JP4269131B2 - Ultrasound contrast drawing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasound contrast drawing apparatus that draws information necessary for diagnosis such as blood flow distribution information using an ultrasound contrast agent, and more particularly to a technique that enables a contrast agent distribution to be drawn as a clear image.
[0002]
[Prior art]
As a method for measuring blood flow distribution information in a living tissue, an ultrasonic contrast drawing method and apparatus using an ultrasonic contrast agent have been studied. For example, the document “Ultrasound in Medicine & Biology, Vol. 26, No. 6, p.965, 2000,” Ultrasound Contrast Imaging: Current and New Potential Methods: Peter JA Frinking et al. . ""It is described in.
[0003]
An ultrasound contrast agent is generally formed by mixing a large number of bubbles in a medium such as physiological saline. The bubbles are formed, for example, by covering an inert gas (C ₃ F ₈ , C ₄ F _10, etc.) with a protein film or a lipid film. The particle size distribution of the bubbles is, for example, a Gaussian normal distribution, and the average particle size is several μm.
[0004]
Such a contrast agent is generally injected into a living body from a vein. When an ultrasound beam is irradiated onto a contrast medium injected into a living body, when the sound pressure is low, bubbles are deformed, and acoustic information associated with the deformation is mixed with the reflected signal and emitted as an ultrasonic response signal. . When the sound pressure is high, the bubbles are destroyed and strong acoustic information is emitted. That is, the ultrasonic contrast agent exhibits a non-linear response to the irradiation of the ultrasonic wave, and when the ultrasonic wave having the fundamental frequency f ₀ is irradiated, the response signal is doubled in addition to the signal corresponding to the fundamental frequency component f _0. It is said to include the signal harmonics 2f ₀ frequency.
[0005]
Therefore, conventionally, to extract the 2f ₀ using a relatively narrow band pass filter center frequency 2f _0, whereby by attenuating the fundamental frequency component f ₀ of the response signal of tissue, detecting the presence of the contrast agent To be done. That is, the presence or absence of 2f ₀ corresponds to the presence or absence of the contrast agent, since the magnitude of the 2f ₀ corresponds to the spatial density distribution of the contrast agent can be a contrast agent in which part of the organization to draw or flows.
[0006]
By the way, in the drawing method using a contrast agent, it is divided roughly into an early stage and a late stage according to the time phase after the contrast agent is injected into the vein. The initial phase is a time phase in which an ultrasound contrast agent injected from a vein flows into a tissue such as a liver to be diagnosed by blood circulation. Further, the latter phase is a time phase in which the ultrasound contrast agent flowing or distributed in the tissue is sufficiently flowed out of the tissue by blood circulation after 3 to 8 minutes after the contrast agent is injected from the vein. In the initial time phase, in general, an ultrasonic sound pressure (for example, MI: mechanical index = 0.2) that does not destroy the contrast agent but generates sufficient harmonics is used. In the late time phase, most of the contrast agent flows out of the tissue, but some is trapped in the tissue. The presence or absence of this trap is considered to be different between the diseased part and the healthy part of the tissue. In this late time phase, when an ultrasonic wave with a high sound pressure (for example, MI = about 0.8 or more) that destroys the contrast agent is irradiated, strong reflection occurs when the contrast agent is destroyed. Produces a signal. Therefore, by detecting this, a region where the contrast agent is trapped, that is, a diseased part, and a region where it is not trapped, that is, a healthy part can be distinguished, which can contribute to diagnosis.
[0007]
On the other hand, U.S. Pat. No. 5,632,277 and U.S. Pat. No. 5,706,819 have conventionally been proposed as methods for extracting harmonics using non-linearity related to the frequency of a contrast agent response signal without using a band pass filter. According to these, after the ultrasonic pulse based on the first ultrasonic signal is irradiated into the living body and the response signal is received, the second is obtained by inverting the polarity of the first ultrasonic signal at a short time interval. An ultrasonic pulse based on the ultrasonic signal is irradiated and a response signal is received. Then, by adding the received signals, the component corresponding to the fundamental frequency component f ₀ in the response signal is removed, and the harmonic component 2f ₀ is emphasized, thereby detecting the contrast agent with high accuracy. I can do it.
[0008]
In Japanese Patent Laid-Open No. 2000-300554, the first ultrasonic signal is divided into a period t _{1 in} which the signal level is a constant positive value and a period t _{2 in} which the signal level is a negative constant value in this order. It is proposed that the first ultrasonic signal be a second ultrasonic signal having a waveform that is inverted with respect to the time axis. According to this, the symmetry of the ultrasonic pulse based on the first and second ultrasonic signals can be increased, and the signal of the fundamental wave component (linearity component) can be reduced.
[0009]
[Problems to be solved by the invention]
Any of the conventional techniques described above is effective for extracting or enhancing the harmonic component 2f ₀ caused by the contrast agent. However, no consideration is given to the case where the harmonic component contained in the tissue response signal is so large that it cannot be ignored compared to the harmonic component contained in the contrast agent response signal.
[0010]
That is, the non-linear phenomenon that is the key to conventional contrast medium detection also occurs when ultrasonic waves propagate through the tissue in addition to the contrast medium. In this case as well, a harmonic component 2f ₀ having a frequency twice the fundamental frequency f ₀ of the irradiated ultrasonic wave is generated. In particular, the intensity of the harmonic component 2f ₀ signal included in the tissue response signal increases as the depth increases, that is, as the propagation length increases. Therefore, the harmonic component 2f ₀ of the tissue response signal is compared to the signal of the harmonic component 2f ₀ included in the response signal of the contrast medium, at the same level or greater level, hinder the contrast agent detection. For example, when detecting a contrast medium in a blood vessel buried in a tissue such as a blood flow in the liver, a harmonic component of 2f ₀ is emitted from both the contrast medium and the tissue. May be detected incorrectly. That is, it the harmonic component emphasizing prior art 2f _0, can not be discriminated harmonics 2f ₀ of the living tissue, the detection accuracy of the harmonic components of the contrast agent is reduced, improving the sharpness of the contrast image May not be possible.
[0011]
Therefore, an object of the present invention is to discriminate and extract a harmonic component included in a response signal of a biological tissue and a harmonic component included in a response signal of a contrast agent.
[0012]
[Means for Solving the Problems]
First, the solution principle of the present invention will be described with reference to FIG. FIG. 2 is a result of a detailed examination of the nonlinear response between the contrast agent and the tissue with respect to the ultrasound irradiation, and schematically shows the spectrum of the response signal when the contrast agent distributed in the tissue is irradiated with the ultrasound. In the figure, the horizontal axis indicates the frequency, and the vertical axis indicates the signal intensity of each component. FIG. 6A shows a response signal from a relatively shallow part close to the probe, and FIG. 4B shows a response signal from a relatively deep part far from the probe. As can be seen from these figures, in both the shallow region and the deep region, the contrast agent response signal 1 includes harmonic components over a wide frequency band in addition to the fundamental component corresponding to the fundamental frequency f _0. include. On the other hand, the response signal 2 organizations, appearing divided into a harmonic component 2b of the fundamental wave component 2a and the second harmonic 2f ₀ of the fundamental frequency f _0. In the case of the shallow part, the harmonic component 2b is not so strong, but becomes very strong in the deep part and becomes stronger than the signal intensity of the response signal 1 of the contrast agent. As described above, this is because the harmonic component 2b included in the tissue response signal is generated by a nonlinear effect when the ultrasonic wave propagates in the tissue, and therefore propagates as it becomes deeper away from the probe. This is because the length increases. Therefore, even if an attempt is made to extract the component of the harmonic 2f ₀ uniformly and enhance the response signal of the contrast agent as in the prior art, the harmonic component 2f ₀ of the tissue is emphasized except in a shallow region. Therefore, the sharpness of the contrast image cannot be improved.
[0013]
Here, items derived from the consideration of FIG. 2 will be organized.
(1) The frequency component (nonlinear response) of the response signal of the contrast agent is not localized at 2f ₀ but is distributed over a wide band. This tendency becomes more prominent as the frequency spectrum of the ultrasonic signal to be transmitted is wider.
(2) The response signal of the contrast agent strongly depends on the diameter of the contrast agent, and is remarkably emphasized at the free resonance frequency fR of the contrast agent. As described above, since the contrast agent has a particle size distribution, harmonics appear in a wide frequency band.
(3) The fundamental wave component of the contrast agent response signal is as strong as the fundamental wave component of the tissue response signal.
(4) The harmonics of the response signal of the tissue are relatively localized near 2f ₀ regardless of the intensity of the ultrasonic sound pressure.
(5) The harmonic of the response signal of the tissue is significantly weaker than the harmonic component of the contrast agent in the case of a relatively low ultrasonic sound pressure and in a shallow region.
[0014]
In view of the above considerations (1) to (5), the present invention solves the above problems by means of a solution having the following characteristics.
(First feature)
An ultrasonic probe that transmits and receives ultrasonic waves to and from a living body, a transmitter that transmits ultrasonic signals to the ultrasonic probe, and an ultrasonic response signal received by the ultrasonic probe. A receiving unit for processing, and a drawing unit for creating a tomogram based on the response signal processed by the receiving unit, wherein the receiving unit extracts a specific frequency component from the response signal; has a filter, the pass band width of the filter is comprised of an average frequency of the transmitted to the ultrasonic probe wherein the ultrasonic signal when the f _0, is set to 0.8f ₀ to 2.5f ₀ super An ultrasound contrast imaging apparatus is used.
[0015]
That is, the contrast agent response signals are distributed over a wide frequency band, and the signal intensity is high over a wide frequency band, so that the contrast signal is not limited to 2f ₀ but covers a wide frequency band of 0.8 to 2.5f _{0 as} in the past. The response signal is extracted by a band pass filter. Thereby, the response signal of the contrast agent can be relatively emphasized as compared with the response signal of the tissue. In particular, in the case of a relatively weak sound pressure (initial time phase), the harmonic component 2f ₀ of the tissue can be ignored, which is effective.
[0016]
In the case of high sound pressure (late time phase) is sometimes not negligible harmonics 2f ₀ of the tissue. In this case, it is preferable to remove the harmonic component 2f ₀ of the tissue by setting the bandwidth of the band pass filter to 0.8 to 1.8f ₀ . That is, to remove or attenuate the harmonic component 2f ₀ was exclusively be emphasized in the prior art, there are other features of the present invention. In this case, although the harmonic component related to the contrast agent distributed in the vicinity of 2f ₀ is attenuated, the response signal of the contrast agent distributed in a wide frequency band near 0.8 to 1.8f ₀ is extracted. , There is more to compensate for the above attenuation.
[0017]
Also, change the harmonic intensity component 2f ₀ of the tissue at a shallow depth portion and a deep depth portion. Therefore, indexing the temporal position of the response signal corresponding to the depth portion of the ultrasound beam, the response signal deeper than the set depth depth, so as to attenuate harmonics 2f ₀ a pass band width of the filter in real time It is desirable to switch. As the filter for attenuating harmonic components 2f _0, et bandpass filter, the center frequency can be used a band-elimination filter 2f _0.
[0018]
Further, the fundamental wave component of the tissue response signal existing in the vicinity of f ₀ includes a component accompanying the respiration and pulsation of the human body, which may be an artifact in the contrast agent image. In this case, it is preferable that 1.2~1.8f to ₀ set the pass bandwidth of the filter somewhat narrow.
[0019]
In this way, the harmonic 2f _{0 of the} tissue can be distinguished from the harmonic contained in the response signal of the contrast agent. Then, by detecting and drawing the contrast medium based on the harmonic of the response signal of the contrast medium extracted by discrimination, the SN ratio of the contrast image can be improved as compared with the conventional technique.
(Second feature)
As described above, the first feature of the present invention is that the passband width of the filter of the receiving unit is widened in order to emphasize and extract the response signal component of the contrast agent. In order to further promote the effect of the first feature, it is preferable that the frequency of the ultrasonic wave applied to the contrast agent is widened. That is, it is desirable that the transmission unit is configured to transmit an ultrasonic signal having a plurality of frequency components to the ultrasonic probe. In this case, the ultrasonic signal may have a waveform in which waveforms having different frequencies are continued. In either case, the average frequency f ₀ is selected as a frequency suitable for the tissue and the device.
[0020]
That is, since the contrast agent has a distributed free resonance frequency corresponding to the particle size distribution, more contrast agents respond by distributing the frequency spectrum of the irradiated ultrasound over a wide band, and the contrast agent The response signal itself is enhanced. As a result, the tissue response signal is centered at f ₀ and 2f ₀ , whereas the contrast agent response signal appears at a strong level over a wider frequency band, so that the tissue harmonic and the contrast agent harmonic are It becomes easier to discriminate.
(Third feature)
The first and second features described above are for the case where contrast drawing is performed based on a response signal received by one irradiation of an ultrasonic beam. However, the first and second features of the present invention are not limited to the one-irradiation contrast-enhanced drawing of the ultrasonic beam, but the so-called two-irradiation-type (or multiple-irradiation-type) contrast drawing method described below. It can also be applied to. In particular, the multiple-irradiation method is effective when drawing is performed by detecting in real time the disappearance due to the movement or destruction of the contrast agent. That is, when detecting the movement or disappearance of the contrast agent, two images before and after the movement or before and after the disappearance are required. However, when the contrast medium is drawn by the one-time irradiation method, the time interval between the two images is limited to one frame time interval (10 to 20 milliseconds). Therefore, when detecting a site where the blood flow velocity is high or a contrast medium rupture, a multiple irradiation method is preferable. In the multiple irradiation method, an ultrasonic beam is irradiated twice or more in the same direction at an extremely short time interval, and the response signal corresponding to each irradiation is compared, and the contrast agent is placed on the ultrasonic beam within a predetermined time interval. It can be detected by comparing the response signals whether the contrast medium has moved or the contrast medium has been destroyed and disappeared.
[0021]
Specifically, the transmission unit has a function of transmitting an ultrasonic beam a plurality of times (M, however, a natural number of M ≧ 2) with a time interval in the same direction, and each ultrasonic signal has a different frequency. It is assumed that the signal consists of a continuation of the waveform, and that each signal is transmitted so as to be asymmetric with respect to polarity inversion. In accordance with this, the receiving unit attenuates the response signal of the biological tissue by adding or subtracting the response signal subjected to the phasing process and the function of phasing the response signal of a plurality of (M) ultrasonic signals. It is characterized by having a function to perform. In this case, it is most preferable that the average frequency f ₀ of each waveform is equal.
[0022]
According to this, since the frequency band of the ultrasonic wave irradiated into the living body is widened compared with the conventional two-time irradiation method, the harmonic component included in the response signal of the contrast agent can be strengthened over a wide frequency band. . At the same time, the frequency spectrum of the response signal of the contrast medium also frequency shift, by adding or subtracting processing, will be widely distributed to the band around 1.2f ₀ to 1.8F _0. As a result, the harmonic component contained in the response signal of the living tissue can be discriminated from the harmonic component contained in the response signal of the contrast agent. Then, by detecting and drawing the contrast agent by the harmonic of the response signal of the contrast agent thus discriminated, the SN ratio of the contrast image can be improved as compared with the conventional case.
[0023]
For example, the frequency spectrum of the contrast agent response signal obtained by the addition or subtraction process is emphasized in the band near 1.2f _{0 to} 1.8f ₀ and rather attenuated near 2f ₀ . Therefore, by receiving and processing the response signal over a wide frequency band, the response signal SN ratio of the contrast agent can be increased, and the response signal of the contrast agent can be selectively drawn.
[0024]
In addition, the configuration of the transmission unit described above has a function of transmitting an ultrasonic beam a plurality of times (M, however, a natural number of M ≧ 2) at intervals in the same direction, and the frequencies are f1, f2,. fn, ..., fN (where natural number N ≧ 2) becomes by continuously of N waveforms, when the average frequency of f1 to fN was _{f 0,} the frequency distribution width Δf of f1 to fN are 0.0f ₀ It is preferable that the signal is set within the range of _{0.4 to 0} and the signals are transmitted so as to be asymmetric with respect to the polarity inversion. According to this, the response signal component of the contrast agent can be further enhanced. Further, although not particularly limited in the frequency distribution width Delta] f, preferably when the range of 0.1f ₀ to 0.4F _0, further 0.2F ₀ to the range of 0.3f _0, practically from the circuit configuration.
[0025]
In addition, the unit waveform which forms each said waveform can use the half cycle of a sine wave, 1 cycle or more. Conversely, it is possible to use a chirp waveform in which the frequency is made finer, such as ¼ cycle and 、 cycle, and the frequency continuously increases and decreases. In the case of a chirp waveform, the start phase of the first irradiation waveform is actually different, but a chirp waveform whose amplitude gradually decreases from the start waveform toward the subsequent waveform, that is, an amplitude-enhanced chirp waveform is suitable for the present invention. It is. According to this, the difference in the frequency spectrum of the contrast medium between the two irradiations can be further emphasized by the amplitude stress.
[0026]
Further, the waveform at each time is set by a code f (A, θ) that defines the frequency f, the amplitude A, and the start phase θ, and f1 (A1, θ1) <f2 (A2, θ2) <. An, θn) <... <FN (AN, θN) N waveforms are continued, the amplitude is A1 = A2 = ... = An = ... = AN, and the phase is θ1 = θ2 = ... = θn = ... = The first waveform is set to θN = 0 ° (or 180 °). On the other hand, f1 ′ (A1 ′, θ1 ′)> f2 ′ (A2 ′, θ2 ′)>...> Fn ′ (An ′, θn ′)>...> FN ′ (AN ′, θN ′) N waveforms. , The amplitude is A1 '= A2' = ... = An '= ... = AN', and the phase is θ1 '= θ2' = ... = θn '= ... = θN' = 0 ° (or 180 °) It is preferable to set the second waveform. That is, the first waveform and the second waveform may have the frequency sequence increase / decrease relationship reversed, the start phase may be the same, and the amplitude may be the same or different. In this case, the response signal subjected to phasing is subtracted to attenuate the response signal of the living tissue.
[0027]
Preferably, the first waveform and the second waveform are set by a code f (A, θ) that defines the frequency f, the amplitude A, and the start phase θ, and the first waveform is f1 (A1, θ1) <f2. N waveforms of (A2, θ2) <... <fn (An, θn) <... <fN (AN, θN) are continuous, and the amplitude is A1 = A2 = ... = An = ... = AN. Is set to θ1 = θ2 = ... = θn = ... = θN = 180 °, and the second waveform is f1 ′ (A1 ′, θ1 ′)> f2 ′ (A2 ′, θ2 ′)>...> Fn ′ (An ′ , Θn ′)>...> FN ′ (AN ′, θN ′), and N waveforms are continued, the amplitude is A1 ′ = A2 ′ =... = An ′ =... = AN ′, and the phase is θ1 ′. = Θ2 '= ... = θn' = ... = θN '= 0 °. In this case, the response signal subjected to the phasing process is added to attenuate the response signal of the living tissue.
[0028]
Here, since the first waveform starts from the falling (negative polarity side) because the start phase is 180 °, it is assumed that the waveform continues from the low frequency f1 <fN, and conversely, the second waveform has a start phase of 0 °. Therefore, since it starts from the rising edge (positive polarity side), it is characterized in that the waveform is continuous from the high frequency fN ′> f1 ′. That is, since the bubbles of the contrast medium is irradiated with ultrasonic waves falling waveform starts deformed from the expanded, the frequency distribution of the response signal is shifted to a lower frequency side than the average frequency f _0. On the other hand, since the contrast medium when irradiated with ultrasonic waves in the rising waveform starts deform from a contracted, the frequency distribution of the response signal is shifted to a frequency side higher than the average frequency f _0. Therefore, by setting the codes of the first and second waveforms as described above, the frequency distribution of the response signal of the contrast agent can be further expanded, and the response signal component of the contrast agent can be further enhanced. There is an effect.
[0029]
In the above case, that the frequency distribution width Δf and Δf of f1 to fN and f1 'to fN'', it is variably set within a range of 0.0f ₀ to 0.4F ₀ depending on the depth of each ultrasound irradiation focused preferable. Alternatively, the frequency distribution widths Δf and Δf ′ of f1 to fN and f1 ′ to fN ′ are set to 0.0f ₀ for a predetermined time after the injection of the contrast agent, for example, 2 minutes, and 0.0f after 2 minutes. ₀ to can variably set to within a range of 0.4F _0.
[0030]
In the third aspect, the receiving unit shall have a filter for extracting a specific frequency component from the response signal response signal of the living tissue is attenuated, the average frequency f ₀ of the pass band of the filter as a reference, it is preferably set to 0.8f ₀ to 1.8F _0. According to this, it is possible to further remove the harmonic 2f ₀ of the tissue remaining in the addition / subtraction process, and to emphasize the signal component of the contrast agent. Further, you are preferable to set the pass bandwidth of the filter to 1.2f ₀ to 1.8F _0. According to this, it is possible to suppress the artifacts that appear in the fundamental frequency f ₀ near the previously mentioned. Furthermore, the pass band width of the filter can be variably set according to the depth of the response signal or the ultrasonic sound pressure to be irradiated. For example, the band pass width of the filter can be widened at a shallow part or an initial time phase, and the filter band pass width can be narrowed at a deep part or a late time phase.
[0031]
In the above description, the waveform of the ultrasonic signal supplied to the ultrasonic probe has been described. However, the present invention also holds true for the waveform of the ultrasonic sound pressure applied to the contrast agent itself. In other words, if the frequency response characteristics of recent ultrasonic probes have a relative bandwidth of 60% or more with respect to the center frequency, it is confirmed that the theory of the waveform of the ultrasonic signal is directly applied to the theory of the acoustic waveform. Yes.
[0032]
Embodiment
Hereinafter, the present invention will be described based on embodiments shown in the drawings. In addition, this invention is not limited by embodiment shown below.
(First embodiment)
FIG. 1 shows an overall configuration diagram of an ultrasonic contrast drawing apparatus according to an embodiment to which the present invention is applied. This embodiment is suitable for implementing the first feature and the second feature of the present invention. As shown in FIG. 1, the ultrasound contrast imaging apparatus 100 includes a probe 10, a wave transmission unit 20, a wave reception unit 30, an image creation display unit 40, and a system control unit 50. The wave transmission unit 20 includes an arbitrary waveform generator 21 and a transmitter 23. The wave receiving unit 30 includes a wave receiver 31, a phasing adder 32, and a band selection filter 34.
[0033]
The arbitrary waveform generator 21 of the transmission unit 20 is configured to generate an ultrasonic signal having a single frequency f ₀ when realizing the first feature, and when realizing the second feature. As shown in a waveform 71 shown in FIG. 3, an ultrasonic signal having a plurality of frequencies and an average frequency f ₀ is generated. The output of the arbitrary waveform generator 21 is supplied to the broadband ultrasonic probe 10 via the transmitter 23. A power amplifier having a necessary number of channels corresponding to the array-type ultrasonic probe 10 is provided in parallel at the output unit of the transmitter 23. Ultrasonic pulses mean frequency f ₀ In this way from the ultrasound probe 10 is irradiated to a living tissue. The response signal from the contrast agent distributed in the living tissue and the response signal from the living tissue are received by the ultrasonic probe 10 as a mixed signal. As shown in FIG. 2, the response signal from the contrast agent includes a harmonic component over a wide frequency band in addition to the component of the fundamental wave f ₀ . The response signal from the tissue includes a component of the fundamental wave f ₀ and twice component harmonic 2f _0.
[0034]
The response signal received by the ultrasonic probe 10 is input to the receiver 31. The receiver 31 includes a preamplifier having the required number of channels, a TGC amplifier, an A / D converter, and the like. The input response signal is amplified and then converted into a digital signal and output to the phasing adder 32. To do. The phasing adder 32 adjusts and adds phases of response signals from a plurality of transducers related to one ultrasonic beam. A specific example of the phasing adder 32 is preferably a so-called digital beamformer in order to minimize the occurrence of distortion during the addition process. The reason is that unnecessary harmonic 2f ₀ component is not generated by the phasing addition processing.
[0035]
The response signal phasing and added by the phasing adder 32 is supplied to the band pass filter 34. The bandwidth of the band pass filter 34 can be variably adjusted as will be described later. The band-pass width is adjusted by forming the band-pass filter 34 with a digital filter known as a digital FIR filter, and each coefficient sequence of the digital FIR filter by the system control unit 50 according to the depth or the ultrasonic sound pressure. This can be realized by varying the value. As the digital filter, a third-order Chebyshoff type filter is particularly suitable. The response signal having the frequency component selected and extracted by the band pass filter 34 is sent to the image creation / display unit 40 as a signal caused by the contrast agent in common or in parallel with processing other than the contrast agent mode. The image creation display unit 40 performs processing including image processing such as normal detection and compression, Doppler processing such as color flow, or scan conversion processing.
[0036]
The above processing operations are performed while scanning the direction of the ultrasonic beam as many times as necessary to cover a desired cross section or region of the living tissue. And by the process of the image preparation display part 40, it displays on a display part as image information, such as a brightness | luminance as distribution of a contrast agent and a magnitude | size. The system control unit 50 controls the series of operations described above.
[0037]
The characteristic operation of the embodiment of FIG. 1 configured as described above will be described next. In contrast agent mode imaging performed by injecting contrast agent, for example, a B-mode tomographic image is captured and displayed on a display monitor, and the contrast mode image obtained by imaging in contrast agent mode is converted into a normal B-mode image. Usually, the images are displayed in an overlapping manner.
[0038]
In normal B-mode imaging, an ultrasonic signal having a single frequency of the fundamental frequency f ₀ is generated from the arbitrary waveform generator 21 based on a control command from the system control unit 50, and is transmitted by the transmitter 23. After the focus processing, the amplification is performed and supplied to the ultrasonic probe 10 to irradiate the living body with the ultrasonic beam. The response signal from the living body is amplified by the receiver 31 and converted into a digital signal, and then the phase of the response signal from the same part received by the plurality of transducers is matched in the phasing adder 32. A response signal of a specific frequency component is selected and extracted from the response signal for each ultrasonic beam subjected to phasing and addition by the band pass filter 34. For normal B-mode image capturing, the bandwidth of the band-pass filter 34 is adjusted to the band having a center frequency basic frequency f _0. The image creation / display unit 40 detects the output of the bandpass filter 34, performs image processing such as compression or scan conversion processing, and creates a two-dimensional image (B-mode image) of the living tissue to display the display (display). To draw.
[0039]
Next, imaging and drawing of a contrast agent mode image according to the features of the present invention will be described. The basic procedure and operation for capturing and drawing a contrast agent mode image are the same as those for normal B-mode image capturing.
[0040]
(When realizing the first feature)
When the first feature of the present invention is realized using the embodiment of FIG. 1, an ultrasonic signal having a single fundamental frequency f ₀ is generated from the arbitrary waveform generator 21 as in the case of tissue imaging. Then, the desired part of the living body is scanned and irradiated with the ultrasonic beam. As is well known, the ultrasonic signal is resembling a waveform in a living body by applying a Hanning weight in the time axis direction. Similarly to the case of tissue imaging, the response signal from the living body is amplified and phased by the receiver 31 and the phasing adder 32 as in the case of tissue imaging.
[0041]
The element according to the first feature of the present invention is a band-pass filter 34 that extracts a contrast agent-derived response signal included in the response signal subjected to the phasing process. That is, as described with reference to FIG. 2, the response signal 1 caused by the contrast agent has a higher signal strength and exists over a wide frequency band than the fundamental wave component 2a and the harmonic component 2b of the tissue response signal. . Therefore, the present embodiment is characterized in that the bandpass width of the bandpass filter 34 is widened to emphasize the contrast agent response signal relative to the tissue response signal. In particular, the bandwidth of the band pass filter 34 is preferably variably adjusted as in the following (A), (B), and (C).
(A) depending on the depth of the contrast agent distribution, in the case of shallow sites, and adjusted to 0.8f ₀ to 2.5f _0, the 0.8f ₀ to 1.8F ₀ if deep, preferably 1.2f ₀ to 1.8F Change to ₀ (or 1.1f _{0 to} 1.8f ₀ ).
(B) In the initial phase after contrast agent injection, the amplitude of the ultrasonic signal to be transmitted is set to the initial low sound pressure (MI = about 0.4 to 0.7). Then, in the case of a shallow region is adjusted to 0.8f ₀ to 2.5f ₀ in the same manner as (1).
(C) In the later phase after injection of the contrast agent, the bandwidth of the bandpass filter 34 is 0.8 f ₀ in conjunction with the amplitude of the ultrasonic signal to be transmitted in the latter period of high sound pressure (MI = about 1.0 to 1.3). or to 1.8F _0, preferably changed to 1.2f ₀ to 1.8F ₀ (or, 1.1f ₀ to 1.8F _0).
[0042]
That is, in the case of a relatively weak sound pressure or the initial time phase, the harmonic component 2f ₀ of the tissue can be ignored. Therefore, by extracting a response signal over a wide frequency band 0.8 to 2.5 f _{0, the} response signal of the contrast agent can be relatively emphasized as compared with the response signal of the tissue. In the case of a deep depth, the high-frequency component 2f _{0 of the} tissue becomes strong, but even if a response signal ranging from 0.8 to 2.5f ₀ is extracted, the response signal of the contrast agent can be emphasized as compared with the prior art. On the other hand, when the sound pressure is high as in the late phase, since the harmonic component 2f ₀ of the tissue cannot be ignored, the bandwidth is set to 0.8 to 1.8f ₀ and the harmonic component 2f ₀ of the tissue is removed or attenuated. To do. In this case, the harmonic component related to the contrast agent distributed in the vicinity of 2f ₀ is attenuated. However, since the response signal of the contrast agent distributed over a wide frequency band is extracted, there is a sufficient compensation for attenuation. In addition, the fundamental component of the response signal of the tissue existing in the vicinity of f ₀ includes a component accompanying the breathing and pulsation of the human body. When artifacts occur in the contrast agent image, the passband width of the filter is slightly narrowed. It is preferable to set to 1.2 to 1.8f ₀ (or 1.1f _{0 to} 1.8f ₀ ).
[0043]
The switching of the bandwidth is controlled by the system control unit 50 based on the set transmission focus or reception focus. For example, since the depth of the response signal corresponds to the time axis, the system control unit 50 sets the bandwidth to 0.8 f ₀ to 2.5 f when the time position of the response signal input to the band pass filter 34 is shallower than the set depth. to _0, a deep range switches in real time 1.2f ₀ to 1.8F _0.
[0044]
By adjusting the bandwidth of the passband filter 34 in this way, it is possible to discriminate the harmonic 2f ₀ of the tissue from the harmonic contained in the response signal of the contrast agent. Then, by detecting and drawing the contrast medium based on the harmonic of the response signal of the contrast medium extracted by discrimination, the SN ratio of the contrast image can be improved as compared with the conventional technique. As the filter for attenuating harmonic components 2f _0, et bandpass filter 34, the center frequency can be used a band-elimination filter 2f _0.
[0045]
(When realizing the second feature)
As described above, the first feature is that the response signal component of the contrast agent is enhanced and extracted by widening the passband width of the bandpass filter 34. In order to further promote this effect, the second feature is that the frequency of the ultrasonic wave irradiated to the contrast medium is widened. That is, the ultrasonic signal generated by the arbitrary waveform generator 21 is converted into an ultrasonic signal having a plurality of frequencies and an average frequency f ₀ , for example, as a waveform 71 shown in FIG. The signal has a frequency component. In FIG. 3, a waveform 71 has a waveform in which one cycle of sine waves of frequencies f ₁ and f ₂ are continued, and the average frequency of these frequencies f ₁ and f ₂ is f ₀ . In the illustrated example, f ₁ <f ₂ is set. As the average frequency f ₀ , a frequency suitable for the tissue and the device is selected. As is well known, a known Hanning weight is applied in the time axis direction to resemble the waveform in the living body. The waveform 71 may be an asymmetrical signal with respect to polarity reversal and an ultrasonic signal having a waveform reversed with respect to the time axis. By irradiating the living body with such ultrasonic signals having a plurality of frequencies, the response signal of the contrast agent becomes stronger over a wide frequency spectrum. That is, since the contrast agent has a distributed free resonance frequency corresponding to the particle size distribution, more contrast agents respond by distributing the frequency spectrum of the irradiated ultrasound over a wide band, and the contrast agent This is because the response signal itself is enhanced.
[0046]
According to a second aspect, the response signal of tissue changes to those around the f ₀ and 2f ₀ no. However, since the contrast agent response signal appears at a strong level over a wider frequency band, it becomes easier to discriminate between the harmonics of the tissue and the harmonics of the contrast agent. Here, the absolute value | f ₁ −f ₂ | of the difference between the frequencies f ₁ and f ₂ , that is, the distribution width Δf of the constituent frequencies is selected within the range of 0.0f _{0 to} 0.4f ₀ . Preferably 0.1f ₀ ~0.4f ₀ C., more preferably it is 0.2f ₀ ~0.3f _0. The arbitrary waveform generator 21 is not limited to the waveform having the _two frequencies f ₁ and f ₂ described above, and a waveform having N (≧ 2) frequencies can be applied as will be described later.
(Second Embodiment)
FIG. 4 shows an overall configuration diagram of an ultrasonic contrast drawing apparatus according to an embodiment suitable for realizing the third feature of the present invention. In the figure, components having the same basic functions as those in FIG. This embodiment is different from the embodiment of FIG. 1 in that a time axis controller 22 is provided between the arbitrary waveform generator 21 and the transmitter 23, and a phasing adder 32 and a band pass filter. 34 is provided with a line adder 33. That is, an image in which an ultrasonic signal is transmitted twice in the same direction of the ultrasonic beam with a time interval and the response signal of the contrast agent is emphasized based on the response signals of the first and second ultrasonic signals. Is going to get. In this embodiment, the waveforms of the first and second ultrasonic signals are generated symmetrically with respect to the phase axis or polarity, and the response signals corresponding to the waveforms are added to emphasize and extract the response signal of the contrast agent. This will be explained with an example.
[0047]
The arbitrary waveform generator 21 is configured to generate an ultrasonic signal having a first waveform 71 (or 72) as shown in FIG. The first waveform 71 has the same requirements as the waveform described in FIG. The second waveform 72 is a waveform that is asymmetric with respect to the polarity inversion of the first waveform 71 and is inverted with respect to the time axis. As will be described later, the first waveform 71 and the second waveform 72 can be coded by frequency, start phase, and amplitude, and the coded one-cycle waveform is continuously generated to generate an arbitrary waveform. Can do.
[0048]
The arbitrary waveform generator 21 generates two ultrasonic signals of the first waveform 71 in FIG. 5A with a time interval in the same ultrasonic beam direction under the control of the system control unit 50. The generated first ultrasonic signal bypasses the time axis controller 22 and is input to the ultrasonic probe 10 via the transmitter 23. On the other hand, the generated second ultrasonic signal is input to the time axis controller 22 under the control of the system control unit 50, where the time axis is inverted and becomes the second waveform 72 of FIG. The signal is input to the ultrasonic probe 10 through the transmitter 23. The time axis controller 22 can be composed of a shift register having a first-in / first-out function and a first-in / last-out function. In this case, a line that bypasses the time controller 23 is not necessary. In addition, when the arbitrary waveform generator 21 has a function of generating both the first waveform 71 and the second waveform 72 that have a time axis inverted relationship, the time axis controller 22 includes a data selector.
[0049]
When the ultrasonic signals of the first waveform 71 and the second waveform 72 are irradiated on the living body, two response signals for the signals are input to the receiver 31. These two response signals are response signals for ultrasonic beams in the same direction, and are input with a time lag. In the receiver 31 and the phasing adder 32, these two response signals are separately amplified, A / D converted, and phasing addition processing is performed, and a line adder / subtracter is provided as a response signal (RF line signal) having phase information. To 33. The line adder / subtracter 33 adds the two response signals to the RF in consideration of the phase, and obtains one response signal (RF line signal) to be displayed.
[0050]
In this way, in the response signal obtained by adding / subtracting the response signal of the two ultrasonic irradiations, the same component (linear component) included in the two response signals is attenuated, and the harmonics of the contrast agent and tissue Non-linear components such as components are input to the band pass filter 34. The passband filter 34 has the same configuration as that described in the embodiment of FIG. 1, and the passband width according to the depth of the response signal component and the time phase of the contrast agent based on a command from the system control unit 50. The response signal relating to the desired contrast agent is enhanced.
[0051]
The system control unit 50 controls a series of operations related to the arbitrary waveform generator 21, the receiver 31, the phasing adder 32, the line adder / subtractor 33, and the band pass filter 34. For example, for the arbitrary waveform generator 21, ultrasonic waveforms 71 and 72 are issued according to a predetermined code.
[0052]
Here, a simulation result will be described regarding that the contrast medium response signal can be effectively enhanced by performing contrast mode imaging using the first waveform 71 and the second waveform 72 shown in FIG. 5A. To do. FIG. 5B shows the line adder / subtracter 33 when the ultrasonic signal having the first waveform 71 shown in FIG. 5A is irradiated for the first time and the ultrasonic signal having the second waveform 72 shown in FIG. 2 shows an example frequency spectrum obtained by simulating a signal output from a signal. The horizontal axis of FIG. (B) is the frequency normalized by the fundamental frequency f _0, the vertical axis represents the signal intensity normalized. In FIG. 5B, a line 73 is a frequency spectrum of a transmission ultrasonic wave, and a line 74 is a frequency spectrum of a response signal output from the line adder / subtractor 33.
[0053]
In this simulation, the first waveform 71 of the first transmission has a frequency of f1 (= 1.8 MHz) in the first one cycle, and a frequency of f2 (= 2.2 MHz) in the next one cycle. f ₀ was set to 2 MHz. Further, the second second waveform 72 of the transmission is the first one cycle frequency f2 (= 2.2MHz), next one cycle at frequency f1 (= 1.8 MHz), the average frequency _{f 0} to 2MHz Set. That is, the first waveform 71 and the second waveform 72 have a symmetrical relationship that is inverted with respect to the time axis. The code “frequency f (amplitude A, phase θ)” of the first waveform 71 of the first transmission is 1.8 MHz (1.0, 180 °) and 2.2 MHz (1.0, 180 °). The codes of the second waveform 72 of the second transmission are 2.2 MHz (1.0, 0 °) and 1.8 MHz (1.0, 0 °). The frequency change width is 0.4 MHz, and the amplitude change width is 0.0. Each waveform is resembling a waveform in a living body by applying a Hanning weight in the time axis direction. The simulation is a differential equation that governs the change in the diameter of a known contrast agent, and finds the change in the contrast agent diameter when a sound pressure waveform of MI = 0.7 is added to a contrast agent having a diameter of 2 microns. The radiation wave when the diameter change is regarded as a secondary sound source is observed at an observation point far from the contrast agent.
[0054]
Here, the characteristics of the frequency spectrum of the response signal obtained by this embodiment shown in FIG. 5B will be described in comparison with the frequency spectrum of the double irradiation method according to the prior art. FIG. 6A shows a conventional ultrasonic transmission waveform, and FIG. 6B shows a frequency spectrum of the transmission signal and the response signal. Their vertical and horizontal axes are the same as in FIG. In FIG. 6A, a first waveform 81 indicates a first transmission waveform, and a second waveform 82 indicates a second transmission waveform. All of these frequencies are set to the fundamental frequency f ₀ = 2 MHz.
[0055]
When the line 74 in FIG. 5B is compared with the line 84 in FIG. 6B, the response signal component in the vicinity of the fundamental frequency f ₀ is greatly attenuated in the conventional technique, and the harmonics of the tissue in the vicinity of 2f ₀ are found. Ingredients are emphasized. This is suitable for so-called tissue harmonic imaging (referred to as Tissue Harmonic Imaging), but the response signal component of the contrast agent widely distributed from f _{0 to} 2f ₀ is attenuated. In particular, the fundamental wave component f ₀ of the response signal of the contrast agent is significantly attenuated. Therefore, in the case of the conventional two-time irradiation method shown in FIG. 6, it is not possible to satisfy the objective of distinguishing and highlighting the response signal of the contrast agent from the harmonic of the tissue. This not only emphasizes the harmonic components of the tissue response signal localized near 2f ₀ together by simply reversing the polarities or time axes of the two-time transmission ultrasonic signal waveform according to the prior art, This is because the fundamental wave component f ₀ of the contrast agent response signal distributed over a wide range is significantly attenuated.
[0056]
In this regard, according to FIG. 5B according to the present invention, the discrimination ratio between the contrast agent response signal and the harmonic of the tissue response signal is the area ratio (energy) of the band in the vicinity of 1.2f ₀ to 1.8f ₀ on the spectrum. Ratio), it is about 10 dB to 20 dB.
[0057]
Therefore, the pass band width of the band pass filter 34 is the same as described in the description of the second feature. That is, the signal obtained by the line adder 32, when the shallow portion drawing, because it contains a response signal of the contrast agent spread wide band of near 0.8f ₀ to 2.5f _0, it is drawn as effect signal of the contrast agent To do. The same applies to normal contrast medium drawing in which the ultrasonic sound pressure is MI = 0.2 to 0.7. On the other hand, if the sound pressure of the ultrasonic wave is high MI value (e.g., 1.3), to 0.8f ₀ to 1.8F _0. Note that a band elimination filter whose center frequency is 28f ₀ may be substituted. In deep portion of the drawing, in order to attenuate the harmonics of tissue near 2f _0, and in order to reduce artifacts tissue fundamental wave by the body movement, it changes the bandwidth to 1.2f ₀ to 1.8F _0. Thereby, the response signal of the contrast agent can be emphasized and drawn as compared with the second feature of the first embodiment.
[0058]
Although not shown, even if the frequencies f1 and f2 of the first waveform 71 and the second waveform 72 in FIG. 5A are interchanged, that is, the frequency f1 of the first code and the frequency f2 of the second code. Even if the relationship is f1> f2, the same effect can be obtained.
[0059]
As described above, in the second embodiment, each waveform of one cycle constituting the ultrasonic transmission waveform is coded by the frequency f, the amplitude A, and the start phase θ, and these waveforms are made continuous. In particular, as shown in the waveform of FIG. 5A, the frequency of the ultrasonic transmission signal to be irradiated twice is emphasized by making the first cycle 71 and the second waveform 72 have different frequencies in the first cycle. It is characterized by. Then, when the transmission signal with frequency emphasis is transmitted twice and the response signal is added, the distribution of the response signal of the contrast agent is a distribution in which a strong signal appears in a band centered on 2f ₀ (FIG. 6 ( B)), it was found that a low frequency shift of the frequency spectrum occurs in the distribution (FIG. 5B) in which strong signals appear in the band of 1.2f0 to 1.8.
[0060]
The reason why the spectrum of the response signal shifts at a low frequency cannot be clearly understood because the contrast agent has a nonlinear response. However, it can be considered as follows. First, the first waveform 71 starts from the fall (negative polarity side) because the start phase is 180 °. Conversely, the second waveform 72 starts from the rising edge (positive polarity side) because the start phase is 0 °. Here, because the bubbles of the contrast agent starts irradiation of ultrasonic waves falling waveform is expanded, the frequency distribution of the response signal is considered to be shifted to a lower frequency side than the average frequency f _0. On the other hand, since the contrast agent to the start of the irradiation rising waveform is contracted, the frequency distribution of the response signal is considered to be shifted to a frequency side higher than the average frequency f _0. Therefore, it is considered that the nonlinear response of the contrast agent changes depending on the relationship between the start phase and the frequency of the first waveform 71 and the second waveform 72, and the frequency spectrum of the response signal varies. In other words, by making the frequency of the start waveform different from the frequency of other waveforms that follow, the frequency spectrum of the contrast agent response signal obtained by the two irradiations is not the same, and the frequency distribution of the response signal of the contrast agent is It can be further expanded to emphasize the response signal component of the contrast agent.
(Modification of the second embodiment)
In the above embodiment, the case of irradiating ultrasonic waves twice with a time interval has been described, but the present invention can also be applied to the case of irradiating three times or more. In other words, the arbitrary waveform generator 21 and the time axis controller 22 preferably output a plurality (M) of ultrasonic signals of at least one cycle of an arbitrary signal wave including a sinusoidal shape with a time interval in the same direction of the ultrasonic beam. However, it is assumed that it has a function of generating a natural number (M ≧ 2) times. The generated ultrasonic signals are two types of ultrasonic signals of a first waveform and a second waveform that are symmetrical with respect to the phase axis or polarity. The first waveform and the second waveform have a plurality of frequency components formed by consecutive N waveforms having frequencies f1, f2,..., Fn,..., FN (where N ≧ 2 is a natural number). And Then, the ultrasonic signals of the first waveform and the second waveform are alternately switched every transmission and transmitted. In this case, it is most preferable to equalize the average frequency f ₀ of the f1 to fN of the first waveform and the second waveform. Then, the frequency distribution width Δf of f1 to fN is set within a range of 0.0f ₀ to 0.4F _0. However, preferably practically from 0.1f ₀ to a range of 0.4F _0, further 0.2F ₀ to the circuit configuration for a range of 0.3f _0.
[0061]
Note that a unit waveform forming the first waveform or the second waveform can use a half cycle of a sine wave, one cycle or more. Conversely, it is possible to use a chirp waveform in which the frequency is made finer, such as ¼ cycle and 、 cycle, and the frequency continuously increases and decreases. In the case of a chirp waveform, the start phase of the first irradiation waveform is actually different, but a chirp waveform whose amplitude gradually decreases from the start waveform toward the subsequent waveform, that is, an amplitude-enhanced chirp waveform is suitable for the present invention. It is. According to this, the difference in the frequency spectrum of the contrast medium between the two irradiations can be further emphasized by the amplitude stress.
[0062]
Further, the first waveform and the second waveform are set by a code f (A, θ) that defines the frequency f, the amplitude A, and the start phase θ, and the first waveform is f1 (A1, θ1) <f2 (A2, θ2) <... <fn (An, θn) <... <fN (AN, θN), and N waveforms are continuous, the amplitude is A1 = A2 =... = An =... = AN, and the phase is .theta.1 = .theta.2. = ... = θn = ... = θN = 180 °. On the other hand, the second waveform is f1 ′ (A1 ′, θ1 ′)> f2 ′ (A2 ′, θ2 ′)>...> Fn ′ (An ′, θn ′)>...> FN ′ (AN ′, θN ′) N waveforms are continuous, the amplitude is A1 '= A2' = ... = An '= ... = AN', and the phase is θ1 '= θ2' = ... = θn '= ... = θN' = 0 ° Set. That is, the first waveform and the second waveform may have the frequency sequence increase / decrease relationship reversed, the start phase may have a 180 ° difference, and the amplitude may be the same or different. In this case, the response signal subjected to the phasing process is added to attenuate the response signal of the living tissue. The start phase may be the same. In this case, the response signal subjected to the phasing process is subtracted to attenuate the response signal of the living tissue.
[0063]
Further, the frequency distribution width Δf and Δf of f1 to fN and f1 'to fN'', it is preferable to variably set within a range of 0.0f ₀ to 0.4F ₀ depending on the depth of the respective ultrasonic irradiation focus. Instead of this, the frequency distribution width Δf and Δf of f1 to fN and f1 'to fN'', a predetermined time after injection of the contrast agent (2 minutes) to 0.0f _0, a predetermined time (2 min) has elapsed after it can be variably set within a range of 0.0f ₀ to 0.4F _0.
[0064]
For example, when N = 3, f1 = 1.8 MHz, f2 = 2 MHz, and f3 = 2.2 MHz. Further, even if N = 4 or more, the gist of the present invention is not impaired. However, as the wave number increases, the difference between the waves is relatively reduced, and it has been confirmed that a wave number of about N <6 is effective. In addition, in the case of M ≧ 3, the addition / subtraction processing extracts the response signal component of the contrast agent, for example, by adding the odd response signals and adding or subtracting the even response signals according to the signal polarity. To do.
[0065]
【The invention's effect】
As described above, according to the present invention, the harmonic component included in the response signal of the contrast agent can be extracted as a relatively strong signal by distinguishing it from the harmonic component included in the response signal of the biological tissue. The sharpness of the agent drawing can be improved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an ultrasonic contrast drawing apparatus according to a first embodiment of the present invention.
FIG. 2 is a graph for explaining the principle that a contrast agent response signal of the present invention can be extracted at a high rate.
FIG. 3 is a diagram showing an example of an ultrasonic transmission waveform according to the first embodiment of the present invention.
FIG. 4 is an overall configuration diagram of an ultrasonic contrast drawing apparatus according to a second embodiment of the present invention.
FIG. 5 is a graph showing an example of a transmission waveform of a two-time irradiation according to the second embodiment of the present invention and a simulation result of a frequency spectrum of a transmission signal and an obtained response signal according to the transmission waveform.
FIG. 6 is a graph showing, for comparison, a transmission waveform of a two-time irradiation according to the prior art, and a simulation result of a frequency spectrum of a transmission signal and the response signal obtained by the transmission waveform.
DESCRIPTION OF SYMBOLS 10 Ultrasonic probe 20 Transmitter 21 Arbitrary waveform generator 22 Time axis controller 23 Transmitter 30 Receiver 31 Receiver 32 Phased adder 33 Line adder 34 Band pass filter 40 Image creation display 50 System controller 71 First waveform 72 Second waveform 73 Transmission signal spectrum 74 Response signal spectrum

Claims (6)

An ultrasonic probe that transmits and receives ultrasonic waves to and from a living body, a transmitter that transmits ultrasonic signals to the ultrasonic probe, and an ultrasonic response signal received by the ultrasonic probe. A receiving unit for processing, and a drawing unit for creating a tomographic image of the living body based on the response signal processed by the receiving unit, wherein the receiving unit has a specific frequency component from the response signal has a filter for extracting, pass bandwidth of the filter, when said average frequency of the ultrasonic probe wherein the ultrasonic signal transmitted to the set to f _0, is set to 0.8f ₀ to 2.5f ₀ An ultrasonic contrast drawing apparatus. An ultrasonic probe that transmits and receives ultrasonic waves to and from a living body, a transmitter that transmits ultrasonic signals to the ultrasonic probe, and an ultrasonic response signal received by the ultrasonic probe. A receiving unit for processing, and a drawing unit for creating a tomographic image of the living body based on the response signal processed by the receiving unit, wherein the receiving unit has a specific frequency component from the response signal And the pass bandwidth of the filter is _0.8 f when the average frequency of the ultrasonic signal transmitted to the ultrasonic probe is f _{0. 0} to that Do is set to 1.8F ₀ ultrasound contrast rendering device. An ultrasonic probe that transmits and receives ultrasonic waves to and from a living body, a transmitter that transmits ultrasonic signals to the ultrasonic probe, and an ultrasonic response signal received by the ultrasonic probe. A receiving unit for processing, and a drawing unit for creating a tomographic image of the living body based on the response signal processed by the receiving unit, wherein the receiving unit has a specific frequency component from the response signal And the pass bandwidth of the filter is 1.2 f when the average frequency of the ultrasonic signal transmitted to the ultrasonic probe is f _{0. 0} to that Do is set to 1.8F ₀ ultrasound contrast rendering device.   The transmitting unit has a function of transmitting an ultrasonic beam a plurality of times in the same direction at time intervals, and each ultrasonic signal consists of a continuation of a waveform having a different frequency, and the respective signals are mutually connected with respect to polarity inversion. A function of generating asymmetrically, and the receiving unit adds response signals of successive ones of the ultrasonic signals of each time after phasing processing, and the addition signal is added to the specific frequency component by the filter. The ultrasonic contrast-enhanced drawing apparatus according to claim 1, wherein the apparatus is extracted.   The ultrasound contrast drawing apparatus according to claim 1, wherein the transmission unit transmits the ultrasound signal having a plurality of frequency components to the ultrasound probe.   The ultrasonic contrast drawing apparatus according to claim 5, wherein the ultrasonic signal has a waveform obtained by continuing waveforms of different frequencies.

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