JP2013244162A - Ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate an acoustic velocity map minimizing an influence of such structures as blood vessels, as much as possible in a short time.SOLUTION: A region 112 of interest is set on a B mode image 110 displayed on a display unit. Ultrasonic waves are transmitted and received in a Doppler scan mode to generate color Doppler information in the region 112 of interest. A region excluding a moving object region 117 in the region 112 of interest is determined as an acoustic velocity measurement region 119 on the basis of the color Doppler information. A plurality of promotion focal points 125 are set in the acoustic velocity measurement region 119 to transmit/receive ultrasonic waves, and RF data corresponding to the acoustic velocity measurement region 119 are generated. A local acoustic velocity value is calculated based on the RF data corresponding to the acoustic velocity measurement region 119 so as to generate an acoustic velocity map of the acoustic velocity measurement region 119.

Description

  The present invention relates to an ultrasonic diagnostic apparatus that generates a sound speed map of a region of interest set in a B-mode image.

  In the medical field, an ultrasonic diagnostic apparatus is often used to make a diagnosis by observing the inside of a subject. The ultrasonic diagnostic apparatus has an ultrasonic probe (probe) that transmits and receives ultrasonic waves, transmits ultrasonic waves from the ultrasonic probe into the subject, and reflects the ultrasonic waves reflected in the subject. By receiving the sound wave with the ultrasonic probe, a B-mode image can be generated based on the received signal. The B-mode image is an image representing the amplitude of the ultrasonic echo by the brightness (luminance) of the point. With this B-mode image, it is possible to observe the outline of a structure (for example, a viscera or a diseased tissue) existing in the subject.

  In recent years, in order to accurately diagnose a diagnostic region within a subject, a local sound velocity in a region of interest (diagnostic region) designated by a doctor on a B-mode image is measured, and a sound velocity map representing a sound velocity distribution in this region of interest is generated. Then, it is displayed superimposed on the B-mode image. A method for measuring the local sound velocity in such a region of interest is disclosed in Patent Document 1, for example.

The method of calculating the local sound velocity of the Patent Document 1, a plurality of lattice points A1, A2 between the lattice point X _ROI and the ultrasound probe regions of interest, set ..., each grid point (X _ROI, The optimum sound speed value at A1, A2,. Here, the optimum sound speed value is a sound speed value at which the contrast value and sharpness value of the image are the highest. Next, the local sound speed at the lattice point X _ROI is obtained based on the optimum sound speed value at each lattice point. Specifically, based on Huygens' principle, the fact that the received wave from the lattice point X _ROI coincides with the received wave obtained by virtually combining the received waves from the lattice points A1, A2,. reference). Thereby, since the local sound speed can be measured accurately, a highly accurate sound speed map can be obtained.

  By the way, in a region where a structure such as a blood vessel or a tissue (organ) having a large movement exists in the region of interest, a sound speed error is likely to occur because the sound speed calculation described above is performed based on the contrast value or sharpness value of the image. . As a result, the reliability of the calculation result of the sound speed calculation is not sufficiently obtained, and a sound speed map that is strongly influenced by a structure such as a blood vessel is generated.

  Patent Document 2 discloses an ultrasonic diagnostic apparatus that generates an elastic image in a region obtained by removing structures such as blood vessels from a region of interest. In the ultrasonic diagnostic apparatus of Patent Document 2, a distortion distribution in a region of interest is obtained, a Doppler signal resulting from blood flow in a blood vessel is extracted from an ultrasonic reception signal, and blood flow is based on the Doppler signal. To generate Doppler data indicating the flow velocity and the like. Next, an elastic image is generated based on the strain distribution obtained by excluding the strain at the portion where the flow velocity is equal to or higher than the predetermined flow velocity from the previously obtained strain distribution. Patent Document 3 also discloses that a blood flow region is detected and removed from elastic image data. Therefore, based on the descriptions in Patent Documents 2 and 3, the local sound speed distribution of the region of interest is obtained, and Doppler data of the region of interest is generated, and structures such as blood vessels are removed from the region of interest based on the Doppler data. There has also been proposed a method of generating a sound speed map based on the local sound speed value of the region.

JP 2010-99452 A JP 2012-61075 A International Publication No. 2009/104525 Pamphlet

  However, in the case where the generation of Doppler data is performed in addition to the calculation of the local sound velocity value at each point in the region of interest, a problem arises in that it takes time to generate the sound velocity map because enormous calculation processing is required. Further, in order to shorten the generation time of the sound velocity map, it is necessary to mount a high-performance arithmetic processing unit (CPU) in the ultrasonic diagnostic apparatus, which causes a problem that the manufacturing cost of the ultrasonic diagnostic apparatus increases. .

  An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of generating a sound velocity map that suppresses the influence of structures such as blood vessels as much as possible in a short time.

  An ultrasonic diagnostic apparatus for achieving an object of the present invention includes an ultrasonic device that includes a plurality of elements that transmit ultrasonic waves to a subject, receive ultrasonic waves reflected by the subject, and output ultrasonic detection signals. A transmission / reception unit for supplying a plurality of drive signals for driving the acoustic probe and the plurality of elements to the plurality of elements and generating reception data based on the ultrasonic detection signals output from the plurality of elements, A transmission / reception unit that forms an ultrasonic beam by adjusting delay amounts of a plurality of drive signals supplied to a plurality of elements, a region of interest setting unit that sets a region of interest in a subject, and a transmission / reception unit, A first transmission / reception control unit that causes a plurality of elements to perform transmission / reception of ultrasonic waves for obtaining information on a moving body within a region of interest, and movement when ultrasonic transmission / reception for obtaining information on the moving body is performed. Reflected by the Doppler shift by the body The Doppler signal accompanying the movement of the moving object is extracted from the received data generated by the transmitting / receiving unit based on the ultrasonic detection signal of the ultrasonic wave, and the moving object region including the moving object in the region of interest is extracted based on the extraction result. Based on the discrimination results of the moving body area discriminating section and the moving body area discriminating section, the area excluding the moving body area from the area of interest is determined as the sound speed measuring area for measuring the sound velocity distribution. And a plurality of ultrasonic beam transmission focal points in the sound velocity measurement area, and the transmission / reception unit transmits / receives ultrasonic beams to / from each transmission focal point, thereby transmitting / receiving reception data for sound velocity measurement in the sound velocity measurement area And a sound speed map generating unit that generates a sound speed map indicating a sound speed distribution in the sound speed measurement region based on reception data for sound speed measurement.

  According to the present invention, it is possible to generate a sound speed map of a sound speed measurement region excluding a moving body region in which a sound speed error is likely to occur from a region of interest.

  A transmission / reception unit is controlled to transmit / receive ultrasonic waves for obtaining tomographic image information in the subject to a plurality of elements, and transmission / reception of ultrasonic waves for obtaining tomographic image information is performed. An image generation unit that generates a B-mode image based on the reception data generated by the transmission / reception unit, and a display unit that displays the B-mode image, and the attention area setting unit displays the attention area on the B-mode image. It is preferable to set. A region of interest can be set while viewing a B-mode image.

  Control of the transmission / reception unit by the first transmission / reception control unit, determination of the moving body region by the mobile body region determination unit, determination of the sound velocity measurement region by the sound velocity measurement region determination unit, and control of the transmission / reception unit by the second transmission / reception control unit And an update control unit that executes a sound speed map update process including generation of a sound speed map by the sound speed map generation unit. Before regenerating the sound velocity map, the moving object region is determined and the sound velocity measurement region is determined again, so the sound velocity map that is not affected by various moving objects such as blood vessels (blood flow) and tissues with large movements is regenerated. (Update process).

  It is preferable that the update control unit execute the sound velocity map update process each time a B-mode image having a predetermined number of frames is generated by the image generation unit. The sound speed map can be updated periodically.

  The moving body includes blood flowing through the blood vessel in the region of interest, and the moving body region determination unit generates blood flow information indicating the blood flow in the region of interest based on the extraction result of the Doppler signal. Thus, it is preferable to determine the moving body region based on the blood flow information. A sound velocity map that is not affected by blood vessels (blood flow) can be generated.

  The moving body includes a tissue that moves within the region of interest, and the moving body region determination unit generates tissue movement information indicating the movement of the tissue within the region of interest based on the extraction result of the Doppler signal. It is preferable to determine the moving body region based on the tissue movement information. A sound velocity map that is not affected by the moving tissue can be generated.

  The moving body region discriminating unit extracts a Doppler signal corresponding to a tissue whose magnitude of movement is greater than or equal to a predetermined threshold in the tissue from the reception data generated by the transmitting / receiving unit, and based on the Doppler signal It is preferable to generate movement information. It is possible to generate a sound velocity map that is not affected by a large-motion organization.

  The display unit preferably superimposes and displays a sound velocity map on the B-mode image.

  The ultrasonic diagnostic apparatus of the present invention determines a region excluding a moving body region including a moving body from a region of interest set on a B-mode image as a sound speed measurement region, and determines a local sound speed value of the sound speed measurement region. Since the sound velocity map is generated by the determination, it is not necessary to determine the local sound velocity value in the entire region within the region of interest. As a result, it is possible to reduce the calculation processing at the time of generating the sound velocity map as compared with the conventional case, so that the sound velocity map which is not affected by various moving bodies such as blood vessels (blood flow) and tissues with large movements is shorter than before. Can be generated in time.

It is a block diagram which shows the electrical constitution of the ultrasonic diagnosing device of 1st Embodiment. It is explanatory drawing of the delay circuit of a transmission circuit. It is a functional block diagram of a Doppler signal processing unit. It is explanatory drawing for demonstrating the filtering process by a filter part. It is the schematic of the speed conversion scale which an encoding calculating part uses. It is the schematic of the superimposed image which superimposed the CFM image on the B mode image. It is explanatory drawing for demonstrating the setting of an attention area. It is a functional block diagram of CPU. It is explanatory drawing for demonstrating the setting process of a transmission focus. It is explanatory drawing for demonstrating transmission / reception of the ultrasonic wave with respect to a transmission focus. It is explanatory drawing for demonstrating the calculation process of the local sound speed value using the Huygens principle. It is the flowchart which showed the outline of the flow of a local sound speed calculation process. It is the flowchart which showed the detail of the flow of a local sound speed calculation process. It is the flowchart which showed the flow of the production | generation and display process of a sound speed map. It is explanatory drawing for demonstrating the superimposition display on the B mode image of a sound speed map. It is explanatory drawing for demonstrating transmission / reception of the ultrasonic wave by Doppler mode scanning before acquisition of RF data of a sound speed measurement area | region. It is a functional block diagram of CPU of the ultrasonic diagnostic apparatus of 2nd Embodiment. It is the flowchart which showed the flow of the production | generation of a sound velocity map and display process of 2nd Embodiment. It is explanatory drawing for demonstrating the setting process of the transmission focus of 2nd Embodiment. It is explanatory drawing for demonstrating the local sound speed value calculation process of 2nd Embodiment.

[Apparatus Configuration of Ultrasonic Diagnostic Apparatus of First Embodiment]
As shown in FIG. 1, the ultrasonic diagnostic apparatus 10 transmits an ultrasonic beam from an ultrasonic probe 300 to a subject OBJ (see FIG. 10) and is reflected by the subject OBJ (ultrasonic wave). This is an apparatus that creates and displays an ultrasound image from an ultrasound detection signal obtained by receiving (sound echo). The ultrasonic diagnostic apparatus 10 is roughly divided into a CPU 100, a storage unit 102, a display unit 104, a display control unit 105, an operation input unit (region of interest setting unit) 200, an ultrasonic probe 300, a transmission / reception unit 400, and an image signal generation. Unit (image generation unit) 500, reproduction unit 600, data analysis measurement unit 700, Doppler signal processing unit (moving body region determination unit) 701, and sound speed measurement region determination unit 702.

  A CPU (Central Processing Unit) 100 controls each block of the ultrasound diagnostic apparatus 10 in accordance with an operation input from the operation input unit 200.

  The operation input unit 200 is an input device that receives an operation input from an operator, and includes an operation console 202 and a pointing device 204. The console 202 includes a keyboard that accepts input of character information (for example, patient information), a display mode switching button for switching display modes, a freeze button for instructing switching between the live mode and the freeze mode, and cine memory playback. It includes a cine memory playback button for instructing and an analysis / measurement button for instructing analysis / measurement of an ultrasonic image.

  The display mode includes a mode for displaying a B-mode image alone, a mode for displaying a B-mode image, a sound speed map indicating a distribution of local sound speeds, or a color flow mapping image indicating a moving speed of blood flow, tissue, and the like. It is included.

  The pointing device 204 is a device that receives an input for designating an area on the screen of the display unit 104, and is, for example, a trackball or a mouse. The pointing device 204 is used for setting a region of interest (also referred to as a region of interest (ROI) on the B-mode image). Note that a touch panel can be used as the pointing device 204.

  The storage unit 102 is a storage device that stores a control program and parameters for controlling the control of each block of the ultrasonic diagnostic apparatus 10 by the CPU 100, and is, for example, a hard disk or a semiconductor memory.

  The display unit 104 is, for example, a CRT (Cathode Ray Tube) display or a liquid crystal display, and displays an ultrasonic image (moving image and still image) display, a sound speed map, a color flow mapping image, various setting screens, and the like. The display control unit 105 displays an ultrasonic image or the like on the display unit 104 based on the image data output from the image signal generation unit 500.

  The ultrasonic probe 300 is a probe used in contact with the subject OBJ, and includes a plurality of elements 302 constituting a one-dimensional or two-dimensional ultrasonic transducer array. Each element 302 transmits an ultrasonic beam to the subject OBJ based on the drive signal applied from the transmission / reception unit 400, receives an ultrasonic echo reflected from the subject OBJ, and outputs a detection signal.

  Each element 302 includes a vibrator formed by forming electrodes on both ends of a piezoelectric material (piezoelectric body). As a piezoelectric body constituting the vibrator, for example, a piezoelectric ceramic such as PZT (lead zirconate titanate) or a polymer piezoelectric element such as PVDF (polyvinylidene difluoride) is used. Can be used. When a voltage is applied by sending an electric signal to the electrodes of the vibrator, the piezoelectric body expands and contracts, and ultrasonic waves are generated in each vibrator by the expansion and contraction of the piezoelectric body. For example, when a pulsed electric signal is sent to the electrode of the vibrator, a pulsed ultrasonic wave is generated, and when a continuous wave electric signal is sent to the electrode of the vibrator, a continuous wave ultrasonic wave is generated. Then, the ultrasonic waves generated in the respective vibrators are combined to form an ultrasonic beam. Further, when an ultrasonic wave is received by each vibrator, the piezoelectric body of each vibrator expands and contracts to generate an electric signal. The electrical signal generated in each transducer is output to the transmission / reception unit 400 as an ultrasonic detection signal.

  As the element 302, it is possible to use a plurality of types of elements having different ultrasonic conversion methods. For example, a vibrator configured of the above-described piezoelectric body may be used as an element that transmits ultrasonic waves, and an optical transducer of an optical detection type may be used as an element that receives ultrasonic waves. Here, the light detection type ultrasonic transducer converts an ultrasonic signal into an optical signal for detection, and is, for example, a Fabry-Perot resonator or a fiber Bragg grating.

  The transmission / reception unit 400 performs transmission / reception control of ultrasonic waves, and includes a transmission circuit 402, a reception circuit 404, and an A / D converter 406. The transmission circuit 402 sends a drive signal to each element 302. The receiving circuit 404 receives a detection signal input from each element 302 and generates a sound ray signal. The A / D converter 406 converts an analog sound ray signal into a digital signal (RF data).

  The image signal generation unit 500 generates image data for display (for example, B-mode image data) based on the RF data input from the transmission / reception unit 400. The signal processing unit 502, DSC (Digital Scan Converter) 504 An image processing unit 506, an image memory 508, and a D / A converter 510. The signal processing unit 502 generates B-mode image data based on the RF data. The DSC 504 converts B-mode image data or the like into image data of a television signal scanning method. The image processing unit 506 performs various image processes on the image data. The image memory 508 temporarily stores image data after image processing. The D / A converter 510 converts digital image data into an analog image signal.

  The playback unit 600 operates in a cine memory playback mode described later, and includes a cine memory 602 and a cine memory playback unit 604. The cine memory 602 is connected to the A / D converter 406 and stores the RF data input from the A / D converter 406. The cine memory reproduction unit 604 sends the RF data stored in the cine memory 602 to the signal processing unit 502.

  The data analysis measurement unit 700 performs analysis / measurement specified by the operator using the RF data. Based on the RF data, the Doppler signal processing unit 701 generates color Doppler information for color Doppler imaging (blood flow imaging, tissue Doppler imaging), that is, the blood flow in the subject OBJ and the movement state of the tissue. Further, the Doppler signal processing unit 701 generates a color flow mapping image (also referred to as a color Doppler tomographic image, hereinafter abbreviated as “CFM image”) from the color Doppler information. The sound speed measurement region determination unit 702 determines a sound speed measurement region in which the local sound speed value is calculated from the region of interest when the sound speed map is generated.

  The ultrasonic diagnostic apparatus 10 has a live mode and a cine memory reproduction mode as operation modes. The live mode is a mode for displaying, analyzing, and measuring an ultrasonic image (moving image) obtained by transmitting and receiving ultrasonic waves by bringing the ultrasonic probe 300 into contact with the subject OBJ. The cine memory playback mode is a mode for displaying, analyzing and measuring an ultrasonic diagnostic image based on RF data stored in the cine memory 602.

<Live mode>
Next, ultrasonic diagnostic processing in the live mode will be described. In the state where the ultrasonic probe 300 is in contact with the subject OBJ, ultrasonic diagnosis is started by an instruction input from the operation input unit 200. The CPU 100 outputs a control signal to the transmission / reception unit 400 to start transmission of an ultrasonic beam to the subject OBJ and reception of an ultrasonic echo from the subject OBJ. Further, the CPU 100 sets the transmission direction of the ultrasonic beam and the reception direction of the ultrasonic echo for each element 302.

  Next, the CPU 100 selects a transmission delay pattern according to the transmission direction of the ultrasonic beam and also selects a reception delay pattern according to the reception direction of the ultrasonic echo. Here, the transmission delay pattern is pattern data of a delay time given to a drive signal in order to form an ultrasonic beam in a desired direction by an ultrasonic wave transmitted from each element 302. The reception delay pattern is pattern data of a delay time given to a detection signal in order to extract an ultrasonic echo from a desired direction by ultrasonic waves received by a plurality of elements 302. These transmission delay pattern and reception delay pattern are stored in the storage unit 102 in advance. The CPU 100 outputs a control signal to the transmission / reception unit 400 according to the transmission delay pattern and the reception delay pattern selected from the storage unit 102 and performs ultrasonic transmission / reception control.

  The transmission circuit 402 generates a drive signal for each element 302 in accordance with a control signal from the CPU 100 and applies each drive signal to each element 302.

  As illustrated in FIG. 2, the transmission circuit 402 includes delay circuits τ <b> 1 to τN for each element 302, and delays the drive signal applied to each element 302 based on the transmission delay pattern selected by the CPU 100. Here, the transmission circuit 402 adjusts (delays) the timing at which the drive signal is applied to each element 302 so that the ultrasonic waves transmitted from the plurality of elements 302 form an ultrasonic beam. Further, the transmission circuit 402 adjusts (delays) the timing at which the drive signal is applied to each element 302 so as to adjust the direction (steer angle α) of the ultrasonic beam. Note that the timing at which the drive signal is applied may be adjusted so that the ultrasonic waves transmitted at a time from the plurality of elements 302 reach the entire imaging region of the subject OBJ.

  Returning to FIG. 1, the reception circuit 404 receives and amplifies the ultrasonic detection signal output from each element 302. Here, since the distance between each element 302 and the ultrasonic wave reflection source in the subject OBJ is different, the time for the reflected wave to reach each element 302 is different. At this time, the reception circuit 404 includes a delay circuit, and the arrival time of the reflected wave according to the reception delay pattern set based on the sound speed selected by the CPU 100 (hereinafter referred to as “assumed sound speed”) or the sound speed distribution. Each detection signal is delayed by an amount corresponding to the difference (delay time).

  Further, the reception circuit 404 performs reception focus processing by matching and adding the detection signals given delay times. At this time, if another ultrasonic reflection source is located at a position different from the ultrasonic reflection source, the ultrasonic detection signal from the other ultrasonic reflection source has a different arrival time. The phases of the ultrasonic detection signals from the two cancel each other. As a result, the received signal from the ultrasonic wave reflection source becomes the largest and is focused. By such reception focus processing, a sound ray signal (hereinafter referred to as “RF signal”) in which the focus of the ultrasonic echo is narrowed is formed.

  The A / D converter 406 converts the analog RF signal output from the receiving circuit 404 into RF data that is a digital RF signal. Here, the RF data includes received wave phase information. The RF data output from the A / D converter 406 is input to the signal processing unit 502 and the cine memory 602, respectively.

  The cine memory 602 sequentially stores the RF data input from the A / D converter 406. The cine memory 602 stores information related to the frame rate input from the CPU 100 (for example, parameters indicating the depth of the reflection position of the ultrasonic wave, the density of the scanning line, and the visual field width) in association with the RF data.

  The signal processing unit 502 performs envelope detection processing on the RF data after correcting attenuation by distance according to the depth of the reflection position of the ultrasonic wave by STC (Sensitivity Time gain Control). Thereby, B-mode image data (image data in which the amplitude of the ultrasonic echo is expressed by the brightness (luminance) of the point) is generated.

  The B-mode image data generated by the signal processing unit 502 is obtained by a scanning method different from a normal television signal scanning method. For this reason, the DSC 504 converts (raster conversion) the B-mode image data into normal image data (for example, image data of a television signal scanning method (NTSC method)). The image processing unit 506 performs various necessary image processing (for example, gradation processing) on the image data input from the DSC 504.

  The image memory 508 stores image data input from the image processing unit 506. The D / A converter 510 converts the image data read from the image memory 508 into an analog image signal and outputs the analog image signal to the display control unit 105. Thereby, an ultrasonic image (moving image) photographed by the ultrasonic probe 300 is displayed on the display unit 104.

  In this embodiment, the detection signal subjected to the reception focus process in the reception circuit 404 is an RF signal, but the detection signal not subjected to the reception focus process may be an RF signal. In this case, a plurality of ultrasonic detection signals output from the plurality of elements 302 are amplified in the reception circuit 404, and the amplified detection signals, that is, RF signals are A / D converted in the A / D converter 406. As a result, RF data is generated. The RF data is supplied to the signal processing unit 502 and stored in the cine memory 602. The reception focus process is performed digitally in the signal processing unit 502.

<Cine memory playback mode>
Next, the cine memory playback mode will be described. When the cine memory playback button on the console 202 is pressed, the CPU 100 switches the operation mode of the ultrasonic diagnostic apparatus 10 to the cine memory playback mode. In the cine memory reproduction mode, the CPU 100 instructs the cine memory reproduction unit 604 to reproduce the RF data designated by the operation input from the operator. The cine memory reproduction unit 604 reads RF data from the cine memory 602 and transmits it to the signal processing unit 502 in accordance with a command from the CPU 100. The RF data transmitted from the cine memory 602 is subjected to predetermined processing (processing similar to that in the live mode) in the signal processing unit 502, DSC 504, and image processing unit 506, and converted into image data. The data is output to the display unit 104 via the D / A converter 510. Accordingly, an ultrasonic image (moving image or still image) based on the RF data stored in the cine memory 602 is displayed on the display unit 104.

<Various functions of ultrasonic diagnostic equipment>
When the freeze button on the console 202 is pressed while an ultrasonic image (moving image) is displayed in the live mode or the cine memory playback mode, the ultrasonic image displayed at the time of the pressing is stopped on the display unit 104. Displayed. Thereby, the operator can observe the still image of the region of interest.

  When the measurement button on the console 202 is pressed, analysis / measurement designated by an operation input from the operator is performed. When the measurement button is pressed in each operation mode, the data analysis measurement unit 605 acquires RF data before image processing is performed from the A / D converter 406 or the cine memory 602, and uses this RF data. Operator-specified analysis / measurement (for example, tissue strain analysis (hardness diagnosis), blood flow measurement, tissue motion measurement, or IMT (Intima-Media Thickness) measurement )I do. The analysis / measurement result by the data analysis measurement unit 605 is output to the DSC 504. The DSC 504 inserts the analysis / measurement result by the data analysis / measurement unit 605 into the image data of the ultrasonic image and outputs the result to the display control unit 105. Thereby, the ultrasonic image and the analysis / measurement result are displayed on the display unit 104.

  When the display mode switching button of the console 202 is pressed, the display mode is switched between the single display mode, the CFM image display mode, the sound velocity map display mode, and the parallel display mode. In the single display mode, the B mode image is displayed alone. In the CFM image display mode, a CFM image (calculation result of the moving speed of blood flow, tissue, etc.) is superimposed on the B-mode image and displayed (for example, color-coded according to the moving speed). In the sound velocity map display mode, a sound velocity map (local sound velocity value determination result) is superimposed and displayed on the B-mode image (for example, a display in which color coding or luminance is changed according to the local sound velocity, or a point where the local sound velocity is equal) Display). In the parallel display mode, the B-mode image and the sound velocity map image or CFM image are displayed side by side.

  By observing the sound velocity map, for example, a lesion can be found. Note that a B-mode image obtained by performing at least one of transmission focus processing and reception focus processing based on the determination result of the local sound speed may be displayed on the display unit 104. Further, by observing the CFM image, it is possible to diagnose a blood circulation state such as a blood flow velocity.

<CFM image display mode>
When the CFM image display mode is selected, the transmission / reception unit 400 transmits / receives ultrasound corresponding to B-mode scanning and obtains color Doppler information (CFM image) to obtain tomographic image information (B-mode image) of the subject OBJ. ), Each element 302 is repeatedly executed to transmit and receive ultrasonic waves corresponding to Doppler mode scanning. In B-mode scanning, a B-mode image is generated by the same processing as in the live mode, and is output to the display unit 104 via the image memory 508 and the D / A converter 510.

  In the Doppler mode scanning, for example, ultrasonic waves for Doppler measurement are continuously transmitted into the subject OBJ, and the ultrasonic echoes (echo signals) are continuously received. In this way, in order to continuously transmit and receive ultrasonic waves, the transmitting element 302 is used only for transmission, and the receiving element 302 is used only for reception (see, for example, Japanese Patent No. 387597). Note that transmission / reception of ultrasonic waves during Doppler mode scanning is not limited to the above-described method, and various methods can be used.

  By transmitting and receiving ultrasonic waves during Doppler mode scanning, RF data based on ultrasonic detection signals reflected and reflected by Doppler shifts by moving bodies such as blood flowing through blood vessels and moving tissues is generated by the transmitting and receiving unit 400. This RF data is input to the Doppler signal processing unit 701.

[Doppler signal processor]
As illustrated in FIG. 3, the Doppler signal processing unit 701 includes a phase detector 705, a filter unit 706, a frequency analysis unit 707, and an encoding calculation unit 708, and performs color Doppler information and CFM image. Is generated.

  The phase detector 705 includes a mixer and a low-pass filter. An echo signal reflected by a moving body such as a blood flow or a moving tissue is subjected to a Doppler shift in its frequency due to the Doppler effect. The phase detector 705 performs phase detection on the Doppler frequency and outputs only the Doppler signal from the RF data to the filter unit 706.

  As shown in FIG. 4, the filter unit 706 removes the Doppler signal D1 corresponding to the tissue with relatively small motion from the Doppler signal phase-detected by the phase detector 705, and corresponds to the tissue with relatively large motion. The Doppler signal D2 and the Doppler signal D3 corresponding to the blood flow are efficiently detected. In this case, the filter unit 706 functions as a high-pass filter. The symbol “HF” in the figure indicates the high-pass filter characteristic of the filter unit 706. This high-pass filter characteristic HF corresponds to the threshold value of the present invention. Therefore, a Doppler signal corresponding to a tissue in which the magnitude of motion is equal to or greater than a threshold value determined by the high-pass filter characteristic HF is obtained in the tissue in the subject OBJ. The Doppler signal filtered by the filter unit 706 is output to the frequency analysis unit 707.

  Returning to FIG. 3, the frequency analysis unit 707 applies the FFT method and the autocorrelation method, which are frequency analysis methods used in ultrasonic Doppler blood flow measurement. The average speed and the maximum speed within the observation time (time window) at each sample point are calculated as speed data. Specifically, for example, using the FFT method or autocorrelation method, the average Doppler shift frequency at each point of the sample (that is, the average speed of movement of the observation target at that point) and the dispersion value (the Doppler spectrum disturbance degree) Further, the maximum value of the Doppler shift frequency (that is, the maximum speed of movement of the observation target at that point) and the like are calculated almost in real time using the FFT method. The analysis result of the Doppler frequency is output as color Doppler information (blood flow information, tissue movement information (also referred to as tissue Doppler information)) to the encoding calculation unit 708 in the next stage.

  The encoding operation unit 708 uses the pre-designated speed conversion scale as shown in FIG. 5 to set the Doppler shift frequency fd sent from the frequency analysis unit 707 for each sample point on the tomographic plane to a predetermined bit. Encodes into a number of speed indication data. Thereby, CFM image data which is a speed display for each sample point is obtained. The CFM image data is output to the DSC 504.

  Returning to FIG. 3, the DSC 504 converts the CFM image data into a television signal scanning method. The CFM image data converted by the DSC 504 is subjected to image processing by the image processing unit 506 and then output to the display control unit 105 via the D / A converter 510.

  As shown in FIGS. 6A to 6C, the display control unit 105 superimposes the CFM image 111 obtained by Doppler mode scanning on the B mode image 110 obtained by B mode scanning. 110a is displayed on the display unit 104. In the CFM image 111 (superimposed image 110a), a tissue (hereinafter referred to as a high-speed moving tissue) 116a that moves relatively large (above the above-described threshold value) in the blood vessel 115 and the tissue 116 is separated from other portions. Are displayed in different colors. Thereby, the moving body region 117 including moving bodies such as the blood flow 115a in the blood vessel 115 and the high-speed moving tissue 116a can be determined.

  In the example illustrated in FIG. 6, the Doppler signal processing unit 701 generates CFM image data corresponding to the entire area of the B-mode image data. However, for example, CFM image data corresponding to the attention area 112 described below is generated. It may be generated.

<Sonic map display mode>
Even when the sound velocity map display mode is selected, the transmission / reception unit 400 transmits / receives ultrasonic waves corresponding to B-mode scanning and ultrasonic waves corresponding to Doppler mode scanning for obtaining color Doppler information (CFM image). Are executed by each element 302. Then, the Doppler signal processing unit 701 sends color Doppler information (or CFM image data is acceptable) to the sound velocity measurement region determination unit 702 (see FIGS. 1 and 3).

  In addition, when the sound speed map display mode is selected as shown in FIG. 7, the attention area 112 is set on the B-mode image 110 displayed on the display unit 104 using the pointing device 204. Thereby, the determination of the sound speed measurement region 119 (see FIG. 9) in the region of interest 112 by the sound speed measurement region determination unit 702 and the generation of the sound speed map of the sound speed measurement region 119 by the CPU 100 are performed.

  As shown in FIG. 8 and FIG. 9A to FIG. 9C, the sound speed measurement region determining unit 702 is based on the color Doppler information or the CFM image data, and the sound speed measurement region 119 (the oblique line in FIG. 9C). To display). The color Doppler information or the CFM image data includes the position, shape, size, and the like of the moving object region 117 that is likely to cause an error when calculating the local sound speed (see FIG. 9B). In FIGS. 9B and 9C, the CFM image 111 is shown instead of the color Doppler information or the CFM image data in order to make it easy to determine the position, shape, size, etc. of the moving body region 117. .

  The sound velocity measurement area determination unit 702 determines whether or not the moving body area 117 is included in the previously set attention area 112 based on the color Doppler information or the CFM image data. Then, the sound velocity measurement region determination unit 702 determines a region excluding the moving body region 117 in the region of interest 112 as the sound velocity measurement region 119. This determination result (position, shape, size, etc. of the sound velocity measurement region 119) is input to the CPU 100.

<CPU function (configuration related to generation of sound velocity map)>
The CPU 100 executes various programs read from the storage unit 102, so that a transmission / reception control unit (first transmission / reception control unit, second transmission / reception control unit, third transmission / reception control unit) 120, local sound speed value calculation unit 121. , Function as a sound velocity map generator 122 and an update controller 123 (see FIG. 8).

  When the single display mode is selected, the transmission / reception control unit 120 controls the transmission / reception unit 400 to cause each element 302 to perform transmission / reception of ultrasonic waves corresponding to the B-mode scanning. Further, when the CFM image display mode is selected, the transmission / reception control unit 120 controls the transmission / reception unit 400 to perform transmission / reception of ultrasonic waves corresponding to B-mode scanning and transmission / reception of ultrasonic waves corresponding to Doppler mode scanning. The element 302 is repeatedly executed.

  Further, the transmission / reception control unit 120 controls the transmission / reception unit 400 when the sound velocity map display mode is selected, and transmits / receives ultrasonic waves corresponding to the Doppler mode scanning and the sound velocity measurement area 119 before generating the sound velocity map. Each element 302 is caused to execute transmission / reception of ultrasonic waves for acquiring RF data for sound speed measurement (received data for sound speed measurement). Before generating the sound velocity map, transmission / reception of ultrasonic waves corresponding to Doppler mode scanning is executed, whereby generation of color Doppler information or CFM image data by the Doppler signal processing unit 701 is executed. Thus, the sound speed measurement region 119 is determined by the sound speed measurement region determination unit 702 before the sound speed map is generated.

[RF data acquisition processing for sound velocity measurement]
The transmission / reception control unit 120 sets a plurality of transmission focal points 125 of the ultrasonic beam B (see FIG. 10) in the sound speed measurement region 119 determined by the sound speed measurement region determination unit 702. The transmission focal point 125 is a point that becomes the lattice point X _ROI , the lattice point A1, the lattice point A2,... In the local sound speed calculation by the local sound speed value calculation unit 121 (see FIG. 11). In the present embodiment, the transmission focal point 125 is set in a substantially lattice shape.

  Next, as illustrated in FIG. 10, the transmission / reception control unit 120 generates a transmission delay pattern for performing transmission focus on each transmission focus 125 and a reception delay pattern for extracting ultrasonic echoes from each transmission focus 125. select. Then, the transmission / reception control unit 120 outputs a control signal to the transmission / reception unit 400 according to each selected transmission delay pattern and each reception delay pattern, and performs ultrasonic transmission / reception control. Thus, an RF signal of each transmission focal point 125 is formed by detecting the ultrasonic echo from each transmission focal point 125 with each element 302 while focusing each transmission focal point 125 on the ultrasonic beam. In the present embodiment, as indicated by each straight line Ls in the figure, the RF signal of each transmission focal point 125 is formed line by line while changing the focal point of the ultrasonic beam in the Y direction (the depth direction of the object OBJ). To do. The RF signal of each transmission focal point 125 is converted into RF data (received data for sound velocity measurement) by the A / D converter 406 and then stored in the cine memory 602.

[Calculation process of local sound velocity value in the sound velocity measurement area]
The local sound speed value calculation unit 121 obtains local sound speed values of individual regions in the region of interest 112 using the local sound speed calculation method using the Huygens principle disclosed in Patent Document 1.

FIGS. 11A and 11B are diagrams schematically illustrating the calculation process of the local sound speed value. A grid point representing the region of interest in the subject OBJ is X _ROI , and a grid point arranged at equal intervals in the XY direction at a position shallower than the grid point X _ROI (that is, on the ultrasonic probe 300 side) is A1. , A2,..., And at least the sound speed of the region R _XA between the lattice point _XROI and each lattice point A1, A2,.

In the present embodiment, the lattice points A1, A2, _(W A1, _{respectively, W A2,} ...) ... received wave from as (T and delay time [Delta] T) is known, the lattice point _{X ROI} and grid points A1, A2, ... The local sound velocity value at the lattice point X _ROI is obtained from the positional relationship of. Specifically, the principle of Huygens, received wave W _X and the lattice point from the lattice point X _ROI A1, A2, utilize the received wave W _SUM obtained by synthesizing the received waves from ... virtually coincide.

The positions of the lattice point _XROI and the lattice points A1, A2,... Are determined based on the position of the transmission focal point 125 described above. For example, in the arrangement of the transmission focal points 125 shown in FIG. 10, when one of the transmission focal points 125 in the second row from the bottom in the drawing is defined as the lattice point X _ROI , the first row from the bottom in the drawing. From the transmission focal point 125, lattice points A1, A2,... Are determined. Further, when one of the transmission focal points 125 in the third row from the bottom in the figure is determined as the lattice point X _ROI , lattice points A1, A2,. Is determined. Then, the local sound speed value is calculated based on the RF data acquired in advance for each lattice point X _ROI , A1, A2,... (Transmission focal point 125) and stored in the cine memory 602.

Here, the lattice points used in the calculation of the time for obtaining the local sound speed value at the lattice point X _ROI A1, A2, ... scope and number of determined in advance. If the range of the lattice point used for the local sound speed value calculation is wide, the error of the local sound speed value becomes large, and if it is narrow, the error with the virtual received wave becomes large. Therefore, the range of the lattice point is determined based on these factors.

  Further, the interval in the X direction between the lattice points A1, A2,... Is determined by the balance between the resolution and the processing time. An interval in the X direction between the lattice points A1, A2,... Is 1 to 1 cm, for example. If the intervals between the lattice points A1, A2,... Are wide, it is difficult to calculate a composite wave (described later), and fine lattice points may be generated by interpolation.

In the flowchart shown in FIG. 12, the local sound velocity value calculation unit 121 sets the lattice points X _ROI , lattice points A1, A2,... As described above (step S1), and then each lattice point (X _ROI , A1). , A2,...) Is determined (step S2). Here, the optimum sound speed value is the sound speed value at which the contrast and sharpness of the image are the highest, and does not necessarily match the actual local sound speed value at each lattice point. As a method for determining the optimum sound speed value in step S2, for example, a method for determining from the contrast of the image, the spatial frequency in the scanning direction, dispersion, and the like (for example, Japanese Patent Application Laid-Open No. 8-317926) can be applied.

  Next, based on the optimum sound speed value at each lattice point, the local sound speed value at each lattice point is determined (step S3). Hereinafter, a method for determining the local sound speed value based on the optimum sound speed value will be described.

First, as shown in FIG. 13, the local sound speed value calculation unit 121, based on the optimum sound speed value at the lattice point X _ROI, virtual receiving wave obtained when the lattice point X _ROI was reflection point (hereinafter, virtual A waveform of W _X (referred to as a received wave) is calculated (step S4).

Next, the local sound speed value calculation unit 121 sets an initial value of the assumed sound speed at the lattice point X _ROI (step S5). Then, the local sound velocity value calculation unit 121 calculates a virtual combined received wave (hereinafter referred to as a virtual combined received wave) _WSUM as described below (step S6). When the local sound speed value at the lattice point _{X ROI} is assumed by V, ultrasound lattice points having propagated from the lattice point _{X ROI} A1, A2, the time to reach ... to _{X ROI A1 / V, X ROI} A2 / V, ... Here, X _ROI A1, X _ROI A2,... _Are the distances between the lattice points A1, A2 _,. Since the optimum sound velocity values at the lattice points A1, A2,... Are known at step S2, the received waves from the lattice points A1, A2,. Therefore, the virtual composite received wave _WSUM is obtained by synthesizing the reflected waves (ultrasonic echoes) emitted from the lattice points A1, A2,... With the delays _XROI A1 / V, _XROI A2 / V _,. Can do.

Actually, since the above processing is performed on the element data (RF signal), the time (T1, T2,...) From the lattice point _XROI to the lattice points A1, A2,. It is represented by (1). Here, X _A1 , X _A2 ,... _Are distances in the scanning direction (X direction) between the lattice points A 1, A 2,. Δt is a time interval in the Y direction of the lattice points.

The T1, T2, ..., the time from the lattice point An of the lattice point _{X ROI} and the same scan line until it reaches the lattice point _{X ROI (Δt} / 2) each grid point in the delay plus A1, A2, ... By synthesizing the received wave from, a virtual synthesized received wave _WSUM can be obtained.

Here, when the lattice points are set at equal intervals (Δt) on the time axis in the Y direction, the intervals in space are not necessarily equal. Therefore, when calculating the time until the ultrasonic wave reaches each lattice point, Δt / 2 corrected in Equation (1) instead of Δt / 2 may be used. Here, the corrected Δt / 2 is, for example, a value obtained by dividing the difference in depth (distance in the Y direction) of A1, A2,... Compared with the lattice point X _ROI and the lattice point An of the same sound line by V. A value obtained by adding / subtracting from / 2. The depth of each lattice point A1, A2,... Is obtained because the local sound speed is known at a lattice point shallower than that.

Further, the virtual composite received wave _WSUM is calculated from predetermined pulse waves (W _A1 , W _A2 , respectively) actually emitted from the lattice points A1, A2,... With delays X _ROI A1 / V, X _ROI A2 / V _,. , ...) are superimposed.

Next, the local sound velocity value calculation unit 121 calculates an error between the virtual received wave W _X and the virtual synthesized received wave W _SUM (step S7). Error between the virtual receiving wave W _X and the assumed resultant received wave W _SUM is a method of cross-correlating with each other, a method of multiplying a delay obtained from the assumed resultant received wave W _SUM to the virtual receiving wave W _X phase matching addition, or conversely over a delay obtained assumed resultant received wave W _SUM from the virtual receiving wave W _X is calculated by the method of phase matching addition. Here, in order to obtain a delay from the virtual received wave W _X , the lattice point X _ROI is used as a reflection point, and the time at which the ultrasonic wave propagated at the sound velocity V arrives at each element 302 may be set as the delay. Further, in order to obtain a delay from the virtual combined received wave _WSUM , an equiphase line is extracted from the phase difference of the combined received wave between the adjacent elements 302, and the equal phase line is used as a delay, or each element is simply set. The phase difference of the maximum (peak) position of the combined received wave 302 may be a delay. Further, the cross-correlation peak position of the combined reception wave from each element 302 may be set as a delay. The error at the time of phase matching addition is obtained by a method of setting the peak to peak of the waveform after the matching addition or a method of setting the maximum value of the amplitude after the envelope detection.

Next, after the assumed sound speed is changed by one step (step S8), steps S6 to S7 are repeated. Then, when the calculation for all assumed sound speed values is completed, the local sound speed value calculation unit 121 determines the local sound speed value at the lattice point X _ROI (step S9). When the Huygens principle is strictly applied, the waveform of the virtual synthesized received wave _WSUM obtained in step S6 is a virtual received wave (reflected wave) assuming that the local sound velocity value at the lattice point _XROI is V. equal to the W _X of the waveform. In step S9, it determines the value of the assumed sound speed difference between the virtual receiving wave W _X and the assumed resultant received wave W _SUM is minimized and local sound speed value at the lattice point X _ROI. Thereby, the local sound velocity value at one lattice point X _ROI in the region of interest 112 is obtained.

Similarly, the local sound speed value calculation unit 121 calculates the local sound speed values of a plurality of other lattice points X _ROI in the region of interest 112 determined based on the position of the transmission focus 125 described above.

<Sonic velocity map generation processing>
Returning to FIG. 8, the sound speed map generation unit 122 shows the distribution of the local sound speed in the attention area 112 based on the local sound speed value of each lattice point X _ROI in the attention area 112 calculated by the local sound speed value calculation section 121. A sound speed map 130 (see FIG. 16) is generated.

<Sonic velocity map update processing>
The update control unit 123 performs transmission / reception control unit 120, Doppler signal processing unit 701, sound speed measurement region determination unit 702 every time a certain period of time elapses, for example, every time B-mode image data of a predetermined number of frames (10 frames or the like) is generated. Then, the local sound speed value calculation unit 121 and the sound speed map generation unit 122 are controlled to update the sound speed map 130. Specifically, Doppler mode scanning, generation of color Doppler information or CFM image data, determination of the sound velocity measurement region 119, acquisition of RF data in the sound velocity measurement region 119, calculation of local sound velocity values, and sound velocity map 130 Generation.

<Operation of Ultrasonic Diagnostic Apparatus of First Embodiment>
Next, the operation of the ultrasonic diagnostic apparatus 10 having the above configuration will be specifically described with reference to the flowchart shown in FIG. When the ultrasound diagnosis in the single display mode is started, the CPU 100 outputs a control signal to the transmission / reception unit 400, transmits an ultrasound beam to the subject OBJ, and receives an ultrasound echo from the subject OBJ. To start. The ultrasonic detection signal detected by each element 302 is converted into digital RF data by the transmission / reception unit 400.

  The RF data generated by the transmission / reception unit 400 is stored in the cine memory 602 and is output to the image signal generation unit 500. Then, B-mode image data is generated based on the RF data by the image signal generation unit 500 and converted into an analog image signal, and then output to the display control unit 105. Based on this image signal, the display control unit 105 displays the B-mode image 110 on the display unit 104 (step S10).

  When the display mode switching button on the console 202 is pressed to switch from the single display mode to the sound velocity map display mode (step S11), the CPU 100 displays a message or the like prompting the setting of the attention area 112 on the display unit 104. The doctor operates the pointing device 204 while viewing the B mode image 110 displayed on the display unit 104 to set the region of interest 112 on the B mode image 110 (step S12).

  When the region of interest 112 is set, the transmission / reception control unit 120 controls the transmission / reception unit 400 to cause each element 302 to perform transmission / reception of ultrasonic waves corresponding to Doppler mode scanning. RF data is generated in the transmission / reception unit 400 by transmission / reception of this ultrasonic wave (step S13), and this RF data is input to the Doppler signal processing unit 701. Note that, after transmission / reception of ultrasonic waves corresponding to Doppler mode scanning, transmission / reception of ultrasonic waves corresponding to B mode scanning and generation / output of B mode image data are repeatedly executed.

  As shown in FIGS. 3 to 5, the Doppler signal processing unit 701 generates color Doppler information or CFM image data from the RF data obtained during Doppler mode scanning (step S14). This color Doppler information or CFM image data is input to the sound velocity measurement region determination unit 702.

  The sound velocity measurement region determination unit 702 determines the sound velocity measurement region 119 obtained by removing the moving body region 117 from the region of interest 112 set previously based on the color Doppler information or the CFM image data from the Doppler signal processing unit 701. (Refer FIG. 9 (a)-FIG.9 (c), step S15). The determination result of the sound speed measurement region determination unit 702 is input to the CPU 100.

  In response to the determination result of the sound speed measurement region 119 from the sound speed measurement region determination unit 702, the transmission / reception control unit 120 sets the transmission focal point 125 in the sound speed measurement region 119, as shown in FIGS. The transmission / reception unit 400 is controlled to cause each element 302 to perform ultrasonic transmission / reception (transmission focus, reception focus). Thereby, RF data of each transmission focal point 125 is acquired (generated / stored) (step S16).

After acquiring the RF data of each transmission focal point 125, the local sound velocity value calculation unit 121 uses Huygens' principle as shown in FIGS. 11 to 13, and uses the Huygens principle for each lattice point X _ROI in the sound velocity measurement region 119. Local sound speed value is calculated. Next, the sound speed map generation unit 122 generates a sound speed map 130 based on the calculation result of the local sound speed value by the local sound speed value calculation unit 121, and outputs the sound speed map 130 to the DSC 504 (step S17).

  The sound speed map 130 is converted into image data of a scanning method of a television signal by the DSC 504, subjected to image processing by the image processing unit 506, stored in the image memory 508, and then converted by the D / A converter 510. It is converted into an analog image signal and output to the display control unit 105.

  As shown in FIG. 15, the display control unit 105 superimposes the sound speed map 130 on the B-mode image 110 based on the image signal of the sound speed map 130 and the image signal of the B-mode image obtained by the B-mode scanning. It is displayed on the display unit 104 (step S18). In the sound speed map 130, the sound speed measurement area 119 is displayed in different colors according to the value of the local sound speed.

  Returning to FIG. 14, as described in step S <b> 10, new B-mode image data is generated and stored in the image memory 508. If a certain period has not elapsed since the generation of the previous sound velocity map 130, specifically, if B-mode image data of a predetermined number of frames (such as 10 frames) has not been generated (NO in step S19), the update is performed. The update process of the sound velocity map 130 by the control unit 123 is not executed. For this reason, the previously generated sound speed map 130 is superimposed on the newly generated B-mode image.

  On the other hand, when a certain period has elapsed since the generation of the previous sound velocity map 130, specifically, when B-mode image data of a predetermined number of frames (such as 10 frames) is generated (YES in step S19), the update control unit 123 causes the sound velocity map 130 to be updated. As a result, the processes from step S13 to step S18 described above are repeatedly executed. As a result, a new sound speed map 130 is superimposed and displayed on the B-mode image 110.

  Thereafter, the above-described processes are repeatedly executed until the sound speed map display mode ends (YES in step S20).

  Note that, as shown in FIG. 16A, in the first embodiment, “D” in the figure immediately before transmission / reception of ultrasonic waves for acquiring RF data in the sound velocity measurement region 119 indicated by “S” in the figure. The ultrasonic wave corresponding to the Doppler mode scanning shown in FIG. In the figure, “B” indicates transmission / reception of ultrasonic waves corresponding to B-mode scanning. At this time, for example, as shown in FIG. 16B, between the transmission / reception of ultrasonic waves corresponding to Doppler mode scanning and the transmission / reception of ultrasonic waves for acquiring RF data in the sound velocity measurement region 119, the B mode You may perform transmission / reception of the ultrasonic wave corresponding to a scan.

<Effect>
As described above, in the present invention, the sound velocity measurement is performed based on the RF data obtained by setting the transmission focus 125 in the sound velocity measurement region 119 in the region of interest 112 and transmitting / receiving ultrasonic waves to / from each transmission focus 125. Since the sound velocity map 130 is generated by obtaining the local sound velocity value in the region 119, it is not necessary to acquire the RF data of the entire region in the region of interest 112. As a result, it is possible to reduce the calculation processing when generating the sound speed map 130 as compared with the conventional case, and thus the time required for generating and displaying the sound speed map 130 is reduced without using a high-performance arithmetic processing unit (CPU). can do. Furthermore, it is possible to generate a sound speed map 130 that is not affected by various moving bodies such as blood vessels (blood flow) and tissues with large movement.

[Configuration of Ultrasonic Diagnostic Apparatus of Second Embodiment]
Next, the ultrasonic diagnostic apparatus 20 according to the second embodiment of the present invention will be described with reference to FIG. In the first embodiment, the local sound speed value in the sound speed measurement area 119 is calculated based on the RF data acquired by setting the transmission focus 125 in the sound speed measurement area 119. On the other hand, in the ultrasonic diagnostic apparatus 20 according to the second embodiment, the local sound velocity value in the sound velocity measurement region 119 is calculated based on the RF data acquired by setting the transmission focus 125 in the region of interest 112.

  The ultrasonic diagnostic apparatus 20 has basically the same configuration as that of the first embodiment except that the CPU 100 functions as a transmission / reception control unit 120a and a local sound velocity value calculation unit 121a different from those of the first embodiment. The same functions and configurations as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The transmission / reception control unit 120a acquires the RF data in the region of interest 112 by setting the transmission focal point 125 in all regions in the region of interest 112 and causing the transmission / reception unit 400 (each element 302) to perform transmission and reception of ultrasonic waves. . Further, the local sound speed value calculation unit 121a selects the RF data corresponding to the transmission focal point 125 in the sound speed measurement area 119 from the RF data in the attention area 112, and calculates the local sound speed value.

<Operation of Ultrasonic Diagnostic Apparatus of Second Embodiment>
The operation of the ultrasonic diagnostic apparatus 20 configured as described above will be specifically described with reference to the flowchart shown in FIG. 18 and the explanatory diagrams shown in FIGS. Note that the processing (from step S10 to step S15) until the determination of the sound speed measurement region 119 is the same as in the first embodiment, and thus the description thereof is omitted.

  As shown in FIG. 19, after determining the sound velocity measurement region 119, the transmission / reception control unit 120 a sets the transmission focal point 125 in all regions within the region of interest 112 and then controls the transmission / reception unit 400 to transmit / receive ultrasonic waves (transmission). Focus, receive focus). Thereby, RF data of each transmission focal point 125 in the entire region of the region of interest 112 is acquired (generated / stored) (step S21). In the present embodiment, the transmission focus 125 is set in a grid pattern, but the setting pattern of the transmission focus 125 may be changed as appropriate. Further, step S21 may be appropriately performed between step S13 and step S15.

  After setting the transmission focal point 125, the local sound speed value calculation unit 121a determines the sound speed measurement region 119 in the region of interest 112 based on the determination result of the sound speed measurement region 119 input from the sound speed measurement region determination unit 702 to the CPU 100.

  Next, as shown in FIG. 20, the local sound velocity value calculation unit 121a transmits the transmission focal point 125 in the sound velocity measurement region 119 (indicated by a black circle in the drawing) from the RF data corresponding to each transmission focal point 125 in the region of interest 112. After selecting the RF data corresponding to (display), the local sound speed value is calculated in the same manner as in the first embodiment. Thereby, the local sound speed value in the sound speed measurement region 119 is obtained. Note that reference numeral “125 ′” in FIG. 20 is a transmission focal point outside the sound velocity measurement region 119 (indicated by a white circle in the figure). The sound speed map generation unit 122 generates the sound speed map 130 based on the calculation result of the local sound speed value by the local sound speed value calculation unit 121a (step S22).

  Hereinafter, as in the first embodiment, the sound speed map 130 is superimposed and displayed on the B-mode image 110. When a certain period of time has elapsed since the generation of the previous sound speed map 130 (for example, every 10 frames), the sound speed map is obtained by repeatedly executing the above steps S13 to S15, S21, S22, and S18. 130 is updated.

  In the ultrasonic diagnostic apparatus 20, the transmission focus 125 is set in the entire region of interest 112 and RF data is acquired. Therefore, although calculation processing and generation time for generating the sound velocity map 130 increase, blood vessels (blood It is possible to generate a sound velocity map 130 that is not affected by the flow).

[Others]
The local sound velocity value calculation units 121 and 121a of the above embodiments obtain the local sound velocity value in the sound velocity measurement region 119 using the local sound velocity calculation method using the Huygens principle disclosed in Patent Document 1. For example, the local sound speed value in the sound speed measurement region 119 may be obtained using the local sound speed calculation method using the refractive index model calculation disclosed in Patent Document 1, and the local sound speed calculation method is not particularly limited.

  In each of the above embodiments, the region of interest 112 is set in a rectangular shape, but the region of interest may be set in various shapes such as a circular shape.

  In each of the above embodiments, the sound speed map 130 is updated every predetermined number of frames (for example, 10 frames). For example, various fixed periods such as a certain time have elapsed since the previous sound speed map 130 was generated. After that, the sound speed map 130 may be updated.

  In each of the above embodiments, the color Doppler information and CFM image data are generated by the Doppler signal processing unit 701. However, the configuration of the Doppler signal processing unit 701 is as long as color Doppler information and CFM image data can be generated. It is not limited to the configuration shown in FIG.

  In each of the above embodiments, the driving of each element 302 (transmission / reception of ultrasonic waves) is different between B-mode scanning and Doppler mode scanning. However, if color Doppler information and CFM image data can be obtained, The drive may be the same. In this case, generation of B-mode image data and generation of color Doppler information and CFM image data can be performed simultaneously.

  DESCRIPTION OF SYMBOLS 10,20 ... Ultrasound diagnostic apparatus, 100 ... CPU, 110 ... B mode image, 112 ... Target area | region, 119 ... Sonic velocity measurement area, 120 ... Transmission / reception control part, 121 ... Local sound speed value calculation part, 122 ... Sonic velocity map generation part , 123 ... Update control unit, 125 ... Transmission focus, 130 ... Sound velocity map, 200 ... Operation input unit, 300 ... Ultrasonic probe, 400 ... Transmission / reception unit, 701 ... Doppler signal processing unit, 702 ... Sound velocity measurement region determination unit

Claims (8)

An ultrasonic probe including a plurality of elements that transmit ultrasonic waves to a subject and receive ultrasonic waves reflected by the subject and output ultrasonic detection signals;
A transmission / reception unit configured to supply a plurality of drive signals for driving the plurality of elements to the plurality of elements and generate reception data based on the ultrasonic detection signals output from the plurality of elements; A transmission / reception unit that forms an ultrasonic beam by adjusting a delay amount of the plurality of drive signals supplied to the element;
A region of interest setting unit for setting a region of interest in the subject;
A first transmission / reception control unit that controls the transmission / reception unit to cause the plurality of elements to perform transmission / reception of ultrasonic waves for obtaining information of a moving body in the region of interest;
The reception generated by the transmission / reception unit based on the ultrasonic detection signal of the ultrasonic wave reflected and reflected by Doppler shift by the mobile body when transmission / reception of ultrasonic waves for obtaining information of the mobile body is performed A moving body region discriminating unit that extracts a Doppler signal accompanying the movement of the moving body from the data and discriminates a moving body region including the moving body in the region of interest based on the extraction result;
Based on the determination result of the mobile body region determination unit, a sound speed measurement region determination unit that determines a region excluding the mobile body region from the region of interest as a sound speed measurement region for measuring the distribution of sound speed;
By setting a plurality of transmission focal points of the ultrasonic beam in the sound velocity measurement region and causing the transmission / reception unit to transmit / receive the ultrasonic beam to / from each transmission focal point, reception data for sound velocity measurement in the sound velocity measurement region A second transmission / reception control unit for generating the transmission / reception unit;
A sound speed map generating unit that generates a sound speed map indicating a sound speed distribution in the sound speed measurement region based on the received data for sound speed measurement;
An ultrasonic diagnostic apparatus comprising: A third transmission / reception control unit for controlling the transmission / reception unit to cause the plurality of elements to perform transmission / reception of ultrasonic waves for obtaining tomographic image information in the subject;
An image generation unit that generates a B-mode image based on the reception data generated by the transmission / reception unit when ultrasonic transmission / reception for obtaining the tomographic image information is performed;
A display unit for displaying the B-mode image,
The ultrasound diagnostic apparatus according to claim 1, wherein the region of interest setting unit sets the region of interest on the B-mode image.   Control of the transmission / reception unit by the first transmission / reception control unit, determination of the mobile body region by the mobile body region determination unit, determination of the sound speed measurement region by the sound speed measurement region determination unit, and second transmission / reception The ultrasonic diagnostic apparatus according to claim 2, further comprising: an update control unit configured to execute a sound speed map update process including control of the transmission / reception unit by a control unit and generation of the sound speed map by the sound speed map generation unit.   The ultrasonic diagnostic apparatus according to claim 3, wherein the update control unit causes the sound velocity map update process to be executed every time the B-mode image having a predetermined number of frames is generated by the image generation unit. The moving body includes blood flowing through blood vessels in the region of interest,
The mobile body region determination unit generates blood flow information indicating the blood flow in the region of interest based on the extraction result of the Doppler signal, and determines the mobile body region based on the blood flow information. The ultrasonic diagnostic apparatus of any one of Claim 1 to 4. The moving body includes a tissue that moves in the region of interest,
The moving body region determination unit generates tissue movement information indicating movement of the tissue within the region of interest based on the extraction result of the Doppler signal, and determines the moving body region based on the tissue movement information. The ultrasonic diagnostic apparatus of any one of Claim 1 to 5.   The mobile body region determination unit extracts the Doppler signal corresponding to a tissue in which the magnitude of movement in the tissue is equal to or greater than a predetermined threshold from the reception data generated by the transmission / reception unit, The ultrasonic diagnostic apparatus according to claim 6, wherein the tissue movement information is generated based on the Doppler signal.   The ultrasonic diagnostic apparatus according to claim 2, wherein the display unit superimposes and displays the sound velocity map on the B-mode image.

Images