampling pulse. A BPF (bandwidth filter) 28 removes Doppler shift (clutter) caused by high frequency components and unnecessary movements of blood vessel walls, etc., and an FFT (fast Fourier transform) calculation circuit 29 subjects the output signal of the BPF 28 to FFT (
Frequency analysis is performed using the Fast Fourier Transform (Fast Fourier Transform) method.

The echo tracking circuit 3 is configured as follows. That is, the tracking circuit main body 30 inputs the echo signal from the adder 16 of the ultrasonic receiving system, shapes the waveform of the echo signal, converts it into a digital signal, and generates a tracking pulse. Using this tracking pulse, the follow-up reference signal generator 23 generates a reference signal whose phase is synchronized with the tracking pulse, and the follow-up sample position generator 31 generates a sampling pulse for tracking inside the blood vessel. Note that the details are the same as those shown in FIGS. 4 to 6.

Details of the abnormal echo detection circuit 4 and the tracking stop circuit 5 will be explained with reference to FIG.

That is, the abnormal echo detection circuit 4 detects whether the received echo is abnormal or normal based on the presence or absence of an edge.
/M-mode image detection detection circuit with seven envelope detection circuits],
A differentiator 4a that differentiates the envelope detection output of the added received echo from 7a, a threshold level setter 4b that can set a threshold level as an abnormal echo reference according to the operator's request, and a differentiator 4a. An edge detector 4c detects the edge of the received echo by setting the output of the threshold level setter 4b, that is, the threshold level, with respect to the output of the edge detector 4c, and an abnormal echo is received based on the output of the edge detector 4c. and an abnormal echo gate width setting device 4d that emits a signal corresponding to the period.

In addition, the tracking stop circuit 5 outputs a pulse (abnormal echo gate width) corresponding to the period of the abnormal echo detected by the abnormal echo detection circuit 4, and a tracking pulse is generated during this time (the main body of the dragging circuit). a gate circuit 5a that outputs a signal on the condition that the signal is received from the echo tracking circuit 30), and a tracking circuit that receives the output of the gate circuit 5a and issues a command to the tracking 0N10FF switch 30g shown in FIG. 6 of the echo tracking circuit 3. and a stop signal generator 5b.

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 to the B/M mode image detection section 17, the Doppler unit 2, and the echo tracking circuit 3 through an ultrasonic reception system including an adder 16.

Here, it is assumed that the echo signal is as shown in FIG. 5 and has an extremely small amplitude.

In such a case, the abnormal echo detection circuit 4 detects the abnormal period of the echo signal, and the detection signal is given to the echo lagging circuit 3 via the tracking stop circuit 5, and the tracking operation is performed within the abnormal echo period. is interrupted. In this case, as shown in Fig. 3, the tracking pulse stops at the position where the operation was interrupted (maintaining the integral value), and when the echo abnormality disappears, the tracking pulse starts operating again from the above-mentioned stop position. Tracking operation is resumed. That is, the tracking pulse d starts tracking the echo signal. However, even during the period when the tracking pulse is stopped, the tracking pulse d drives the follow-up reference signal generator 23. This reference signal is input to mixer 20a via switch 22.

Then, the echo signal is mixed with the tracking reference signal by the mixer 20a, low-pass filtered by the LPF 20b, and quadrature phase detected. This detection output is sampled by a sample circuit 24, passed through an integration/hold circuit 27, high frequency components and clutter are removed by a BPF 28, and then frequency analyzed by an FFT calculation circuit 29 to obtain blood flow information. can.

In this way, according to this embodiment, the tracking pulse is
By stopping during the abnormal period determined based on the envelope detection output of the echo signal, the detected information accurately captures the blood flow information in the fluctuating blood vessel. This allows for accurate diagnosis.

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, the present invention includes means for stopping the operation of the tracking means when it is determined that the echo signal is abnormal based on the output of envelope detection of the echo signal. Even if the echo signal of the blood vessel being tracked becomes extremely small, the tracking operation is stopped when an echo that causes tracking to be lost is received, which prevents the presentation of erroneous information. , it becomes possible to perform accurate diagnosis.

Therefore, according to the present invention, it is possible to provide an ultrasonic Doppler apparatus that can perform accurate blood flow diagnosis even when the echo signal of the blood vessel being tracked becomes extremely small.

[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. 20 is a diagram showing details of an abnormal echo detection circuit and a tracking stop circuit in the same embodiment, and Fig. 3 is a diagram showing details of an abnormal echo detection circuit and a tracking stop circuit in the same embodiment. 4 is a diagram showing the echo tracking method, FIG. 5 is a diagram showing the generation of tracking pulses, and FIG. 6 is a diagram showing the echo tracking circuit. UP...Ultrasonic array probe, 1...Ultrasonic B/
M-mode image visualization device, 2... Doppler unit, 3.
...Echo tracking circuit, 30...Tracking circuit main body, 31...Following type sample position generator, 4...Abnormal echo detection circuit, 5...Tracking stop circuit.

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 ultrasonic 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, the echo signal is detected based on the output of envelope detection of the echo signal. An ultrasound Doppler apparatus comprising means for stopping the operation of the tracking means when it is determined that the echo signal is abnormal.