JP4226882B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus capable of diagnosis by a contrast echo method using a contrast agent.
[0002]
[Prior art]
An ultrasonic diagnostic apparatus can obtain a tomographic image of a soft tissue in a living body non-invasively from the body surface by an ultrasonic pulse reflection method, such as an X-ray diagnostic apparatus, an X-ray CT apparatus, an MRI diagnostic apparatus, a nuclear medicine diagnostic apparatus, etc. Compared to other diagnostic apparatuses, it has features such as small size, low cost, real-time display, high safety without exposure to X-rays, and blood flow imaging. Because of this convenience, it is now widely used in the heart, abdomen, urology, and gynecology.
[0003]
In this ultrasonic image diagnostic apparatus, there are various imaging methods. One typical example is an imaging technique called a contrast echo method. In this contrast echo method, an ultrasonic contrast agent composed of microbubbles or the like is administered into a blood vessel of a subject to enhance the ultrasonic scattering echo.
[0004]
In recent years, an ultrasound contrast agent capable of intravenous administration has been developed, and an imaging method suitable for this contrast agent has been developed. For example, a filtering method (a method of imaging based on a single pulse transmitted per scanning line: see, for example, Patent Document 1), a Doppler method (two or more same transmissions per scanning line). A method of imaging based on a phase pulse), a phase inversion method (a method of imaging based on two pulses whose phase is inverted per one scanning line: see, for example, Patent Document 2), phase inversion. Doppler method (a method of imaging based on three or more pulses having different phases transmitted per scanning line: see, for example, Patent Document 3).
[0005]
When the contrast echo method is performed by each of the above methods, conventionally, ultrasonic waves with medium sound pressure or high sound pressure with an MI value of 0.5 or more are transmitted. This is to cause the contrast agent (bubble) to collapse to some extent and contribute to the shadowing. For example, the contrast agent Levovist of Schering, which is widely used in general, may not be properly imaged unless an ultrasonic wave with a high sound pressure with an MI value of 0.8 or higher is transmitted.
[0006]
Such ultrasonic transmission due to high sound pressure and the burst of bubbles generated thereby have many effects on imaging. For example, when a high sound pressure ultrasonic wave propagates through a tissue, a harmonic component is generated. However, the filtering method and the phase inversion method described above cannot separate the harmonic component from the tissue (hereinafter referred to as THI component) and the harmonic component from the bubble. Therefore, when performing display based on bubbles by the filter method or the phase inversion method, it is difficult to provide contrast, and it is difficult to distinguish and display blood flow and substantial staining from the stained image. .
[0007]
In addition, bubble collapse generates a broadband echo signal when, for example, an ultrasonic wave is transmitted twice or more to one scanning line. This broadband echo signal is called a pseudo Doppler signal, and can be used for imaging by suppressing the tissue and THI component of the fundamental wave.
[0008]
However, the color Doppler image based on the pseudo Doppler signal becomes a thin blood vessel or an intra-substantial dye image composed of innumerable folding points, and does not become an image displaying a correct blood flow velocity. This is because the pseudo Doppler signal does not indicate the correct blood flow direction unlike the Doppler signal from the normal blood flow. Therefore, the contrast echo method does not use a color Doppler display that is good for expressing the blood flow velocity, and mostly uses a power Doppler display.
[0009]
In order to solve these problems, the present applicant can realize a suitable color Doppler display in Japanese Patent Application No. 2001-304013 using an ultrasonic contrast agent that is stained even if the MI value is 0.1 or less. A system is proposed. In this system, in a state where the MI value is low and the generation of the THI component is suppressed, the harmonic signal from the contrast agent is extracted, and the power signal and velocity signal from the contrast agent are calculated. From the three signals obtained by adding the B-mode information of the fundamental wave to the power signal and velocity signal, only the B-mode information is displayed in gray scale before contrast, and the blood flow in the blood vessel is stained by the contrast agent. It is displayed in red or blue, and in green when the blood flow in the tissue is stained.
[0010]
However, in this method, since a very weak ultrasonic wave having an MI value of 0.1 or less is used, and because a second harmonic signal is used, it is greatly affected by frequency-dependent attenuation. There are cases where the S / N is insufficient and the penetration is poor.
[0011]
By the way, signals obtained by the phase inversion method and the phase inversion Doppler method are in principle higher harmonics. Therefore, a nonlinear signal that can be used under conditions that do not involve bubble collapse using the filter method, the phase inversion method, and the phase inversion Doppler method is practically a second harmonic signal. In consideration of harmonics that can be used in addition to the second harmonic signal, the third harmonic can be obtained in principle by the filter method. However, there is a problem that a very wide band probe is required and a problem that it is subject to a large amount of frequency-dependent attenuation, which does not meet the purpose of improving the penetration.
[0012]
However, in general, sensitivity is lowered by a method using the second harmonic. As a solution, for example, a method using a nonlinear signal in the fundamental wave region has been proposed. As a method of using a nonlinear signal in the fundamental wave region, there is a method in which the amplitude is changed, a transmission pulse is transmitted twice, and the received signal is gain-corrected to obtain a difference (see, for example, Patent Document 4). Further, a method for changing both the amplitude and the phase has been proposed (see, for example, Patent Document 5). In addition, a method has been proposed in which a second harmonic is obtained with high sensitivity using a pulse compression technique using a chirp signal (see, for example, Patent Document 6).
[0013]
However, in these solutions, the amplitude information as in the B mode is only visualized. Therefore, in contrast echo method, velocity information such as blood cannot be accurately extracted from a nonlinear signal in the fundamental wave region.
[0014]
[Patent Document 1]
US Pat. No. 5,678,553
[0015]
[Patent Document 2]
US Pat. No. 5,632,277
[0016]
[Patent Document 3]
US Pat. No. 6,095,980
[0017]
[Patent Document 4]
US Pat. No. 5,577,505
[0018]
[Patent Document 5]
US Pat. No. 6,063,033
[0019]
[Patent Document 6]
US Pat. No. 6,213,947
[0020]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides an ultrasonic diagnostic apparatus that can display a blood flow image that correctly represents the direction of blood flow in contrast echo method and that has good penetration. It is aimed.
[0021]
[Means for Solving the Problems]
In order to achieve the above object, the present invention takes the following measures.
[0022]
According to a first aspect of the present invention, in an ultrasonic diagnostic apparatus that scans a predetermined portion of a subject to which a contrast medium is administered with an ultrasonic probe using an ultrasonic probe to acquire an ultrasonic image, each scanning line In contrast, the first ultrasonic pulse and at least one type of modulated ultrasonic wave obtained by amplitude-modulating the first ultrasonic pulse at a predetermined ratio, and the first ultrasonic pulse are repeatedly transmitted. Receiving means for receiving an echo signal based on a sound wave pulse and the at least one type of modulated ultrasound; and corresponding to a fundamental wave of the first ultrasonic pulse and the at least one type of modulated ultrasound of the echo signal. Extraction means for extracting a non-linear reflection component from the frequency band; calculation means for obtaining a speed signal value relating to the moving object present in the subject based on the non-linear reflection component; and based on the speed signal value An ultrasonic diagnostic apparatus characterized by comprising an image generating device which generates an ultrasonic image.
[0023]
According to a second aspect of the present invention, there is provided an ultrasonic diagnostic apparatus that scans a predetermined portion of a subject to which a contrast medium has been administered with an ultrasonic probe using an ultrasonic probe to acquire an ultrasonic image. In contrast, the first ultrasonic pulse and at least one type of modulated ultrasonic wave obtained by phase modulation and amplitude modulation of the first ultrasonic pulse at a predetermined ratio, the transmission means, Receiving means for receiving an echo signal based on the first ultrasonic pulse and the at least one type of modulated ultrasonic wave; and the basic of the first ultrasonic pulse and the at least one type of modulated ultrasonic wave among the echo signals. Extraction means for extracting a nonlinear reflection component from a frequency band corresponding to a wave; calculation means for obtaining a velocity signal value relating to a moving object existing in the subject based on the nonlinear reflection component; and the velocity signal value Based on the an ultrasonic diagnostic apparatus characterized by comprising an image generating device which generates an ultrasonic image.
[0024]
According to such a configuration, in the contrast echo method, a blood flow image that correctly represents the direction of blood flow can be displayed, and an ultrasonic diagnostic apparatus with good penetration can be realized.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, first to fifth embodiments of the present invention will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.
[0026]
(First embodiment)
FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus 10 according to this embodiment. First, the block configuration of the ultrasonic diagnostic apparatus 10 will be described with reference to FIG.
[0027]
The ultrasonic diagnostic apparatus 10 includes an ultrasonic probe 13, a transmission circuit 15, a reception circuit 17, a B-mode processing system 19, a color Doppler processing system 21, a B-mode processing system coordinate conversion memory 23, and a color Doppler processing system coordinate conversion memory 25. An image composition circuit 27, a control circuit 31, a display monitor 33, and an operation unit 35.
[0028]
The ultrasonic probe 13 has a piezoelectric vibrator as an acoustic / electric reversible conversion element such as a piezoelectric ceramic. A plurality of piezoelectric vibrators arranged in parallel and provided at the tip of the probe 13 generate ultrasonic waves based on the voltage pulse applied from the transmission circuit 15.
[0029]
The transmission circuit 15 includes a pulse generator, a transmission delay circuit, and a pulser, and is connected to the probe 13. The pulse generator of the transmission circuit 15, for example, converts a rate pulse at a rate frequency fr Hz (period: 1 / fr sec) of 5 kHz, as described later, amplitude modulation (AM), or AM and phase modulation (PM: Repeatedly with Phase Modulation. This rate pulse is distributed to the number of channels and sent to the transmission delay circuit. The transmission delay circuit provides each rate pulse with a delay time necessary for focusing the ultrasonic wave into a beam and determining transmission directivity. The transmission delay circuit is supplied with a trigger from a trigger signal generator (not shown) as a timing signal. The pulser applies a voltage pulse to the probe 13 for each channel at the timing of receiving the rate pulse from the transmission delay circuit. Thereby, AM, AM and PM ultrasonic beams are transmitted to the subject.
[0030]
The reception circuit 17 includes a preamplifier, an A / D converter, a reception delay circuit, and an adder. The preamplifier amplifies the echo signal captured by the receiving circuit 17 via the probe 13 for each channel. The amplified echo signal is given a delay time necessary for determining the reception directivity by the reception delay circuit, and is added by the adder. By this addition, an echo signal (RF signal) in which the reflection component from the direction corresponding to the reception directivity of the echo signal is emphasized is generated. The overall directivity of ultrasonic transmission / reception (ie, “scan line”) is determined by the reception directivity and the transmission directivity.
[0031]
The B mode processing system 19 includes an echo filter 19a, a detection circuit 19b, and a LOG compression circuit 19c. The echo filter 19a is a bandpass filter (bandpass filter), performs phase detection, and extracts a signal in a desired frequency band. The detection circuit 19b detects the envelope of the echo signal output from the echo filter 19a, and obtains a B-mode signal for each scanning line constituting a B-mode image that visualizes the fundamental wave component with the contents described later. The LOG compression circuit 19c performs compression processing by logarithmic conversion on the B-mode detection data.
[0032]
The color Doppler processing system 21 includes a CTB (Corner Turning Buffer :) 21a, a wall filter 21b, and a speed / dispersion / power estimation circuit 21c. The CTB 21a is a device that temporarily stores an input data string based on color Doppler. The data string stored in the CTB 21a is output to the wall filter 21b in a predetermined order. In the present embodiment, the wall filter 21b uses the fundamental wave component for the purpose of separating the harmonic component, and has the characteristics of a low-pass filter. Details will be described later. The velocity / dispersion / power estimation circuit 21c is a circuit that calculates an average frequency by calculating a correlation between signals based on a plurality of echo signals having different phases. The velocity / dispersion / power estimation circuit 21c calculates blood flow velocity / dispersion / power estimation in color Doppler. Based on the extracted harmonic component, the speed / dispersion / power estimation circuit 21c estimates the power signal for each scanning line constituting the power image and the speed signal for each scanning line constituting the speed image with the content described later. To do.
[0033]
The B-mode processing system coordinate conversion memory 23 and the color Doppler processing system coordinate conversion memory 25 orthogonalize the scanning line signal sequence of the ultrasonic scan input from the B-mode processing system 19 or the color Doppler processing system 21 based on spatial information. Convert to coordinate system data.
[0034]
The image composition circuit 27 employs any one of the B-mode signal value B, the power signal value P, and the speed signal value V input from the coordinate conversion memories 23 and 25 as the pixel value of the display image. And a predetermined color and luminance are assigned in accordance with the determined signal value. The configuration of the image composition circuit 27 will be described in detail later.
[0035]
The control circuit 31 controls the operation of the ultrasonic diagnostic apparatus as a control center of the entire system.
[0036]
The display monitor 33 is a monitor made of a CRT or the like, and displays a tomographic image representing a subject tissue shape based on an input video signal. The display monitor 33 displays a composite image generated by the image composition circuit 27 and composed of a B mode signal, a power signal, and a speed signal.
[0037]
The operation unit 35 is connected to the device 10 and is an input device (mouse, trackball, mode, etc.) for setting a region of interest (ROI) for incorporating various instructions, commands, and information from the operator into the device body 22. Changeover switch, keyboard, etc.) are provided.
[0038]
(Image composition circuit)
Next, the configuration of the image composition circuit 27 will be described in detail.
[0039]
FIG. 2 shows a block configuration diagram of the image composition circuit 27. As shown in FIG. 2, the image composition circuit 27 includes a TFD memory (Tissue / Flow Decision memory) 271, a multiplexer 272, and a color map memory 273.
[0040]
The TFD memory 271 receives the B-mode signal value B, the power signal value P, and the speed signal value V of each pixel, and uses either B or P as the pixel value of the display image based on a predetermined function table. To decide. The determined use signal value information for each pixel is output from the TFD memory 271 to the multiplexer 272 as use signal value information.
[0041]
The multiplexer 272 selectively selects one of the B mode signal value B, the power signal value P, and the speed signal value V for each pixel based on the use signal value information for each pixel determined by the TFD memory 271. This switch outputs to the device.
[0042]
The color map memory 273 is a memory that stores a color map assigned to each signal value. The color map memory 273 generates a composite image composed of a B-mode signal, a power signal, and a speed signal by assigning a predetermined color and luminance according to the signal value for each pixel input from the multiplexer 272, and displays the display monitor. To output.
[0043]
(Ultrasonic image collection / composition / display processing)
Next, a series of processes over ultrasonic image collection, synthesis, and display realized by the ultrasonic diagnostic apparatus 10 will be described with reference to FIGS. 3 to 5. Through this series of processing, a blood flow image that correctly represents the direction of blood flow can be displayed using a contrast medium, and blood flow, substantial staining, and unstained tissue can be clearly distinguished. Can display ultrasound images
<Ultrasonic image collection: Steps S1 to S5>
In ultrasonic scanning for ultrasonic image acquisition, low sound pressure ultrasonic waves with an MI (Mechanical Index) of about 0.1 are transmitted, and nonlinear signals contained in the reflected waves (reflected echoes) are compared. A contrast agent that can be obtained with a sufficiently large intensity, in other words, a contrast agent that can receive a nonlinear signal sufficient for diagnosing a subject is used. Specifically, Bracco's contrast agent SonoVue or the like can be used.
[0044]
The present inventor has found that when such a contrast agent is used at a low sound pressure with an MI of about 0.1, for example, there are the following advantages. First, since bubble collapse is small, it is possible to reduce the generation of pseudo Doppler signals that do not correctly indicate the direction of blood flow when compared with the case of transmission with a high MI value. This is because bubble collapse when transmitting ultrasonic waves twice or more to one scanning line causes a pseudo Doppler signal. Secondly, if the MI is a low sound pressure of about 0.1, the harmonic component (THI component) from the tissue can be suppressed very slightly. This is because the THI component is generated by non-linearity based on the distortion of the ultrasonic waveform in propagation. However, if the sound pressure is low, the distortion of the ultrasonic waveform in propagation is small. Third, the transmission amplitude or amplitude and phase are changed multiple times, the gain is corrected during reception, the fundamental component is suppressed, and the nonlinear signal in the fundamental region is extracted. The signal can be extracted almost from the bubble. This is because the THI component occurs most frequently in the second harmonic region and does not occur much in the fundamental wave region.
[0045]
In view of the above-described advantages, in the present embodiment, transmission is performed a plurality of times by changing the transmission amplitude, and the direction in which the contrast agent moves on the bloodstream is correctly reflected from the nonlinear signal in the fundamental wave region of the reflected wave. The Doppler signal from the bubble is acquired, thereby obtaining a correct blood flow image. The nonlinear signal in the fundamental wave region refers to a nonlinear signal of a reception reflected echo existing in the ultrasonic transmission frequency band. Specifically, a part of the second harmonic and a third-order distortion component are included.
[0046]
FIG. 3 is a flowchart for explaining a series of processing over ultrasonic image collection / synthesis / display realized by the ultrasonic diagnostic apparatus 10. FIG. 4 is a diagram for explaining the Doppler method based on amplitude modulation.
[0047]
In FIG. 3, first, an ultrasound contrast agent is injected into the subject (step S1). As described above, even when this contrast medium transmits ultrasonic waves with low MI and low sound pressure, the non-linear signal contained in the reflected wave (reflected echo) is obtained with a relatively large intensity.
[0048]
Subsequently, the subject is irradiated with a plurality of amplitude-modulated ultrasonic waves according to a predetermined pulse sequence (step S2). That is, as shown in the upper part of FIG. 4, the transmission circuit 15 has a predetermined time interval (that is, PRF: Pulse Repetition frequency) with respect to one scanning line, and the ratio is 0.5 at the first time. The voltage (for example, a voltage for MI = 0.05) is driven with a voltage having a ratio of 1 (for example, a voltage for MI = 0.1) for the second time, and this is repeated until the fifth time after the third time. The transmission pulse sequence in the example of FIG. 4 is expressed as “the ratio is [0.5, 1, 0.5, 1, 0.5]. The series of pulses differ only in the driving voltage, and other conditions. Note that the transmission frequency is set to the most sensitive frequency within the probe band considering the frequency-dependent attenuation in the living body.
[0049]
In the transmission, the amplitude of the transmission ultrasonic wave was modulated by voltage control. On the other hand, the configuration may be such that the voltage applied in each ultrasonic transmission is constant and the amplitude of the ultrasonic wave to be transmitted is controlled by controlling the number of channels used by the ultrasonic probe 13. For example, when transmitting [0.5, 1, 0.5, 1, 0.5] with an ultrasonic probe in which vibration elements are arranged one-dimensionally, the number of channels used for transmission of 0.5 Is half the number of channels used in one transmission. In addition, as shown in FIG. 16, the first transmission uses one jumping vibration element (channel), the second transmission uses all vibration elements, and the third transmission is used for the first transmission. The configuration may be such that the vibration element that has not been used is used, all vibration elements are used for the fourth transmission, and this is repeated thereafter. In voltage control, linearity may not be maintained between the applied voltage and the transmitted ultrasonic wave as its output due to the non-linearity of the electronic circuit. Control by sex can be realized.
[0050]
Subsequently, the echo signal from the subject is received from the probe 13, and the receiving circuit 17 performs a phasing addition process to generate an RF signal, and converts the RF signal into a baseband I signal and a Q signal (step) S3). The conversion to the I signal and the Q signal is performed with the desired frequency of the RF signal as the center frequency.
[0051]
In order to obtain a second harmonic signal, the frequency at the reception is set to about twice the transmission frequency. However, in this embodiment, since the nonlinear signal in the fundamental wave region is visualized, the frequency is set to be approximately the same as the transmission frequency. Of course, it is recommended to make this frequency variable according to the depth, and to lower the frequency as the depth increases. The I signal and Q signal are output to the B mode processing system 19 and the color Doppler processing system 21, respectively.
[0052]
Next, in the color Doppler processing system 21, a power signal value and a velocity signal value are generated (a power image and a velocity image are generated) (step S4). That is, first, the I signal and the Q signal are temporarily stored in the CTB 21a, extracted as a beam in the same direction, and output to the wall filter 21b. In the wall filter 21b, as shown in the middle part of FIG. 4, the reception filter [1, -1, 1] is replaced with the reception data string a.₀, A₁, A₂And a₂, A₃, A₄Call against. The reception filters in this case can be expressed as [1, -1,1,0,0] and [0,0,1-1,1].
[0053]
Various methods other than those described above are conceivable for the transmission pulse sequence and the reception filter. For example, as a simpler method, there are modifications such as transmission [0.5, 1, 0.5], reception [2, -1, 0], and [0, -1, 2]. In the example according to the present embodiment, five pulse sequences are necessary, whereas in the method according to this modification, only three pulse sequences are required. Therefore, the frame rate can be increased. However, compared to the example according to the present embodiment, it becomes more susceptible to the movement of the linear signal from the tissue, and motion artifacts increase. Which one of the two is selected can be determined based on, for example, the balance between the frame rate and the motion artifact.
[0054]
Next, the speed / dispersion / power estimation circuit 21c calculates the power signal value for each scanning line constituting the power image and the speed signal value for each scanning line constituting the speed image based on the extracted harmonic components. (See the lower part of FIG. 4).
[0055]
P = {| b₀｜²+ | B₁｜²} / 2 (1)
V = tan^-1c (2)
However,
b₀= A₀-A₁+ A₂
b₁= A₂-A_Three+ A_Four
c = b₀ ^*b₁          (B₀ ^*Is b₀Complex conjugate)
Further, the B-mode processing system 19 obtains a B-mode signal value for each scanning line constituting a B-mode image that visualizes the fundamental wave component (step S5). Since one reception signal is sufficient to obtain the B-mode signal, for example, as shown in FIG.₀The B-mode signal value B at the predetermined depth is obtained as follows using the above signal.
[0056]
B = | a₀| (3)
The B-mode signal value B, the power signal value P, and the speed signal value V thus obtained are preferably logarithmically compressed and output to a subsequent device. Logarithmic compression processing for speed signals is not common. However, this logarithmic compression is due to the high folding speed, or the low flow rate is important to distinguish between slow blood flow bubbles and tissue. Specifically, for each of the signal values B and P calculated by the equations (1) to (3), a value obtained by performing logarithmic compression and making it 8 bits long is used. Further, when the speed signal value V obtained by Expression (2) is a signed N-bit length and the speed signal after logarithmic compression is a signed M bit, logarithmic compression is performed by the following calculation.
[0057]
V ′ = sign (V) * (2^M-1/ N-1) * log₂(| V |) (4)
Where V = sign (V₀) Is V₀Is a sign function that outputs 1 or −1 depending on whether it is positive or negative. In the following description, M = 8 and V ′ is a signed 8-bit length.
[0058]
An example of specific numerical values in the processing from step S1 to step S5 is as follows. For example, when the transmission frequency is 2.5 MHz, the reception center frequency is 2.5 MHz, and the PRF is 5 kHz, the return speed at the fundamental wave center frequency is 76.8 cm / s. At this flow rate, it is considered that folding does not occur in the abdominal blood flow. Further, assuming that the folding speed is 76 cm / s, the flow rate when V ′ = 127 is 76 according to Equation (4), so that when V = 1, the flow rate is 0.6 cm / s, which is the minimum detected flow rate.
[0059]
FIG. 6B is a diagram illustrating primary, secondary, and tertiary Doppler frequency characteristics obtained by transmission and reception (that is, transmission and reception by AM) in the present embodiment. On the other hand, FIG. 6A shows the primary, secondary, and third-order Doppler frequency characteristics obtained as transmission [1, -1, 1] and reception [1, 2, 1] by the conventional PM method. FIG. The first order, second order, and third order here are coefficients of respective orders when modeled by a polynomial, and the first order corresponds to linear, the second order corresponds to the second harmonic, and the third order corresponds to the third harmonic. To be precise, it is not a third-order harmonic but a nonlinear signal generated in the fundamental band from a third-order nonlinear term. However, here, it is described briefly as the third harmonic. As can be seen from FIG. 6A, in the PM method, only the second harmonic is generated from the stationary bubble. On the other hand, as can be seen from FIG. 6B, according to the method according to the present embodiment, the second harmonic and the third harmonic can be acquired from the stationary bubble.
[0060]
In this ultrasonic diagnostic apparatus 10, as shown in FIG. 6B (or FIG. 6C described later), a stationary signal is suppressed with respect to secondary and higher-order responses. No processing is performed. Therefore, while a normal color Doppler image has a low flow rate cut by the HPF characteristics of the wall filter, this system can accurately calculate the low flow rate for secondary and higher-order responses. Is possible.
[0061]
FIG. 7 is a diagram showing echo signal characteristics from the tissue when MI = 0.1 in an actual living body, for each method of one pulse, PM, and AM. FIG. 8 is a diagram showing echo signal characteristics from the contrast agent SonoVue for each technique of one pulse, PM, and AM when MI = 0.1 in an actual living body.
[0062]
As can be seen from FIG. 7, the echo signal from the tissue obtained by PM is the second harmonic (2f_n) Has a large frequency component, but the fundamental wave (f_n) Frequency component is small. On the other hand, in the echo signal from the tissue obtained by AM, the second harmonic (2f_n) And fundamental wave (f_n) Frequency components are both small. This indicates the occurrence of THI.
[0063]
Further, as can be seen from FIG. 8, the echo signal from the contrast agent obtained by PM is the fundamental wave (f_n) Frequency component is small. On the other hand, in the echo signal from the tissue obtained by AM, the fundamental wave (f_n) Has a large frequency component. In this way, the fundamental wave (f_nThe frequency component of) is large because of an increase in non-linear signals. This is because the signal from the tissue (considered as a substantially linear signal) is suppressed as shown in FIG.
[0064]
In this embodiment, since a nonlinear signal in the fundamental wave region is used, it seems that there is a possibility that the movement of the tissue becomes a problem. However, in the case of the abdomen, the tissue movement is usually 5 mm / s or less, and therefore the tissue movement is not a problem under the above conditions. In addition, by selecting a pulse sequence that takes a long filter length for transmission and reception, the tissue suppression performance of the wall filter can be improved. Further, as shown in FIG. 6B, the secondary and tertiary terms can be visualized even if the bubble is stationary. The first order term can be completely suppressed if the tissue is stationary as shown in FIG. 6 (b).
[0065]
<Image composition processing: Steps S6 and S7>
Next, the image composition process will be described.
[0066]
First, based on the B-mode signal value B and the power signal value P for each pixel, it is determined whether the B-mode signal value B is used as the pixel value, or whether the power signal value P and the speed signal value V are used. It performs (step S6). This determination is performed qualitatively as follows, for example, according to the function table shown in FIG.
[0067]
That is, in the function table shown in FIG. 5, when P of a predetermined pixel is considerably small (power signal value P <first threshold Th1), the B-mode signal value B is used as the pixel value of the pixel. . The reason why the B-mode signal value B is preferentially displayed in this way is that when the power signal value P <Th1, the power signal value P is often noise. On the other hand, when the power signal value P ≧ the first threshold value Th1, the power signal value P reflects blood flow information, so the power signal value P and the velocity signal value V corresponding thereto are displayed with priority. To do.
[0068]
Note that the threshold value set in the function table does not necessarily have to be a fixed value as long as it can be selected by comparing the values of the B-mode signal value B and the power signal value P. For example, the function table shown in FIG. 5 is defined by three linear functions.
[0069]
The use signal value information for each pixel thus determined is output to the multiplexer 272 (see FIG. 2). The multiplexer 272 selectively outputs the signal value B or the signal value P and the signal value V for each pixel to the color map memory 273 according to the input information.
[0070]
Next, the color map memory 273 performs coloring for each pixel (step S7). The coloring for each pixel is executed as follows, for example. That is, for pixels using the signal value B, gray scale coloring is performed with a value of Red = Green = Blue = B (0 to 255). On the other hand, as shown in FIG. 9, the pixels using the signal value P and the signal value V are divided into four regions according to the values of P and V, and are changed according to the signal values V and P of the pixel. Color. Hereinafter, an example of coloring is shown assuming that P = 0 to 255 and V = −128 to 127.
[0071]
Region A
(P> 320-2 * | V | and V ≧ 0) Red coloring
Red = min (1.12 * P, 255)
Green = Blue = 0.98 * P
Region B
(P> 320-2 * | V | and V <0) Blue coloring
Blue = min (1.12 * P, 255)
Red = Blue = 0.98 * P
Region C
(When P <320-2 * | V | and V ≧ 0) Red to green coloring
R1 = min (1.12 * P, 255)
G1 = B1 = 0.98 * P
R2 = B2 = 0.9 * P
G2 = min (P * 1.25, 255)
a = | V | / (160−P / 2)
Red = a * R1 + (1-a) * R2
Green = a * G1 + (1-a) * G2
Blue = a * B1 + (1-a) * B2
Region D
(When P <320-2 * | V | and V <0) Coloring from blue to green
B1 = min (1.12 * P, 255)
R1 = G1 = 0.98 * P
R2 = B2 = 0.9 * P
G2 = min (P * 1.25, 255)
a = | V | / (160−P / 2)
Red = a * R1 + (1-a) * R2
Green = a * G1 + (1-a) * G2
Blue = a * B1 + (1-a) * B2
By performing such coloring, each biological information of the subject is assigned the following color and brightness, and is displayed in the form shown in FIG. That is, (1) Bubbles flowing through blood with a high flow velocity such as an artery are colored red or blue depending on the direction. (2) Bubbles flowing through a slow blood flow in the venous system are colored green. (3) Bubbles in the tissue have a dark green color because of their slow flow rate and low power. (4) The tissue that is not shaded is colored in gray scale (gray).
[0072]
These four colorings (ie, red, blue, green, and gray) change continuously, so the boundaries are smooth, and ultimately the observer can determine the time phase and continuity of the blood vessels. Can be determined in consideration.
[0073]
In addition, when the fundamental wave clutter remains undisturbed, the speed becomes high near the Nyquist flow velocity. The power is small because it is considerably suppressed by the LPF. Thus, in the case of a small power value in the vicinity of the Nyquist flow velocity, by displaying with a gradation close to a gray scale, it is possible to observe as a tissue image display in the B mode while displaying power.
[0074]
(Image display processing: Step S8)
Next, a composite image obtained by combining the B, P, and V signals in the image composition circuit 27 is displayed on the display monitor 33 (step S8). Thus, the observer can observe the composite image.
[0075]
The series of processing from step S1 to step S8 described above is sequentially repeated in real time at the time of diagnosis. Accordingly, the observer can observe the ultrasonic image in real time on the display monitor 33 in the following form, for example.
[0076]
FIGS. 11A to 11E are diagrams for explaining a composite image (an example of the liver) that can be observed by the observer on the display monitor 33. FIG. First, as shown in FIG. 11A, since there is no contrast effect before contrast medium administration, the signal value P is very small. Therefore, the signal value B is used as the pixel value of each pixel, and only the B mode image is displayed. Is displayed.
[0077]
FIG. 11B shows an ultrasonic image in which, for example, 5 to 10 seconds have elapsed from the administration of the contrast agent, and a large blood vessel is mainly shaded with red or blue coloring. (In the figure, the upward and downward slanting areas represent the blood flow that is dyed. According to the above color assignment, the upward and oblique sloping areas in the figure are colored red and the downward sloping area in blue. (The same applies hereinafter.)
FIG. 11 (c) shows an ultrasonic image in which, for example, 10 to 30 seconds have elapsed from the administration of the contrast medium, the contrast medium flows into the capillaries, and the entire tissue (substantially) is shaded (in the figure). (The dot area represents the shaded area. According to the above color assignment, the area is colored green. The same applies hereinafter.) Note that a portion where no contrast medium flows, such as the diaphragm, is displayed as a B-mode image.
[0078]
FIG. 11D shows an ultrasound image in which, for example, about 30 to 300 seconds elapse from the administration of the contrast agent, and the blood flow shadow gradually disappears.
[0079]
FIG. 11 (e) shows an ultrasonic image in which, for example, 5 minutes or more have elapsed since the administration of the contrast agent, and the substance in which the contrast agent such as the spleen and the liver is likely to remain is stained.
[0080]
According to the configuration described above, the following effects can be obtained.
[0081]
According to the ultrasonic diagnostic apparatus according to the present embodiment, the flow velocity value can be correctly estimated using a nonlinear signal. That is, in this ultrasonic diagnostic apparatus, a contrast agent that is stained even at a low MI, such as Bracco's ultrasonic contrast agent SonoVue, is used, and two types of super values with MI values of 0.05 and 0.1 are used. A sound wave pulse is irradiated and the reflected wave is received. At this time, the amplitude is changed as described above (or both the amplitude and the phase are changed as described in the second embodiment), and the nonlinear signal included in the obtained fundamental wave is extracted and used. Speed estimation. In the inventor's experiment, the nonlinear signal extracted according to the present embodiment provides a value that is quite close to the estimated value of the velocity from the linear signal obtained when the MI value is 1.0 in the absence of contrast agent. . As a result, a blood flow image that correctly represents the direction of blood flow can be displayed in the contrast echo method.
[0082]
In addition, for example, when using the ultrasonic contrast agent Levovist of Schering, the image is not dyed unless the pulse is collapsed at a high MI. For this reason, the flow velocity value cannot be obtained correctly by the same method or different methods.
[0083]
Moreover, according to this embodiment, an ultrasonic diagnostic apparatus with good penetration can be provided. That is, in this ultrasonic diagnostic apparatus, the amplitude of the transmission ultrasonic wave (in the second embodiment, the amplitude and phase) is changed to acquire a nonlinear signal in the fundamental wave region, and a Doppler signal is obtained therefrom. Therefore, the frequency-dependent attenuation is reduced by the lower frequency, and the penetration can be improved. Moreover, THI generation in the fundamental wave region is smaller than THI generation in the second harmonic region. Therefore, if the same level of THI is included, the MI value can be increased and the penetration can be improved when the fundamental wave region is used rather than when the second harmonic is used. On the other hand, in the conventional method of extracting the Doppler signal from the second harmonic signal such as the phase, inversion, and Doppler method, the deep penetration is inevitably insufficient.
[0084]
According to the inventor's experiment, when a nonlinear signal in the fundamental wave region is used as in the present embodiment, the penetration is improved by, for example, about 4 cm in an abdominal application as compared with the case where a conventional second harmonic is used. be able to.
[0085]
Further, according to the ultrasonic diagnostic apparatus according to the present embodiment, in the contrast echo method, a change in bubble over time can be visualized as a composite image of a B-mode signal, a power signal, and a speed signal. Accordingly, it is possible to display an ultrasonic image that can clearly distinguish blood flow, substantial staining, and unstained tissue.
[0086]
In the ultrasonic diagnostic apparatus 10, in the contrast echo method, an ultrasonic image is selectively generated based on a power signal and a blood flow signal in a region where blood flow information is effective. Therefore, a blood flow image that correctly represents the direction of blood flow can be displayed. In addition, since the color is assigned to the substance (tissue) according to the intensity of the signal value, it is possible to display an ultrasonic image that can clearly distinguish blood flow, substantial staining, and non-stained tissue.
[0087]
(Second Embodiment)
In the first embodiment, a pulse sequence amplitude-modulated by transmission is used. On the other hand, in the second embodiment, a pulse sequence that combines amplitude modulation and phase modulation is used.
[0088]
For example, in the present embodiment, ultrasonic waves are transmitted to the subject as [0.5, -1, 0.5] in steps S2 to S5 shown in FIG. 3, and the reflected wave is transmitted as [1, 1, 1]. A B-mode image, a power image, and a velocity image are generated.
[0089]
That is, as shown in the upper part of FIG. 12, the transmission circuit 15 is a voltage having a ratio of 0.5 at a predetermined time interval (that is, PRF: Pulse Repetition frequency) with respect to one scanning line. (For example, the voltage at which MI = 0.05) The second time, the polarity is reversed and the ratio is driven with a voltage of 1 (for example, the voltage at which MI = 0.1), and the third and subsequent times are repeated up to the fifth time ( Step S2). As in the first embodiment, the series of pulses differ only in drive voltage, and other conditions are the same. In addition, the transmission frequency is set to the most sensitive frequency within the probe band considering the frequency dependent attenuation in the living body.
[0090]
Subsequently, the echo signal from the subject is received from the probe 13, and the receiving circuit 17 performs a phasing addition process to generate an RF signal, and converts the RF signal into a baseband I signal and a Q signal (step) S3).
[0091]
Next, in the color Doppler processing system 21, a power signal value and a velocity signal value are generated (a power image and a velocity image are generated) (step S4). That is, first, the I signal and the Q signal are temporarily stored in the CTB 21a, extracted as a beam in the same direction, and output to the wall filter 21b. In the wall filter 21b, as shown in the middle part of FIG. 12, a reception filter [1, 1, 1] is replaced with a reception data string a.₀, A₁, A₂And a₂, A₃, A₄Call against. The reception filter in this case can be expressed as [1, 1, 1, 0, 0] and [0, 0, 1, 1, 1].
[0092]
Next, the speed / dispersion / power estimation circuit 21c estimates the power signal value for each scanning line constituting the power image and the speed signal value for each scanning line constituting the speed image based on the extracted harmonic component. (See the lower part of FIG. 12). Note that the calculation method and display method for each value of B, P, and V are the same as those in the first embodiment.
[0093]
FIG. 6C is obtained by transmission and reception in this embodiment (that is, transmission and reception by AM + PM with transmission [0.5, -1, 0.5] and reception [1, 1, 1]). It is the figure which showed the primary, secondary, and third-order Doppler frequency characteristics. Comparing FIG. 6C and FIG. 6B, at the point where the Doppler frequency is 0 (that is, the center frequency), the method according to the present embodiment has a higher secondary component than a tertiary component. For this reason, the reception center frequency is set to be substantially the same as the transmission frequency in the first embodiment, whereas in the present embodiment, it is preferably set higher than the transmission frequency. However, since the object of the present invention is to improve the penetration, a frequency that maximizes the penetration (for example, 1.5 times the transmission frequency) may be selected.
[0094]
Various methods other than those described above are conceivable for the transmission pulse sequence and the reception filter. As a method for changing the amplitude and phase other than the above, for example, a pulse sequence of transmission [0.5, -1, -1, 0.5], reception [2, 1, 0] and [0, 2, 1] ] Has the advantage of improving the frame rate because a signal can be obtained by four transmissions and receptions. However, there is a drawback that motion artifacts increase.
[0095]
According to the present embodiment described above, the same effect as that of the first embodiment can be obtained.
[0096]
(Third embodiment)
In the first and second embodiments, as shown in FIGS. 6B and 6C, a non-linear signal in the fundamental wave region is a signal in which second-order and third-order terms are mixed. As in each embodiment, when the MI value is about 0.1, the non-linear signal from the tissue is small, so the THI included in the secondary is not a problem. However, when the MI value is increased to improve the sensitivity, the influence of THI becomes a problem.
[0097]
Therefore, in the third embodiment, a method of using only the third-order term by suppressing the first-order and second-order terms will be described.
[0098]
For example, in this embodiment, ultrasonic waves are transmitted to the subject as [0.5, -1, 1, -0.5] in steps S2 to S5 shown in FIG. , 2] to receive the reflected wave and generate a B-mode image, a power image, and a velocity image. Processing other than ultrasonic transmission / reception by phase modulation and amplitude modulation is the same as in the first and second embodiments.
[0099]
FIG. 13 shows transmission and reception in this embodiment (that is, transmission and reception by AM + PM with transmission [0.5, -1,1, −0.5] and reception [−2, −1,1,2]). FIG. 6 is a diagram illustrating primary, secondary, and tertiary Doppler frequency characteristics obtained by the above-described method. As shown in FIG. 13, at the Doppler center frequency, it can be seen that the first order (fundamental wave) and second order terms are suppressed and only the third order terms exist. Since the third-order term exists in the primary band, this signal in the fundamental band can be used.
[0100]
In this way, transmission / reception by AM + PM is performed with transmission [0.5, -1, 1, -0.5] and reception [-2, -1, 1, 2], and then the first or second By performing the same processing as in the embodiment, it is possible to visualize power and speed according to the third-order term of the fundamental band. In the method according to the present embodiment, the second-order term can be suppressed, so that the occurrence of THI can be reduced even when the MI value is increased.
[0101]
(Fourth embodiment)
In the first to third embodiments, a normal pulse has been used as the ultrasonic pulse. In the fourth embodiment, a method using a pulse compression technique will be further described. According to this method, the sensitivity can be further improved.
[0102]
FIG. 14 shows an example of a chirp waveform. A signal having this waveform can be obtained by applying Gaussian apodization to a signal whose frequency changes with time. Further, this signal can be converted (pulse-compressed) into a short pulse as shown in FIG. 15 by filtering using a matched filter, an inverse filter, a Wiener filter, or the like, or a method for correcting the phase. This filtering may be performed with an RF signal or an IQ signal in the receiving circuit 17 of FIG.
[0103]
In the present embodiment, in steps S2 to S5 shown in FIG. 3, the chirp waveform is used to transmit the amplitude or the amplitude and the phase are changed for each transmission, and the B mode image and the power image based on the received reflected wave. Generate a velocity image.
[0104]
That is, for example, as an example in which only the amplitude is changed, five transmissions [0.5, 1, 0.5, 1, 0.5] are performed as in the first embodiment, and Receive reflected waves.
[0105]
When a nonlinear signal in the fundamental wave region is extracted from the received reflected wave, first, pulse compression is performed using the same filter as that for pulse compression of a normal fundamental wave. The pulse compression shown in FIG. 15 is executed by applying reception filters [1, -1, 1, 0, 0] and [0, 0, 1, -1, 1] to the signal sequence after compression. Is done. After that, imaging is performed by the same method as in the first embodiment.
[0106]
When using the second harmonic, the phase is 2 in comparison with the case where pulse compression is applied to the normal fundamental wave.^1/2Pulse compression is performed using a compression filter that changes twice as fast. By applying reception filters [1, -1, 1, 0, 0] and [0, 0, 1, -1, -1] to this signal sequence, the pulse compression shown in FIG. Can be executed.
[0107]
When a frequency approximately 1.5 times that of the fundamental wave is used, pulse compression is performed using a compression filter whose phase changes approximately 1.2 times faster than in the case of pulse compression of an ordinary fundamental wave. . By applying reception filters [1, -1, 1, 0, 0] and [0, 0, 1, -1, -1] to this signal sequence, the pulse compression shown in FIG. Can be executed.
[0108]
In this way, the peak sound pressure can be reduced while using the same energy by using the chirp signal. Therefore, the generation of nonlinear signals from the tissue can be further reduced, and at the same time, the collapse of the bubbles of the ultrasonic contrast agent can be reduced. As a result, the S / N ratio can be improved and an ultrasonic diagnostic apparatus with high sensitivity can be provided.
[0109]
Although the present invention has been described based on the embodiments, those skilled in the art can come up with various changes and modifications within the scope of the idea of the present invention. It is understood that it belongs to the scope of the present invention. For example, as shown in the following (1) to (4), various modifications can be made without changing the gist thereof.
[0110]
(1) In each embodiment, the B mode image for viewing the tissue and the power image and the velocity image for viewing the blood flow are combined and displayed. However, in order to visualize an organization, the use of the B mode is not essential. This is because the tissue can be seen with the harmonic component because the THI component is slightly present, and the tissue can be seen with the fundamental wave component because of the slight asymmetry of the positive and negative of the transmission pulse.
[0111]
Since these amplitudes are small, the image may be displayed darkly. However, when observing substantial dyeing, it is often convenient. It is preferable that the display / non-display of the B mode can be manually operated by a predetermined switch.
[0112]
(2) In each of the above embodiments, in step S6 in FIG. 3, the signal value B is used as the pixel value according to the function table defined by the signal value B and the signal value P shown in FIG. Whether to use was determined for each pixel. On the other hand, the signal value used as the pixel value is determined by the function table defined by the signal value B and the signal value V or the function table defined by the signal value B, the signal value P, and the signal value V. You may go.
[0113]
(3) In the second embodiment, the method of performing amplitude modulation and phase modulation by transmission has been described. Here, a nonlinear signal in the fundamental wave region can be extracted even if only phase modulation is performed.
[0114]
For example, as shown in FIG. 6A, in the transmission by the phase modulation of [1, −1, 1], it is not possible to obtain signals by the second and third order terms near the center of the Doppler frequency. However, for example, if transmission [j, -1, j] and reception [-j, 2, -j] are performed, as shown in FIG. 13, it depends on the second and third order terms near the center of the Doppler frequency. A signal can be obtained, and an image similar to that in each of the above embodiments can be obtained. J is a symbol for changing the phase by 90 °.
[0115]
In addition to those shown in the above embodiments, any video method shown in the above embodiments may be used as long as it is a pulse sequence that changes at least one of the amplitude and phase of a transmission pulse and that can obtain power information and speed information. Is possible.
[0116]
(4) In each of the above-described embodiments, the first ultrasonic pulse and the second ultrasonic wave having the relationship of amplitude modulation (or amplitude modulation and phase modulation) are set to, for example, [0 .5, 1, 0.5, 1, 0.5], and nonlinear components were extracted from the fundamental wave band of the echo signal. However, the ultrasonic waves transmitted by amplitude modulation (or amplitude modulation and phase modulation) are not limited to two types. For example, a configuration using three types of amplitude modulation (or amplitude modulation and phase modulation) ultrasonic waves such as [1, 0.5, 0.25] may be used. That is, it may be a stationary configuration in which two or more types of amplitude modulation (or amplitude modulation and phase modulation) ultrasonic waves are transmitted and nonlinear components are extracted from the fundamental wave band of the echo signal.
[0117]
Further, the transmission order of ultrasonic waves is not particularly limited. For example, after transmitting a first ultrasonic wave to a plurality of scanning lines, a second ultrasonic wave having a relationship of amplitude modulation (or amplitude modulation and phase modulation) with the first ultrasonic wave is transmitted to the plurality of scanning lines. It may be configured to transmit to the scanning line. That is, when two scanning lines are taken as an example, the first ultrasonic wave (scanning line 1), the first ultrasonic wave (scanning line 2), the second ultrasonic wave (scanning line 1), and the second ultrasonic wave For example, the configuration may be such that the first ultrasonic wave and the second ultrasonic wave are alternately transmitted in units of multiple times, such as (scanning line 2).
[0118]
Further, the embodiments may be combined as appropriate as possible, and in that case, the combined effect can be obtained. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention If at least one of the following is obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.
[0119]
【The invention's effect】
As described above, according to the present invention, in the contrast echo method, a blood flow image that correctly represents the direction of blood flow can be displayed, and an ultrasonic diagnostic apparatus with good penetration can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus 10 according to the present embodiment.
FIG. 2 shows a block configuration diagram of an image composition circuit 27. FIG.
FIG. 3 is a flowchart for explaining a series of processing over ultrasonic image collection / composition / display realized by the ultrasonic diagnostic apparatus 10;
FIG. 4 is a diagram for explaining a Doppler method based on amplitude modulation;
FIG. 5 shows an example of a function table used for image composition processing.
FIG. 6A is a diagram showing primary, secondary, and tertiary Doppler frequency characteristics obtained as transmission and reception by a conventional PM method. FIG. 6B is a diagram illustrating primary, secondary, and tertiary Doppler frequency characteristics obtained by transmission and reception (that is, transmission and reception by AM) in the present embodiment. FIG. 6C is a diagram showing primary, secondary, and tertiary Doppler frequency characteristics obtained by transmission / reception (that is, transmission / reception by AM + PM) in the present embodiment.
FIG. 7 is a diagram showing echo signal characteristics from a tissue when MI = 0.1 in an actual living body, for each method of one pulse, PM, and AM.
FIG. 8 is a diagram showing echo signal characteristics from the contrast agent SonoVue for each technique of one pulse, PM, and AM when MI = 0.1 in an actual living body.
FIG. 9 is a diagram illustrating an example of a color map used for image composition processing.
FIG. 10 is a diagram illustrating an example of a color map used for image composition processing.
FIGS. 11A to 11E are diagrams for explaining a composite image (an example of a liver) that an observer can observe on the display monitor 33. FIG.
FIG. 12 is a diagram for explaining a Doppler method using AM + PM (amplitude modulation and phase modulation) according to the second embodiment;
FIG. 13 is a diagram illustrating primary, secondary, and tertiary Doppler frequency characteristics obtained by transmission and reception (transmission / reception by AM + PM) in the second embodiment.
FIG. 14 shows an example of an ultrasonic chirp waveform transmitted in the fifth embodiment.
FIG. 15 is a diagram illustrating a waveform after pulse compression is applied to the chirp waveform illustrated in FIG. 14;
FIG. 16 is a diagram showing a modification of the ultrasonic transmission mode;
[Explanation of symbols]
10. Ultrasonic diagnostic equipment
13 ... Ultrasonic probe
15 ... Transmission circuit
17 ... Receiving circuit
19 ... B-mode processing system
19a ... Echo filter
19b ... Detection circuit
19c ... LOG compression circuit
21 ... Color Doppler treatment system
21a ... CTB
21b ... Wall filter
21c: Speed / dispersion / power estimation circuit
23 ... B-mode processing system coordinate conversion memory
25 ... Color Doppler processing system coordinate conversion memory
27. Image composition circuit
31 ... Control circuit
33 ... Display monitor
35. Operation unit
271 ... TFD memory
272: Multiplexer
273 ... Color map memory

Claims (14)

In an ultrasonic diagnostic apparatus that scans a predetermined part of a subject to which a contrast agent is administered with an ultrasonic probe using an ultrasonic probe to acquire an ultrasonic image,
Transmission means for repeatedly transmitting the first ultrasonic pulse and at least one type of modulated ultrasonic wave obtained by amplitude-modulating the first ultrasonic pulse at a predetermined ratio for each scanning line;
Receiving means for receiving an echo signal based on the first ultrasonic pulse and the at least one type of modulated ultrasonic wave;
An extraction means for extracting a non-linear reflection component from a frequency band corresponding to a fundamental wave of the first ultrasonic pulse and the at least one type of modulated ultrasonic wave of the echo signal;
Calculation means for obtaining a velocity signal value relating to a moving object existing in the subject based on the nonlinear reflection component;
Image generating means for generating the ultrasonic image based on the velocity signal value;
An ultrasonic diagnostic apparatus comprising: The ultrasonic diagnostic apparatus according to claim 1, wherein the calculation unit obtains a power signal value related to a moving object existing in the subject based on the nonlinear reflection component. B-mode signal generating means for generating a B-mode signal corresponding to the amplitude intensity of the echo signal;
For each pixel of the ultrasonic image, a determination unit that compares the B-mode signal value with the velocity signal value or the power signal value to determine whether to use the B-mode signal value; In addition,
The image generation unit assigns a first color with luminance based on the B mode signal value to the pixel determined by the determination unit to use the B mode signal value, and the determination unit uses the B mode signal value. For the pixel determined not to be generated, the ultrasonic image is generated by assigning a second color different from the first color in luminance based on the flow velocity signal value and the power signal value;
The ultrasonic diagnostic apparatus according to claim 2. The extraction means performs a filter operation by weighting that cancels the ratio with respect to the echo signal based on the first ultrasonic pulse and the at least one type of modulated ultrasonic wave, thereby linearly reflecting a component of the echo signal The ultrasonic diagnostic apparatus according to claim 1, wherein the nonlinear reflection component is extracted. 5. The ultrasonic diagnostic apparatus according to claim 1, wherein the transmission unit performs the amplitude modulation by controlling the number of channels of the ultrasonic probe used in ultrasonic transmission. 6. . The first ultrasonic pulse and the at least one type of modulated ultrasonic wave have a chirp waveform,
The extraction means extracts a nonlinear reflection component after pulse-compressing the echo signal;
The ultrasonic diagnostic apparatus according to any one of claims 1 to 5, wherein: The extraction means extracts the nonlinear reflection component from a frequency band corresponding to approximately 1.5 times the fundamental frequency of the first ultrasonic pulse and the at least one type of modulated ultrasonic wave in the echo signal. The ultrasonic diagnostic apparatus according to any one of claims 1 to 6, wherein: In an ultrasonic diagnostic apparatus that scans a predetermined part of a subject to which a contrast agent is administered with an ultrasonic probe using an ultrasonic probe to acquire an ultrasonic image,
Transmission means for repeatedly transmitting a first ultrasonic pulse and at least one type of modulated ultrasonic wave obtained by phase-modulating the first ultrasonic pulse at a predetermined ratio and a predetermined ratio for each scanning line When,
Receiving means for receiving an echo signal based on the first ultrasonic pulse and the at least one type of modulated ultrasonic wave;
An extraction means for extracting a non-linear reflection component from a frequency band corresponding to a fundamental wave of the first ultrasonic pulse and the at least one type of modulated ultrasonic wave of the echo signal;
Calculation means for obtaining a velocity signal value relating to a moving object existing in the subject based on the nonlinear reflection component;
Image generating means for generating the ultrasonic image based on the velocity signal value;
An ultrasonic diagnostic apparatus comprising: The ultrasonic diagnostic apparatus according to claim 1, wherein the calculation unit obtains a power signal value related to a moving object existing in the subject based on the nonlinear reflection component. B-mode signal generating means for generating a B-mode signal corresponding to the amplitude intensity of the echo signal;
For each pixel of the ultrasonic image, a determination unit that compares the B-mode signal value with the velocity signal value or the power signal value to determine whether to use the B-mode signal value; In addition,
The image generation unit assigns a first color with luminance based on the B mode signal value to the pixel determined by the determination unit to use the B mode signal value, and the determination unit uses the B mode signal value. For the pixel determined not to be generated, the ultrasonic image is generated by assigning a second color different from the first color in luminance based on the flow velocity signal value and the power signal value;
The ultrasonic diagnostic apparatus according to claim 9. The extraction means performs a filter operation by weighting that cancels the ratio with respect to the echo signal based on the first ultrasonic pulse and the at least one type of modulated ultrasonic wave, thereby linearly reflecting a component of the echo signal The ultrasonic diagnostic apparatus according to claim 8, wherein the nonlinear reflection component is extracted. The ultrasonic diagnostic apparatus according to claim 8, wherein the transmission unit performs the amplitude modulation by controlling the number of channels of the ultrasonic probe used in ultrasonic transmission. . The first ultrasonic pulse and the at least one type of modulated ultrasonic wave have a chirp waveform,
The extraction means extracts a nonlinear reflection component after pulse-compressing the echo signal;
The ultrasonic diagnostic apparatus according to claim 8, wherein: The extraction means extracts the nonlinear reflection component from a frequency band corresponding to approximately 1.5 times the fundamental frequency of the first ultrasonic pulse and the at least one type of modulated ultrasonic wave in the echo signal. The ultrasonic diagnostic apparatus according to any one of claims 8 to 13, wherein the apparatus is an ultrasonic diagnostic apparatus.

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