JPH1085211A - Ultrasonic image pickup method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an ultrasonic image pickup using a microballoon contrast medium without depending on second harmonic wave by forming an image on the basis of the change of echo signal by scintillation of microballoons. SOLUTION: A transceiver part TRX successively scans the inner part of a subject OBJ with a sound ray through an ultrasonic probe PRB and receives the echo, and a CFM processing part CMP orthogonally detects the echo received signal followed by MTI processing, determines the self-correlation to determines the average flow velocity from the self-correlation result, and further determines the dispersion and power. When the sound ray passes the part where a contrast medium is present, the data showing the scintillation distribution of microballoons BLN on the sound ray is formed. An image processing part IMP stores the CFM data every sound ray in a sound ray data memory, and the image processing circuit forms a color image data on the basis of the average flow velocity data and the dispersion data within the sound ray data memory.

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 microballoon.
n) An ultrasonic imaging method and apparatus for imaging a subject containing a contrast agent based on novel characteristics of microballoons.

[0002]

2. Description of the Related Art In recent years, attempts have been made to use microballoon (or microbubble) contrast agents for ultrasonic imaging. The microballoon contrast agent is obtained by mixing minute bubbles having a diameter of about several μm into a liquid at a predetermined concentration. The bubbles have a shell made of a polymer material or the like, and the surface of the shell is provided with hydrophilicity.

[0003] When an ultrasonic wave of a specific frequency is irradiated, the microballoon produces an echo including its second harmonic. The specific frequency is the resonance frequency of the microballoon and is determined according to the diameter. That is, the microballoon has a non-linear echogenicity.

[0004] Based on such an 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 the contrast imaging by the second harmonic imaging, it is necessary to prevent the echo reception signal from including the second harmonic component not depending on the contrast agent. Otherwise, even non-contrast agents are imaged and confused. However, the second harmonic is also generated by waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system, or non-linear distortion during propagation of the ultrasonic pulse in the subject. It is difficult to completely escape.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an ultrasonic imaging method and apparatus for performing ultrasonic imaging using a microballoon contrast agent without using a second harmonic. It is to realize.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on ultrasonic imaging using a microballoon contrast agent, and as a result, have discovered a novel characteristic regarding the echogenicity of a microballoon. The present invention has been made by utilizing this novel property of the microballoon.

Prior to describing the means for solving the problems, new characteristics of the microballoon discovered by the inventor will be described. The inventor has developed a solid phantom in which a number of microballoons are dispersed in agar to simulate a subject containing a microballoon contrast agent.
(phantom). Here, the micro balloon is
PVC (polyvinylchlo) with an average diameter of 4 μm and a porosity of 95%
ride) It is a hollow sphere. The surface of the PVC is coated with a hydrophilic film. 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 is imaged by an existing ultrasonic imaging apparatus in a CFM mode (color flow mapping mode) for visualizing the distribution of blood flow velocity in a living body, no flow exists. I discovered that the interior of a phantom that should not have been displayed in a random and brilliantly changing color pattern. FIG. 10 is a monochrome copy image obtained by copying a color photograph obtained by capturing a CFM image of the agar phantom at that time by a copying machine. The image on the left is CF
It is an M image.

[0010] A sample volume is set in the phantom portion displayed in this color pattern, and the frequency analysis of the Doppler signal in that portion reveals a uniform white band over both side bands (double side band). (white) frequency spectrum (spectrum)
Was obtained. This is shown in the image on the right side of FIG. This video shows a time-change image of the frequency spectrum of the Doppler signal with the vertical axis taking the frequency and the horizontal axis taking the time. The spectrum images of both side bands are shown side by side.

The above two facts indicate that microballoons impart random modulation or "flicker" to the phase and amplitude of the ultrasonic echo due to a mechanism that has not yet been elucidated. Although this is detected by Doppler signal processing in the CFM mode, it is different from the normal Doppler phenomenon due to the translational movement of the echo source.
(scintillation) Similar to the phenomenon.

Therefore, in the present invention, this is tentatively called scintillation of microballoons and used for imaging microballoon contrast agents. In addition, the echo received signal from the phantom is converted to a beamformer (beam form).
er) and a range gate at the stage of the RF (radio frequency) signal output from the
The frequency spectrum as shown in FIG. 1 was obtained. FIG.
In the graph, the vertical axis represents signal strength, and the horizontal axis represents frequency. The left of the two peaks at the center of the screen is the fundamental frequency f
An echo of 0 and an echo of the second harmonic 2f0 are on the right.

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. ing. The frequency spectrum was obtained by measuring echoes from an agar phantom not containing microballoons under the same conditions and performing frequency analysis. The component of the second harmonic 2f0 slightly existing in the frequency spectrum is due to nonlinear distortion in the transmission / reception system or the propagation of the ultrasonic wave.

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. And the fundamental frequency f
It can be seen that a high-level signal is included in a frequency band between 0 and the second harmonic frequency 2f0.

Thus, it has been found that the microballoon "radiates" a broadband ultrasonic signal at an intermediate portion between the fundamental frequency f0 and the second harmonic 2f0. Since the 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 acoustic radiation induced by the ultrasonic transmission signal.

Therefore, in the present invention, this is tentatively referred to as induced acoustic radiation of microballoons and is used for imaging microballoon contrast agents. [1] The invention according to claim 1, which solves the above problem, is an ultrasonic imaging method of irradiating a subject containing a microballoon contrast agent with an ultrasonic wave to form an image based on an echo,
An image is formed based on a change in an echo signal due to scintillation of a micro balloon.

According to the first aspect of the present invention, the micro balloon is visualized based on a change in the echo signal due to the scintillation of the micro balloon. This makes it possible to realize an ultrasonic imaging method that performs ultrasonic imaging using a microballoon contrast agent without using the second harmonic.

Since it does not rely on the second harmonic, waveform distortion during signal conversion and amplification in the ultrasonic transmission / reception system as in the case of second harmonic imaging, or the propagation of an ultrasonic pulse in the subject Is not affected by nonlinear distortion or the like.

[2] The invention according to claim 2, which solves the above-mentioned problem, is an ultrasonic imaging apparatus which irradiates a subject containing a microballoon contrast medium with ultrasonic waves and forms an image based on echoes. It is characterized by comprising detecting means for detecting a change in an echo signal due to scintillation of a balloon, and image forming means for forming an image based on an output signal of the detecting means.

According to the second aspect of the present invention, the detecting means detects the scintillation of the echo signal, and the image forming means forms an image based on the output signal of the detecting means. This makes it possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without using the second harmonic.

Since it does not rely on the second harmonic, waveform distortion during signal conversion and amplification in the ultrasonic transmission / reception system as in the case of second harmonic imaging, or the propagation of the ultrasonic pulse in the subject Is not affected by nonlinear distortion or the like.

[3] A third aspect of the present invention for solving the above-mentioned problem is characterized in that, in the second aspect of the present invention, the detecting means has a Doppler signal processing means. According to the third aspect of the present invention, the detecting means detects the phase change of the echo signal due to the scintillation of the micro balloon by the Doppler signal processing means. This makes it possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without using the second harmonic.

Since it does not rely on the second harmonic, waveform distortion during signal conversion and amplification in the ultrasonic transmission / reception system as in the case of second harmonic imaging, or the propagation of an ultrasonic pulse in the subject Is not affected by nonlinear distortion or the like.

[4] According to a fourth aspect of the present invention, there is provided a method for irradiating a subject containing a microballoon contrast medium with ultrasonic waves, and generating an image based on acoustic radiation from the microballoon induced by the ultrasound. It is characterized by forming.

According to the fourth aspect of the present 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 that performs ultrasonic imaging using a microballoon contrast agent without using the second harmonic.

Since it does not rely on the second harmonic, waveform distortion during signal conversion and amplification in the ultrasonic transmission / reception system as in the case of second harmonic imaging, or propagation of the ultrasonic pulse in the subject Is not affected by nonlinear distortion or the like.

[5] The invention according to claim 5, which solves the above problem, is an ultrasonic irradiation means for irradiating an ultrasonic wave to a subject containing a microballoon contrast agent, and an ultrasonic wave irradiated from the ultrasonic irradiation means. Detecting means for detecting acoustic radiation induced from the micro-balloon, and image forming means for forming an image based on an output signal of the detecting means.

According to the fifth aspect of the present invention, the object containing the microballoon contrast medium is irradiated with ultrasonic waves by the ultrasonic irradiation means, the induced acoustic radiation from the microballoons is detected by the detection means, and the induced sound is emitted by the image forming means. An image is formed based on the acoustic radiation. This makes it possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without using the second harmonic.

Since it does not rely on the second harmonic, waveform distortion during signal conversion and amplification in the ultrasonic transmission / reception system as in the case of second harmonic imaging, or the propagation of ultrasonic pulses in the subject Is not affected by nonlinear distortion or the like.

[6] According to a sixth aspect of the present invention to solve the above problem, in the fifth aspect of the present invention, the detecting means has a frequency between a fundamental frequency and a second harmonic frequency of the irradiated ultrasonic wave. It is characterized by having extraction means for extracting a signal.

According to the present invention, a signal having a frequency between the fundamental frequency and the second harmonic frequency of the irradiated ultrasonic wave is extracted by the extracting means. This makes it possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using a microballoon contrast agent without using the second harmonic.

Since it does not rely on the second harmonic, waveform distortion during signal conversion and amplification in the ultrasonic transmission / reception system as in the case of second harmonic imaging, or propagation of the ultrasonic pulse in the subject Is not affected by nonlinear distortion or the like.

[0033]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiment.

[Embodiment 1] FIG. 1 is a block diagram of an ultrasonic imaging apparatus. This device is an example of an embodiment of the present invention. Note that an example of an embodiment relating to the device of the present invention is shown by the configuration of the present device. Also,
An example of an embodiment relating to the method of the present invention is shown by the operation of the present apparatus.

As shown in FIG. 1, the apparatus has an ultrasonic probe PRB. Ultrasonic probe PRB
Are a plurality of ultrasonic transducers (not shown)
cer). The array is constituted by, for example, 128 ultrasonic transducers arranged one-dimensionally. Each ultrasonic transducer is made of, for example, PZT (lead zirconate titanate) ceramics (cer
amics). The ultrasonic probe PRB is used in contact with the subject OBJ. The microballoon contrast agent BLN has been injected into the subject OBJ in advance.

The ultrasonic probe PRB is connected to the transmitting / receiving unit TRX. The transmission / reception unit TRX includes the ultrasonic probe P
A drive signal is given to the RB to transmit an ultrasonic wave into the object OBJ. The ultrasonic wave is transmitted as a beam into the object OBJ. The transmission of the ultrasonic beam is repeatedly performed at predetermined time intervals.

The transmission direction of the ultrasonic beam is sequentially changed,
The inside of the subject OBJ is scanned by an ultrasonic beam (sound ray). This is called sound ray sequential scanning. The formation and scanning of such an ultrasonic beam are performed, for example, by using a so-called phased array technique that gives a time difference to the driving of the individual ultrasonic transducers in the array.

The transmitting / receiving unit TRX receives an echo signal from the subject OBJ received by the ultrasonic probe PRB. The reception of the echo signal is performed during the repetition of the transmission of the ultrasonic wave. The echo signal is received along a reception sound ray corresponding to the sound ray of the ultrasonic wave transmission. Accordingly, the received sound ray is also scanned in accordance with the transmitted sound ray.

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

The transmission / reception unit TRX includes a B mode processing unit B
It is connected to the MP and the CFM processing unit CMP. The echo reception signal for each sound ray output from the transmission / reception 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. The B-mode processing unit BMP includes a logarithmic amplifier LOG and an envelope detector D as shown in FIG.
Has ET. The B-mode processing unit BMP logarithmically amplifies the echo reception signal with the logarithmic amplifier LOG, performs envelope detection with the envelope detection circuit DET, and indicates a signal representing the intensity of the echo at each reflection point on the sound ray, that is, the A scope. (scope)
A signal is obtained, and B-mode image data is formed using the instantaneous amplitude of the A scope signal as a luminance value.

The CFM processing unit CMP forms CFM data. The CFM processing unit CMP includes a quadrature detection circuit QDR and an MTI (moving target indic
ation) filter MFL, autocorrelation circuit ACR, average flow 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
R performs quadrature detection on the echo reception signal, and outputs an MTI filter MF
L to extract the Doppler signal by performing MTI processing, perform autocorrelation calculation with the autocorrelation circuit ACR, and calculate the average flow velocity calculation circuit AVR
, The average flow velocity is obtained from the autocorrelation calculation result, the variance calculation circuit DSR obtains the variance of the flow velocity from the autocorrelation calculation result, and the power calculation circuit PWR obtains the power of the Doppler signal from the autocorrelation calculation result.

As a result, data representing the average flow velocity of the blood flow and the like in the subject OBJ, the variance thereof, 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 the flow is distinguished between a direction approaching and a direction away from it.

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

The auto-correlation circuit ACR performs an auto-correlation calculation on such a “Doppler” signal, and calculates an average flow speed calculated by the average flow speed calculation circuit AVR.
By the dispersion calculation by the dispersion calculation circuit DSR and the power calculation by the power calculation circuit PWR, each signal is obtained for each sound ray as if it were the average flow velocity of the blood flow and its variance and the power of the Doppler signal. . Similar to the above case, these signals are distributed on the sound ray and indicate values at respective positions. These indicate the distribution of the scintillation generation points on the sound ray, that is, the distribution of the microballoons in their respective forms. These data are also referred to herein as CFM data. 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 a Doppler processing unit.

The B-mode processing unit BMP and the CFM processing unit CMP are connected to the image processing unit IMP. The image processing unit IMP forms a B-mode image and a CFM image based on 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 an embodiment of an image forming unit in the present invention.

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

Digital Scan Converter DSC
Is for converting data in a sound ray data space into data in a 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 data in the image memory IMM, respectively. Details of the data processing will be described later.

The display section DIS is connected to the image processing section IMP. The display unit DIS receives image data from the image processing unit IMP, and displays an image based on the image data. That is, a B-mode image is displayed based on the B-mode image data, and a C-mode image is displayed based on the CFM image data.
Display an FM image.

The transmitting / receiving section TRX and the 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 supplies a control signal to each of these units to control the operation. Under the control of the control unit CNT, B
The mode operation and the CFM mode operation are executed.

An operation unit OPC is connected to the control unit CNT. The operation unit OPC is operated by an operator, and inputs desired commands and information to the control unit CNT. The operation unit OPC includes, 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 an imaging operation.

The transmitting / receiving unit TRX scans the inside of the object OBJ in the order of sound rays 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 a luminance value at each instantaneous value for each sound ray.

The image processing unit IMP includes 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 into the image memory IMM. Thereby, the image memory IM
In M, B-mode image data in the physical space is obtained.

Next, the imaging of a CFM image will be described. The transmission / reception unit TRX scans the inside of the object OBJ in the order of sound rays through the ultrasonic probe PRB, and receives the echo one by one. At this time, transmission of ultrasonic waves and reception of echoes are performed 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 by L, an autocorrelation is calculated by an autocorrelation circuit ACR, an average flow velocity is calculated by an average flow velocity calculation circuit AVR, a variance is calculated by a variance calculation circuit DSR, and a power is calculated by a power calculation circuit PWR from the autocorrelation result.

When the sound ray passes through the blood flow portion, these data become the data representing the average flow velocity of the blood flow, its variance, and the distribution of the power of the blood flow signal on the sound ray. Is passed, the data represents the distribution of the scintillation of the micro balloon BLN on the sound ray. Note that MT in the MTI filter MFL
The I processing is performed using a plurality of echo reception signals per sound ray.

The image processing unit IMP is a CFM processing unit CMP
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 dispersion data in the sound ray data memory AMM. In the color image data, for example, the blood flow in the approaching direction is represented by red, the flow in the moving away direction is represented by blue, the speed is represented by luminance, and the variance is represented by the degree of green mixing. Image processing circuit I
The MK also forms power image data according to the power data. The power image data indicates the location of the flow, regardless of the speed and direction of the flow. The display color is, for example, yellow, and is distinguished from the speed image.

[0062] Regarding the scintillation of the microballoons, color image data and power image data are formed in exactly the same manner. However, these do not indicate blood flow but indicate scintillation.

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

Such image data is given to the display unit DIS and displayed as a visible image, so that, for example, as shown in FIG.
Color image IMc superimposed on Mb or tomographic image IMb of tissue
Is displayed.

When scanning the blood circulation system such as the heart with the ultrasonic beam, the color image IMc and the power image IMp
Is an image of blood flow. The color image IMc is a CFM image that displays the direction, velocity, and dispersion of the blood flow in color. This CFM image is rhythmically (rhythmic) with the heartbeat.
thmical).

When scanning the injection site of the contrast medium with the ultrasonic beam, the color image IMc and the power image IMp are obtained by imaging the scintillation of the microballoons, whereby the distribution of the contrast medium in the tissue is reduced. It is visualized. The color image IMc is displayed as a color pattern in which the color tone changes randomly and brilliantly.
Such a color pattern can be clearly distinguished and observed from a rhythmically changing one such as a CFM image of a blood flow, and there is no possibility of being confused.

In this way, it is possible to visualize the microballoon contrast agent without using the second harmonic imaging. For this reason, as in the case of the second harmonic imaging, it is affected by waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system, or nonlinear distortion during propagation of the ultrasonic pulse in the subject. There is 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. Note that an example of an embodiment relating to the device of the present invention is shown by the configuration of the present device. Further, an example of an embodiment relating to the method of the present invention is shown by the operation of the present apparatus.

As shown in FIG. 6, the present apparatus has an ultrasonic probe PRB. The ultrasonic probe PRB is similar to the one shown in FIG. The ultrasonic probe PRB is used in contact with the subject OBJ. The microballoon contrast agent BLN has been injected into the subject OBJ in advance.

The ultrasonic probe PRB is connected to the transmitting / receiving unit TRX. The transmission / reception unit TRX includes the ultrasonic probe P
A drive signal is given to the RB to transmit an ultrasonic wave into the object OBJ. The ultrasonic wave is transmitted as a beam into the object OBJ. The transmission of the ultrasonic beam is repeatedly performed at predetermined time intervals. The ultrasonic probe PRB and the transmission / reception unit TRX are examples of the embodiment of the ultrasonic irradiation unit in the present invention.

The transmitting direction of the ultrasonic beam is sequentially changed,
The inside of the object OBJ is scanned by the ultrasonic beam in the order of sound rays. The formation and scanning of the ultrasonic beam are performed in the same manner as in the apparatus shown in FIG.

The transmission of the ultrasonic waves is performed by, for example, 8 to 16 tone burst signals. Thereby, narrow-band ultrasonic transmission in which the frequency spectrum gathers around the fundamental frequency f0 is performed. The narrowing of the ultrasonic transmission may be performed using a filter. This is preferable in that the band is precisely narrowed. On the other hand, the method using the tone burst signal is preferable because no filter is required.

The transmitting / receiving unit TRX receives an echo signal from the subject OBJ received by the ultrasonic probe PRB. The reception of the echo signal is performed during the repetition of the transmission of the ultrasonic wave. The echo signal is received along a reception sound ray corresponding to the sound ray of the ultrasonic wave transmission. Accordingly, the received sound ray is also scanned in accordance with the transmitted sound ray. Each reception forms an echo reception signal for each sound ray. The formation of such an echo reception signal is performed in the same manner as in the apparatus shown in FIG.

As shown in FIG. 7, the transmitting / receiving section TRX
It has a system of filters FLT1, FLT2 and FLT3. The pass band of the filter FLT1 matches the frequency band of the transmitted ultrasonic wave. This is shown by band B1 in FIG.
The pass band of the filter FLT3 is the micro balloon BLN
In the frequency band of the second harmonic echo. This is shown by band B3 in FIG. The pass band of the filter FLT2 is matched to the band of the ultrasonic wave by the induced acoustic radiation. This is shown by band B2 in FIG. The band B2 is a band between the band B1 and the band B2.

The echo reception signal is applied to these filters FLT1
To FLT3. Thereby, the fundamental frequency echo is extracted by the filter FLT1, the induced sound signal is extracted by the filter FLT2, and the filter FLT1 is extracted.
A second harmonic echo is extracted by LT3. The filter FLT2 is an example of an embodiment of a detecting unit according to the present invention, and is an example of an embodiment of an extracting unit.

The transmitting / receiving section TRX is connected to the B-mode processing section BMP. The three-system reception signals 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 forms three B-mode image data based on the three received signals.

The B-mode processing unit BMP has three systems of a logarithmic amplifier LOG and an envelope detector DET as shown in FIG. The B-mode processing unit BMP logarithmically amplifies the received signal with a logarithmic amplifier LOG and generates an envelope detector DET.
To obtain a signal representing the intensity of the echo or acoustic radiation at each position on the sound ray, that is, an A-scope signal, and using the instantaneous amplitude of the A-scope signal as a brightness value, respectively, and obtaining a B-mode image. Data.

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

The image processing section IMP includes 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 B-mode image data input from the B-mode processing unit BMP for each sound ray are 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 a sound ray data space into data in a 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 data in the image memory IMM, respectively. Details of the data processing will be described later.

The display section DIS is connected to the image processing section IMP. The display unit DIS receives image data from the image processing unit IMP, and displays an image based on the image data.

The transmission / reception unit TRX and the B mode processing unit B
The MP, the image processing unit IMP, and the display unit DIS are controlled by the control unit C.
Connected to NT. The control unit CNT supplies a control signal to each of these units to control the operation thereof. 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, and inputs desired commands and information to the control unit CNT. The operation unit OPC includes, for example, an operation panel including a keyboard and other operation tools.

Next, the operation of the present 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 an imaging operation. The transmission / reception unit TRX scans the inside of the object OBJ in the order of sound rays through the ultrasonic probe PRB, receives the ultrasonic signals returning from the object OBJ one by one, and receives the fundamental frequency echo signal and the induced acoustic signal from the received signals by the filters FLT1 to FLT3. And the second harmonic echo signal.

The B mode processing unit BMP includes a transmitting / receiving unit TRX
The three-system B-mode image data is formed for each sound ray from the three-system reception signals input from the CPU. The image processing unit IMP
The three systems 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 each of the three sets of 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 them into the image memory IMM. As a result, the image memory IMM has three systems 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 induced acoustic radiation, and the B-mode image data is based on the second harmonic echo. Different display colors are designated for the respective image data.

In 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 induced acoustic radiation in the subject OBJ in alignment with each other, and also writes an image based on the fundamental frequency echo and an image based on the second harmonic echo. Subject OB
Write the position within 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, the induced acoustic image IMi is formed on the fundamental wave echo image, that is, the tomographic image IMb of the tissue. And an image obtained by superimposing the second harmonic echo image IMh on the tomographic image IMb of the tissue.

In this way, by utilizing the induced acoustic radiation, it is possible to visualize the microballoon contrast agent without using the second harmonic imaging. For this reason, as in the case of the second harmonic imaging, it is affected by waveform distortion at the time of signal conversion or amplification in the ultrasonic transmission / reception system, or nonlinear distortion during propagation of the ultrasonic pulse in the subject. There is no practical effect.

[0090]

As described above in detail, according to the first aspect of the present invention, the microballoon is visualized based on the change in the echo signal due to the scintillation of the microballoon. An ultrasonic imaging method in which the used ultrasonic imaging is performed without using the second harmonic can be realized.

According to the second aspect of the present invention, the detection means detects the scintillation of the echo signal and the image forming means forms an image based on the output signal of the detection means. It is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using irrespective of the second harmonic.

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

According to the fourth aspect of the present invention, the subject containing the microballoon contrast agent is irradiated with ultrasonic waves to form an image based on the induced acoustic radiation from the microballoon. An ultrasonic imaging method that performs ultrasonic imaging using a balloon contrast agent without using the second harmonic can be realized.

According to the fifth aspect of the present invention, the object containing the microballoon contrast agent is irradiated with ultrasonic waves by the ultrasonic irradiation means, and the induced acoustic radiation from the microballoons is detected by the detection means. Since the image is formed by the forming means based on the induced acoustic radiation, it is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging using the microballoon contrast agent without using the second harmonic.

According to the sixth aspect of the present invention, a signal having a frequency between the fundamental frequency and the second harmonic frequency of the irradiation ultrasonic wave is extracted by the extracting means. It is possible to realize an ultrasonic imaging apparatus that performs ultrasonic imaging without using the second harmonic.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device 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 embodiment of the present invention;

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

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

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

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

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

FIG. 8 is a diagram illustrating a frequency band of a received signal according to an example of an embodiment of the present invention.

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

FIG. 10 is a diagram showing a CFM image and a Doppler spectrum image of a phantom containing an i-micro balloon displayed on a display by 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 containing no microballoons displayed on a display as a photograph of a halftone image.

[Explanation of symbols]

 OBJ Subject BLN Micro-balloon contrast agent PRB Ultrasound probe TRX transmitting / receiving unit BMP B-mode processing unit CMP CFM processing unit IMP Image processing unit DIS display unit 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 flow velocity operation circuit DSR Distributed operation circuit PWR Power operation circuit AMM Sound ray data memory DSC Digital scan converter IMM Image memory IMK Image processing circuit FLT1 to FLT3 Filter

Claims (6)

[Claims] 1. An ultrasonic imaging method for irradiating a subject containing a microballoon contrast agent with an ultrasonic wave to form an image based on an echo, wherein the image is formed based on a change in an echo signal due to scintillation of the microballoon. Forming an ultrasonic imaging method. 2. An ultrasonic imaging apparatus for irradiating a subject containing a microballoon contrast medium with an ultrasonic wave to form an image based on an echo, and detecting a change in an echo signal due to scintillation of the microballoon. And an image forming means for forming an image based on an output signal of the detecting means. 3. The ultrasonic imaging apparatus according to claim 2, wherein said detection means has a Doppler signal processing means. 4. An ultrasonic imaging method, comprising: irradiating a subject containing a microballoon contrast medium with ultrasonic waves; and forming an image based on acoustic radiation from the microballoons induced by the ultrasonic waves. 5. An ultrasonic irradiator for irradiating an ultrasonic wave to a subject containing a microballoon contrast agent, and detection for detecting acoustic radiation induced from the micro balloon by the ultrasonic wave radiated from the ultrasonic irradiator. And an image forming means for forming an image based on an output signal of the detecting means. 6. The apparatus according to claim 5, wherein said detecting means has an extracting means for extracting a signal having a frequency between a fundamental frequency and a second harmonic frequency of said irradiated ultrasonic wave. Ultrasound imaging device.