JP4568080B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that measures a blood flow velocity in a high PRF mode (high pulse repetition frequency mode).

  An ultrasonic diagnostic apparatus is a medical imaging device that non-invasively obtains a tomographic image of soft tissue in a living body from a body surface by an ultrasonic pulse reflection method. Compared to other medical imaging equipment, this ultrasonic diagnostic device has features such as small size, low cost, no exposure to X-rays, high safety, blood flow imaging, etc., and the heart, abdomen, urology, Widely used in obstetrics and gynecology.

  In this type of ultrasonic diagnostic apparatus, there is known a method of observing fast blood flow in the deep part of the body without turning back using a High PRF mode in which the pulse repetition frequency (PRF) is doubled as compared with a normal pulse reflection method. However, in the method using the High PRF mode, a pseudo sample gate exists between the sample gate which is a blood flow observation place and the body surface. If blood flow also exists in this pseudo sample gate, it is displayed overlapping the blood flow at the observation location, resulting in misdiagnosis.

Therefore, when the PRF is adjusted so that the desired flow velocity range can be obtained, the frequency of the transmission / reception signal is automatically changed to prevent the pseudo sample gate from being obtained from the pseudo sample gate. There has been proposed a technique for avoiding the position (for example, Patent Document 1).
Patent No. 2719710.

  However, the method of changing the position of the pseudo sample gate by changing the transmission / reception frequency cannot set the desired frequency. Although a method of limiting the PRF so that the pseudo sample gate is not positioned at the strong signal source is conceivable, the flow velocity range to be set cannot be obtained. Further, it is conceivable to intentionally lower the preamplifier gain, but in this case, the received signal from the sample gate cannot be amplified.

  Accordingly, an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of avoiding saturation by changing the position of a pseudo sample gate from a strong signal source without changing the frequency or PRF of a transmission / reception signal.

In order to achieve the above object, the present invention is configured as follows.
A signal generating means for sequentially generating a plurality of high pulse repetition frequency mode pulse signals having different rates, and an ultrasonic probe for transmitting an ultrasonic wave corresponding to the pulse signal to the subject and receiving a reflected wave of the ultrasonic wave A stop unit that stops transmission of a pulse signal at an arbitrary rate among a plurality of pulse signals, a filter unit that passes a signal component obtained by removing the stopped rate component from the received signal obtained by the ultrasonic probe, and a filter A conversion means for converting the output of the means from a time axis signal into a frequency axis signal, and a display means for performing image processing on the output of the conversion means and displaying the processing result are provided.

  According to this configuration, when the same sample gate is obtained by a plurality of pulse signals in the high pulse repetition frequency mode, by stopping transmission of one pulse signal, a signal representing the same sample gate is sent at the same time. It can prevent receiving. Therefore, saturation due to the pseudo sample gate can be avoided without changing the frequency or PRF of the transmission / reception signal, and the target sample gate can be reliably obtained.

  Further, at the time of reception, only the necessary frequency component is extracted from the received signal, and FFT processing is performed to perform image processing, thereby obtaining target sample gate information without deteriorating reception sensitivity. it can.

  A signal generating means for sequentially generating a plurality of high pulse repetition frequency mode pulse signals having different rates, and an ultrasonic probe for transmitting an ultrasonic wave corresponding to the pulse signal to the subject and receiving a reflected wave of the ultrasonic wave A stop unit that stops transmission of a pulse signal at an arbitrary rate among a plurality of pulse signals, an interpolation unit that performs interpolation processing on a time axis for a reception signal obtained by an ultrasonic probe, and an output of the interpolation unit Conversion means for converting the time axis signal into the frequency axis signal, and display means for performing image processing on the output of the conversion means and displaying the processing result.

  According to this configuration, at the time of reception, the received signal is subjected to interpolation processing on the time axis, and the signal after this interpolation processing is subjected to FFT processing and image processing, whereby sample gate information for all frequency components is obtained. Can be acquired.

It further comprises transmission power adjusting means for increasing the transmission power of each of the plurality of pulse signals to transmit according to the stop time by the stop means.
According to this configuration, since the transmission sensitivity of the pulse signal can be increased so as to be transmitted according to the stop time, it is possible to observe a place that is not normally visible with a high probability.

When the transmission of the pulse signal is stopped by the stop unit, the image acquisition unit is further provided with an image acquisition unit obtained by scanning a two-dimensional image or a color image of the subject.
According to this configuration, for example, when operating simultaneously with the B mode, the display speed of the two-dimensional image or color image of the subject can be increased, and the user wants to see the two-dimensional image or color image of the subject. Sometimes you can see without waiting.

  As described above in detail, according to the present invention, it is possible to provide an ultrasonic diagnostic apparatus capable of avoiding saturation by separating the position of the pseudo sample gate from the strong signal source without changing the frequency or PRF of the transmission / reception signal. it can.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing the configuration of the first embodiment of the ultrasonic diagnostic apparatus according to the present invention.

  The apparatus shown in FIG. 1 is roughly divided into a transmission system and a reception system. The high pulse generation timing setting unit 11 in the transmission system includes a plurality of pulses having different rates as shown in FIG. 2 based on the timing signal from the PRF control unit 13 when the high PRF mode is selected by the mode selection unit 12. Signals are sequentially generated from the pulse generator 14. The PRF control unit 13 generates three pulse signals from the pulse generator 14 and then stops transmission of the subsequent three pulse signals.

  The pulse signal generated by the pulse generator 14 is modulated based on the reference signal generated by the reference signal generator 15. The output of the pulse generator 14 is converted into a drive signal to be supplied to the ultrasonic probe 17 by the transmission circuit 16 and then supplied to the ultrasonic probe 17.

  The ultrasonic probe 17 is provided with a plurality of piezoelectric vibrators that generate ultrasonic waves based on a drive signal from the transmission circuit 16 and convert reflected waves from a subject (not shown) into electric signals, and the piezoelectric vibrators. A matching layer, and a backing material for preventing the ultrasonic wave from propagating backward from the compression vibrator.

  Ultrasonic pulses transmitted from the ultrasonic probe 17 to the subject are successively reflected by acoustic impedance discontinuous surfaces such as in-vivo tissues and blood flow, and are received by the ultrasonic probe 17 as echo signals.

  The echo signal received by the ultrasonic probe 17 is supplied to the receiving circuit 18. The reception circuit 18 performs predetermined reception processing on the echo signal, and its output is supplied to the phase detection circuits 19 and 20 and the envelope detection circuit 21.

  The phase detection circuit 19 extracts the modulation component given to the pulse signal based on the reference signal generated by the reference signal generator 22, and detects the Doppler frequency from the frequency deviation included in the modulation component. The detection output is supplied to a low pass filter (LPF) 23. The low-pass filter 23 outputs the signal to the range gate circuit 24 through only the signal component of the High PRF mode among the outputs of the phase detection circuit 19.

  The range gate circuit 24 samples the output of the low-pass filter 23, and the sampling result is supplied to the integration circuit 25. The integrating circuit 25 integrates the output signal from the range gate circuit 24 to remove the influence of noise and the like, and its output is supplied to a sample hold (S / H) circuit 26. The sample hold circuit 26 extracts a sample gate signal at an arbitrary depth from the output of the integration circuit 25.

  The output of the sample and hold circuit 26 passes through a high-pass filter (HPF) 27 and a low-pass filter (LPF) 28, whereby a signal in an arbitrary frequency band is extracted and supplied to the arithmetic circuit 29.

  On the other hand, the phase detection circuit 20 extracts a modulation component given to the pulse signal based on the reference signal generated by the reference signal generator 22 and phase-shifted by 90 ° by the phase shifter 30, and is included in this modulation component. The Doppler frequency is detected from the frequency deviation, and the detection output is supplied to a low-pass filter (LPF) 31. The output of the low pass filter 31 is supplied to the arithmetic circuit 29 after being processed by the range gate circuit 32, the integration circuit 33, the sample hold circuit 34, the high pass filter 35 and the low pass filter 36.

  The arithmetic circuit 29 performs FFT processing on the outputs of the low-pass filters 28 and 36 under the control of the arithmetic frequency designation control unit 37, converts the time axis signal into a frequency axis signal, and uses the frequency axis signal as an image signal as an image memory. 38.

  The calculation frequency designation control unit 37 controls the bandwidth and the center frequency of the high-pass filters 27 and 35 and the low-pass filters 28 and 36 so as to extract only the designated frequency, that is, the signal component of the rate that is not stopped.

  The image signal stored in the image memory 38 is read out and supplied to the TV monitor 40 based on the address generated by the address generator 39, and is displayed on the TV monitor 40.

  Further, the envelope detection circuit 21 detects a B / color reception signal band component in the output of the reception circuit 18, and the detection output is supplied to the logarithmic amplifier 41. The logarithmic amplifier 41 amplifies the output of the envelope detection circuit 21 and then stores it in the image memory 38. Thereafter, the B / color image signal is selectively read out from the image memory 38 by the address generator 39, supplied to the TV monitor 40, and displayed on the TV monitor 40.

Next, the processing operation in the above configuration will be described.
In the arithmetic circuit 29, as shown in FIG. 3, there are four sample gates obtained by one pulse signal. In this case, signals representing the same sample gate from a plurality of pulse signals are received at the same time, and blood flow information cannot be obtained due to saturation of the received signals.

  Therefore, in this embodiment, in order to avoid a reception signal from one pseudo sample gate located at a short distance, for example, a pulse signal for three rates is transmitted and received, and a pulse signal for the next three rates is transmitted. I try to stop. That is, assuming that the number of sample gates when set to the expected PRF is N, and m is the number of pseudo sample gates to be avoided in the short distance, (N−m) transmissions and (N−1) times Repeat sending stop. This can be realized by a control program of the PRF control unit 13.

  In the reception process, the arithmetic circuit 29 is assumed to obtain data of four sample gates as shown in FIG. Here, in order to simplify the explanation, it is assumed that one of four data (y (0) to y (3) (y (2)) is missing.

  Here, W2, W3, and W4 may solve simultaneous equations of frequency components that are 2, 3, and 4 times the fundamental frequency, respectively. However, since there is no data “2”, the expression y (2) cannot be obtained. Moreover, since there are four unknowns C1 to C4 and three equations, it cannot be solved. Therefore, it is not necessary to obtain the coefficient of C1, which is a low frequency component. This can be realized by a control program of the calculation frequency designation control unit 37.

  As described above, in the first embodiment, when the same sample gate is obtained by a plurality of ultrasonic pulses in the High PRF mode, the PRF control unit 13 increases the frequency in order to avoid a strong reception signal from a short distance. The transmission of one ultrasonic pulse generated from the pulse generator 14 is stopped by controlling the pulse generation timing setting unit 11 to prevent receiving signals representing the same sample gate at the same time. . Therefore, saturation due to the pseudo sample gate can be avoided without changing the frequency or PRF of the transmission / reception signal, and the target sample gate can be reliably obtained.

  At the time of reception, only the necessary frequency components are extracted from the received signal by the high-pass filters 27 and 35 and the low-pass filters 28 and 36, and the frequency component signal extracted by the arithmetic circuit 29 is subjected to FFT processing and image processing. Since the information is displayed on the TV monitor 40, it is possible to obtain target sample gate information without deteriorating the reception sensitivity.

  In the first embodiment, it is also possible to increase the transmission power of ultrasonic pulses so that transmission is performed according to the number of stopped rates. In this case, the transmission rate of the ultrasonic pulse transmitted from the ultrasonic probe 17 can be doubled because the ratio is such that transmission at three rates is stopped with respect to six rates. That is, assuming that the number of sample gates when set to the expected PRF is N, and m is the number of pseudo sample gates to be avoided at a short distance, ((N−m) + (N−1)) / (N− m) The power corresponding to double times can be increased more than usual.

  As a result, the transmission sensitivity of the ultrasonic pulse to be transmitted can be increased, so that a place that is not normally visible can be observed with a high probability.

  Furthermore, in the first embodiment, it is possible to scan and display a two-dimensional image or a color image in another mode on the TV monitor 40 using the time during which the transmission of the ultrasonic pulse is stopped. In this case, in order to avoid saturation, the other modes transmit at low power.

  Thereby, for example, when operating simultaneously with the B mode, the display speed of the two-dimensional image or color image of the subject can be increased, and when the user wants to see the two-dimensional image or color image of the subject, You can see without waiting.

(Second Embodiment)
FIG. 5 is a block diagram showing a schematic configuration of the second embodiment of the ultrasonic diagnostic apparatus according to the present invention. In FIG. 5, the same parts as those of FIG.

  In the second embodiment, an interpolation circuit 42 is interposed between the low-pass filters 28 and 36 and the arithmetic circuit 29. The interpolation circuit 42 interpolates the outputs of the low-pass filters 28 and 36 on the time axis. As the interpolation method, linear, spline, cubic, polynomial approximation by the least square method, or the like is used.

  Thus, in the case of the second embodiment, at the time of reception, the interpolation circuit 42 performs interpolation processing on the low-pass filters 28 and 36 on the time axis, and the signal after the interpolation processing is subjected to FFT by the arithmetic circuit 29. Since the image is processed and processed and displayed on the TV monitor 40, the information of the sample gate for all frequency components can be acquired.

  Therefore, as in the first embodiment, saturation due to the pseudo sample gate can be avoided without changing the frequency or PRF of the transmission / reception signal, and the target sample gate can be obtained reliably.

(Other embodiments)
The present invention is not limited to the above embodiments. For example, in the second embodiment, the received signal is passed through the high-pass filter and the low-pass filter, and then interpolation processing on the time axis is performed. However, the sample hold is not performed through the high-pass filter and the low-pass filter. The output of the circuit may be subjected to interpolation processing on the time axis as it is.

  Although the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.

1 is a block diagram showing the configuration of a first embodiment of an ultrasonic diagnostic apparatus according to the present invention. The figure shown in order to demonstrate the several ultrasonic pulse transmitted in the said 1st Embodiment. The figure shown in order to demonstrate the several sample gate obtained by one ultrasonic pulse in the said 1st Embodiment. The figure shown in order to demonstrate the mode of the frequency analysis process of the some sample gate obtained at the time of reception in the 1st Embodiment. The block diagram which shows the structure of 2nd Embodiment of the ultrasonic diagnosing device concerning this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... High pulse generation timing setting part, 12 ... Mode selection part, 13 ... PRF control part, 14 ... Pulse generator, 15, 22 ... Reference signal generator, 16 ... Transmission circuit, 17 ... Ultrasonic probe, 18 ... Reception Circuit, 19, 20 ... Phase detection circuit, 21 ... Envelope detection circuit, 23, 28, 31, 36 Low pass filter, 24, 32 ... Range gate circuit, 25, 33 ... Integration circuit, 26, 34 ... Sample hold circuit, 27, 35 ... high-pass filter, 29 ... arithmetic circuit, 37 ... arithmetic frequency designation control unit, 38 ... image memory, 39 ... address generation unit, 40 ... TV monitor, 42 ... interpolation circuit.

Claims (5)

Signal generating means for sequentially generating a plurality of high pulse repetition frequency mode pulse signals having different rates from each other;
An ultrasonic probe for transmitting an ultrasonic wave corresponding to the pulse signal to a subject and receiving a reflected wave of the ultrasonic wave;
Stop means for stopping transmission of a pulse signal at an arbitrary rate among the plurality of pulse signals;
Filter means for passing a signal component obtained by removing the stopped rate component from the received signal obtained by the ultrasonic probe;
Conversion means for converting the output of the filter means from a time axis signal to a frequency axis signal;
An ultrasonic diagnostic apparatus comprising: display means for performing image processing on the output of the conversion means and displaying the processing result. Signal generating means for sequentially generating a plurality of high pulse repetition frequency mode pulse signals having different rates from each other;
An ultrasonic probe for transmitting an ultrasonic wave corresponding to the pulse signal to a subject and receiving a reflected wave of the ultrasonic wave;
Stop means for stopping transmission of a pulse signal at an arbitrary rate among the plurality of pulse signals;
Interpolation means for performing interpolation processing on the time axis with respect to the reception signal obtained by the ultrasonic probe;
Conversion means for converting the output of the interpolation means from a time axis signal to a frequency axis signal;
An ultrasonic diagnostic apparatus comprising: display means for performing image processing on the output of the conversion means and displaying the processing result. The ultrasonic diagnostic apparatus according to claim 2, further comprising a filter unit that passes an arbitrary signal component from a reception signal obtained by the ultrasonic probe and outputs the signal component to the interpolation unit. The ultrasonic diagnostic apparatus according to claim 1, further comprising transmission power adjustment means for increasing transmission power of each of the plurality of pulse signals so as to be transmitted according to a stop time by the stop means. 3. The method according to claim 1, further comprising image acquisition means obtained by scanning a two-dimensional image or a color image of the subject when transmission of a pulse signal is stopped by the stop means. Ultrasonic diagnostic equipment.

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