JP3519882B2 - Ultrasound imaging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic imaging method and apparatus, and more particularly to a microbaloo.
n) An ultrasonic imaging method and device for imaging a subject containing a contrast agent based on the novel characteristics of microballoons.

[0002]

2. Description of the Related Art In recent years, it has been attempted to use a microballoon (or microbubble) contrast agent for ultrasonic imaging. The microballoon contrast agent is a liquid in which minute bubbles having a diameter of about several μm are mixed at a predetermined concentration. The bubbles have a shell made of a polymer material or the like, and the surface of the shell is rendered hydrophilic.

When a microballoon is irradiated with ultrasonic waves of a specific frequency, it produces an echo containing its second harmonic. The specific frequency is the resonant frequency of the microballoon and depends on the diameter. That is, microballoons have a non-linear echogenicity.

On the basis of such echogenicity, an image is formed using the second harmonic component of the echo reception signal, and the distribution of the contrast agent in the subject is imaged. This is called 2nd harmonics imaging.

[0005]

In order to perform contrast imaging by the second harmonic imaging, it is necessary to prevent the echo reception signal from containing the second harmonic component that does not depend on the contrast agent. Otherwise, even a non-contrast agent will be imaged and confusing. However, the second harmonic is also generated by waveform distortion during signal conversion or amplification in the ultrasonic transmission / reception system, or non-linear distortion during propagation of the ultrasonic pulse in the subject, and so their effects are affected. It is difficult to escape completely.

The present invention has been made to solve the above problems, and an object thereof is an ultrasonic imaging method and apparatus for performing ultrasonic imaging using a microballoon contrast agent without depending on the second harmonic. Is to be realized.

[0007]

Means for Solving the Problems The inventor of the present invention, as a result of earnest research on ultrasonic imaging using a microballoon contrast agent, has found a novel characteristic regarding the echogenicity of the microballoon. The present invention has been made by utilizing this novel characteristic of the microballoon.

Before describing the means for solving the problems, the novel characteristics of the microballoon discovered by the inventor will be described. The inventor has proposed a solid phantom in which a large number of microballoons are dispersed in agar as an imitation of a subject containing a microballoon contrast agent.
I made (phantom). Where the microballoon is
PVC (polyvinylchlo) with an average diameter of 4 μm and porosity of 95%
ride) It is a hollow sphere. A hydrophilic film is applied to the surface of PVC. This was dispersed almost uniformly in agar at a weight ratio of about 100 ppm.

When this phantom is left standing in a water tank and imaged in a CFM mode (color flow mapping mode) for visualizing the distribution of blood flow velocity of a living body by an existing ultrasonic imaging device, no flow exists. I discovered that the inside of a phantom, which should not be, is displayed in a random and glittering color pattern. FIG. 10 is a monochrome copy image obtained by copying a CFM image of the agar phantom at that time with a copying machine. The image on the left is CF
It is an M image.

When a sample volume is set in the part of the phantom displayed with this color pattern and the Doppler signal in that part is subjected to frequency analysis, it is uniform and white across both side bands. (white) frequency spectrum (spectrum)
I have found that. This is shown in the image on the right side of FIG. This image shows a time change image of the frequency spectrum of the Doppler signal, with the vertical axis representing frequency and the horizontal axis representing time. Spectral images of both sidebands are shown side-by-side.

The above two facts indicate that the microballoons impart a random modulation or "flicker" to the phase and amplitude of the ultrasonic echo by a mechanism that has yet to be elucidated. Although this is detected by the Doppler signal processing in the CFM mode, it is different from the normal Doppler phenomenon due to the translational motion of the echo source, and is rather scintillation.
Similar to the (scintillation) phenomenon.

Therefore, in the present invention, this is tentatively referred to as microballoon scintillation and is used for imaging a microballoon contrast agent. In addition, the echo received signal from the above phantom is converted into a beamformer (beam form).
1), the frequency is analyzed by a range gate at the stage of the RF (radio frequency) signal output from FIG.
The frequency spectrum as shown in 1 was obtained. Figure 11
In, the vertical axis represents signal intensity and the horizontal axis represents frequency. Of the two peaks in the center of the screen, the left side is the fundamental frequency f
The echo of 0, and the right side is the echo of the second harmonic wave 2f0.

The ultrasonic transmission signal at this time is a tone burst signal of 8 to 16 waves, and its frequency spectrum is concentrated around the fundamental frequency f0 as shown in FIG. 12, and has a sufficiently narrow band. ing. This frequency spectrum is obtained by measuring echoes from an agar phantom containing no microballoon under the same conditions and performing frequency analysis. The component of the second harmonic wave 2f0, which is slightly present in the frequency spectrum, is due to the non-linear distortion in the transmission / reception system and during the ultrasonic wave propagation.

Comparing the two figures, it is natural that the frequency spectrum shown in FIG. 11 includes a fundamental wave component which is an echo of the agar substance and a second harmonic component which is a non-linear echo of the microballoon, but the others. And the fundamental frequency f
It can be seen that a high level signal is included in the frequency band between 0 and the second harmonic frequency 2f0.

From this, it was found that the microballoon "radiates" a wideband ultrasonic signal in the intermediate portion between the fundamental frequency f0 and the second harmonic 2f0. Since this ultrasonic signal has no correlation with the ultrasonic transmission signal, it cannot be said to be an echo in the original sense, but rather should be an acoustic radiation induced by the ultrasonic transmission signal.

Therefore, in the present invention, this is tentatively referred to as evoked acoustic radiation of microballoons and used for imaging microballoon contrast agents. [1] The invention according to claim 1 for solving the above-mentioned problems is an ultrasonic imaging method for irradiating a subject containing a microballoon contrast agent with ultrasonic waves to form an image based on an echo,
It is characterized in that an image is formed based on a change in an echo signal due to scintillation of a microballoon.

According to the first aspect of the invention, the microballoon is imaged based on the change in the echo signal due to the scintillation of the microballoon. This makes it possible to realize an ultrasonic imaging method in which ultrasonic imaging using a microballoon contrast agent is performed without using the second harmonic.

Since it does not depend on the second harmonic, the waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system, as in the case of the second harmonic imaging, or the propagation of the ultrasonic pulse in the subject. Not affected by non-linear distortion, etc.

[2] An invention according to claim 2 for solving the above-mentioned problems is an ultrasonic imaging apparatus for irradiating a subject containing a microballoon contrast agent with ultrasonic waves to form an image based on an echo. It is characterized in that it is provided with a detecting means for detecting a change in the echo signal due to scintillation of the balloon, and an image forming means for forming an image based on the output signal of the detecting means.

According to the second aspect of the invention, the scintillation of the echo signal is detected by the detecting means, and the image is formed by the image forming means based on the output signal of the detecting means. Accordingly, it is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without depending on the second harmonic.

Since it does not depend on the second harmonic, the waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system as in the case of the second harmonic imaging, or the propagation of the ultrasonic pulse in the subject. Not affected by non-linear distortion, etc.

[3] The invention of claim 3 for solving the above-mentioned problems is characterized in that, in the invention of claim 2, the detecting means includes a Doppler signal processing means. In the invention of claim 3, the detection means detects the phase change of the echo signal due to the scintillation of the microballoon by the Doppler signal processing means. Accordingly, it is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without depending on the second harmonic.

Since it does not depend on the second harmonic, waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system, as in the case of the second harmonic imaging, or the propagation of the ultrasonic pulse in the subject. Not affected by non-linear distortion, etc.

[4] The invention according to claim 4 which solves the above-mentioned problems, irradiates a subject containing a microballoon contrast agent with ultrasonic waves, and forms an image based on the acoustic radiation from the microballoons induced thereby. It is characterized by forming.

According to the fourth aspect of the invention, the subject containing the microballoon contrast agent is irradiated with ultrasonic waves, and an image is formed based on the induced acoustic radiation from the microballoon.
This makes it possible to realize an ultrasonic imaging method in which ultrasonic imaging using a microballoon contrast agent is performed without using the second harmonic.

Since it does not depend on the second harmonic, the waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system as in the case of the second harmonic imaging, or the propagation of the ultrasonic pulse in the subject. Not affected by non-linear distortion, etc.

[5] The invention according to claim 5 for solving the above-mentioned problems, ultrasonic irradiation means for irradiating a subject containing a microballoon contrast agent with ultrasonic waves, and ultrasonic waves irradiated from said ultrasonic irradiation means. It is characterized in that it comprises: a detection means for detecting the acoustic radiation induced from the microballoon by means of; and an image forming means for forming an image based on the output signal of the detection means.

In the fifth aspect of the invention, the ultrasonic wave irradiating means irradiates the subject containing the microballoon contrast agent with ultrasonic waves, the detecting means detects the evoked acoustic radiation from the microballoons, and the image forming means evokes it. Form an image based on acoustic radiation. Accordingly, it is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without depending on the second harmonic.

Since it does not depend on the second harmonic, waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system as in the case of the second harmonic imaging, or the propagation of the ultrasonic pulse in the subject. Not affected by non-linear distortion, etc.

[6] The invention of claim 6 for solving the above-mentioned problems is the invention of claim 5, wherein the detecting means has a frequency between the fundamental frequency and the second harmonic frequency of the irradiated ultrasonic wave. It is characterized by having an extraction means for extracting a signal.

In the sixth aspect of the invention, the extraction means extracts a signal having a frequency between the fundamental frequency of the irradiation ultrasonic wave and the second harmonic frequency. Accordingly, it is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without depending on the second harmonic.

Since it does not depend on the second harmonic, the waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system as in the case of the second harmonic imaging, or the propagation of the ultrasonic pulse in the subject. Not affected by non-linear distortion, etc.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment.

[First Embodiment] FIG. 1 is a block diagram of an ultrasonic imaging apparatus. This device is an example of an embodiment of the present invention. It should be noted that the configuration of the present apparatus shows an example of an embodiment relating to the apparatus of the present invention. Also,
The operation of the apparatus shows an example of an embodiment relating to the method of the present invention.

As shown in FIG. 1, the present apparatus has an ultrasonic probe PRB. Ultrasonic probe PRB
Are multiple ultrasonic transducers (transdu
cer) array. The array is composed of, for example, 128 ultrasonic transducers arranged one-dimensionally. The individual ultrasonic transducers are, for example, PZT (lead zirconate titanate) ceramics (cer).
It is composed of a piezoelectric material such as amics). The ultrasonic probe PRB is used by being brought into contact with the subject OBJ. The microballoon contrast agent BLN is previously injected into the subject OBJ.

The ultrasonic probe PRB is connected to the transceiver TRX. The transmitter / receiver TRX includes an ultrasonic probe P.
A drive signal is given to the RB to transmit ultrasonic waves into the subject OBJ. The ultrasonic waves are transmitted as a beam into the object OBJ. The transmission of the ultrasonic beam is repeated at predetermined time intervals.

The transmitting direction of the ultrasonic beam is sequentially changed,
The inside of the object OBJ is scanned with an ultrasonic beam (sound ray). This is called sound ray sequential scanning. The formation of such an ultrasonic beam and its scanning are performed, for example, by using a so-called phased array method that gives a time difference to the drive of each ultrasonic transducer in the array.

The transmitter / receiver TRX is also adapted to receive an echo signal from the subject OBJ received by the ultrasonic probe PRB. The reception of the echo signal is performed between repetitions of ultrasonic wave transmission. The echo signal is received along the received sound ray corresponding to the sound ray of the ultrasonic wave transmission. Therefore, the received sound ray is also scanned according to the transmitted sound ray.

By each reception, an echo reception signal for each sound ray is formed. The formation of such an echo reception signal is performed, for example, by using a so-called phased array method of adjusting the time difference for adding the reception signals of the individual ultrasonic transducers in the array.

The transceiver unit TRX is a B mode processing unit B.
It is connected to the MP and CFM processing unit CMP. The echo reception signal for each sound ray output from the transceiver unit TRX is
It is input to the B-mode processing unit BMP and the CFM processing unit CMP.

The B-mode processing unit BMP forms B-mode image data. As shown in FIG. 2, the B-mode processing unit BMP includes a logarithmic amplifier circuit LOG and an envelope detection circuit D.
Equipped with ET. The B-mode processing unit BMP logarithmically amplifies the echo reception signal by the logarithmic amplification circuit LOG, performs envelope detection by the envelope detection circuit DET, and represents the intensity of the echo at each reflection point on the acoustic line, that is, the A scope. (scope)
A signal is obtained and B-mode image data is formed by using each instantaneous amplitude of the A-scope signal as a luminance value.

The CFM processing unit CMP forms CFM data. As shown in FIG. 3, the CFM processing unit CMP includes a quadrature detection circuit QDR and an MTI (moving target indicator).
ation) filter MFL, autocorrelation circuit ACR, average velocity calculation circuit AVR, dispersion calculation circuit DSR and power (pow)
er) An arithmetic circuit PWR is provided.

The CFM processing unit CMP includes a quadrature detection circuit QD.
The echo reception signal is quadrature detected by R, and MTI filter MF
MTI processing is performed in L to extract the Doppler signal, autocorrelation calculation is performed in the autocorrelation circuit ACR, and average velocity calculation circuit AVR
The average flow velocity is calculated from the autocorrelation calculation result, the dispersion of the flow velocity is calculated from the autocorrelation calculation result by the dispersion calculation circuit DSR, and the power of the Doppler signal is calculated from the autocorrelation calculation result by the power calculation circuit PWR.

As a result, data representing the average flow velocity of the blood flow in the object OBJ, its dispersion, and the power of the Doppler signal are obtained for each sound ray. The average flow velocity data is distributed on the sound ray and indicates the average flow velocity at each position on the sound ray. The same applies to dispersion and power. These are called CFM data. The flow velocity is obtained as a component in the sound ray direction. The direction of flow is distinguished from the approaching direction and the away direction.

At this time, the phase change of the echo reception signal due to the scintillation of the microballoon is also extracted by the MTI filter MFL as if it were a Doppler signal. This is extracted even when the microballoon contrast agent has spread to a predetermined contrast region and has stopped moving, and is different from the original Doppler signal due to the translational movement of the echo source.

With respect to such a "Doppler" signal, the autocorrelation circuit ACR performs autocorrelation calculation, and the average flow velocity calculation circuit AVR calculates the average flow velocity of the result.
By the dispersion calculation by the dispersion calculation circuit DSR and the power calculation by the power calculation circuit PWR, respective signals such as the average flow velocity of the blood flow and its dispersion and the power of the Doppler signal can be obtained for each sound ray. . Similar to the above case, these signals are distributed on the sound ray and show the values at the respective positions. These show the distribution of scintillation generation points on the sound ray, that is, the distribution of microballoons in each form. These data are also called CFM data here. CFM processing unit CMP
Is an example of an embodiment of the detection means in the present invention,
It is also an example of an embodiment of the Doppler processing means.

The B-mode processor BMP and the CFM processor CMP are connected to the image processor IMP. The image processing unit IMP forms a B-mode image and a CFM image, respectively, based on the data respectively input from the B-mode processing unit BMP and the CFM processing unit CMP. The image processing unit IMP is an example of the embodiment of the image forming means in the present invention.

The image processing unit IMP, as shown in FIG.
It comprises a sound ray data memory AMM, a digital scan converter DSC, an image memory IMM and an image processing circuit IMK which are connected by a bus BUS.
The B-mode image data and the CFM data input from the B-mode processing unit BMP and the CFM processing unit CMP for each sound ray are respectively stored in the sound ray data memory AMM.
A sound ray data space is formed in the sound ray data memory AMM.

Digital scan converter DSC
Is for converting data in the sound ray data space into data in the physical space by scan conversion. The image memory IMM is
The image data of the physical space converted by the digital scan converter DSC is stored. The image processing circuit IMK performs predetermined data processing on the data in the sound ray data memory AMM and the image memory IMM. Details of the data processing will be described later.

A display unit DIS is connected to the image processing unit IMP. Image data is given to the display unit DIS from the image processing unit IMP, and an image is displayed based on the image data. That is, the B-mode image is displayed based on the B-mode image data, and the C-mode image is displayed based on the CFM image data.
Display the FM image.

Transmitting / receiving section TRX, B mode processing section B
The MP, the CFM processing unit CMP, the image processing unit IMP and the display unit DIS are connected to the control unit CNT. Control unit C
The NT applies a control signal to each of these parts to control its operation. Under the control of the control unit CNT, B
Mode operation and CFM mode operation are performed.

An operation unit OPC is connected to the control unit CNT. The operation unit OPC is operated by an operator to input desired commands and information to the control unit CNT. The operation unit OPC is composed of, for example, an operation panel provided with a keyboard and other operation tools.

Next, the operation of the present apparatus will be described by taking B-mode imaging as an example. The ultrasonic probe PRB is positioned at a desired position on the subject OBJ, and the operation unit OPC is operated to start the imaging operation.

The transmitter / receiver TRX scans the inside of the object OBJ in a sound ray sequence through the ultrasonic probe PRB and receives the echoes one by one. The B-mode processing unit BMP obtains an A-scope signal from the echo reception signal input from the transmission / reception unit TRX, and forms B-mode image data having each instantaneous value thereof as a luminance value for each sound ray.

The image processing unit IMP is a B mode processing unit BM.
The B-mode image data for each sound ray input from P is stored in the sound ray data memory AMM. As a result, a sound ray data space is formed in the sound ray data memory AMM.

The image processing circuit IMK converts the sound ray data in the sound ray data memory AMM into image data in the physical space by the digital scan converter DSC and writes it in the image memory IMM. This allows the image memory IM
B mode image data in the physical space is obtained in M.

Next, the CFM image capturing will be described. The transmitting / receiving unit TRX scans the inside of the object OBJ in order of sound rays through the ultrasonic probe PRB and receives the echoes one by one. At this time, ultrasonic waves are transmitted and echoes are received a plurality of times per sound ray.

The CFM processing unit CMP performs quadrature detection on the echo reception signal by the quadrature detection circuit QDR and outputs the MTI filter MF.
The MTI processing is performed in L, the autocorrelation circuit ACR obtains the autocorrelation, the average flow velocity calculation circuit AVR obtains the average flow velocity, the dispersion calculation circuit DSR obtains the dispersion, and the power calculation circuit PWR obtains the power from the autocorrelation result.

When the sound ray passes through the blood flow portion, these are data representing the average flow velocity of the blood flow and its dispersion, and the distribution of the power of the blood flow signal on the sound ray. When passing through the part where the is present, the data becomes the scintillation distribution of the microballoon BLN on the sound ray. Note that MT in the MTI filter MFL
The I processing is performed by using the echo reception signals a plurality of times per sound ray.

The image processing unit IMP is a CFM processing unit CMP.
The CFM data for each sound ray input from is stored in the sound ray data memory AMM. As a result, a sound ray data space is formed in the sound ray data memory AMM.

The image processing circuit IMK forms color image data based on the average flow velocity data and the dispersed data in the sound ray data memory AMM. In the color image data, for example, regarding blood flow, the flow in the approaching direction is represented by red, the flow in the distant direction is represented by blue, the velocity is represented by luminance, and the dispersion is represented by the mixing degree of green. Image processing circuit I
The MK also forms power image data with the power data. The power image data indicates the location of the flow regardless of the velocity and the direction of the flow. The display color is, for example, yellow, and is distinguished from the velocity image.

With respect to the scintillation of the microballoon, the color image data and the power image data are formed in exactly the same manner. However, these do not indicate blood flow but scintillation.

Such color image data or power image data is scan-converted by the digital scan converter DSC and written in the image memory IMM as in the case of the B-mode image pickup. At this time, for example, the B-mode image is overwritten by aligning the position in the subject.

Such image data is given to the display unit DIS and displayed as a visible image, so that, for example, as shown in FIG. 5, a B-mode image, that is, a tomographic image I of a tissue is obtained.
Color image IMc superimposed on Mb or tomographic image IMb of tissue
The power image IMp overlaid on is displayed.

When the blood circulation system such as the heart is being scanned by the ultrasonic beam, the color image IMc and the power image IMp are obtained.
Is an image of blood flow. The color image IMc is a CFM image that displays the direction, velocity, and dispersion of blood flow in color. This CFM image shows rhythmic (rhy
(thmical).

When the injection site of the contrast agent is scanned by the ultrasonic beam, the color image IMc and the power image IMp are images of scintillation of the microballoons, respectively, whereby the distribution of the contrast agent in the tissue is It is visualized. The color image IMc is displayed as a color pattern in which the color tone changes randomly and glitteringly.
Such a color pattern can be clearly distinguished and observed from a rhythmically changing one such as a CFM image of blood flow, and there is no possibility of confusion.

In this way, the microballoon contrast agent can be visualized without using the second harmonic imaging. Therefore, as in the case of the second harmonic imaging, it is affected by waveform distortion during signal conversion or amplification in the ultrasonic transmission / reception system, or non-linear distortion during the propagation of ultrasonic pulses in the subject. It has no practical effect.

[Embodiment 2] FIG. 6 is a block diagram of an ultrasonic imaging apparatus. This device is an example of an embodiment of the present invention. It should be noted that the configuration of the present apparatus shows an example of an embodiment relating to the apparatus of the present invention. The operation of the present apparatus also shows an example of an embodiment relating to the method of the present invention.

As shown in FIG. 6, this device has an ultrasonic probe PRB. The ultrasonic probe PRB is similar to that shown in FIG. The ultrasonic probe PRB is used by being brought into contact with the subject OBJ. The microballoon contrast agent BLN is previously injected into the subject OBJ.

The ultrasonic probe PRB is connected to the transmitter / receiver TRX. The transmitter / receiver TRX includes an ultrasonic probe P.
A drive signal is given to the RB to transmit ultrasonic waves into the subject OBJ. The ultrasonic waves are transmitted as a beam into the object OBJ. The transmission of the ultrasonic beam is repeated at predetermined time intervals. The ultrasonic probe PRB and the transmission / reception unit TRX are an example of the embodiment of the ultrasonic wave irradiation means in the present invention.

The transmitting direction of the ultrasonic beam is sequentially changed,
The inside of the object OBJ is scanned by an ultrasonic beam in a ray-sequential manner. The formation of the ultrasonic beam and its scanning are performed in the same manner as in the apparatus shown in FIG.

The ultrasonic waves are transmitted by tone burst signals of 8 to 16 waves, for example. As a result, narrow-band ultrasonic transmission in which the frequency spectrum is concentrated around the fundamental frequency f0 is performed. The narrow band of ultrasonic transmission may be performed by using a filter. This is preferable from the viewpoint of performing precise band narrowing. On the other hand, the method using the tone burst signal is preferable because no filter is required.

The transmitter / receiver TRX is also adapted to receive the echo signal from the object OBJ received by the ultrasonic probe PRB. The reception of the echo signal is performed between repetitions of ultrasonic wave transmission. The echo signal is received along the received sound ray corresponding to the sound ray of the ultrasonic wave transmission. Therefore, the received sound ray is also scanned according to the transmitted sound ray. By each reception, an echo reception signal for each sound ray is formed. Formation of such an echo reception signal is performed in the same manner as the device shown in FIG.

As shown in FIG. 7, the transmission / reception unit TRX has 3 units.
The system includes filters FLT1, FLT2 and FLT3. The pass band of the filter FLT1 is matched with the frequency band of transmitted ultrasonic waves. This is indicated by band B1 in FIG.
The pass band of the filter FLT3 is a microballoon BLN.
Is adjusted to the frequency band of the second harmonic echo of. This is indicated by band B3 in FIG. The pass band of the filter FLT2 is matched to the band of ultrasonic waves due to the stimulated acoustic emission. This is indicated by band B2 in FIG. Band B2 is a band between bands B1 and B2.

The echo received signal is filtered by these filters FLT1.
~ Common input to FLT3. As a result, the fundamental frequency echo is extracted by the filter FLT1, the evoked acoustic signal is extracted by the filter FLT2, and the filter F is extracted.
The second harmonic echo is extracted by LT3. The filter FLT2 is an example of the embodiment of the detecting means in the present invention, and is also an example of the embodiment of the extracting means.

The transmitter / receiver TRX is connected to the B-mode processor BMP. The reception signals of the three systems for each sound ray output from the transmission / reception unit TRX are input to the B-mode processing unit BMP. The B-mode processing unit BMP is configured to form B-mode image data of three systems based on the reception signals of these three systems.

The B-mode processing unit BMP includes three systems of a logarithmic amplifier circuit LOG and an envelope detection circuit DET as shown in FIG. The B-mode processing unit BMP logarithmically amplifies the received signal by the logarithmic amplifier circuit LOG, and the envelope detection circuit DET.
A signal indicating the intensity of the echo or acoustic radiation at each position on the sound line, that is, the A-scope signal, is obtained by envelope detection with the A-scope signal, and each instantaneous amplitude of the A-scope signal is used as a luminance value to obtain a B-mode image. It is designed to form data.

The B-mode processing unit BMP is the image processing unit IMP.
It is connected to the. The image processing unit IMP forms B-mode images of three systems based on the three systems of data input from the B-mode processing unit BMP. The image processing unit IMP is an example of the embodiment of the image forming means in the present invention.

The image processing unit IMP comprises a sound ray data memory AMM, a digital scan converter DSC, an image memory IMM and an image processing circuit IMK as shown in FIG. The three systems of B-mode image data input from the B-mode processing unit BMP for each sound ray are respectively stored in the sound ray data memory AMM. A sound ray data space is formed in the sound ray data memory AMM.

Digital scan converter DSC
Is for converting data in the sound ray data space into data in the physical space by scan conversion. The image memory IMM is
The image data of the physical space converted by the digital scan converter DSC is stored. The image processing circuit IMK performs predetermined data processing on the data in the sound ray data memory AMM and the image memory IMM. Details of the data processing will be described later.

A display unit DIS is connected to the image processing unit IMP. Image data is given to the display unit DIS from the image processing unit IMP, and an image is displayed based on the image data.

Transmitting / receiving unit TRX and B mode processing unit B described above
MP, image processing unit IMP and display unit DIS are control units C
Connected to NT. The control unit CNT applies a control signal to each of these units to control its operation. The B-mode operation is executed under the control of the control unit CNT.

An operation unit OPC is connected to the control unit CNT. The operation unit OPC is operated by an operator to input desired commands and information to the control unit CNT. The operation unit OPC is composed of, for example, an operation panel equipped with a keyboard and other operation tools.

Next, the operation of this apparatus will be described. The ultrasonic probe PRB is positioned at a desired position on the subject OBJ, and the operation unit OPC is operated to start the imaging operation. The transmitter / receiver TRX scans the inside of the object OBJ in a sound ray sequence through the ultrasonic probe PRB and receives the ultrasonic signals returning from there one by one, and the filters FLT1 to FLT3 receive the fundamental frequency echo signal and the induced acoustic signal from the received signal. And separating the second harmonic echo signal.

The B-mode processing unit BMP includes a transmitting / receiving unit TRX.
The B-mode image data of three systems is formed for each sound ray from the reception signals of three systems input from. The image processing unit IMP
The three modes of B-mode image data for each sound ray input from the B-mode processing unit BMP are stored in the sound ray data memory AMM.

The image processing circuit IMK converts the sound ray data of the three systems of the sound ray data memory AMM into image data of the physical space by the digital scan converter DSC, and writes them in the image memory IMM. As a result, the image memory IMM has three lines of B in the physical space.
Mode image data is obtained. These image data are
The B-mode image data is based on the fundamental frequency echo, the B-mode image data is based on the stimulated acoustic emission, and the B-mode image data is based on the second harmonic echo. A different display color is designated for each image data.

When writing to the image memory IMM,
The image processing circuit IMK writes, for example, an image based on the fundamental frequency echo and an image based on the evoked acoustic emission at positions aligned in the object OBJ, and also writes an image based on the fundamental frequency echo and an image based on the second harmonic echo. Subject OB
Write at the same position in J.

Such image data is given to the display section DIS and displayed as a visible image, so that, for example, as shown in FIG. 9, a fundamental acoustic wave image, that is, a tomographic image IMb of the tissue, is induced acoustic image IMi. An image in which the second harmonic echo image IMh is superimposed on the image and the tomographic image IMb of the tissue are displayed.

In this way, by utilizing the stimulated acoustic emission, the microballoon contrast agent can be visualized without using the second harmonic imaging. Therefore, as in the case of the second harmonic imaging, it is affected by waveform distortion during signal conversion or amplification in the ultrasonic transmission / reception system, or non-linear distortion during the propagation of ultrasonic pulses in the subject. It has no practical effect.

[0090]

As described in detail above, according to the invention of claim 1, the microballoon is visualized based on the change of the echo signal due to the scintillation of the microballoon. It is possible to realize an ultrasonic imaging method in which the used ultrasonic imaging is performed without using the second harmonic.

According to the second aspect of the invention, the scintillation of the echo signal is detected by the detecting means, and the image is formed by the image forming means based on the output signal of the detecting means. It is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using the method without using the second harmonic.

According to the third aspect of the invention, since the phase change of the echo signal due to the scintillation of the microballoon is detected by the Doppler signal processing means, the second ultrasonic imaging using the microballoon contrast agent is performed.
It is possible to realize an ultrasonic imaging apparatus that does not rely on harmonics.

According to the fourth aspect of the invention, the subject containing the microballoon contrast agent is irradiated with ultrasonic waves to form an image based on the evoked acoustic radiation from the microballoon. It is possible to realize an ultrasonic imaging method in which ultrasonic imaging using a balloon contrast agent is performed without using the second harmonic.

According to the invention of claim 5, ultrasonic waves are radiated to the subject containing the microballoon contrast agent by the ultrasonic wave irradiating means, and the evoked acoustic radiation from the microballoons is detected by the detecting means to obtain an image. Since the forming means forms the image based on the induced acoustic radiation, it is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without using the second harmonic.

Further, according to the invention of claim 6, since the signal having a frequency between the fundamental frequency of the irradiation ultrasonic wave and the second harmonic frequency is extracted by the extracting means, the microballoon contrast agent is used. It is possible to realize an ultrasonic imaging apparatus that performs the previously performed ultrasonic imaging without using the second harmonic.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus according to an example of an embodiment of the present invention.

FIG. 2 is a block diagram of a part of an apparatus according to an example of an embodiment of the present invention.

FIG. 3 is a block diagram of a part of an apparatus according to an example of an embodiment of the present invention.

FIG. 4 is a block diagram of a part of an apparatus according to an example of an embodiment of the present invention.

FIG. 5 is a diagram showing an image display example in the apparatus according to the exemplary embodiment of the present invention.

FIG. 6 is a block diagram of an apparatus according to an example of an embodiment of the present invention.

FIG. 7 is a block diagram of a part of an apparatus according to an example of an embodiment of the present invention.

FIG. 8 is a diagram showing a frequency band of a received signal in the example of the embodiment of the present invention.

FIG. 9 is a diagram showing an image display example in the apparatus according to the exemplary embodiment of the present invention.

FIG. 10 is a diagram showing a CFM image and a Doppler spectrum image of a phantom containing an immicroballoon displayed on a display as a photograph of a halftone image.

FIG. 11 is a diagram showing a frequency spectrum of an echo from a phantom containing a microballoon displayed on a display as a photograph of a halftone image.

FIG. 12 is a diagram showing a frequency spectrum of an echo from a phantom not containing a microballoon displayed on a display as a photograph of a halftone image.

[Explanation of symbols]

OBJ subject BLN microballoon contrast agent PRB ultrasonic probe TRX transceiver BMP B-mode processing unit CMP CFM processing unit IMP image processing unit DIS display CNT control unit OPC operation unit LOG logarithmic amplifier circuit DET envelope detection circuit QDR quadrature detection circuit MFL MTI filter ACR autocorrelation circuit AVR average velocity calculation circuit DSR distributed arithmetic circuit PWR power operation circuit AMM sound ray data memory DSC Digital Scan Converter IMM image memory IMK image processing circuit FLT1 to FLT3 filters

Claims (4)

(57) [Claims] 1. An ultrasonic wave irradiating means for irradiating an object containing a microballoon contrast agent with ultrasonic waves, and detecting acoustic radiation induced from the microballoons by the ultrasonic wave irradiating from the ultrasonic wave irradiating means, The acoustic emission detected by the first filter which does not include the fundamental frequency and the second harmonic frequency of the irradiated ultrasonic wave and passes only the signal having a frequency between the fundamental frequency and the second harmonic frequency. And an image forming unit that forms an image on the basis of the filtered output signal of the detecting unit. 2. The ultrasonic imaging apparatus according to claim 1, wherein the image formed by the image forming unit is a B-mode image. 3. The second filter that passes a signal having the fundamental frequency that does not overlap the frequency band of the first filter, and the detection unit that does not overlap the frequency band of the first filter. A third filter for passing a signal having a second harmonic frequency, wherein the image forming unit includes the second filter and the third filter.
3. A B-mode image based on a fundamental frequency echo and a B-mode image based on a second harmonic echo are respectively formed based on the respective output signals of the detecting means filtered by the filter of FIG. Ultrasonic imaging device. 4. The image forming means converts the B-mode image data based on the stimulated acoustic emission, the B-mode image data based on the fundamental frequency echo, and the B-mode image data based on the second harmonic echo. The ultrasonic imaging apparatus according to claim 3, wherein different display colors are designated.