JP2006271791A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an S/N ratio of an image imaged using a contrast medium. <P>SOLUTION: This equipment is provided with a measuring means of a 3-pulse method and a measuring means of a 2-pulse method. The 3-pulse method forms N-number of (N is an integer of ≥3) transmission pulses by rotating the phase of a carrier wave of ultrasonic waves amplitude-modulated with a common envelope signal by 360°/N each time, sends N-number of transmission pulses from an ultrasonic probe to a subject in order, and reconstitutes one image based on a signal obtained by adding N-number of echo signals received by the ultrasonic probe. The 2-pulse method sends two transmission pulses formed by rotating the phase of the carrier wave of the ultrasonic waves by 180° from the ultrasonic probe to the subject in order, and reconstitutes one image based on a signal obtained by adding two echo signals received by the ultrasonic probe. The 3-pulse method where the S/N ratio of an imaged echo image is high and the 2-pulse method where a frame rate is high are switched optionally to obtain an image suitable for use. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasound diagnostic apparatus, and more particularly to an ultrasound apparatus that performs imaging using a microbubble-based contrast agent.

  The ultrasonic diagnostic apparatus is used for medical diagnosis by transmitting ultrasonic waves to a living body as a subject, receiving ultrasonic echo signals generated from the living body, and imaging the inside of the living body.

  By the way, in the field of image diagnosis using an X-ray imaging apparatus or a magnetic resonance imaging apparatus (MRI apparatus) among image diagnostic modalities, contrast agents have been used for vascular system imaging. In other words, by administering a contrast medium into the blood, it is possible to obtain an image with enhanced contrast of the structure and distribution of the vascular system. Can be diagnosed.

  In contrast, contrast agents have not been widely used in the field of ultrasonic diagnosis. However, in recent years, contrast agents capable of stabilizing microbubbles having a size on the order of microns have emerged, and are beginning to be widely used. The principle of a contrast agent used for ultrasonic diagnosis is that a microbubble having a diameter of about 1 micron resonates with an ultrasonic wave of several MHz used for ultrasonic diagnosis and vibrates with a large amplitude. Is used to take advantage of the fact that contrast is generated.

  A feature of the microbubble-based ultrasonic contrast agent (hereinafter, appropriately abbreviated as contrast agent) is that it has a strong nonlinear ultrasonic scattering characteristic. This non-linear characteristic is attributed to the property that the volume increase of the microphone mouth bubble when receiving a negative pressure is much larger than the volume reduction of the microphone mouth bubble when receiving a positive pressure of the same amplitude. Because of this characteristic, the echo signal scattered by the micro-habble contains many second harmonic components having a frequency twice that of the transmitted ultrasonic wave. A method of obtaining a blood flow Doppler signal emphasized for a soft tissue of a living body based on the second harmonic component was first reported in 1992 (Non-patent Document 1). However, since only the bandpass filter is used to extract the second harmonic component from the echo signal, there remains a problem that the pulse of the second harmonic echo signal obtained as the output signal becomes long. This is because the amplitude of the fundamental wave component included in the echo signal is at least one digit greater than that of the second harmonic component, so that a filter having a sharp band cutoff characteristic or a narrow band pass characteristic must be used. This problem is particularly serious when the blood flow is displayed in a two-dimensional image because the resolution in the distance direction is deteriorated.

  In order to solve the problem caused by such a band-pass filter, a pulse inversion (PI: Pulse) is performed in which transmission / reception is performed twice using a transmission pulse waveform in which positive and negative are inverted, and two obtained echo signals are added. Inversion) has been proposed. According to this PI method, one phase of the fundamental wave components of the two echo signals from the soft tissue where the motion can be ignored is rotated by 180 ° with respect to the other phase, so that it is canceled by addition. On the other hand, the second harmonic component contained in the two echo signals has a relationship in which one phase is rotated by 360 ° with respect to the other phase, so that adding them increases the amplitude twice. To do. According to this PI method, although the number of transmissions is doubled, the fundamental wave component from the soft tissue can be removed without using a band-pass filter in principle, so that the second harmonic having excellent distance resolution. An engineering signal can be obtained. In addition, according to the PI method, the fundamental wave echo signal is completely canceled for a scatterer in which the morphological change that occurs between two transmissions and receptions cannot be ignored, such as a microbubble-based contrast agent in the bloodstream. Therefore, it meets the purpose of obtaining an echo image in which the contrast medium is enhanced with respect to the soft tissue. The PI method is described in detail in Patent Document 1 and the like.

  On the other hand, the speed of sound in many substances such as soft tissue of a living body is higher under high pressure than under low pressure. Therefore, when an ultrasonic transmission pulse propagates through a soft tissue, a portion with a high sound pressure propagates faster than a portion with a low sound pressure. As a result, the transmission waveform that originally has a sine wave shape, while propagating, changes to an N wave shape that gradually decreases and then has a harmonic component such as a second harmonic wave. If this is scattered in the soft tissue, an echo signal having a harmonic component returns from the soft tissue even if no contrast agent is present. The method of forming an echo image based on this harmonic component is called a tissue harmonic imaging (THI) method, and preferably has a higher acoustic S / N ratio than the echo image of the fundamental component. Rarely, it has recently become popular. However, because of the tissue harmonics, even if the PI method is used, an echo signal in which a harmonic component generated by nonlinear scattering of the contrast agent and a harmonic component generated by nonlinear propagation in the soft tissue are mixed is used. Imaging that distinguishes the agent from soft tissue is difficult.

  By the way, non-linear scattering by a contrast agent generally tends to be observed even at a low sound pressure as compared with non-linear propagation in soft tissue. Therefore, it is widely performed that the generation of tissue harmonic components caused by nonlinear propagation is suppressed by the PI method in which the transmission sound pressure is kept low, and an echo image is formed mainly by the harmonic components from the contrast agent. However, according to this, since the signal amplitude cannot be obtained sufficiently, it is difficult to obtain an echo image having a high S / N ratio that is sufficient for performing a definitive diagnosis expected for contrast diagnosis.

  As a method for solving this problem to some extent, a method of performing transmission / reception three times by reversing the positive / negative of the transmission pulse waveform and simultaneously changing the amplitude has been proposed (Non-Patent Document 2). This is a method of performing transmission and reception three times using three transmission pulses whose amplitudes are sequentially modulated to 0.5, -1, and 0.5, and adding three echo signals obtained thereby. That is, while the same pulse waveform is used for the first transmission and the third transmission, the second waveform uses a pulse waveform that is inverted in phase and doubled in amplitude. According to this method, the echo signal component from the linear scatterer that changes slowly is canceled, and the even harmonic component of the echo signal generated by nonlinear scattering or nonlinear propagation is emphasized. This point is the same as the normal PI method, but according to this method, all components including the fundamental wave are extracted by amplitude modulation among echo signal components generated by nonlinear scattering and nonlinear propagation. There is. Therefore, higher sensitivity to echo signals due to nonlinear scattering and nonlinear propagation is expected than that of the normal PI method. That is, the method described in Non-Patent Document 2 utilizes the fact that the dependence of the nonlinear scattering by the contrast agent on the amplitude of the incident sound pressure is much larger than the dependence of the nonlinear propagation. Due to this increase in sensitivity, the effect of nonlinear scattering can be detected even at transmission sound pressures where the effect of nonlinear propagation is relatively small. Therefore, it is easy to distinguish the contrast medium from soft tissue as compared with the normal PI method.

1992 IEEE Ultrasonics Symposium Proceedings, pp. 1175-1177 US Patent Publication USP No. 6,095,980 2001 IEEE Ultrasonics Symposium Proceedings, pp, 1739-1745

  However, in the method described in Non-Patent Document 2, since the tissue harmonic component of the echo signal generated by the nonlinear propagation of the transmission pulse in the soft tissue remains, only the harmonic component of the echo signal derived from the contrast agent remains. Cannot be discriminated. Therefore, the contrast agent and the soft tissue cannot be distinguished and imaged. As a result, it is not possible to obtain a contrast echo image with a high S / N ratio sufficient to perform a definitive diagnosis.

  In view of the present situation as described above, an object of the present invention is to further increase the S / N ratio of a contrast echo image using a microbubble-based contrast agent.

  The principle of the present invention for solving the above-described problem is that the phase of an ultrasonic carrier wave whose amplitude is modulated by a common envelope signal for N transmission pulses (where N is an integer of 3 or more) is 360 ° / N. Based on a signal formed by rotating and transmitting the N transmission pulses sequentially from the ultrasonic probe to the subject and adding the N echo signals received by the ultrasonic probe. One image is reconstructed and displayed.

  According to the principle of the present invention, by adding N echo signals, the fundamental wave component and the second harmonic component of the echo signal scattered by the linear scatterer whose change can be ignored are simultaneously canceled. In other words, focusing on the phase of N echo signals from the linear scatterer, the phase of the fundamental wave component is rotated by 360 ° / N. Therefore, when these N fundamental wave components are combined, that is, added, they cancel each other. Will fit. Further, since the phase of the second harmonic component of the N echo signals rotates by 2 × (360 ° / N), the addition of these second harmonic components cancels each other. Similarly, components up to the (N-1) th harmonic are canceled simultaneously.

  On the other hand, the phase of the echo signal generated by being scattered by the microbubble contrast agent is affected by the amplitude (sound pressure) of the envelope signal due to the strong nonlinear resonance characteristic of the contrast agent, and the phase of the carrier wave of the transmission pulse There is no fixed relationship with. Therefore, even if N echo signals obtained by transmitting and receiving N times by rotating the phase of the carrier wave of the transmission pulse by 360 ° / N are added, the echo signals generated by scattering by the contrast agent are canceled out. Ingredients remain. Since the remaining echo signal component is a component derived from the contrast agent, imaging using this makes it possible to perform ultrasonic imaging in which the contrast agent is clearly distinct from the soft tissue.

  By the way, according to the principle of the present invention described above, only the harmonic components derived from the contrast agent can be distinguished, so that the S / N ratio of the contrast echo image using the contrast agent can be improved. However, since the transmission / reception must be performed N times in order to obtain one two-dimensional image, the frame rate is lowered. On the other hand, when the intensity of the echo signal obtained is weak depending on the region to be diagnosed, the resolution of the image obtained by the principle of the present invention (hereinafter, abbreviated as the three-pulse method for convenience) and the conventional PI It is conceivable that there is no difference between the resolution of the image obtained by the method (hereinafter, abbreviated as the two-pulse method for convenience). Thus, if there is no difference in the resolution of the image, the diagnostic efficiency is better when the frame rate is increased.

  Therefore, in the above principle of the present invention, N is 6 and 6 transmission pulses are repeatedly transmitted, and 6 echo signals corresponding to each transmission pulse are repeatedly stored in the memory and stored in this memory. The frame rate of the 3-pulse method can be increased by reconstructing one image based on a signal obtained by adding three echo signals whose carrier phases are 120 ° apart from each other among the six echo signals. .

  That is, by repeatedly transmitting six transmission pulses, six echo signals having different phases are always stored in the memory. Therefore, based on three echo signals that are 120 ° apart from each other at each transmission timing. Images are obtained. Therefore, even if the 3-pulse method is applied, a contrast image can be acquired at the same frame rate as that of a normal B-mode image. In the present invention, the carrier phases of N transmission pulses may have a tolerance of ± 10 °.

  The ultrasonic diagnostic apparatus of the present invention, instead of the above, changes the phase of an ultrasonic carrier wave obtained by amplitude-modulating N transmission pulses (where N is an integer of 3 or more) with a common envelope signal. The N transmission pulses are sequentially transmitted from the ultrasonic probe to the subject, and the N echo signals received by the ultrasonic probe are added. First measurement means for reconstructing one image based on the signal, and two transmission pulses formed by rotating the phase of the ultrasonic carrier wave by 180 ° from the ultrasonic probe to the subject And a second measuring unit configured to reconstruct one image based on a signal obtained by sequentially transmitting and adding two echo signals received by the ultrasonic probe. That is, it can be configured to have both the measurement function of the three-pulse method according to the present invention and the measurement function of the conventional PI method (two-pulse method).

  According to this, it is possible to switch between the first measuring means and the second measuring means by the switching means and freely measure by the three-pulse method with excellent image quality or by the PI method with a high frame rate. Can be switched.

  In this switching, the addition signal of the first measurement unit and the second measurement unit are compared, and for example, an image can be generated by the measurement unit of the addition signal having a larger amplitude.

  Furthermore, another ultrasonic diagnostic apparatus according to the present invention includes transmission pulse forming means for forming six transmission pulses by rotating the phase of an ultrasonic carrier wave whose amplitude is modulated by a common envelope signal by 60 °, and A transmission control means for repeatedly transmitting the six transmission pulses from the ultrasonic probe to the subject while shifting the time, and six echo signals received by the ultrasonic probe are stored. A memory, first processing means for selecting and adding three echo signals whose phases of the carrier wave are 120 ° apart from each other among the six echo signals stored in the memory, and storing in the memory Second processing means for selecting and adding two echo signals whose carrier phases are 180 ° apart from each other among the six echo signals that have been added, and adding by the first and second processing means Less based on the received signal Both can be configured to include image generating means for reconstructing one image and display means for displaying the reconstructed image.

  According to this, measurement data of the 3-pulse method and the 2-pulse method can be collected at the same time. Accordingly, the first means for generating the first image based on the signal added by the first processing means, and the second means for generating the second image based on the signal added by the second processing means. 2 means, and the first and second images can be displayed side by side on the display means. Further, the display unit can combine and display at least a part of the first and second images into one image.

  As described above, according to the present invention, the S / N ratio of a contrast echo image using a microbubble contrast agent can be further increased.

Hereinafter, the present invention will be described based on embodiments.
(Basic form 1)
FIG. 1 is a block diagram showing an example of an ultrasonic diagnostic apparatus according to the basic form of the present invention. As shown in the figure, each vibration element constituting the ultrasonic probe (probe) 1 is connected to a transmission beam former (transmission BF) 3 and a reception beam former (reception BF) via a changeover switch 2. ) 10. The transmission beamformer 3 uses the waveform selected by the transmission waveform selection unit 4 and read from the transmission waveform memory 5 according to the control by the transmission / reception sequence control unit 6, and has directivity when transmitted through each vibration element. A signal that is an ultrasonic pulse is generated. This signal is converted into an ultrasonic pulse by each vibration element of the ultrasonic probe 1 and transmitted to a living body of a subject (not shown). The ultrasonic echo signal reflected or scattered in the living body and returned to the ultrasonic probe 1 is received by each vibration element and converted into an electric signal, and is received as a received signal via the changeover switch 2 as a received signal. Input to the former 10.

  The reception beamformer 10 gives a delay time to each reception signal and adds them to each other in order to generate reception sensitivity having directivity according to control by the transmission / reception sequence control unit 6. The echo signal of the time series signal obtained by this delay addition is once written in one bank in the reception waveform memory 12 selected by the reception memory selection unit 11 according to the control by the transmission / reception sequence control unit 6. After echo signals to be added to each other are prepared in the reception waveform memory 12, they are read out by the adder 13 and added together. The output signal of the adder 13 passes through a band-pass filter 14 that removes noise components, is converted into an envelope signal by an envelope detector 16, and is input to a scan converter 18.

  On the other hand, a part of the echo signal written in the reception waveform memory 12 passes through the band-pass filter 15 that removes noise components without being added to each other while being read, and is detected by the envelope detector 17. It is converted into an envelope signal and input to the scan converter 18. The scan converter 18 generates and controls signals so that a plurality of input signals are appropriately superimposed and displayed on the display unit 19 in two or three dimensions.

  Here, in the transmission waveform memory 5, waveforms of three transmission pulses having different phases obtained by rotating the phase of an ultrasonic carrier wave amplitude-modulated by a common envelope signal by 120 ° are written. The transmission waveform selection unit 4 executes the sequence of selecting and transmitting one of them three times while changing the waveform. Thus, an example of three echo signals written to each bank in the reception waveform memory 12 is shown in FIGS. 2 (a), 2 (b), and 2 (c). In FIG. 2, for the sake of simplicity, an echo signal that is reflected by one point-like reflector after the transmission pulse has propagated through the soft tissue of the living body is obtained by numerical simulation. Here, the carrier frequency of the transmission pulse was 2 MHz. (D) of the figure is an output signal obtained by adding the three echo signals shown in (a), (b), and (c) by the adder 13. Since the transmission pulse propagates nonlinearly in the soft tissue of the living body, FIGS. 2A, 2B, and 2C include not only the fundamental wave component but also the second harmonic component. However, in FIG. 2D, which is the output of the adder 13, as predicted from the principle of the present invention, not only the fundamental wave components cancel each other, but also the second harmonic components cancel each other, and the signal The amplitude is almost zero.

  Here, the principle by which the fundamental wave component and the harmonics caused by nonlinear propagation are canceled by the addition of the adder 13 according to the basic form 1 of the present invention will be described. This principle is easy to understand when considering the vibration problem of a reciprocating 4-stroke inline engine. When the crankshaft is rotating at a constant angular velocity, the linear velocity at which each piston constituting the reciprocating engine vibrates includes not only a fundamental wave component of this angular velocity but also a harmonic component having a non-negligible amplitude. A four-stroke in-line four-cylinder engine is usually configured such that two sets of two in-phase pistons arranged symmetrically form a crank angle of 180 °. As shown in FIG. 3, the four-stroke in-line four-cylinder engine cancels out the fundamental wave component generated by each pair of pistons, but the second harmonic component grows twice as a result. Vibration with a frequency twice as high as the shaft rotation speed becomes a problem. In the figure, the solid line indicates the phase of vibration due to the first piston set, and the dotted line indicates the phase of vibration due to the second piston set. The reason why there is a 4-cylinder engine equipped with a balancer that rotates at an angular velocity twice that of the crankshaft is to counteract this vibration.

  In contrast, a 4-stroke in-line 6-cylinder engine is usually configured such that three sets of two in-phase pistons arranged symmetrically form a crank angle of 120 °. As shown in FIG. 4, in a 4-stroke in-line 6-cylinder engine, the fundamental wave components generated by each pair of pistons are generated so as to form 120 ° in the crank angle and cancel each other. The second harmonic components are also generated with a phase of 120 ° × 2 = 240 ° counted from the crank angle, that is, 120 ° counted from the reverse, and thus cancel each other. This is why the in-line 6-cylinder engine has less vibration. In the figure, the alternate long and short dash line indicates the phase of vibration caused by the third set of pistons.

  That is, the configuration of the in-line four-cylinder engine in which the second harmonic vibration in FIG. 3 is emphasized in principle corresponds to the PI method. The configuration of the in-line 6-cylinder engine in which not only the fundamental wave of FIG. 4 but also the vibration of the second harmonic is canceled in principle corresponds to the principle method of the present invention. Here, in general, when N is an integer of 3 or more, the vibration of the in-line 2N cylinder engine will be described. The fundamental wave, that is, the vibration from the first harmonic to the (N-1) th harmonic is the principle. Will be countered. If this is replaced with the case of the ultrasonic imaging of the present invention, the envelope signal of the transmission pulse waveform is made common, the carrier wave phase is rotated by 360 ° / N, and N transmission / reception N times obtained are performed. By adding the echo signals, the components from the fundamental wave to the (N-1) th harmonic of the echo signal scattered by the linear scatterer whose change can be ignored are simultaneously canceled.

  Next, for comparison with the principle method of the present invention, FIG. 5 shows a simulation result of an echo signal obtained by the conventional PI method. In order to realize the conventional PI method, the waveforms of two transmission pulses having different phases obtained by rotating the phase of an ultrasonic carrier wave amplitude-modulated by a common envelope signal by 180 ° are transmitted to the transmission waveform memory 5. Write. Then, the transmission waveform selection unit 4 alternately selects and transmits them. Thus, an example of two echo signals written to each bank in the reception waveform memory 12 is shown in FIGS. FIG. 4C shows the output signal of the adder 13 obtained at that time. As illustrated, the fundamental wave components cancel each other, but the second harmonic components are signals that are rather emphasized. This signal is called a tissue harmonic (TH) signal, and has an advantage that a high acoustic S / N ratio can be obtained when rendering a living soft tissue, but only the distribution and dynamics of a contrast agent are affected by the soft tissue. If you want to draw it distinctly, it will be the biggest factor that hinders it.

  Next, using the contrast agent, the received echo signal obtained by implementing the principle method of the present invention in FIG. 2 with 3 pulses and the received echo signal implemented by 2 pulses of the conventional PI method in FIG. As shown in FIG. These figures show, as an example, a result of obtaining a received echo signal generated by being scattered by a micro hubble having a radius of 1.5 μm by numerical simulation. 7 and 9 show input / output signals of the band pass filter 14 at that time. 6 to 9, the vertical axis represents the signal amplitude proportional to the sound pressure, the scale is common, and the horizontal axis represents time (μs).

  When the three-pulse method shown in FIG. 2 is used, the signals written in the banks in the reception waveform memory 12 are as shown in FIGS. 6 (a), (b), and (c). The output signal of the adder 13 at this time, that is, the input signal of the Obihiro filter 14 is shown in FIGS. 6 (d) and 7 (a). 7 (b), (c), (d), (e), and (f) show the passband center frequency of the bandpass filter 14 as the fundamental frequency (2 MHz) and 1.5 times higher harmonics of the carrier wave, respectively. This is an output signal when the wave frequency (3 MHz), the second harmonic frequency (4 MHz), the 2.5-fold harmonic frequency (5 MHz), and the third harmonic frequency (6 MHz) are set.

  On the other hand, when implemented by the two-pulse method based on the PI method of FIG. 5, the signals written to the respective banks in the reception waveform memory 12 are FIGS. 8 (a) and 8 (b). The output signal, that is, the input signal of the band pass filter 14 is shown in FIG. 8 (c) and FIG. 9 (a). 9 (b), (c), (d), (e), and (f) are output signals of the band pass filter 14 when the pass band center frequency of the band pass filter 14 is set in the same manner as in FIG. It is.

As is clear from these figures, according to the two-pulse PI method originally designed to emphasize the second harmonic component in the echo signal, as shown in FIGS. 9 (c) and 9 (d), It is natural that a signal derived from a contrast medium containing a large amount of the second harmonic component from the 1.5-fold harmonic can be obtained. On the other hand, according to the three-pulse method according to the present invention devised to cancel out the component caused by nonlinear propagation among the second harmonic components in the echo signal, FIGS. 7 (d), (e) and (f) As shown, an echo signal having a sufficient amplitude derived from a contrast agent containing a lot of second to third harmonic components is obtained. This is a remarkable phenomenon, and this peculiar and useful phenomenon is due to the fact that the contrast agent microhubble is a resonator having strong nonlinearity. More generally speaking, the delay time has a response characteristic depending on the amplitude. That is, even if there is nonlinearity between the input and output sound pressures, if the delay response time does not depend on the amplitude, the second harmonic component in the output signal is canceled as shown in FIG. End up. On the other hand, a simple linear resonator is out of the question because the second harmonic component itself does not occur.
(Basic form 2)

  According to the basic mode 1 described above, even if the second harmonic component is intentionally superimposed on the transmission pulse, an echo signal having a sufficient amplitude derived from the contrast agent can be obtained while canceling it. That is, as described in the literature (IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Contro1, vo1 43, no. 6, pp. 1054-1062), the second harmonic component is intended for the ultrasonic transmission pulse waveform. By superimposing them, it is possible to emphasize the vibration, growth, and collapse of the micro hubble in the living body or in the liquid, or to suppress the opposite. The technique of superimposing the second harmonic described in this document on the transmission pulse is considered to be useful in the case of ultrasonic imaging using a micro-habble contrast agent.

  This basic mode 2 is an example in which the second harmonic component is intentionally superimposed on the waveform of the transmission pulse stored in the transmission waveform memory 5 of FIG. 10 to 12 show examples of echo signals measured by the three-pulse method using a transmission pulse waveform that intentionally superimposes the second harmonic component. In the transmission waveform memory 5, the waveforms of three transmission pulses having different phases obtained by rotating the phases of the fundamental wave and the second harmonic wave, which are amplitude-modulated by a common envelope signal, by 120 °, are provided. Has been written. The transmission waveform selection unit 4 executes a sequence of selecting and transmitting one of them three times, changing the waveform. Thus, an example of three received echo signals written to each bank in the received waveform memory 12 is obtained in the same manner as in FIG. 2 and shown in FIGS. 10 (a), 10 (b), and 10 (c). The output signal of the adder 13 obtained at that time is shown in FIG. Further, the reception echo signal generated by being scattered by the contrast agent is obtained in the same manner as in FIG. 6, and the signals written in the respective banks in the reception waveform memory 12 are shown in FIGS. 11 (a), 11 (b) and 11 (c). Shown in Furthermore, the output signal of the adder 13 obtained at that time, that is, the input signal of the bandpass filter 14 is shown in FIGS. 11 (d) and 12 (a). 12B, 12C, 12D, 12E, and 12F are output signals when the passband center frequency of the bandpass filter 14 is set in the same manner as in FIG.

  As is clear from FIG. 10D, even when the second harmonic component is intentionally superimposed on the transmission pulse waveform, the received echo signal generated by being scattered by the point reflector is not the same as the input signal of the adder 13. The second harmonic components cancel each other in the same manner as the second harmonic component generated by nonlinear propagation in the case of FIG. 2, and the amplitude of the output signal of the adder 13 is almost zero. On the other hand, the received echo signal generated by being scattered by the contrast agent has a sufficient amplitude containing a large amount of the second to third harmonic components without being canceled by the addition by the adder 13 as in the case of FIG. An echo signal is obtained.

  Further, the results of examining the error range necessary for obtaining the effect of the three-pulse method of the present invention for the phase of the transmission pulse will be described. When the phase of the second transmission pulse is shifted by 20 °, the output signal of the adder 13, that is, the input signal of the bandpass filter 14, and the filter when the passband center frequency is matched with the fundamental wave and the second harmonic wave The output signal is obtained in the same manner as in FIG. 2 and shown in FIGS. 13 (b) and 13 (c). For comparison, FIG. 5A shows signals in the case of FIG. 5, that is, when the PI method can be performed without phase error. In FIG. 13C, the phase of the third transmission pulse is shifted by 10 ° in correspondence with the phase shift of 20 ° of the second transmission pulse so that the sum signal of the three transmission pulses becomes zero. This is a case of adjustment.

Assuming that the envelope signal of the transmission pulse is A (t) as a function of time t, the first to third transmission pulses P1 (t), P2 (t), and P3 (t) according to the present invention are: When there is no phase error
P1 (t) = A (t) sinωt (1)
P2 (t) = A (t) sin (ωt + 2π / 3) (2)
P3 (t) = A (t) sin (ωt−2π / 3) (3)
Can be written. At this time,
P1 (t) + P2 (t) + P3 (t) = 0 (4)
The relationship is established. When a phase error φ occurs in the second transmission pulse, the second transmission pulse is
P2 (t) = A (t) sin (ωt + 2π / 3 + φ) (5)
Can be written. At this time, the third transmission pulse is
P3 (t) = A3 (t) sin (ωt−2π / 3 + φ / 2) (6)
A3 (t) = 2A (t) cos (π / 3 + φ / 2) (7)
(4) can be satisfied regardless of the phase error φ. FIG. 13C shows the result of performing such correction of the third transmission pulse, and the fundamental wave component in the output signal of the adder 13 despite the phase error of the second transmission pulse. Can be counteracted. Since the expression (4) holds, generally, the sum signal of N transmission pulse waveforms used for transmission is substantially zero, so that N reception echo signals are added. The fundamental wave component in the generated signal is canceled.

  FIG. 14 shows the peak-to-peak (pp) value of the amplitude of the output signal of the adder 13 as a function of the phase error given to the second transmission pulse. The signal amplitude normalized with the value when the PI method can be performed without phase error is indicated by a solid line (a) when the third transmission pulse is not corrected, and the dotted line (b) when the correction is performed. Show. When the phase error reaches 20 °, even if the third transmission pulse is corrected, the signal amplitude derived from non-linear propagation in the soft tissue and not derived from the contrast agent becomes more than half that of the conventional PI method. The effect of the present invention will not be exhibited sufficiently. From this result, it is concluded that the phase error of the transmission pulse is preferably about 10 ° or less in order to sufficiently obtain the effects of the present invention.

  As described above, according to the basic modes 1 and 2 of the present invention, the signal derived only from the contrast microhables is extracted from the echo signal without including the signal component derived from the non-linear propagation in the soft tissue. be able to. Further, the noise is removed by the band-pass filter 14, the S / N ratio is improved, and the envelope signal is obtained by the envelope detector 16, which is scanned as a signal representing the spatial distribution of the micro-havable contrast agent. Input to the converter 18.

  On the other hand, an envelope signal is obtained by an envelope detector 17 from a signal whose S / N ratio is improved by passing a signal written in one bank in the reception waveform memory 12 through a band-pass filter 15, and this is a soft part. A signal representing the position and morphology of the tissue is input to the scan converter 18. In the scan converter 18, the output signal of the envelope detector 17 is used as a background, and the output signal of the envelope detector 16 is superimposed and displayed on the display unit 19 in different colors so that it can be easily distinguished from the background. . In this way, the distribution of the contrast medium in the body of the patient to be examined can be displayed in a clear manner by a two-dimensional or three-dimensional image.

  In the basic forms 1 and 2 described above, the case where a signal written in one bank in the reception waveform memory 12 is used as it is as a signal representing the position and form of the soft tissue has been described. An addition signal obtained by appropriately weighting the signals written in the three banks in the memory 12 can be used.

As described above, according to the present invention, a signal derived only from a contrast-enhanced microhabble is extracted from an echo signal without including a signal component derived from non-linear propagation or the like in soft tissue. As a signal representing the spatial distribution of the microhabul for use, it can be displayed in an easily understandable manner in a two-dimensional or three-dimensional image by superimposing it in an identifiable color tone on the background representing the position and form of the soft tissue. As a result, it is possible to provide a diagnostic image having a high S / N ratio sufficient for performing a definitive diagnosis based on the contrast echo image. Thus, the medical diagnostic utility of the apparatus embodying the present invention is extremely great, and therefore, the significance of the present invention in the industry supporting medical diagnosis is also great.
(Embodiment 1)

  Next, an embodiment of the present invention using the principle of the present invention will be described. According to the basic aspects 1 and 2 of the present invention described above, the frame rate is lowered because N times of transmission / reception must be performed to obtain one two-dimensional image. On the other hand, depending on the region to be diagnosed, when the intensity of the obtained echo signal is weak, the resolution of the image obtained by the principle method of the present invention (hereinafter, abbreviated as the three-pulse method for convenience) In some cases, there is no difference in the resolution of an image obtained by the PI method (hereinafter, abbreviated as a two-pulse method for convenience). In such a case, a higher frame rate provides better diagnostic efficiency. Therefore, an embodiment of the ultrasonic diagnostic apparatus of the present invention is provided that has a function of performing two types of measurement of a three-pulse method and a two-pulse method, and switches between these two functions to enable measurement by either one of the functions. Is shown in FIG.

  As shown in FIG. 15, the present embodiment adds a function of performing the measurement of the two-pulse method to the ultrasonic diagnostic apparatus according to the basic form 1 shown in FIG. 1 and functions of the three-pulse method and the two-pulse method. , And the resolution priority or the frame rate priority can be selected. Therefore, the transmission waveform memory 5 includes three transmission pulse waveforms having different phases obtained by rotating the phase of an ultrasonic carrier wave amplitude-modulated by a common envelope signal for each of the three-pulse methods by 120 °, and 2 For the pulse method, two transmission pulse waveforms with different phases are written by rotating the phase of an ultrasonic carrier wave amplitude-modulated with a common envelope signal by 180 °. The transmission waveform selection unit 4 selects a transmission pulse waveform of the three-pulse method or the two-pulse method based on a command from the transmission / reception sequence control unit 6 and outputs it to the transmission beamformer 3.

  Further, the output of the adder 13 obtained by the three-pulse method is temporarily stored in the frame memory 20 before being sent to the band pass filter 14. The data recorded in the frame memory 20 may be, for example, data obtained by scanning conversion into a display image format, or a result obtained by temporarily recording a so-called RF signal according to a received beam and then performing addition processing in each sequence. In the case of an RF signal, it can be recorded as a complex signal having a real part and an imaginary part.

  On the other hand, a time series signal composed of two echo signals obtained by executing an imaging sequence by the two-pulse method in accordance with control by the transmission / reception sequence control unit 6 is processed by the reception beamformer 10 and is received by the reception memory selection unit 11. The data is once written in the selected bank in the received waveform memory 21. After the time series signals to be added together are prepared in the reception waveform memory 21, they are read out by the adder 22 and added to each other. The two echo signals added by the adder 22 are stored in the frame memory 23. Data stored in the frame memory 23 can be configured in the same manner as the frame memory 20.

  The switch 24 outputs one of the outputs of the adder 13 and the adder 22 recorded in the frame memory 20 and the frame memory 23 to the band pass filter 14. The comparator 25 takes in the outputs of the adder 13 and the adder 22 recorded in the frame memory 20 and the frame memory 23 and compares the echo signals obtained by the 3-pulse method and the 2-pulse method. That is, a difference in data (for example, luminance) is obtained for each pixel of echo signals recorded in the frame memory 20 and the frame memory 23, or a ratio is obtained and compared. This comparison result is stored in the comparison result memory 26 for each pixel. The frame memory 20, the frame memory 23, and the comparison result memory 26 have the same address configuration and can use the same address control signal. The determination unit 27 comprehensively determines the comparison results stored in all addresses or specific addresses in the comparison result memory 26. For example, even if there is a difference in the comparison result of a specific address, if there is no difference in most other comparison results, it is determined that there is no difference as a whole. Details of this criterion will be described later.

  The determination unit 27 outputs the determination result to the transmission selection control unit 28 and switches the switch 24 based on the determination result. The transmission selection control unit 28 selects a 3-pulse method or a 2-pulse method based on the determination result output from the determination unit 27, sends a command to the transmission / reception sequence control unit 6, and performs ultrasonic diagnosis based on the selected sequence. The device is to be operated. Further, the reception waveform memory 12, the adder 13, the frame memory 20, the reception waveform memory 21, the adder 22, the frame memory 23, the comparator 25, the comparison result memory 26, and the determination unit 27 are controlled according to the selection. It is like that.

  The operation of the embodiment configured as described above will be described with reference to the flowcharts shown in FIGS. First, the transmission selection control unit 28 outputs a command to obtain an image by performing measurement by the three-pulse method to the transmission / reception sequence control unit 6 (S1). The transmission / reception sequence control unit 6 instructs the transmission waveform selection unit 4 to select and output the waveform of the transmission pulse for 3 pulses from the transmission waveform memory 5 (S2). The transmission beamformer 3 sequentially transmits the three transmission pulses output from the transmission waveform selection unit 4 to the probe 1 via the changeover switch 2 with a 120 ° phase difference in accordance with a command from the transmission / reception sequence control unit 6 ( S3). The reception beamformer 10 takes in an echo signal input from the probe 1 via the changeover switch 2 in accordance with a command from the transmission / reception sequence control unit 6, performs a known reception process and phasing addition process, and performs a reception memory. It outputs to the selection part 11 (S4). The reception memory selection unit 11 selects three echo signals corresponding to the three pulses and records them in the corresponding banks of the reception waveform memory 12 (S5). The adder 13 adds three echo signals corresponding to the three pulses recorded in the reception waveform memory 12, and stores the addition result in the frame memory 20 (S6).

  Next, as shown in FIG. 17, the transmission selection control unit 28 outputs a command for obtaining an image by performing measurement by the two-pulse method to the transmission / reception sequence control unit 6 (S11). The transmission / reception sequence control unit 6 instructs the transmission waveform selection unit 4 to select and output the waveform of the transmission pulse for two pulses from the transmission waveform memory 5 (S12). The transmission beamformer 3 sequentially transmits the two transmission pulses output from the transmission waveform selection unit 4 to the probe 1 via the changeover switch 2 with a 180 ° phase difference in accordance with a command from the transmission / reception sequence control unit 6 ( S13). The reception beamformer 10 takes in an echo signal input from the probe 1 via the changeover switch 2 in accordance with a command from the transmission / reception sequence control unit 6, performs a known reception process and phasing addition process, and performs a reception memory. It outputs to the selection part 11 (S14). The reception memory selection unit 11 selects two echo signals corresponding to two pulses and records them in the corresponding banks of the reception waveform memory 21 (S15). The adder 22 adds two echo signals corresponding to the two pulses recorded in the reception waveform memory 21 and stores the addition result in the frame memory 23 (S16).

  The comparator 25 compares the addition results of the echo signals respectively stored in the frame memory 20 and the frame memory 23, and stores the result in the comparison result memory 26 (S21). For example, the comparator 25 can compare the amplitudes of the echo signals of the 3-pulse method and the 2-pulse method that correlate with the luminance of the image. The comparison result can be a difference in amplitude or a ratio of amplitudes. The determination unit 27 makes a comprehensive determination based on the comparison result stored in the comparison result memory 26, and outputs the determination result to the switch 24 and the transmission selection control unit 28 (S22). Here, the determination unit 27 comprehensively determines the comparison result stored on the memory address of the comparison result memory 26 or the comparison result stored on the specific address based on all the results of the comparison. It is determined whether the amplitude difference of the echo signal of the method is larger than the set value than the amplitude of the echo signal of the two-pulse method. This setting value can be input and set from a console such as a keyboard. If the echo signal obtained by the three-pulse method is recognized to be sufficiently larger than the amplitude of the echo signal obtained by the two-pulse method, the measurement result by the three-pulse method is effective. Is output. On the other hand, if it is recognized that there is no difference between the 3-pulse method and the 2-pulse method, it is preferable to increase the frame rate, so that a determination result indicating that measurement by the 2-pulse method should be output. . The switch 24 transfers the echo signal stored in the frame memory 20 or the frame memory 23 to the band pass filter 14 according to the determination result (S23). The band pass filter 14 filters the input echo signal and outputs it to the envelope detector 16 (S24). The envelope detector 16 detects the envelope signal of the input echo signal, and outputs the detected envelope signal to the scan converter 18 (S25). The scan converter 18 once records the input envelope signal, converts it into image data, and outputs it to the display unit 19 (S26). The display unit 19 displays input image data on a display screen.

  Also in this embodiment, as described in the basic modes 1 and 2, in addition to the measurement by the 3-pulse method or the 2-pulse method, normal B-mode image measurement is performed, and the echo signal is transmitted to the band-pass filter 15 and the envelope. The image data processed by the line detector 17 and the image data obtained thereby can be combined with the contrast image data measured by the scan converter 18 by the three-pulse method or the two-pulse method and displayed on the display 19. .

  In the present embodiment, the switching between the three-pulse method and the two-pulse method is automatically performed by the comparator 25 and the determination unit 27. However, the present invention is not limited to this, and various modifications can be made as described below. can do. For example, according to conditions such as a diagnostic part, a diagnostic depth, a use frequency, and the like, switching can be performed based on an examiner's intention by using a technique. Moreover, it can also be made to switch by a preset procedure according to those conditions.

  Further, in the determination by the determination unit 27 described above, it is possible to make a comprehensive determination by weighting the physical quantity to be compared in accordance with conditions such as the depth direction or the beam scanning direction. Furthermore, it is possible to add an evaluation based on a plurality of images over time.

  Furthermore, instead of the method of switching based on the measurement results of the 3-pulse method and 2-pulse method, the 3-pulse method and 2-pulse method can be switched according to the sound pressure of the transmitted pulse. That is, as described with reference to FIG. 2, when the amplitude signal proportional to the sound pressure is sufficiently large, the addition of three echo signals by the three-pulse method eliminates the fundamental wave component and obtains a contrast image with less noise. It is done. This contrast image has less noise than the two-pulse contrast image described in FIG. However, when the sound pressure is low, it is conceivable that there is no difference in the resolution between the contrast images. If there is no difference in the image quality of the contrast image, the two-pulse method with a high frame rate is excellent in diagnostic efficiency. Therefore, the intensity of the echo signal can be monitored and switched to the 3-pulse method when the intensity is greater than the set value, and switched to the 2-pulse method when the intensity falls below the set value. This set value can also be input from the console.

As described above, according to the present embodiment, the measurement function of both the three-pulse method capable of obtaining a contrast image with excellent image quality using a contrast agent and the two-pulse method having a high frame rate is provided. Therefore, they can be used properly according to the purpose of diagnosis, and an ultrasonic diagnostic apparatus excellent in usability can be realized.
(Embodiment 2)

  FIGS. 19 and 20 show the configuration of an ultrasonic diagnostic apparatus according to an embodiment that improves the frame rate of the three-pulse method according to the first embodiment. A feature of the present embodiment is that six types of transmission pulses having different phases obtained by rotating the phase of an ultrasonic carrier wave amplitude-modulated by a common envelope signal by 60 ° are repeatedly transmitted. Then, six types of echo signals are held in the reception waveform memory in accordance with the transmission pulse, and are overwritten when the next echo signal having the same phase is received. As a result, the received waveform memory always holds six types of echo signals whose phases are different by 60 °.

  Therefore, a three-pulse contrast image is obtained by reading out and adding three types of echo signals whose phases are different by 120 ° from the received waveform memory. When this set of three kinds of echo signals to be read is executed while shifting the phase by 60 ° for each transmission pulse interval, a one-frame contrast image by the three-pulse method is obtained at the same interval as the transmission pulse transmission interval. . Therefore, a three-pulse contrast image can be obtained at a normal B-mode image frame rate without reducing the frame rate.

  Hereinafter, it demonstrates in detail using figures. As shown in FIG. 19, in the present embodiment, an image data collection unit 30 is provided between the reception memory selection unit 11 and the bandpass filters 14 and 15 of the embodiment of FIG. 20 is configured as shown in FIG. Further, the functional configurations of the transmission waveform selection unit 4, the transmission waveform memory 5, and the transmission / reception sequence control unit 6 are different. That is, in the transmission waveform memory 5, there are six types (0 °, 60 °, 120 °, 180 °, 240 °, 300 °) in which the phase of the ultrasonic carrier wave modulated by the common envelope signal is different by 60 °. ) Is stored. The transmission waveform selection unit 4 is configured to repeatedly select and transmit six types of transmission pulses based on a command from the transmission / reception sequence control unit 6.

  On the other hand, as shown in FIG. 20, the image data collection unit 30 includes six reception waveform memories 31 a to 31 f that respectively store echo signals corresponding to six types of transmission pulses. The echo signals a to f stored in the reception waveform memories 31 a to 31 f are formed so as to be readable by the echo signal selection unit 32. The echo signal selection unit 32 is configured to take in six types of echo signals a to f and select three echo signals having phases different by 120 °. The three echo signals thus selected are added by the adder 33. The reception waveform memories 31a to 31f, the echo signal selection unit 32, and the adder 33 are controlled by an echo signal selection control unit 34.

  First, the echo signal selection control unit 34 stores the echo signal output from the reception memory selection unit 11 in accordance with the transmission / reception timing of the ultrasonic wave based on the command of the transmission / reception sequence control unit 6. 31f is sequentially switched. In accordance with the switching, the echo signal selection control unit 34 causes the echo signal selection unit 32 to capture the six types of echo signals a to f and to select three types of echo signals having phases different by 120 °. That is, the echo signal selection unit 32 has a function of selecting three types of echo signals having different combinations from the six types of echo signals a to f. For example, an echo signal (a, c, e) is selected at a certain transmission / reception timing. The echo signal (b, d, f) is selected at the next transmission / reception timing. Further, the echo signal (c, e, a) is selected at the next transmission / reception timing.

  The echo signals selected by the echo signal selection unit 32 and having different phases by 120 ° are added by the adder 33 to obtain an echo signal in which the fundamental wave component is canceled as described with reference to FIG. By outputting the output of the adder 33 to the band-pass filter 14 of FIG. 19, a contrast image of the three-pulse method can be obtained.

As described above, according to the present embodiment, it is possible to obtain a three-pulse contrast image with excellent image quality at the frame rate of a normal B-mode image.
(Embodiment 3)

  In FIG. 21, the block diagram of other embodiment of the image data collection part 30 is shown. In this embodiment, contrast image data of the 3-pulse method and 2-pulse method can be collected simultaneously. The difference between the present embodiment and the second embodiment shown in FIGS. 19 and 20 is the configuration of the image data collection unit 30. That is, as shown in FIG. 21, an echo signal selection unit 35 for the two-pulse method is provided in parallel with the echo signal selection unit 32 for the three-pulse method, and an adder 36 is provided in accordance with this, and further an adder 33 is provided with a correlation processing unit 37 that takes in the outputs of 33 and the adder 36 and performs correlation processing to generate contrast image data.

  Here, the configurations and operations of the echo signal selection unit 32 and the adder 33 for the three-pulse method are the same as described with reference to FIG. The echo signal selection unit 35 is configured to take in six types of echo signals a to f and select two echo signals whose phases are different by 180 °. The two echo signals thus selected are added by the adder 36. The echo signal selection unit 35 and the adder 36 are controlled by the echo signal selection control unit 34.

  The operation of this embodiment will be described. First, the echo signal selection control unit 34 stores the echo signal output from the reception memory selection unit 11 in accordance with the transmission / reception timing of the ultrasonic wave based on the command of the transmission / reception sequence control unit 6. 31f is sequentially switched. In the same manner as described in the second embodiment, the echo signal selection unit 32 has a phase of 120 degrees from the six types of echo signals a to f in accordance with the transmission / reception timing of the ultrasonic wave according to the command of the echo signal selection control unit 34. Three different types of echo signals are selected. On the other hand, the echo signal selection unit 35 has a function of selecting two types of echo signals whose phases are different from each other by 180 ° from the six types of echo signals a to f in accordance with an instruction from the echo signal selection control unit 34. For example, the echo signal (a, d) is selected at a certain transmission / reception timing. The echo signal (b, e) is selected at the next transmission / reception timing. Further, the echo signal (c, f) is selected at the next transmission / reception timing. Then, this selection operation is repeated. The echo signals selected by the echo signal selection unit 35 and having phases different by 180 ° are added by the adder 36, so that the fundamental components cancel each other and the second harmonic components cancel each other as described in FIG. Echo signals emphasized by each other are obtained.

  In this way, echo signals (contrast image data) of the 3-pulse method and the 2-pulse method are obtained simultaneously from the adder 33 and the adder 36 at every ultrasonic transmission / reception timing. The contrast image data of the three-pulse method and the two-pulse method are input to the correlation processing unit 37. The correlation processing unit 37 determines which one of the three-pulse method and the two-pulse method is displayed on the display unit. As this determination criterion, the determination criterion of the determination unit 27 described in the first embodiment can be applied. In this case, it is possible to determine for each pixel of both contrast images, and switch to each pixel to generate a one-frame contrast image in which contrast images of the three-pulse method and the two-pulse method are mixed. The contrast image data output from the correlation processing unit 37 in this way is input to the band pass filter 14, processed by the envelope detector 16 and the scan converter 18, and then displayed on the display unit 19.

  It should be noted that instead of the correlation processing unit 37, it is possible to use a simple switch and select and switch any contrast image in a practical manner. Further, as described in the first embodiment, switching can be performed according to conditions such as a diagnostic part, a diagnostic depth, and a use frequency. Further, switching can be performed according to a preset procedure in accordance with these conditions. Further, the correlation processing unit 37 can also make a comprehensive determination by assigning a weight to the physical quantity to be compared in accordance with conditions such as the depth direction or the beam scanning direction. Furthermore, it is possible to add an evaluation based on a plurality of images over time.

  Further, the correlation processing unit 37 can be omitted, and the band-pass filter and the envelope detector can be increased by one series, and the contrast image of the 3-pulse method and the 2-pulse method can be individually displayed on the display unit 19.

1 is an overall configuration diagram of an ultrasonic diagnostic apparatus according to a basic form of the present invention. It is a figure which shows an example of the echo signal from the point reflector in the biological soft tissue which has the nonlinear propagation characteristic obtained by the 3 pulse method of this invention. It is a figure explaining the principle of PI method based on the principle of vibration of an in-line 4 cylinder 4 stroke engine. It is a figure explaining the principle of the 3 pulse method of this invention based on the principle of a vibration of an inline 6 cylinder 4 stroke engine. It is a figure which shows an example of the echo signal from the point reflector in the biological soft tissue which has the nonlinear propagation characteristic obtained by PI method. It is a figure which shows an example of the scattering echo signal by the micro-habble type contrast agent obtained by the 3 pulse method of this invention. It is a figure which shows an example of the waveform after the band-pass filter of the scattered echo signal by the micro-habble type contrast agent obtained by the 3 pulse method of this invention. It is a figure which shows an example of the scattering echo signal by the micro-habble type contrast agent obtained by PI method. It is a figure which shows an example of the scattering echo signal by the micro-habble type contrast agent obtained by PI method. In the 3-pulse method of this invention, it is a figure which shows an example of the echo signal from the point reflector in the biological soft tissue obtained when a 2nd harmonic is intentionally superimposed on a transmission pulse. In the three-pulse method of this invention, it is a figure which shows an example of the scattering echo signal by the contrast agent of a microhavable system obtained when a 2nd harmonic is intentionally superimposed on a transmission pulse. In the three-pulse method of this invention, it is a figure which shows an example of the waveform after a band-pass filter of the scattered echo signal by the micro-habble type contrast agent obtained when a 2nd harmonic is intentionally superimposed on a transmission pulse wave. is there. It is a figure which shows an example of the waveform of the adder output signal of the echo signal from the point reflector in the biological soft tissue obtained when there is an error in the phase of the transmitted pulse in the three-pulse method of the present invention. In the three-pulse method of the present invention, it is a diagram showing the phase error dependence of the amplitude of the adder output signal of the echo signal from the point reflector in the living soft tissue obtained when there is an error in the phase of the transmitted pulse is there. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. It is a flowchart explaining the processing operation of the 3 pulse method of FIG. 15 embodiment. It is a flowchart explaining the processing operation of the 2 pulse method of FIG. 15 embodiment. It is a flowchart explaining the processing operation | movement which determines automatically the image displayed based on the echo signal obtained by the 3 pulse method and 2 pulse method of FIG. 15 embodiment. It is a whole block diagram of the ultrasound diagnosing device of other embodiment of this invention. It is a figure which shows an example of a structure of the principal part of one Embodiment of FIG. It is a figure which shows another example of a structure of the principal part of one Embodiment of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic probe 2 Changeover switch 3 Transmission beam former 4 Transmission waveform selection part 5 Transmission waveform memory 6 Transmission / reception sequence control part 10 Reception beam former 11 Reception memory selection part 12, 21 Reception waveform memory 13, 22 Adder 14, 15 Bandpass filter 16, 17 Envelope detector 18 Scan converter 19 Display unit 20, 23 Frame memory 24 Switcher 25 Comparator 26 Comparison result memory 27 Judgment unit 28 Transmission selection control unit

Claims (9)

  N transmission pulses (where N is an integer greater than or equal to 3) are formed by rotating the phase of an ultrasonic carrier wave whose amplitude is modulated by a common envelope signal by 360 ° / N. The N transmission pulses Is sequentially transmitted from the ultrasonic probe to the subject, and one image is reconstructed and displayed based on a signal obtained by adding N echo signals received by the ultrasonic probe. Diagnostic device.   The N is 6, the six transmission pulses are repeatedly transmitted, the six echo signals corresponding to the transmission pulses are repeatedly stored in a memory, and the six echoes stored in the memory are stored. The ultrasonic diagnostic apparatus according to claim 1, wherein the one image is reconstructed based on a signal obtained by adding three echo signals whose phases of the carrier wave are 120 ° apart from each other.   The ultrasonic diagnostic apparatus according to claim 1, wherein the phase of the carrier wave of the N transmission pulses has an allowable error of ± 10 °. N transmission pulses (where N is an integer greater than or equal to 3) are formed by rotating the phase of an ultrasonic carrier wave whose amplitude is modulated by a common envelope signal by 360 ° / N. The N transmission pulses Are sequentially transmitted from the ultrasonic probe to the subject, and a first measuring means for reconstructing one image based on a signal obtained by adding N echo signals received by the ultrasonic probe. When,
Two transmission pulses formed by rotating the phase of an ultrasonic carrier wave by 180 ° are sequentially transmitted from the ultrasonic probe to the subject and received by the ultrasonic probe. And a second measuring means for reconstructing one image based on a signal obtained by adding the echo signals.   The ultrasonic diagnostic apparatus according to claim 4, further comprising a switching unit that switches between the first measuring unit and the second measuring unit.   6. The switching means switches the first measuring means and the second measuring means by comparing the addition signals of the first measuring means and the second measuring means. An ultrasonic diagnostic apparatus according to 1.   Transmission pulse forming means for forming six transmission pulses by rotating the phase of an ultrasonic carrier wave whose amplitude is modulated by a common envelope signal by 60 °, and ultrasonic waves by shifting the six transmission pulses by shifting the time Transmission control means for repeatedly transmitting from the probe to the subject, a memory for storing each of the six echo signals received by the ultrasonic probe, and the six of the above-mentioned stored in the memory First processing means for selecting and adding three echo signals whose phases of the carrier wave are 120 ° apart from each other among the echo signals, and among the six echo signals stored in the memory, A second processing means for selecting and adding two echo signals whose phases are 180 ° apart from each other; and at least one image is reconstructed based on the signals added by the first and second processing means Image generation means to And an ultrasonic diagnostic apparatus comprising display means for displaying the reconstructed image. The image generation means includes a first means for generating a first image based on the signal added by the first processing means, and a second based on the signal added by the second processing means. A second means for generating an image;
The ultrasonic diagnostic apparatus according to claim 7, wherein the display unit displays the first and second images side by side.   The ultrasonic diagnostic apparatus according to claim 8, wherein the display unit combines and displays at least a part of the first and second images into one image.

Images