Ultrasonic diagnostic apparatus and image processing method

Abstract

To suitably collect contrast medium-based images and blood flow images.SOLUTION: An ultrasound diagnosis apparatus according to the embodiment includes a transmission and reception unit and an image generation unit. The transmission and reception unit performs, via an ultrasound probe, a first ultrasound scan for a first region within a subject injected with a contrast medium and a second ultrasound scan, including transmitting and receiving each of two ultrasound waves with at least one of amplitude and phase different from each other, for at least a portion of a second region overlapping the first region within the subject. The image generation unit generates, using a Doppler method, one frame of blood flow image on the basis of a data train comprising reception data acquired from each of multiple passes of the first ultrasound scan performed, interposed with the second ultrasound scan, on the same position in the first region, and generates a contrast medium-based image on the basis of a result of at least one pass of the second ultrasound scan.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to an ultrasonic diagnostic apparatus.

Background Art

[0002] Conventionally, various imaging methods have been performed in ultrasonic diagnostic apparatuses. For example, in an ultrasonic diagnostic apparatus, a contrast echo method called contrast harmonic imaging (CHI) is performed. In contrast harmonic imaging, for example, in an examination of the heart, liver, etc., a contrast agent is injected from a vein and imaging is performed. By contrast harmonic imaging, for example, a contrast image in which blood vessels in a subject are depicted can be obtained.

[0003] Also, in an ultrasonic diagnostic apparatus, for example, a Doppler method for imaging the blood flow using the Doppler effect is performed. For example, the ultrasonic diagnostic apparatus applies an MTI (Moving Target Indicator) filter to a data series at the same position to suppress signals (clutter signals) derived from stationary tissues or tissues with slow movement, and extracts signals derived from the blood flow. Then, the ultrasonic diagnostic apparatus estimates blood flow information such as the velocity of the blood flow, the dispersion of the blood flow, and the power of the blood flow from this blood flow signal, and generates blood flow image data showing a blood flow image in which the distribution of the estimation result is color-displayed in two dimensions, for example (color Doppler image).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide an ultrasonic diagnostic apparatus capable of suitably collecting contrast images and blood flow images.

Means for Solving the Problem

[0006] The ultrasonic diagnostic apparatus according to the embodiment includes a transmission / reception unit and an image generation unit. The transmission / reception unit includes a first ultrasonic scan of a first region in a subject injected with a contrast agent, and transmission and reception of two types of ultrasonic waves each having at least one of amplitude and phase different, and performs a second ultrasonic scan of at least a part of a second region in the subject that overlaps the first region via an ultrasonic probe. The image generation unit generates a blood flow image for one frame using the Doppler method based on a data series composed of reception data obtained by each of a plurality of first ultrasonic scans performed on the same position within the first region with the second ultrasonic scan interposed therebetween, and generates a contrast image based on the result of at least one second ultrasonic scan.

Brief Description of the Drawings

[0007]

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DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an ultrasonic diagnostic apparatus according to an embodiment will be described with reference to the drawings. Note that the content described in one embodiment or modification may be similarly applied to other embodiments or other modifications.

[0009] (First Embodiment) FIG. 1 is a block diagram showing a configuration example of an ultrasonic diagnostic apparatus 1 according to the first embodiment. As illustrated in FIG. 1, the ultrasonic diagnostic apparatus 1 according to the first embodiment includes an apparatus main body 100, an ultrasonic probe 101, an input device 102, and a display 103.

[0010] The ultrasonic probe 101 has, for example, a plurality of elements such as piezoelectric vibrators. These plurality of elements generate ultrasonic waves based on a drive signal supplied from a transmission circuit 110a of a transmission / reception circuit 110 included in the apparatus main body 100. Further, the ultrasonic probe 101 receives a reflected wave from the subject P and converts it into an electrical signal. In addition, the ultrasonic probe 101 has, for example, a matching layer provided on the piezoelectric vibrator and a backing material that prevents the propagation of ultrasonic waves backward from the piezoelectric vibrator. Note that the ultrasonic probe 101 is detachably connected to the apparatus main body 100.

[0011] When ultrasonic waves are transmitted from the ultrasonic probe 101 to the subject P, the transmitted ultrasonic waves are successively reflected at the discontinuity surfaces of the acoustic impedance in the body tissues of the subject P, and are received by a plurality of elements included in the ultrasonic probe 101 as reflected wave signals. The amplitude of the received reflected wave signal depends on the difference in acoustic impedance at the discontinuity surface where the ultrasonic wave is reflected. When the transmitted ultrasonic pulse is reflected at the surface of moving blood flow, the heart wall, or the like, the reflected wave signal undergoes a frequency shift depending on the velocity component of the moving object with respect to the ultrasonic transmission direction due to the Doppler effect. Then, the ultrasonic probe 101 outputs the reflected wave signal to the receiving circuit 110b of the transmission / reception circuit 110 described later.

[0012] The ultrasonic probe 101 is detachably provided to the apparatus main body 100. When performing a two-dimensional scan (2D scan) of a two-dimensional region within the subject P, the operator connects, for example, a 1D array probe in which a plurality of piezoelectric vibrators are arranged in a row to the apparatus main body 100 as the ultrasonic probe 101. The 1D array probe is a linear ultrasonic probe, a convex ultrasonic probe, a sector ultrasonic probe, or the like. When performing a three-dimensional scan (3D scan) of a three-dimensional region within the subject P, the operator connects, for example, a mechanical 4D probe or a 2D array probe to the apparatus main body 100 as the ultrasonic probe 101. The mechanical 4D probe can perform a two-dimensional scan using a plurality of piezoelectric vibrators arranged in a row like a 1D array probe, and can perform a three-dimensional scan by swinging a plurality of piezoelectric vibrators at a predetermined angle (swing angle). The 2D array probe can perform a three-dimensional scan with a plurality of piezoelectric vibrators arranged in a matrix, and can perform a two-dimensional scan by focusing and transmitting ultrasonic waves.

[0013] The input device 102 is realized by input means such as a mouse, a keyboard, a button, a panel switch, a touch command screen, a foot switch, a trackball, a joystick, or the like. The input device 102 receives various setting requests from the operator of the ultrasonic diagnostic apparatus 1 and transfers the received various setting requests to the apparatus main body 100.

[0014] The display 103 displays, for example, a GUI (Graphical User Interface) for an operator of the ultrasonic diagnostic apparatus 1 to input various setting requests using the input device 102, or displays an ultrasonic image or the like indicated by ultrasonic image data generated in the apparatus main body 100. The display 103 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, or the like.

[0015] The apparatus main body 100 generates ultrasonic image data based on the reflected wave signal received by the ultrasonic probe 101. Note that the ultrasonic image data is an example of image data. The apparatus main body 100 can generate two-dimensional ultrasonic image data based on the reflected wave data corresponding to a two-dimensional region of the subject P received by the ultrasonic probe 101. Further, the apparatus main body 100 can generate three-dimensional ultrasonic image data based on the reflected wave data corresponding to a three-dimensional region of the subject P received by the ultrasonic probe 101. As shown in FIG. 1, the apparatus main body 100 includes a transmission / reception circuit 110, a buffer memory 120, a B-mode processing circuit 130, a Doppler processing circuit 140, an image generation circuit 150, an image memory 160, a storage circuit 170, and a control circuit 180.

[0016] The transmission / reception circuit 110, under the control of the control circuit 180, causes the ultrasonic probe 101 to transmit ultrasonic waves and causes the ultrasonic probe 101 to receive ultrasonic waves (reflected waves of ultrasonic waves). That is, the transmission / reception circuit 110 executes an ultrasonic scan (ultrasonic wave scanning) via the ultrasonic probe 101. The transmission / reception circuit 110 is an example of a transmission / reception unit. The transmission / reception circuit 110 includes a transmission circuit 110a and a reception circuit 110b.

[0017] The transmission circuit 110a receives control from the control circuit 180 and causes the ultrasonic probe 101 to transmit ultrasonic waves. The transmission circuit 110a includes a rate pulsar generation circuit, a transmission delay circuit, and a transmission pulsar, and supplies a drive signal to the ultrasonic probe 101. When scanning a two-dimensional region within the subject P, the transmission circuit 110a causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the two-dimensional region. Also, when scanning a three-dimensional region within the subject P, the transmission circuit 110a causes the ultrasonic probe 101 to transmit an ultrasonic beam for scanning the three-dimensional region.

[0018] The rate pulsar generation circuit repeatedly generates rate pulses for forming transmitted ultrasonic waves (transmission beams) at a predetermined rate frequency (PRF: Pulse Repetition Frequency). As the rate pulses pass through the transmission delay circuit, voltages are applied to the transmission pulsar in a state having different transmission delay times. For example, the transmission delay circuit provides, for each rate pulse generated by the rate pulsar generation circuit, the transmission delay time for each piezoelectric vibrator necessary for focusing the ultrasonic waves generated from the ultrasonic probe 101 into a beam shape and determining the transmission directivity. The transmission pulsar applies a drive signal (drive pulse) to the ultrasonic probe 101 at the timing based on such rate pulses. Note that the transmission delay circuit arbitrarily adjusts the transmission direction of the ultrasonic waves from the piezoelectric vibrator surface by changing the transmission delay time given to each rate pulse.

[0019] The drive pulse is transmitted from the transmission pulsar to the piezoelectric vibrator within the ultrasonic probe 101 via a cable, and then is converted from an electrical signal to a mechanical vibration at the piezoelectric vibrator. The ultrasonic waves generated by this mechanical vibration are transmitted into the living body. Here, the ultrasonic waves having different transmission delay times for each piezoelectric vibrator are focused and propagated in a predetermined direction.

[0020] Note that the transmission circuit 110a has a function that can instantaneously change the transmission frequency, transmission drive voltage, etc. in order to execute a predetermined scanning sequence under the control of the control circuit 180. In particular, the change in the transmission drive voltage is realized by a linear amplifier type transmission circuit that can instantaneously switch its value, or by a mechanism that electrically switches a plurality of power supply units.

[0021] The reflected wave of the ultrasonic wave transmitted by the ultrasonic probe 101 reaches the piezoelectric vibrator inside the ultrasonic probe 101, and then at the piezoelectric vibrator, it is converted from mechanical vibration into an electrical signal (reflected wave signal) and input to the receiving circuit 110b. The receiving circuit 110b includes a preamplifier, an A / D (Analog to Digital) converter, a quadrature detection circuit, etc., and performs various processes on the reflected wave signal received by the ultrasonic probe 101 to generate reflected wave data. Then, the receiving circuit 110b stores the generated reflected wave data in the buffer memory 120.

[0022] The preamplifier amplifies the reflected wave signal for each channel and performs gain adjustment (gain correction). The A / D converter converts the gain-corrected reflected wave signal into a digital signal by performing A / D conversion on the gain-corrected reflected wave signal. The quadrature detection circuit converts the A / D-converted reflected wave signal into an in-phase signal (I signal, I: In-phase) and a quadrature signal (Q signal, Q: Quadrature-phase) in the baseband band. Then, the quadrature detection circuit stores the I signal and the Q signal (IQ signal) in the buffer memory 120 as reflected wave data.

[0023] The receiving circuit 110b generates two-dimensional reflected wave data from the two-dimensional reflected wave signal received by the ultrasonic probe 101. Also, the receiving circuit 110b generates three-dimensional reflected wave data from the three-dimensional reflected wave signal received by the ultrasonic probe 101.

[0024] Here, the ultrasonic diagnostic apparatus 1 according to the present embodiment simultaneously displays a blood flow image indicating blood flow information, a contrast image in which tissue perfusion such as fine capillaries is depicted, and a tissue image indicating a tissue shape. The blood flow image is an image indicated by color Doppler image data which is blood flow image data. The contrast image is an image indicated by B-mode image data which is contrast image data. The tissue image is an image indicated by B-mode image data which is tissue image data.

[0025] Then, in order to perform such display, the transmission / reception circuit 110 executes an ultrasonic scan (first ultrasonic scan) for collecting blood flow image data in Doppler mode and an ultrasonic scan (second ultrasonic scan) for collecting tissue image data and contrast image data in B-mode. The first ultrasonic scan is an ultrasonic scan of a region (first region) in the subject P injected with a contrast agent, and is an ultrasonic scan for acquiring blood flow information in the first region. The second ultrasonic scan is an ultrasonic scan for acquiring information on the tissue shape in a region (second region) in the subject P and information on tissue perfusion such as fine capillaries.

[0026] That is, when collecting the tissue image data and the contrast image data, the transmission / reception circuit 110 does not separately perform an ultrasonic scan for collecting the tissue image and an ultrasonic scan for collecting the contrast image, but executes one second ultrasonic scan. That is, by simply executing two types of ultrasonic scans, the first ultrasonic scan and the second ultrasonic scan, by the transmission / reception circuit 110, the ultrasonic diagnostic apparatus 1 can collect three types of images: a blood flow image, a tissue image, and a contrast image.

[0027] It is sufficient that the first region and the second region overlap at least partially. The range of the first region and the range of the second region may be the same range, the range of the first region may be smaller than the range of the second region, or the range of the second region may be smaller than the range of the first region.

[0028] The buffer memory 120 is a memory that temporarily stores the reflected wave data generated by the transceiver circuit 110. For example, the buffer memory 120 stores the reflected wave data for several frames or the reflected wave data for several volumes. For example, the buffer memory 120 stores the reflected wave data for a predetermined number of frames under the control of the receiving circuit 110b. Then, when a new frame of reflected wave data is generated by the receiving circuit 110b while the buffer memory 120 stores the reflected wave data for a predetermined number of frames, the buffer memory 120 discards the reflected wave data for the oldest one frame generated, under the control of the receiving circuit 110b, and stores the newly generated reflected wave data for one frame. For example, the buffer memory 120 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory. Note that the reflected wave data for one frame generated by the transceiver circuit 110 is the reflected wave data for one acquisition frame.

[0029] The B-mode processing circuit 130 and the Doppler processing circuit 140 are signal processing units that read the reflected wave data from the buffer memory 120 and perform various signal processes on the read reflected wave data.

[0030] The B-mode processing circuit 130 performs logarithmic amplification, envelope detection processing, etc. on the reflected wave data read from the buffer memory 120 to generate data (B-mode data) in which the signal intensity (amplitude intensity) for each sample point is expressed by the brightness of the luminance. The B-mode processing circuit 130 outputs the generated B-mode data to the image generation circuit 150. The B-mode processing circuit 130 is realized by, for example, a processor.

[0031] Note that the B-mode processing circuit 130 can change the frequency band to be imaged by changing the detection frequency. By using the function of this B-mode processing circuit 130, the ultrasonic diagnostic apparatus 1 according to the first embodiment can execute contrast harmonic imaging (CHI) for imaging non-linear signals from the contrast agent. For example, the B-mode processing circuit 130 can generate B-mode data (second B-mode data) that is the basis of the contrast image data. Specific processing performed by the B-mode processing circuit 130 according to the first embodiment will be described in detail later.

[0032] The Doppler processing circuit 140 extracts motion information of a moving object (such as blood flow, tissue, contrast agent echo components, etc.) based on the Doppler effect by performing frequency analysis on the reflected wave data read from the buffer memory 120, and generates data (Doppler data) indicating the extracted motion information. For example, the Doppler processing circuit 140 extracts, at multiple points, the average velocity, average variance value, average power value, etc. as the motion information of the moving object, and generates Doppler data indicating the extracted motion information of the moving object. The Doppler processing circuit 140 outputs the generated Doppler data to the image generation circuit 150.

[0033] Using the functions of the above-described Doppler processing circuit 140, the ultrasonic diagnostic apparatus 1 according to the first embodiment can execute a color Doppler method, also called a color flow mapping (CFM) method. In the color flow mapping method, ultrasonic transmission and reception are performed a plurality of times on a plurality of scan lines. Then, in the color flow mapping method, by applying an MTI (Moving Target Indicator) filter to the data series at the same position, signals (clutter signals) derived from stationary tissues or tissues with slow movement are suppressed from the data series at the same position, and signals derived from blood flow are extracted. Then, in the color flow mapping method, blood flow information such as the velocity of blood flow, the dispersion of blood flow, and the power of blood flow is estimated from this blood flow signal. The image generation circuit 150 described later generates ultrasonic image data (blood flow image data: color Doppler image data) in which the distribution of the estimation results of blood flow information is color-displayed in two dimensions, for example. Then, the display 103 displays the blood flow image indicated by the blood flow image data.

[0034] The Doppler processing circuit 140 according to the present embodiment uses an adaptive MTI filter that changes coefficients according to an input signal as an MTI filter. For example, the Doppler processing circuit 140 uses a filter called "Eigenvector Regression Filter" as an adaptive MTI filter. Hereinafter, the "Eigenvector Regression Filter", which is an adaptive MTI filter using eigenvectors, will be referred to as an "eigenvector type MTI filter".

[0035] The eigenvector type MTI filter calculates eigenvectors from a correlation matrix and calculates coefficients used for clutter component suppression processing from the calculated eigenvectors. This method applies a technique used in principal component analysis, Karhunen-Loeve transform, and eigen-space method.

[0036] The Doppler processing circuit 140 according to the first embodiment using the eigenvector type MTI filter calculates the correlation matrix of the first region from the data sequence of the continuous reflected wave data at the same position (same sample point). Then, the Doppler processing circuit 140 calculates the eigenvalues of the correlation matrix and the eigenvectors corresponding to the eigenvalues. Then, the Doppler processing circuit 140 calculates, as a filter matrix for suppressing the clutter component, a matrix obtained by reducing the rank of the matrix formed by arranging the eigenvectors based on the magnitude of each eigenvalue.

[0037] Then, the Doppler processing circuit 140 uses the filter matrix to identify a data sequence in which the clutter component is suppressed and the blood flow signal derived from the blood flow is extracted from the data sequence of the continuous reflected wave data at the same position (same sample point). Then, the Doppler processing circuit 140 performs operations such as autocorrelation calculation using the identified data sequence to estimate the blood flow information. Then, the Doppler processing circuit 140 outputs Doppler data indicating the estimated blood flow information to the image generation circuit 150. The specific processing performed by the Doppler processing circuit 140 according to the first embodiment will be described in detail later. The Doppler processing circuit 140 is realized by, for example, a processor. The Doppler processing circuit 140 is an example of a blood flow information acquisition unit.

[0038] The B-mode processing circuit 130 and the Doppler processing circuit 140 are capable of processing both two-dimensional reflected wave data and three-dimensional reflected wave data.

[0039] The image generation circuit 150 generates ultrasonic image data from the data output by the B-mode processing circuit 130 and the Doppler processing circuit 140. The image generation circuit 150 generates two-dimensional B-mode image data in which the intensity of the reflected wave is represented by luminance from the two-dimensional B-mode data generated by the B-mode processing circuit 130. Also, the image generation circuit 150 generates two-dimensional Doppler image data in which blood flow information is visualized from the two-dimensional Doppler data generated by the Doppler processing circuit 140. The two-dimensional Doppler image data is velocity image data, variance image data, power image data, or image data combining these. The image generation circuit 150 generates blood flow image data in which blood flow information is displayed in color or blood flow image data in which one blood flow information is displayed in grayscale as Doppler image data from the Doppler data as blood flow information. The image generation circuit 150 is realized by a processor.

[0040] Here, the image generation circuit 150 generally converts (scanning conversion) the scanning line signal sequence of the ultrasonic scan into the scanning line signal sequence of a video format typified by a television or the like, and generates ultrasonic image data for display. For example, the image generation circuit 150 generates ultrasonic image data for display by performing coordinate conversion according to the scanning form of the ultrasonic wave by the ultrasonic probe 101. Also, in addition to the scanning conversion, the image generation circuit 150 performs various image processes, for example, an image process (smoothing process) for regenerating an average value image of luminance using a plurality of image frames after the scanning conversion, an image process (edge enhancement process) using a differential filter in the image, and the like. Also, the image generation circuit 150 synthesizes character information, scales, body marks, and the like of various parameters with the ultrasonic image data.

[0041] Furthermore, the image generation circuit 150 generates three-dimensional B-mode image data by performing coordinate transformation on the three-dimensional B-mode data generated by the B-mode processing circuit 130. Also, the image generation circuit 150 generates three-dimensional Doppler image data by performing coordinate transformation on the three-dimensional Doppler data generated by the Doppler processing circuit 140. That is, the image generation circuit 150 generates "three-dimensional B-mode image data and three-dimensional Doppler image data" as "three-dimensional ultrasonic image data (volume data)". Then, the image generation circuit 150 performs various rendering processes on the volume data in order to generate various two-dimensional image data for displaying the volume data on the display 103.

[0042] Examples of the rendering processes performed by the image generation circuit 150 include a process of generating MPR image data from volume data by performing a cross-sectional reconstruction method (MPR: Multi Planar Reconstruction). Also, examples of the rendering processes performed by the image generation circuit 150 include a volume rendering (VR: Volume Rendering) process of generating two-dimensional image data that reflects three-dimensional information. The image generation circuit 150 is an example of an image generation unit.

[0043] The B-mode data and the Doppler data are ultrasonic image data before scan conversion processing, and the data generated by the image generation circuit 150 is ultrasonic image data for display after scan conversion processing. Note that the B-mode data and the Doppler data are also called raw data.

[0044] The image memory 160 is a memory that stores various types of image data generated by the image generation circuit 150. Further, the image memory 160 also stores the data generated by the B-mode processing circuit 130 and the Doppler processing circuit 140. The B-mode data and Doppler data stored in the image memory 160 can be called by the operator after diagnosis, for example, and become ultrasonic image data for display via the image generation circuit 150. For example, the image memory 160 is realized by a semiconductor memory element such as a RAM or a flash memory, a hard disk, or an optical disk.

[0045] The storage circuit 170 stores a control program for performing ultrasonic transmission / reception, image processing, and display processing, diagnostic information (for example, patient ID, doctor's findings, etc.), diagnostic protocols, and various data such as various body marks. Further, the storage circuit 170 is also used for storing the data stored in the image memory 160 as needed. For example, the storage circuit 170 is realized by a semiconductor memory element such as a flash memory, a hard disk, or an optical disk.

[0046] The control circuit 180 controls the overall processing of the ultrasonic diagnostic apparatus 1. Specifically, the control circuit 180 controls the processing of the transmission / reception circuit 110, the B-mode processing circuit 130, the Doppler processing circuit 140, and the image generation circuit 150 based on various setting requests input from the operator via the input device 102 and various control programs and various data read from the storage circuit 170. Further, the control circuit 180 controls the display 103 to display the ultrasonic image indicated by the ultrasonic image data for display stored in the image memory 160. The control circuit 180 is an example of a display control unit or a control unit. The control circuit 180 is realized by a processor, for example. The ultrasonic image is an example of an image.

[0047] Further, the control circuit 180 controls the ultrasonic probe 101 via the transmission / reception circuit 110 to control the ultrasonic scan. For example, the control circuit 180 controls the first ultrasonic scan and the second ultrasonic scan described above.

[0048] In the above description, the term "processor" used means, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), or a programmable logic device (for example, a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). The processor realizes its function by reading and executing the program stored in the storage circuit 170. Instead of storing the program in the storage circuit 170, it may be configured to directly incorporate the program into the circuit of the processor. In this case, the processor realizes its function by reading and executing the program incorporated into the circuit. Each processor of the present embodiment is not limited to being configured as a single circuit for each processor, and a plurality of independent circuits may be combined to form one processor to realize its function. Further, a plurality of components in FIG. 1 may be integrated into one processor to realize its function. As described above, the overall configuration of the ultrasonic diagnostic apparatus 1 according to the first embodiment has been described.

[0049] In the first embodiment, the transmission / reception circuit 110 alternately executes the first ultrasonic scan and the second ultrasonic scan via the ultrasonic probe 101. The scanning form of the first ultrasonic scan is a scanning form in which ultrasonic transmission and reception in a first region formed by a plurality of scanning lines are performed once for each scanning line. With such a scanning form, the frame rate can be improved. Hereinafter, the above first ultrasonic scan will be referred to as the "ultrasonic scan for high frame rate", and the CFM method performed by the "ultrasonic scan for high frame rate" will be referred to as the "high frame rate method".

[0050] Here, in the normal color Doppler method, ultrasonic transmission and reception are performed multiple times in the same direction, and a blood flow signal is extracted from the signal received thereby. A data series of reflected wave signals (reflected wave data) from the same position obtained by such ultrasonic transmission and reception is called a packet. The packet size is the number of times of ultrasonic transmission and reception performed in the same direction to obtain blood flow information for one frame. The packet size in a general color Doppler method is about 5 to 16. The performance of the eigenvector type MTI filter improves as the packet size increases, but when the packet size is increased, the frame rate decreases.

[0051] On the other hand, in the high frame rate method, processing can be performed in the frame direction (time direction) on the data series at the same position in each frame. For example, in the high frame rate method, the MTI filter processing can be changed from processing of finite-length data called a packet to processing of infinite-length data. As a result, the performance of the MTI filter can be improved by the high frame rate method, and as a result, blood flow information regarding low-flow blood can also be detected, and a blood flow image showing blood flow information can be displayed at a high frame rate.

[0052] The control circuit 180 according to the first embodiment causes the second ultrasonic scan to be executed in the scanning mode described below, together with the first ultrasonic scan by the high frame rate ultrasonic scan.

[0053] The control circuit 180 divides the second region into a plurality of divided regions, and causes the ultrasonic probe 101 to perform a second ultrasonic scan for each of the plurality of divided regions in a time-division manner during the first ultrasonic scan. That is, the transmission / reception circuit 110 alternately performs the first ultrasonic scan and the second ultrasonic scan for each of the plurality of divided regions obtained by dividing the second region via the ultrasonic probe 101. Therefore, in the first embodiment, the transmission / reception circuit 110 performs the second ultrasonic scan during the first ultrasonic scan, and completes the second ultrasonic scan for one frame within the period of performing the first ultrasonic scan for several frames. With such a scanning mode, the ultrasonic diagnostic apparatus 1 according to the first embodiment can independently set ultrasonic transmission / reception conditions (image quality conditions) for the first ultrasonic scan and the second ultrasonic scan.

[0054] The first ultrasonic scan and the second ultrasonic scan will be described. FIGS. 2 and 3 are diagrams for explaining an example of the first ultrasonic scan and the second ultrasonic scan according to the first embodiment. As shown in FIG. 2, the control circuit 180 divides the second region into four divided regions (first divided region to fourth divided region) based on an instruction from an operator, initially set information, or the like. "C" shown in FIG. 2 indicates a divided region in which the second ultrasonic scan is performed using the transmission / reception conditions for contrast harmonic imaging in the B mode. The divided region is formed by at least one scanning line.

[0055] For example, in the present embodiment, in the second ultrasonic scan, a phase modulation method (PM: Phase Modulation) may be used. The phase modulation method is, for example, a method of transmitting two types of ultrasonic waves having different phases on each scanning line constituting a scanning range, and adding reflected wave data based on the reflected waves of the two types of ultrasonic waves. In the present embodiment, when the phase modulation method is used, the transmission / reception circuit 110 transmits two types of ultrasonic waves having different phases on each scanning line constituting the divided region, and the B mode processing circuit 130 adds the reflected wave data based on the reflected waves of the two types of ultrasonic waves. When the phase modulation method is used, the second ultrasonic scan includes transmission and reception of two types of ultrasonic waves having different phases.

[0056] In the second ultrasonic scan, the amplitude modulation method (AM: Amplitude Modulation) may be used. The amplitude modulation method is a method in which, for example, three ultrasonic waves whose amplitude ratios are modulated to "1:2:1" with the same phase are transmitted on each scanning line constituting the scanning range, and the reflected wave data based on the reflected waves of each of the three ultrasonic waves are subjected to addition and subtraction processing. In the present embodiment, when the amplitude modulation method is used, the transmission / reception circuit 110 transmits ultrasonic waves with an amplitude of "0.5", ultrasonic waves with an amplitude of "1", and ultrasonic waves with an amplitude of "0.5" in this order on each scanning line constituting the divided region. That is, the transmission / reception circuit 110 transmits two types of ultrasonic waves with different amplitudes. Then, the B-mode processing circuit 130 performs addition and subtraction processing on the reflected wave data based on the reflected waves of each of the three ultrasonic waves (two types of ultrasonic waves). When the amplitude modulation method is used, the second ultrasonic scan includes transmission and reception of each of two types of ultrasonic waves with different amplitudes.

[0057] In the second ultrasonic scan, which of the phase modulation method and the amplitude modulation method is used is selected by the operator. For example, in the phase modulation method, since the frequency of the transmitted ultrasonic wave is relatively high and the reception frequency is relatively high for extracting the second harmonic component from the contrast agent, an ultrasonic image with relatively high spatial resolution can be obtained, but it has the characteristic that the penetration is not good. On the other hand, in the amplitude modulation method, since the frequency of the transmitted ultrasonic wave is relatively low and the reception frequency is substantially the same as the transmission frequency, the penetration is good, but the spatial resolution of the ultrasonic image is relatively low. The operator operates the input device 102 to select either the phase modulation method or the amplitude modulation method in consideration of such characteristics.

[0058] For example, when the phase modulation method is selected by the operator, the control circuit 180 stores information "0" indicating the phase modulation method in a predetermined area of all the storage areas of the storage circuit 170. Also, when the amplitude modulation method is selected by the operator, information "1" indicating the amplitude modulation method is stored in a predetermined area of the storage circuit 170. Then, when executing the second ultrasonic scan, the control circuit 180 refers to the predetermined area of the storage circuit 170. If the information obtained as a result of the reference indicates "0", the control circuit 180 controls the transmission / reception circuit 110 and the B-mode processing circuit 130 so that the processing using the above-described phase modulation method is executed. On the other hand, if the information obtained as a result of the reference indicates "1", the control circuit 180 controls the transmission / reception circuit 110 and the B-mode processing circuit 130 so that the processing using the above-described amplitude modulation method is executed.

[0059] Also, "D" shown in FIG. 2 indicates a first area where the first ultrasonic scan is performed using the transmission / reception conditions for the color Doppler mode. For example, "D" shown in FIG. 2 is a range where the ultrasonic scan performed by the above high frame rate method is being performed. That is, the first ultrasonic scan does not transmit ultrasonic waves a plurality of times in the same direction and receive a plurality of reflected waves like a general color Doppler method, but performs ultrasonic transmission / reception once for each scan line. The transmission / reception circuit 110 performs ultrasonic transmission / reception once for each of a plurality of scan lines forming the first area as the first ultrasonic scan, thereby executing an ultrasonic scan based on a method (high frame rate method) of acquiring blood flow information using reflected waves for a plurality of frames (a plurality of acquisition frames).

[0060] As shown in FIG. 2, first, the transceiver circuit 110 executes a second ultrasonic scan for the first divided region (step S1), and executes a first ultrasonic scan for the first region (one frame) (step S2). Then, the transceiver circuit 110 executes a second ultrasonic scan for the second divided region (step S3), and executes a first ultrasonic scan for the first region (step S4). Then, the transceiver circuit 110 executes a second ultrasonic scan for the third divided region (step S5), and executes a first ultrasonic scan for the first region (step S6). Then, the transceiver circuit 110 executes a second ultrasonic scan for the fourth divided region (step S7), executes a first ultrasonic scan for the first region (step S8), and returns to step S1.

[0061] Here, as illustrated in FIG. 2, the control circuit 180 that controls the first ultrasonic scan by the transceiver circuit 110 makes the intervals at which the first ultrasonic scan is performed equal. That is, the "point X" on the "certain scan line" of the first region is scanned once each by the first ultrasonic scans in steps S2, S4, S6, and S8 in FIG. 2, and the scan intervals are controlled to be a constant "T". For example, the control circuit 180 makes the intervals at which the first ultrasonic scan is performed equal by making the time required for the second ultrasonic scan the same. For example, the control circuit 180 controls the time required for the second ultrasonic scans performed in steps S1, S3, S5, and S7 in FIG. 2 to be the same time. The control circuit 180 makes the sizes of the divided regions obtained by dividing the second region, the number of scan lines, the scan line density, the depth, etc. the same. For example, if the number of scan lines is the same, the time required for the second ultrasonic scan is the same. The Doppler processing circuit 140 performs the processing described later on the data series at the same position between the frames of the first region (the "X n-3 , X n-2 , X n-1 , X n , ···") shown in FIG. 2, and outputs the blood flow information of the "point X". Note that in the above method, the control circuit 180 having the display control function updates not the tissue image displayed on the display 103 at "4T" intervals, but a part of the tissue image corresponding to the divided region at "T" intervals.

[0062] In the conventional color Doppler processing, "MTI filter processing" and "velocity / dispersion / power estimation processing" are performed on a data sequence closed within a packet. Therefore, in the conventional color Doppler processing, only one blood flow information can be output per packet. In contrast, in the color Doppler processing performed in the scanning mode of the high frame rate method, there is no concept of a packet in the scanning itself. Therefore, in the color Doppler processing performed in the above scanning mode, the data length of the data sequence used for the process of outputting one blood flow information can be arbitrarily changed.

[0063] Furthermore, in the color Doppler processing performed in the above scanning mode, it is possible to overlap the data sequence used for the process of outputting the blood flow information of the previous time phase and the data sequence used for the process of outputting the blood flow information of the next time phase.

[0064] This point will be described with reference to FIG. 3. In FIG. 3, an example is shown where the first region and the second region have the same scanning range, and this scanning range is formed by eight scanning lines from the first scanning line to the eighth scanning line. Also, in FIG. 3, each of the eight scanning lines is shown as "1, 2, 3, 4, 5, 6, 7, 8" along the azimuth direction (the array direction of the vibrators of the ultrasonic probe 101). Further, in FIG. 3, the second ultrasonic scan is shown as a black-filled rectangle, and the first ultrasonic scan is shown as a white-filled rectangle. FIG. 3 is a diagram illustrating the case where the scanning range shown in FIG. 2 is scanned in the scanning mode performed in the first embodiment. Specifically, in FIG. 3, the first region shown in FIG. 2 is formed by eight scanning lines, and a case is shown where a divided region obtained by dividing the second region, which is the same region as the first region, into four is formed by two scanning lines.

[0065] In the scan illustrated in FIG. 3, the second ultrasonic scan is performed in order from the first scanning line to the second scanning line. After the second ultrasonic scan of the second scanning line is performed, the first ultrasonic scan (the first-time first ultrasonic scan) is performed in order from the first scanning line to the eighth scanning line.

[0066] After the first first ultrasonic scan is performed, the second ultrasonic scan is performed in the order from the third scanning line to the fourth scanning line. After the second ultrasonic scan of the fourth scanning line is performed, again, the first ultrasonic scan (the second first ultrasonic scan) is performed in the order from the first scanning line to the eighth scanning line.

[0067] Then, after the second ultrasonic scan is performed in the order from the fifth scanning line to the sixth scanning line, again, the first ultrasonic scan (the third first ultrasonic scan) is performed in the order from the first scanning line to the eighth scanning line.

[0068] Then, after the second ultrasonic scan is performed in the order from the seventh scanning line to the eighth scanning line, again, the first ultrasonic scan (the fourth first ultrasonic scan) is performed in the order from the first scanning line to the eighth scanning line. Also after the fourth first ultrasonic scan, similarly, the second ultrasonic scan and the first ultrasonic scan are alternately executed. That is, in the first embodiment, the transmission / reception circuit 110 alternately executes the first ultrasonic scan for the first region and the second ultrasonic scan for a part (divided region) of the second region.

[0069] Here, for example, a case where the data length of the data sequence is set to "4" and the number of overlaps of the data sequence between the displayed frames is set to "3" will be described. In such a case, the Doppler processing circuit 140 generates Doppler data for the first frame from the reflected wave data collected from the first first ultrasonic scan to the fourth first ultrasonic scan. That is, the Doppler processing circuit 140 generates Doppler data for the first frame from the reflected wave data collected by the first ultrasonic scan four times corresponding to the data length "4" of the data sequence. This Doppler data is the data that becomes the basis of the blood flow image data. Then, the image generation circuit 150 generates the blood flow image data of the first frame from the Doppler data for the first frame. Then, the control circuit 180 causes the display 103 to display the blood flow image of the first frame indicated by the blood flow image data of the first frame.

[0070] Next, the Doppler processing circuit 140 generates Doppler data for the second frame from the reflected wave data collected from the second to fifth first ultrasonic scans. Here, the reflected wave data collected from the second to fifth first ultrasonic scans and the reflected wave data collected from the first to fourth first ultrasonic scans described above overlap in the reflected wave data collected from the second to fourth first ultrasonic scans. That is, the reflected wave data overlaps by a number corresponding to the multiple "3".

[0071] Then, blood flow image data for the second frame is generated from the Doppler data for the second frame. And the blood flow image of the second frame indicated by the blood flow image data of the second frame is displayed on the display 103. Similarly, Doppler data for the third frame is generated from the reflected wave data collected from the third to sixth first ultrasonic scans. That is, when N is a positive integer, Doppler data for the Nth frame is generated from the reflected wave data collected from the Nth first ultrasonic scan to the (N + 3)th first ultrasonic scan.

[0072] Note that one second ultrasonic scan is completed when four first ultrasonic scans are completed, as illustrated in FIG. 3. In the case illustrated in FIG. 3, while one frame of the blood flow image is being displayed, the images of the divided regions (a part of the tissue image and a part of the contrast image) obtained by dividing the second region into four are updated.

[0073] Next, an example of the case where the phase modulation method is used in the second ultrasonic scan will be described. FIG. 4 is a diagram for explaining an example of the case where the phase modulation method is used in the first embodiment. When the phase modulation method is used, the transmission / reception circuit 110 causes the ultrasonic probe 101 to transmit two types of ultrasonic waves 11 and 12 having different polarities as shown in FIG. 4 on the same scanning line.

[0074] Then, the transmission / reception circuit 110 generates reflected wave data based on the reflected wave of the ultrasonic wave 11 and reflected wave data based on the reflected wave of the ultrasonic wave 12. Then, the B-mode processing circuit 130 performs envelope detection processing or the like on the reflected wave data based on the reflected wave of the ultrasonic wave 11 to generate B-mode data (first B-mode data) that is the basis of the tissue image data. Further, the B-mode processing circuit 130 performs envelope detection processing or the like on the data obtained by adding the reflected wave data based on the reflected wave of the ultrasonic wave 12 to the reflected wave data based on the reflected wave of the ultrasonic wave 11 to generate B-mode data (second B-mode data) that is the basis of the contrast image data. Then, the image generation circuit 150 generates tissue image data indicating a part (divided region) of the tissue image 54 based on the first B-mode data. Further, the image generation circuit 150 generates contrast image data indicating a part (divided region) of the contrast image 51 in which the non-linear signal from the contrast agent is visualized based on the second B-mode data.

[0075] Next, an example of the case where the amplitude modulation method selectable in the second ultrasonic scan is used will be described. FIG. 5 is a diagram for explaining an example of the case where the amplitude modulation method is used in the first embodiment. When the amplitude modulation method is used, the transmission / reception circuit 110 transmits ultrasonic waves 13a with an amplitude of "0.5", ultrasonic waves 13b with an amplitude of "1", and ultrasonic waves 13c with an amplitude of "0.5" in this order on the same scanning line, for example, as shown in FIG. 5. That is, the transmission / reception circuit 110 transmits two types of ultrasonic waves, namely, ultrasonic waves 13a and 13c with an amplitude of "0.5" and ultrasonic waves 13b with an amplitude of "1".

[0076] Then, the B-mode processing circuit 130 performs addition and subtraction processing on the reflected wave data based on the reflected waves of each of the three ultrasonic waves (two types of ultrasonic waves). Specifically, assuming that the reflected wave data based on the reflected wave of the ultrasonic wave 13a is "R1", the reflected wave data based on the reflected wave of the ultrasonic wave 13b is "R2", and the reflected wave data based on the reflected wave of the ultrasonic wave 13c is "R3", the B-mode processing circuit 130 performs the following processing. For example, the B-mode processing circuit 130 performs envelope detection processing and the like on the data obtained by performing addition and subtraction processing of "R1 - R2 + R3" to generate B-mode data (second B-mode data) that serves as the basis for the contrast image data. In addition, the B-mode processing circuit 130 performs envelope detection processing and the like on the reflected wave data "R2" based on the reflected wave of the ultrasonic wave 13b to generate B-mode data (first B-mode data) that serves as the basis for the tissue image data.

[0077] Then, the image generation circuit 150 generates tissue image data indicating a part (divided region) of the tissue image 54 based on the first B-mode data. In addition, the image generation circuit 150 generates contrast image data indicating a part (divided region) of the contrast image 51 in which the non-linear signal from the contrast agent is visualized based on the second B-mode data.

[0078] In this way, regardless of whether the phase modulation method or the amplitude modulation method is used, a part of the reflected wave data collected by the second ultrasonic scan, which is a scan for collecting the contrast image data, is used to generate the tissue image data. That is, the image generation circuit 150 generates the tissue image data based on a part of the reflected wave data collected by the second ultrasonic scan. Therefore, according to the present embodiment, it is possible to collect the contrast image and the tissue image by simply performing one second ultrasonic scan.

[0079] Next, an example of the first ultrasonic scan will be described. FIG. 6 is a diagram for explaining an example of the first ultrasonic scan according to the first embodiment.

[0080] In the first ultrasonic scan, the transmission / reception circuit 110 performs ultrasonic transmission and reception only once for each scanning line via the ultrasonic probe 101. Specifically, as the first ultrasonic scan, the transmission / reception circuit 110 transmits ultrasonic wave 14 once for each of a plurality of scanning lines forming the first region, and receives the reflected wave of the ultrasonic wave 14. Then, the transmission / reception circuit 110 generates reflected wave data based on the reflected wave of the ultrasonic wave 14 for each scanning line. Then, the transmission / reception circuit 110 repeats the process of generating reflected wave data in this way for a plurality of frames. Then, the Doppler processing circuit 140 estimates blood flow information based on the reflected wave data based on the reflected waves of the ultrasonic wave 14 for a plurality of frames. Then, the Doppler processing circuit 140 generates Doppler data indicating the estimated blood flow information. Then, the image generation circuit 150 generates blood flow image data indicating the blood flow image 52 based on this Doppler data.

[0081] Next, an example of a method for generating the MTI filter matrix according to the first embodiment will be described. First, the Doppler processing circuit 140 calculates the correlation matrix of the scanning range from the data sequence of the continuous reflected wave data at the same position collected by repeating the scanning mode in which ultrasonic transmission and reception in the first region formed by a plurality of scanning lines is performed once for each scanning line.

[0082] Specifically, the Doppler processing circuit 140 calculates the correlation matrix "R xx " according to the following formula (1).

Equation

[0083] Here, "x m " shown in formula (1) is a column vector of the data sequence at a certain position "m". The length "L" of the column vector "x m " is the data length used for the estimation calculation of the Doppler data (blood flow information) of one frame. For example, in the case illustrated in FIG. 3, "L" is "4". Also, "x m H " shown in formula (1) represents the transposed matrix of the matrix obtained by taking the complex conjugate of each element of "x m ".

[0084] Here, the position "m" is the position of the sample points set in the entire space where the high frame rate ultrasonic scan is performed. The position "m" is represented in a two-dimensional coordinate system in the case of two-dimensional scanning, and in a three-dimensional coordinate system in the case of three-dimensional scanning. Also, "M" shown in Equation (1) is the total number of positions "m".

[0085] That is, the Doppler processing circuit 140 calculates the autocorrelation matrix of the data series at each of the plurality of sample points according to Equation (1), and calculates the average of the autocorrelation matrices of each of the plurality of sample points. Thereby, the Doppler processing circuit 140 calculates the correlation matrix of the first region. The correlation matrix "R xx " becomes a matrix of L rows and L columns according to Equation (1). As described above, the data length "L" of the data series for which the correlation matrix is calculated can be arbitrarily changed. Also, the data series for which the correlation matrix is calculated can be set to overlap between display frames.

[0086] Then, the Doppler processing circuit 140 calculates the eigenvalues of the correlation matrix and the eigenvectors corresponding to the eigenvalues. That is, the Doppler processing circuit 140 calculates L sets of eigenvalues and eigenvectors from the correlation matrix "R xx ". Then, the Doppler processing circuit 140 sets a matrix "V" formed by arranging L eigenvectors based on the magnitudes of the respective eigenvalues. Then, the Doppler processing circuit 140 calculates a matrix with the rank of the matrix "V" reduced as an MTI filter matrix for suppressing clutter components. The Doppler processing circuit 140 uses each of the L eigenvectors as L column vectors, and arranges the L column vectors in descending order of the eigenvalues as a matrix "V", and calculates the MTI filter matrix "W" according to the following Equation (2).

Equation

[0087] Here, "V H " shown in Equation (2) is the complex conjugate transpose matrix of "V". Also, on the right side of Equation (2), "V" and "V HThe matrix between "」" is an L-by-L diagonal matrix. The MTI filter matrix "W" becomes an L-by-L matrix according to Equation (2). Here, the number of ranks to be reduced is determined by how many diagonal elements of the L-by-L diagonal matrix are set to "0". Hereinafter, the number of ranks to be reduced is referred to as the "rank cut number".

[0088] The column vector (eigenvector) with large eigenvalues corresponds to clutter components with small frequency offsets due to the Doppler effect within the scanning range for Doppler, that is, with low moving speeds. Equation (2) calculates a matrix obtained by cutting off components corresponding to the rank cut number from the components with larger eigenvalues of the matrix "V", and performs an inverse transformation on this matrix by "V H ". By this Equation (2), the MTI filter matrix "W" that functions as a high-pass filter for removing the moving components (clutter components) of the tissue can be obtained.

[0089] Here, the Doppler processing circuit 140 determines the value of the rank cut number based on, for example, a preset value or a value specified by the operator. In the above manner, an adaptive MTI filter is generated. That is, the Doppler processing circuit 140 acquires a data sequence collected by a plurality of first ultrasonic scans for each position in the first region, and generates an adaptive MTI filter based on this data sequence. Then, the Doppler processing circuit 140 inputs the data sequence to the generated adaptive MTI filter to acquire blood flow information. Then, the image generation circuit 150 generates blood flow image data based on the blood flow information acquired by the Doppler processing circuit 140.

[0090] Next, with reference to FIG. 7, an example of the display mode of the image according to the first embodiment will be described. FIG. 7 is a diagram for explaining an example of the display mode of the image according to the first embodiment. As shown in FIG. 7, in the first embodiment, the control circuit 180 arranges the contrast image 51, the superimposed image 53 in which the blood flow image 52 is superimposed on the contrast image 51, and the tissue image 54 horizontally and causes them to be displayed on the display 103. Further, the control circuit 180 causes the contrast image 51, the superimposed image 53, and the tissue image 54 to be simultaneously displayed on the display 103. Note that FIG. 7 shows a case where the range of the second region is larger than the range of the first region.

[0091] Here, the control circuit 180 may cause the contrast image 51, the superimposed image 53, and the tissue image to be simultaneously displayed on the display 103 in real time, or may cause the contrast image 51, the superimposed image 53, and the tissue image to be simultaneously displayed on the display 103 as post-processing.

[0092] When displaying various images in real time, the following processing is executed as the processing of the entire ultrasonic diagnostic apparatus 1. For example, each time the transmission / reception circuit 110 receives a reflected wave signal from the ultrasonic probe 101, it generates reflected wave data based on the received reflected wave signal. Then, each time the reflected wave data is generated by the transmission / reception circuit 110, the B-mode processing circuit 130 generates B-mode data based on the reflected wave data. Further, each time the reflected wave data is generated by the transmission / reception circuit 110, the Doppler processing circuit 140 generates Doppler data based on the reflected wave data.

[0093] Then, each time B-mode data is generated by the B-mode processing circuit 130, the image generation circuit 150 generates B-mode image data (contrast image data, tissue image data) based on the B-mode data. Also, each time Doppler data is generated by the Doppler processing circuit 140, the image generation circuit 150 generates Doppler image data (blood flow image data) based on the Doppler data. Note that the image generation circuit 150 generates only a part of the contrast image data of the contrast image 51 or a part of the tissue image data of the tissue image 54 based on one piece of B-mode data based on one second ultrasonic scan. Also, the image generation circuit 150 generates the contrast image data of the entire contrast image 51 or the tissue image data of the entire tissue image 54 based on a plurality of pieces of B-mode data based on a plurality of (the number of divided regions obtained by dividing the second region) second ultrasonic scans. That is, the image generation circuit 150 generates the contrast image 51 and the tissue image 54 based on the results of a plurality of second ultrasonic scans.

[0094] Then, each time the contrast image data and the tissue image data are generated by the image generation circuit 150, the control circuit 180 causes a part of the contrast image 51 indicated by the contrast image data and a part of the tissue image 54 indicated by the tissue image data to be displayed on the display 103, and updates a part of the contrast image 51 and a part of the tissue image 54.

[0095] Also, each time the contrast image data and the blood flow image data are generated, the image generation circuit 150 superimposes the contrast image data on the blood flow image data to generate superimposed image data. Then, each time the superimposed image data is generated by the image generation circuit 150, the control circuit 180 causes the superimposed image 53 indicated by the superimposed image data to be displayed on the display 103.

[0096] Also, when displaying various images as post - processing, the following processing is executed as the processing of the entire ultrasonic diagnostic apparatus 1. For example, the control circuit 180 reads out blood flow image data, contrast image data, and tissue image data from the image memory 160. Then, the control circuit 180 outputs the contrast image data and the blood flow image data to the image generation circuit 150. When the image generation circuit 150 receives the contrast image data and the blood flow image data, it generates superimposed image data by superimposing the contrast image data on the blood flow image data.

[0097] Then, the control circuit 180 causes the display 103 to display the contrast image 51 indicated by the contrast image data, the superimposed image 53 indicated by the superimposed image data, and the tissue image 54 indicated by the tissue image data.

[0098] Next, with reference to FIG. 8, an example of the flow of the first generation process for generating blood flow image data will be described. FIG. 8 is a flowchart for explaining an example of the flow of the first generation process performed by the Doppler processing circuit 140 and the image generation circuit 150 according to the first embodiment. The first generation process is executed when the reflected wave data for the number of scan frames (data length) to be processed is stored in the buffer memory 120. Also, the first generation process is executed each time new reflected wave data is stored in the buffer memory 120 by the transmission - reception circuit 110 while the reflected wave data for the data length is stored in the buffer memory 120.

[0099] As shown in FIG. 8, the Doppler processing circuit 140 calculates the correlation matrix of the first region (step S101). Then, the Doppler processing circuit 140 calculates L sets of eigenvalues and eigenvectors from the correlation matrix (step S102).

[0100] Then, the Doppler processing circuit 140 calculates an MTI filter matrix based on the L sets of eigenvalues and eigenvectors (step S103). Then, the Doppler processing circuit 140 performs MTI filter processing on the reflected wave data for the data length at the same position (step S104). Then, the Doppler processing circuit 140 performs autocorrelation operation processing using the output data output by the MTI filter processing (step S105). Then, the Doppler processing circuit 140 estimates blood flow information from the result of the autocorrelation operation processing and generates Doppler data indicating the blood flow information (step S106).

[0101] Then, the image generation circuit 150 generates blood flow image data from the Doppler data indicating the blood flow information (step S107). That is, the image generation circuit 150 generates a blood flow image based on the results of a plurality of first ultrasonic scans executed for the same position within the first region with the second ultrasonic scan in between. In this way, in step S107, the image generation circuit 150 generates a blood flow image for one image frame using the Doppler method based on a data sequence composed of received data acquired in each of the plurality of first ultrasonic scans. Here, the blood flow image for one image frame is not an image generated from the reflected wave data of a single-phase acquisition frame, but an image generated from the reflected wave data of a plurality of acquisition frames of a plurality of time phases. Then, the image generation circuit 150 stores the blood flow image data in the image memory 160 (step S108) and ends the first generation process. The blood flow image data generated in this way is read out by the control circuit 180 and displayed as a blood flow image on the display 103.

[0102] Next, with reference to FIG. 9, an example of the flow of the second generation process for generating tissue image data and contrast image data will be described. FIG. 9 is a flowchart for explaining an example of the flow of the second generation process performed by the B-mode processing circuit 130 and the image generation circuit 150 according to the first embodiment. Note that the second generation process is executed at the same timing as the first generation process.

[0103] As shown in FIG. 9, the B-mode processing circuit 130 generates first B-mode data that is the source of the tissue image data (step S201). Then, the B-mode processing circuit 130 generates second B-mode data that is the source of the contrast image data (step S202).

[0104] Then, the image generation circuit 150 generates tissue image data from the first B-mode data (step S203). Then, the image generation circuit 150 stores the tissue image data in the image memory 160 (step S204).

[0105] Then, the image generation circuit 150 generates contrast image data from the second B-mode data (step S205). Then, the image generation circuit 150 stores the contrast image data in the image memory 160 (step S206) and ends the second generation process.

[0106] The ultrasonic diagnostic apparatus 1 according to the first embodiment has been described above. In the first embodiment, as described above, the frame rate of the blood flow image can be improved. Also, in the first embodiment, by the second ultrasonic scan for collecting the contrast image, not only the contrast image but also the tissue image is collected. Therefore, according to the first embodiment, an ultrasonic scan for collecting only the tissue image is not required, so that the frame rates of the contrast image and the tissue image can also be improved. Therefore, according to the ultrasonic diagnostic apparatus 1 according to the first embodiment, at least two images of the blood flow image, the contrast image, and the tissue image can be suitably collected.

[0107] Also, as shown in steps S108, S204, and S206, the image generation circuit 150 stores the blood flow image data, tissue image data, and contrast image data in the image memory 160 independently of each other. For example, even when two types of images among the blood flow image, tissue image, and contrast image are being displayed on the display 103, as described above, the three types of image data are stored in the image memory 160 as image data for browsing. In this way, since various types of image data for browsing are stored in the image memory 160, according to the first embodiment, when the operator wants to view various images, they can be displayed on the display 103 at any time.

[0108] Note that Patent Document 2 (Japanese Patent Application Laid-Open No. 2009-119134) describes forming contrast mode image information, B-mode image information, and CFM image information using a reception echo train acquired by multiple ultrasonic transmissions and receptions. However, in Patent Document 2, since a general CFM method is used, it is difficult to detect blood flow information regarding low-flow blood as in the ultrasonic diagnostic apparatus 1 according to the first embodiment. Also, if the amplitude modulation method is applied to the technology of Patent Document 1 (International Publication No. 2014 / 115782) like the ultrasonic diagnostic apparatus 1 according to the first embodiment, there is a possibility of affecting the CFM image information.

[0109] (First Modification Example of the First Embodiment) In the first embodiment, the case where the transmission / reception circuit 110 performs scanning on a part (divided region) of the second region in one second ultrasonic scan has been described. However, the transmission / reception circuit 110 may perform scanning on the entire second region in one second ultrasonic scan. Therefore, such a modification example will be described as the first modification example of the first embodiment.

[0110] For example, when the size of the second region is relatively small and the number of scanning lines forming the second region is relatively small, the transmission / reception circuit 110 may perform scanning on the entire second region in one second ultrasonic scan. Further, when it is possible to scan the entire second region by transmitting a plane wave or a wide convergent wave as the ultrasonic wave, the transmission / reception circuit 110 may perform scanning on the entire second region by transmitting a plane wave or a convergent wave in one second ultrasonic scan. That is, the transmission / reception circuit 110 may alternately perform the first ultrasonic scan on the first region and the second ultrasonic scan on at least a part of the second region. In this case, the image generation circuit 150 may generate the contrast image 51 and the tissue image 54 based on the result of at least one second ultrasonic scan.

[0111] (Second Modification of the First Embodiment) In the first embodiment, the case where scanning is performed on the divided region in one second ultrasonic scan has been described. However, the region scanned in one second ultrasonic scan is not limited to the divided region. Therefore, another example will be described as the second modification of the first embodiment.

[0112] For example, in the second modification, scanning may be performed on each of a plurality of regions that cover the second region in one second ultrasonic scan. Here, in the second modification, a part of two adjacent regions overlaps with each other.

[0113] (Third Modification of the First Embodiment) In the first embodiment, the case where either the phase modulation method or the amplitude modulation method is selected by the operator in the second ultrasonic scan has been described. However, the control circuit 180 may select either the phase modulation method or the amplitude modulation method. Therefore, such a modification will be described as the third modification of the first embodiment.

[0114] In the third modification example, for example, the control circuit 180 selects either the phase modulation method or the amplitude modulation method according to the flow velocity range. Here, the flow velocity range is the range of flow velocity values of blood flow that can be represented as a blood flow image which is a color Doppler image. That is, in the ultrasonic diagnostic apparatus 1, it is the range of flow velocity values of detectable blood flow. The flow velocity range can be set by the operator, for example, by the operator operating the input device 102. For example, when the upper limit value of the flow velocity range is equal to or higher than a predetermined threshold value, the control circuit 180 selects the amplitude modulation method. On the other hand, when the upper limit value of the flow velocity range is less than the predetermined threshold value, the control circuit 180 selects the phase modulation method. Then, in the second ultrasonic scan, the transmission and reception circuit 110 transmits ultrasonic waves based on the selected method. In this case, the control circuit 180 may vary the number of divided regions for dividing the second region when the phase modulation method is selected and when the amplitude modulation method is selected.

[0115] Note that the control circuit 180 may change the interval “T” at which the first ultrasonic scan shown in FIG. 2 above is performed according to the flow velocity range. For example, when the operator wants to observe blood flow at a lower flow velocity (for example, a flow velocity of 0.5 cm / s or less of a specific flow velocity), the operator changes the flow velocity range so as to lower the lower limit value of the flow velocity range. In this case, in order to detect blood flow at a lower flow velocity, the interval “T” needs to be lengthened. Therefore, the control circuit 180 changes the interval “T” so that the interval “T” becomes longer as the lower limit value of the flow velocity range becomes lower. Then, the control circuit 180 controls the transmission circuit 110a so that the first ultrasonic scan is performed on the ultrasonic probe 101 at the changed interval “T”. Thereby, it is possible to appropriately change the interval “T” at which the first ultrasonic scan is performed corresponding to the lower limit value of the flow velocity range in order to allow the operator to observe a blood flow image showing blood flow information regarding blood flow at a lower flow velocity.

[0116] (Fourth Modification Example of the First Embodiment) Next, a fourth modification of the first embodiment will be described. In the fourth modification, an example of a display mode of another image different from the display mode of the image described with reference to FIG. 7 in the first embodiment will be described. Note that various images described in the fourth modification can be displayed in real time or as post-processing in the same manner as the method described in the first embodiment.

[0117] FIGS. 10 to 29 are diagrams for explaining an example of a display mode of another image according to the fourth modification of the first embodiment. As shown in FIG. 10, the control circuit 180 may display a superimposed image 55 in which a blood flow image 52 is superimposed on a contrast image 51 and a tissue image 54 side by side in the horizontal direction on the display 103. Further, as shown in FIG. 11, the control circuit 180 may display the contrast image 51 and the superimposed image 53 side by side in the horizontal direction on the display 103.

[0118] Further, as shown in FIG. 12, the control circuit 180 may display a maximum luminance image 56, a superimposed image 53, and a tissue image 54 side by side in the horizontal direction on the display 103. Here, the maximum luminance image 56 is generated by the image generation circuit 150. For example, the image generation circuit 150 generates the maximum luminance image 56 using MFI (Micro flow imaging), which is a technique for clearly visualizing the structure of minute blood flow. Specifically, the image generation circuit 150 performs a maximum luminance holding operation (maximum value holding operation) on a plurality of contrast images 51, selects the maximum luminance for each pixel from among the plurality of contrast images 51, and generates a maximum luminance image 56 in which each pixel is shown with the selected maximum luminance. Here, in MFI, the transmission / reception circuit 110 performs transmission of high-pressure ultrasonic waves (also called a flash) to sweep away bubbles, and then the image generation circuit 150 visualizes reperfusion. Note that whether or not to perform such transmission of high-pressure ultrasonic waves is selected by the operator.

[0119] Further, as shown in FIG. 13, the control circuit 180 may cause the display 103 to display the maximum luminance image 56 and the superimposed image 55 side by side in the horizontal direction. Further, as shown in FIG. 14, the control circuit 180 may cause the display 103 to display the maximum luminance image 56 and the superimposed image 53 side by side in the horizontal direction.

[0120] Further, as shown in FIG. 15, the control circuit 180 may cause the display 103 to display the integrated image 57, the superimposed image 53, and the tissue image 54 side by side in the horizontal direction. Here, the integrated image 57 is generated by the image generation circuit 150. For example, the image generation circuit 150 generates an integrated image 57 obtained by integrating a plurality of contrast images 51 in the time direction.

[0121] Further, as shown in FIG. 16, the control circuit 180 may cause the display 103 to display the integrated image 57 and the superimposed image 55 side by side in the horizontal direction. Further, as shown in FIG. 17, the control circuit 180 may cause the display 103 to display the integrated image 57 and the superimposed image 53 side by side in the horizontal direction.

[0122] Further, as shown in FIGS. 18 to 29, the control circuit 180 may cause the display 103 to display various images side by side in a matrix. For example, as shown in FIG. 18, the control circuit 180 sets four regions on the display area of the display 103 where two images can be arranged in the left-right direction and two images can be arranged in the up-down direction. Hereinafter, the upper left region in the drawing is referred to as the upper left region, the upper right region is referred to as the upper right region, the lower left region is referred to as the lower left region, and the lower right region is referred to as the lower right region.

[0123] Then, as shown in FIG. 18, the control circuit 180 may control the display 103 such that the contrast image 51 is displayed in the upper left region, the superimposed image 53 is displayed in the upper right region, and the tissue image 54 is displayed in the lower right region.

[0124] Further, as shown in FIG. 19, the control circuit 180 may control the display 103 such that the maximum luminance image 56 is further displayed in the lower left region from the display state of FIG. 18.

[0125] Further, as shown in FIG. 20, the control circuit 180 may control the display 103 so that an integration image 57 is displayed instead of the maximum luminance image 56 displayed in the lower left region in FIG. 19.

[0126] Further, as shown in FIG. 21, the control circuit 180 may control the display 103 so that an assistance image 58 is displayed instead of the maximum luminance image 56 displayed in the lower left region in FIG. 19. Here, the assistance image 58 is an image for assisting the operation of the ultrasonic diagnostic apparatus 1 by an operator such as a doctor or a clinical laboratory technician and the examination using the ultrasonic diagnostic apparatus 1, and is generated by the image generation circuit 150.

[0127] For example, the image generation circuit 150 performs a predetermined measurement on a part of the subject P depicted in at least one of the contrast image 51, the tissue image 54, and the blood flow image 52, and generates an assistance image 58 indicating the measurement result. In performing such a measurement, in this modification, three cursors (triple cursors) that move simultaneously while synchronizing on the three images of the contrast image 51, the tissue image 54, and the blood flow image 52 may be used as measurement cursors. When there are four images to be measured, similarly, four cursors (quad cursors) that move simultaneously while synchronizing on the four images may be used.

[0128] The image generation circuit 150 may generate an image indicating the inspection procedure as the assistance image 58. Further, the image generation circuit 150 may generate an image indicating at least one image quality condition of the first ultrasonic scan and the second ultrasonic scan as the assistance image 58.

[0129] Further, as shown in FIG. 22, the control circuit 180 may control the display 103 so that an analysis result image 59 is displayed instead of the maximum luminance image 56 displayed in the lower left region in FIG. 19. Here, the analysis result image 59 is an image indicating the result (analysis result) of analyzing at least one of the contrast image 51, the tissue image 54, and the blood flow image 52, and is generated by the image generation circuit 150.

[0130] For example, the image generation circuit 150 may perform TCA (Time Curve Analysis) as an analysis of a plurality of contrast images 51 or blood flow images 52 in the time direction. TCA observes, for example, the temporal change in the concentration of a contrast agent within an analysis region such as a region of interest, generates a graph showing the temporal change in the concentration of the contrast agent, or identifies a tumor from the temporal change in the concentration of the contrast agent. The image generation circuit 150 performs TCA to generate, as the analysis result image 59, an image showing a graph indicating the temporal change in the concentration of the contrast agent or an image indicating the result of tumor identification.

[0131] Further, for example, the image generation circuit 150 may generate the analysis result image 59 by parametric imaging. Parametric imaging is an image representation method that represents blood flow information collected after injection of a contrast agent by a predetermined parameter value. For example, the image generation circuit 150 calculates a time density curve (TDC) of the contrast agent for each pixel of the contrast image 51 by parametric imaging, and calculates various parameter values using the calculated TDC. Here, as parameter values in parametric imaging, for example, the time to peak (TTP) in the TDC, the peak height (PH), the area under the curve (AUC) of the TDC, the arrival time (AT) of the contrast agent, the time until the contrast agent has completely flowed out from the peak (Wash Out), the mean transit time (MTT), etc. are calculated. Then, the image generation circuit 150 calculates, by parametric imaging, parameter values corresponding to the blood flow information desired by the observer for each pixel, and generates, as the analysis result image 59, an image in which each pixel on the image is colored with a color corresponding to the calculated parameter value.

[0132] Further, for example, the image generation circuit 150 may generate an analysis result image 59 that quantitatively shows the direction and movement speed of the contrast agent flowing by tracking each of the microbubbles used as the contrast agent using the technique described in Japanese Patent Application Laid-Open No. 2018-15155.

[0133] For example, the image generation circuit 150 specifies the positions of the contrast agent in the contrast image 51 (first contrast image) corresponding to a certain phase and the contrast image 51 (second contrast image) corresponding to another phase. Then, the image generation circuit 150 calculates a vector representing the movement of the contrast agent based on the positions of the contrast agent in the first contrast image and the second contrast image. Then, the image generation circuit 150 generates, as the analysis result image 59, a superimposed image in which an indicator having a shape indicating the vector is superimposed on the tissue image 54.

[0134] Further, as shown in FIG. 23, the control circuit 180 may control the display 103 so that a reference image 60 is displayed instead of the maximum luminance image 56 displayed in the lower left region in FIG. 19. Here, the reference image 60 may be a medical image of the subject P collected by another medical image diagnostic apparatus different from the ultrasonic diagnostic apparatus (such as an X-ray computed tomography (CT) apparatus or a magnetic resonance imaging (MRI) apparatus). For example, the control circuit 180 may use a so-called fusion function to display, on the display 103, an MPR (MultiPlanar Reconstruction) image generated from volume data by another medical image diagnostic apparatus and having the same cross section as the contrast image 51, blood flow image 52, or tissue image 54 being displayed as the reference image 60. The reference image 60 changes as the contrast image 51, blood flow image 52, or tissue image 54 being displayed changes due to the movement of the ultrasonic probe 101 or the like.

[0135] Further, the reference image 60 may be an image collected by the ultrasonic diagnostic apparatus 1. For example, the reference image 60 may be a blood flow image in the same phase as the displayed blood flow image 52 and may be a blood flow image collected by the ultrasonic diagnostic apparatus 1 in a past examination. Similarly, the reference image 60 may be a contrast image in the same phase as the displayed contrast image 51 and may be a contrast image collected by the ultrasonic diagnostic apparatus 1 in a past examination. Further, the reference image 60 may be a tissue image in the same phase as the displayed tissue image 54 and may be a tissue image collected by the ultrasonic diagnostic apparatus 1 in a past examination.

[0136] Also, for example, the reference image 60 may be a blood flow image collected in the same examination as the displayed blood flow image 52 and may be a blood flow image with a different phase from the displayed blood flow image 52. Similarly, the reference image 60 may be a contrast image collected in the same examination as the displayed contrast image 51 and may be a contrast image with a different phase from the displayed contrast image 51. Further, the reference image 60 may be a tissue image collected in the same examination as the displayed tissue image 54 and may be a tissue image with a different phase from the displayed tissue image 54. For example, when the late-phase contrast image 51 is displayed on the display 103, the control circuit 180 may cause the arterial-phase contrast image to be displayed on the display 103 as the reference image 60.

[0137] Also, as shown in FIG. 24, the control circuit 180 may control the display 103 such that the contrast image 51 is displayed in the upper left region, the tissue image 54 is displayed in the upper right region, the superimposed image 55 is displayed in the lower left region, and the composite image 61 is displayed in the lower right region. Here, the composite image 61 is an image in which the contrast image 51 and the tissue image 54 are combined and is generated by the image generation circuit 150. For example, the image generation circuit 150 combines the contrast image 51 and the tissue image 54 to generate the composite image 61.

[0138] Also, as shown in FIG. 25, the control circuit 180 may control the display 103 such that the superimposed image 53 is displayed instead of the superimposed image 55 displayed in the lower left region in FIG. 24.

[0139] Further, as shown in FIG. 26, the control circuit 180 may control the display 103 so that a superimposed image 63 in which the maximum luminance image 62 is superimposed on the tissue image 54 is displayed instead of the superimposed image 55 displayed in the lower left region in FIG. 24.

[0140] Here, the maximum luminance image 62 and the superimposed image 63 are generated by the image generation circuit 150. For example, the image generation circuit 150 generates the maximum luminance image 62 using the above-described MFI (Micro flow imaging). Specifically, the image generation circuit 150 performs a maximum luminance holding operation process on a plurality of blood flow images 52, selects the maximum luminance for each pixel from among the plurality of blood flow images 52, and generates the maximum luminance image 62 in which each pixel is shown with the selected maximum luminance. Then, the image generation circuit 150 generates the superimposed image 63 by superimposing the maximum luminance image 62 on the tissue image 54.

[0141] Further, as shown in FIG. 27, the control circuit 180 may control the display 103 so that a superimposed image 65 in which the integrated image 64 is superimposed on the tissue image 54 is displayed instead of the superimposed image 55 displayed in the lower left region in FIG. 24. Here, the integrated image 64 and the superimposed image 65 are generated by the image generation circuit 150. For example, the image generation circuit 150 generates the integrated image 64 obtained by integrating a plurality of blood flow images 52 in the time direction. Then, the image generation circuit 150 generates the superimposed image 65 by superimposing the integrated image 64 on the tissue image 54.

[0142] Further, as shown in FIG. 28, the control circuit 180 may control the display 103 so that a superimposed image 66 in which the maximum luminance image 62 is superimposed on the contrast image 51 is displayed instead of the superimposed image 55 displayed in the lower left region in FIG. 24. Here, the superimposed image 66 is generated by the image generation circuit 150. For example, the image generation circuit 150 generates the superimposed image 66 by superimposing the maximum luminance image 62 on the contrast image 51.

[0143] Further, as shown in FIG. 29, the control circuit 180 may control the display 103 so that a superimposed image 67 in which an integrated image 64 is superimposed on a contrast image 51 is displayed instead of the superimposed image 55 displayed in the lower left region in FIG. 24. Here, the superimposed image 67 is generated by the image generation circuit 150. For example, the image generation circuit 150 generates the superimposed image 67 by superimposing the integrated image 64 on the contrast image 51.

[0144] (Fifth Modification of the First Embodiment) In the third modification of the first embodiment, the case where the control circuit 180 changes the interval “T” at which the first ultrasonic scan is performed according to the flow velocity range has been described. However, the control circuit 180 may change the interval “T” according to other conditions. Therefore, such a modification will be described as the fifth modification of the first embodiment.

[0145] In the fifth modification, for example, the input device 102 receives priority information from the operator. Here, the priority information is, for example, information indicating whether to prioritize increasing the display frame rate of the blood flow image 52 displayed on the display 103 or to prioritize displaying a blood flow image indicating blood flow information regarding a lower blood flow velocity (for example, a blood flow velocity of 0.5 cm / s or less). It is assumed that a predetermined initial value is set as the interval “T” at which the first ultrasonic scan is performed before the input device 102 receives the priority information.

[0146] Then, the control circuit 180 changes the interval “T” at which the first ultrasonic scan is performed according to the priority information received by the input device 102. For example, the case where the priority information indicates prioritizing increasing the display frame rate of the blood flow image 52 will be described. In this case, the control circuit 180 changes the interval “T” so that the interval “T” becomes shorter from the initial value.

[0147] Next, a case will be described where the priority information indicates that a blood flow image showing blood flow information regarding lower blood flow is to be preferentially displayed. In this case, the control circuit 180 changes the interval "T" so that the interval "T" becomes longer from the initial value. Then, the control circuit 180 controls the transmission circuit 110a so as to cause the ultrasonic probe 101 to perform the first ultrasonic scan at the changed interval "T".

[0148] (Second Embodiment) In the first embodiment described above, the first ultrasonic scan and the second ultrasonic scan are alternately executed. However, there may be a case where the residual echo of the ultrasonic wave finally transmitted in the first ultrasonic scan enters the reception period of the reflected wave of the ultrasonic wave first transmitted in the second ultrasonic scan. This is considered to be caused by the transmission and reception circuit 110 transmitting an ultrasonic wave in the second ultrasonic scan before receiving the reflected wave from the deep part of the ultrasonic wave finally transmitted in the first ultrasonic scan.

[0149] FIGs. 30A and 30B are diagrams showing an example of a residual echo. First, a case where the phase modulation method is used in the second ultrasonic scan will be described. In this case, as shown in FIG. 30A, after transmitting the last ultrasonic wave 70 in the first ultrasonic scan, the transmission and reception circuit 110 transmits two ultrasonic waves 71 and 72 having different phases on the first scanning line in the second ultrasonic scan. Then, the transmission and reception circuit 110 transmits two ultrasonic waves 73 and 74 having different phases on the second scanning line in the second ultrasonic scan.

[0150] At this time, as shown in FIG. 30A, the residual echo 70a of the ultrasonic wave 70 enters the reception period of the reflected wave of the ultrasonic wave 71. Similarly, the respective residual echoes 71a to 73a of the ultrasonic waves 71 to 73 enter the reception periods of the respective reflected waves of the ultrasonic waves 72 to 74. At this time, in the second scanning line of the second ultrasonic scan, the residual echo 72a and the residual echo 73a have phases that are 180 degrees different from each other and the same amplitude. Therefore, the residual echo 73a is added to the residual echo 72a and the residual echo becomes "0". However, in the first scanning line of the second ultrasonic scan, the residual echo 70a and the residual echo 71a have the same phase and the amplitude is not "0". Therefore, even if the residual echo 71a is added to the residual echo 70a, the residual echo does not become "0".

[0151] Next, a case where the amplitude modulation method is used in the second ultrasonic scan will be described. In this case, as shown in FIG. 30B, after transmitting the last ultrasonic wave 70 in the first ultrasonic scan, the transmission / reception circuit 110 transmits an ultrasonic wave 81 with an amplitude of "0.5", an ultrasonic wave 82 with an amplitude of "1", and an ultrasonic wave 83 with an amplitude of "0.5" in this order on the first scanning line in the second ultrasonic scan. Then, the transmission / reception circuit 110 transmits an ultrasonic wave 84 with an amplitude of "0.5", an ultrasonic wave 85 with an amplitude of "1", and an ultrasonic wave 86 with an amplitude of "0.5" in this order on the second scanning line in the second ultrasonic scan.

[0152] At this time, as shown in FIG. 30B, the residual echo 70a of the ultrasonic wave 70 enters the reception period of the reflected wave of the ultrasonic wave 81. Similarly, the respective residual echoes 81a, 82a, 84a, 85a of the ultrasonic waves 81, 82, 84, 85 enter the reception periods of the respective reflected waves of the ultrasonic waves 82, 83, 85, 86. At this time, on the second scanning line of the second ultrasonic scan, the residual echo 84a, the residual echo 85a, and the residual echo 86a of the ultrasonic wave 86 have the same phase, and the amplitude ratio is (1:2:1). Therefore, when the residual echo 86a is subtracted from the residual echo obtained by subtracting the residual echo 84a from the residual echo 85a, the residual echo becomes "0". On the other hand, on the first scanning line of the second ultrasonic scan, since the residual echo 70a exists, the residual echo does not become "0".

[0153] Therefore, an ultrasonic diagnostic apparatus according to a second embodiment for taking measures against residual echoes will be described. The ultrasonic diagnostic apparatus according to the second embodiment has, in addition to various functions of the ultrasonic diagnostic apparatus 1 according to the first embodiment, a function of taking measures against residual echoes.

[0154] FIG. 31A is a diagram for explaining measures against residual echoes when the phase modulation method is used in the second ultrasonic scan. As shown in FIG. 31A, the transmission / reception circuit 110 according to the second embodiment transmits an ultrasonic wave 74 having the same phase and the same amplitude as the ultrasonic wave 72 as the ultrasonic wave finally transmitted in the first ultrasonic scan. As a result, as shown in FIG. 31A, the residual echo 74a of the ultrasonic wave 74 enters the reception period of the reflected wave of the ultrasonic wave 71. At this time, on the first scanning line of the second ultrasonic scan, the residual echo 74a and the residual echo 71a have phases that are 180 degrees different from each other and the same amplitude. Therefore, when the residual echo 71a is added to the residual echo 74a, the residual echo becomes "0". Therefore, the residual echo can be made "0" on the first scanning line of the second ultrasonic scan.

[0155] FIG. 31B is a diagram for explaining a countermeasure against residual echoes when the amplitude modulation method is used in the second ultrasonic scan. As shown in FIG. 31B, the transmission / reception circuit 110 according to the second embodiment transmits the first ultrasonic wave 81 in the second ultrasonic scan at a timing when a predetermined time has elapsed after the ultrasonic wave 70 is transmitted.

[0156] Here, the predetermined time is, for example, the time it takes for the ultrasonic wave (ultrasonic waves 81 to 86) transmitted in the second ultrasonic scan to travel a distance 2D obtained by doubling the distance D from the piezoelectric vibrator of the ultrasonic probe 101 to the depth in the contrast image 51 based on the second ultrasonic scan. That is, the predetermined time is the time corresponding to the depth in the contrast image 51.

[0157] As a result, as shown in FIG. 31B, the residual echo 70a of the ultrasonic wave 70 does not enter the reception period of the reflected wave of the ultrasonic wave 81. At this time, in the first scanning line of the second ultrasonic scan, the residual echoes 81a, 82a, and the residual echo 83a of the ultrasonic wave 83 have the same phase and the amplitude ratio is (1:2:1). Therefore, when the residual echo 81a is subtracted from the residual echo obtained by subtracting the residual echo 83a from the residual echo 82a, the residual echo becomes "0". Therefore, the residual echo can be made "0" in the first scanning line of the second ultrasonic scan.

[0158] FIG. 32 is an example of a contrast image based on the second ultrasonic scan shown in FIG. 30A or FIG. 30B. As shown in FIG. 32, the residual echo appears as a streak-like artifact in the contrast image. FIG. 33 is an example of a contrast image based on the second ultrasonic scan shown in FIG. 31A or FIG. 31B. In the contrast image shown in FIG. 33, since the residual echo is "0" in FIG. 31A or FIG. 31B, no artifact due to the residual echo occurs.

[0159] The above describes the ultrasonic diagnostic apparatus according to the second embodiment. According to the ultrasonic diagnostic apparatus according to the second embodiment, as described above, countermeasures against residual echoes can be taken. Further, according to the ultrasonic diagnostic apparatus according to the second embodiment, similar to the ultrasonic diagnostic apparatus 1 according to the first embodiment, at least two images of a blood flow image, a contrast image, and a tissue image can be suitably collected.

[0160] In addition, in each of the above-described embodiments and each modification, the case where the phase modulation method or the amplitude modulation method is used in the second ultrasonic scan has been described. However, in the second ultrasonic scan, the amplitude-phase modulation method (AMPM) may be used. The amplitude-phase modulation method is, for example, a method in which two types of ultrasonic waves having different phases and amplitudes are transmitted on each scanning line constituting a scanning range, and reflected wave data based on the reflected waves of each of the two types of ultrasonic waves are added. For example, as two types of ultrasonic waves, the first type of ultrasonic wave and the second type of ultrasonic wave will be described as an example.

[0161] For example, the ratio (A1:A2) of the amplitude "A1" of the first type of ultrasonic wave to the amplitude "A2" of the second type of ultrasonic wave is "1:2". Also, the phase of the first type of ultrasonic wave and the phase of the second type of ultrasonic wave are different. For example, the phase of the first type of ultrasonic wave and the phase of the second type of ultrasonic wave are 180 degrees different.

[0162] For example, when the amplitude-phase modulation method is used, the transmission-reception circuit 110 transmits three ultrasonic waves, namely, the first type of ultrasonic wave, the second type of ultrasonic wave, and the first type of ultrasonic wave, in this order on each scanning line constituting the divided region. Then, the B-mode processing circuit 130 adds the reflected wave data based on the reflected waves of each of the three ultrasonic waves. When the amplitude-phase modulation method is used, the second ultrasonic scan includes transmission and reception of each of two types of ultrasonic waves having different amplitudes and phases.

[0163] Also, in the above-described third modification example, the case where the control circuit 180 selects either the phase modulation method or the amplitude modulation method according to the flow velocity range using one threshold value has been described. However, the control circuit 180 may select any one of the phase modulation method, the amplitude modulation method, or the amplitude-phase modulation method according to the flow velocity range using two threshold values in a similar manner. In this case, the control circuit 180 may vary the number of divided regions that divide the second region depending on whether the phase modulation method is selected, whether the amplitude modulation method is selected, or whether the amplitude-phase modulation method is selected.

[0164] According to at least one of the above-described embodiments or modification examples, at least two images of a blood flow image, a contrast image, and a tissue image can be suitably collected.

[0165] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Description of Reference Numerals

[0166] 1 Ultrasonic diagnostic apparatus 110 Transmission / reception circuit 150 Image generation circuit

Claims

1. A first ultrasonic scan execution unit that executes a plurality of first ultrasonic scans on a first region of a subject injected with a contrast agent; A second ultrasonic scan execution unit that executes a second ultrasonic scan for each of a plurality of divided regions obtained by dividing a second region including the first region in a time-division manner with respect to the plurality of first ultrasonic scans; A blood flow image generation unit that generates a blood flow image for the first region based on the execution results of the plurality of first ultrasonic scans for the first region; A tissue image generation unit that generates a tissue image for the second region based on the execution results of the second ultrasonic scans for the divided regions; A contrast image generation unit that generates a contrast image for the second region based on the execution results of the second ultrasonic scans for the divided regions; A display control unit that displays the blood flow image generated by the blood flow image generation unit, the tissue image generated by the tissue image generation unit, and the contrast image generated by the contrast image generation unit on a display unit. An ultrasonic diagnostic apparatus comprising: An ultrasonic diagnostic apparatus.

2. The tissue image generation unit generates the tissue image for the second region based on tissue partial images of the plurality of divided regions obtained from the execution results of the second ultrasonic scans, The contrast image generation unit generates the contrast image for the second region based on contrast partial images of the plurality of divided regions obtained from the execution results of the second ultrasonic scans. The ultrasonic diagnostic apparatus according to Claim 1. The ultrasonic diagnostic apparatus according to Claim 1.

3. The tissue image generation unit generates the tissue image for the second region in parallel with the generation of the blood flow image for the first region by the blood flow image generation unit, The contrast image generation unit generates the contrast image for the second region in parallel with the generation of the blood flow image for the first region by the blood flow image generation unit. The ultrasonic diagnostic apparatus according to Claim 1. The ultrasonic diagnostic apparatus according to Claim 1.

4. The display control unit displays the blood flow image, the tissue image, and the contrast image on the display unit by arranging two images including a first superimposed image in which the blood flow image for the first region generated by the blood flow image generation unit and the tissue image for the second region generated by the tissue image generation unit are superimposed, and a second superimposed image in which the tissue image for the second region generated by the tissue image generation unit and the contrast image for the second region generated by the contrast image generation unit are superimposed. The ultrasonic diagnostic apparatus according to claim 1.

5. The display control unit displays the blood flow image, the tissue image, and the contrast image on the display unit by arranging two images including a superimposed image in which the blood flow image for the first region generated by the blood flow image generation unit and the tissue image for the second region generated by the tissue image generation unit are superimposed, and the contrast image for the second region generated by the contrast image generation unit. The ultrasonic diagnostic apparatus according to claim 1.

6. The second ultrasonic scan includes two types of ultrasonic waves having at least one of different amplitudes and phases. Based on the reception data of one of the plurality of ultrasonic waves acquired by the second ultrasonic scan, the tissue image generation unit generates the tissue partial image for the divided region where the second ultrasonic scan is executed. Based on the reception data of both of the plurality of ultrasonic waves acquired by the second ultrasonic scan, the contrast image generation unit generates the contrast partial image for the divided region where the second ultrasonic scan is executed. The ultrasonic diagnostic apparatus according to claim 2.

7. The second ultrasonic scan includes a plurality of ultrasonic waves having at least one of different amplitudes and phases. Based on the reception data of a part of the plurality of ultrasonic waves acquired by the second ultrasonic scan, the tissue image generation unit generates the tissue partial image for the divided region where the second ultrasonic scan is executed. Based on the reception data of all of the plurality of ultrasonic waves acquired by the second ultrasonic scan, the contrast image generation unit generates the contrast partial image for the divided region where the second ultrasonic scan is executed. The ultrasonic diagnostic apparatus according to claim 2.

8. The second ultrasonic scan execution unit executes one second ultrasonic scan during the two first ultrasonic scans executed by the first ultrasonic scan execution unit. The ultrasonic diagnostic apparatus according to claim 1.

9. A blood flow information acquisition unit that acquires a data series collected based on the execution results of a plurality of first ultrasonic scans for each position in the first region, and inputs the data series to an adaptive MT I (Motion Target Indicator) filter generated based on the data series to acquire blood flow information. The blood flow image generation unit generates the blood flow image based on the blood flow information. The ultrasonic diagnostic apparatus according to claim 1.

10. The apparatus further includes an integrated image generation unit that generates an integrated image obtained by integrating a plurality of the contrast images or a plurality of the blood flow images in the time direction. The display control unit further displays the integrated image on the display unit. The ultrasonic diagnostic apparatus according to claim 1.

11. The apparatus further includes a maximum luminance image generation unit that selects the maximum luminance for each pixel from among a plurality of the contrast images or a plurality of the blood flow images, and generates a maximum luminance image in which each pixel is represented by the maximum luminance. The display control unit further displays the maximum luminance image on the display unit. The ultrasonic diagnostic apparatus according to claim 1.

12. The display control unit further displays, on the display unit, an analysis result image showing an analysis result for at least one of the blood flow image, the contrast image, and the tissue image. The ultrasonic diagnostic apparatus according to claim 1.

13. The display control unit further displays, on the display unit, a support image showing a measurement result regarding the subject, an operation procedure of an operator, or an image quality condition of at least one scan of the first ultrasonic scan and the second ultrasonic scan, using at least one of the blood flow image, the contrast image, and the tissue image. The ultrasonic diagnostic apparatus according to claim 1.

14. The display control unit further displays, on the display unit, a reference image of the subject collected by a medical image diagnostic apparatus other than the ultrasonic diagnostic apparatus, or a reference image collected by the ultrasonic diagnostic apparatus, the reference image having a different time phase or the same time phase as the blood flow image, the contrast image, or the tissue image being displayed. The ultrasonic diagnostic apparatus according to claim 1.

15. The apparatus further includes a control unit that changes the interval at which the first ultrasonic scan is performed according to the flow velocity range. The ultrasonic diagnostic apparatus according to claim 1.

16. A control unit that changes the interval at which the first ultrasonic scan is performed according to information indicating whether to increase the display frame rate of the blood flow image displayed on the display unit or to prioritize the display of a blood flow image indicating blood flow information regarding blood flow at or below a specific flow rate. The ultrasonic diagnostic apparatus according to claim 1.

17. A first ultrasonic scan execution step of performing a plurality of first ultrasonic scans on a first region of a subject injected with a contrast agent; A second ultrasonic scan execution step of performing a second ultrasonic scan on each of divided regions obtained by dividing a second region including the first region into a plurality of regions in a time-division manner with respect to the plurality of first ultrasonic scans; A blood flow image generation step of generating a blood flow image for the first region based on the execution results of the plurality of first ultrasonic scans for the first region; A tissue image generation step of generating a tissue image for the second region based on the execution results of the second ultrasonic scans for the divided regions; A contrast image generation step of generating a contrast image for the second region based on the execution results of the second ultrasonic scans for the divided regions; A display control step of displaying the blood flow image generated in the blood flow image generation step, the tissue image generated in the tissue image generation step, and the contrast image generated in the contrast image generation step on a display unit. An image processing method.

Images