JP2019050961A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

To provide a technology to select a mode of a frame correlation according to an extent of compression to a diagnostic site in acquiring elasticity information.SOLUTION: A displacement computing part 40 forms a displacement frame based on a present frame and a plurality of past frames. A compression determination part 50 determines an extent of compression to a diagnostic site using a displacement magnitude acquired from the displacement frame as an index, and determines a type of a compression procedure for the diagnostic site. A displacement frame selection part 60 selects a small number frame correlation or a large number frame correlation according to a result of the determination by the compression determination part 50, and selects a displacement frame acquired by the small number frame correlation or the large number frame correlation as a representative displacement frame. An elastic image formation part 70 forms an elastic image based on the selected representative displacement frame.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that obtains elasticity information.

  2. Description of the Related Art Ultrasonic diagnostic apparatuses that obtain tissue elasticity information are known. For example, there is known elastography that forms an elastic image of a tissue by compressing the tissue in the subject from the body surface of the subject and measuring the displacement of the tissue caused by the compression with ultrasound. In elastography, an elastic image is formed based on displacement information between a pair of frames composed of two temporally adjacent frames.

  For example, Patent Document 1 describes a technique for extracting an appropriate pair for displacement calculation from stored frame data in an ultrasonic diagnostic apparatus that forms an elastic image of a living tissue by elastography. Patent Document 2 describes a technique for generating an elastic image by selecting a frame interval based on information on a statistical feature amount of elastic frame data. Japanese Patent Application Laid-Open No. 2004-228561 describes a technique for adjusting a frame interval of frame data for displacement calculation and obtaining an appropriate elastic image.

JP 2010-119630 A Japanese Patent No. 5225158 Japanese Patent No. 5802790

  By the way, frame data used for forming an elastic image in elastography, for example, is susceptible to the influence of diagnostic conditions such as the compression state of the tissue in the subject and the properties of the tissue in the subject. Therefore, for example, in displacement calculation for obtaining elasticity information, it is desirable to select a frame correlation based on an appropriate frame according to a diagnosis situation.

  One of the objects of the present invention is to provide a technique for selecting a frame correlation mode in accordance with the degree of pressure applied to a diagnostic site in obtaining elasticity information.

  Another object of the present invention is to provide a technique for switching the number of displacement images or the number of pairs of RF frame data used when generating an elastic image in accordance with the type of compression technique for the diagnostic region. It is in.

  An ultrasonic diagnostic apparatus suitable as a specific example of the present invention includes an acquisition unit that acquires frame data based on data obtained from an area including a diagnostic part by transmitting and receiving ultrasonic waves, and a correlation calculation based on the frame data. Using the obtained calculation amount as an index, a determination unit that determines the degree of compression on the diagnosis site, and when it is determined that the degree of compression is small, a multi-frame correlation is selected, and when the degree of compression is determined to be large It comprises selection means for selecting a minority frame correlation, and forming means for forming an image relating to a diagnostic region based on the selected majority frame correlation or elasticity information obtained by the minority frame correlation.

  In the above configuration, the degree of compression (degree of compression) includes the size of compression (amplitude value of the intensity of compression), the magnitude of change per unit time of compression, and the like. The amount of calculation obtained by the correlation calculation is an amount of calculation that serves as an index for determining the degree of compression, and is preferably an amount of calculation that changes according to the degree of compression. For example, the amount of displacement, the amount of distortion, the correlation coefficient, and the like at the diagnostic site are included in preferred specific examples of the calculation amount. The majority frame correlation is a correlation calculation that uses more frames than the minority frame correlation. For example, a preferred specific example of the minority frame correlation is a set of frame correlations using the current frame and the immediately preceding frame, and a preferred specific example of the majority frame correlation uses the current frame and three past frames. Three sets of frame correlation. Note that a plurality of sets (for example, two or three sets) of frame correlations may be used as the minority frame correlation, and a plurality of sets (for example, four or five sets) of frame correlations may be used as the majority frame correlation. Good.

  According to the above configuration, in obtaining the elasticity information, it is possible to select a frame correlation mode according to the degree of pressure on the diagnostic region. For example, the minority frame correlation is selected when the degree of compression is relatively large. When the degree of compression is relatively large, the displacement of the tissue at the diagnosis site is large, and therefore, for example, the minority frame correlation that emphasizes the correlation between the current frame and the immediately preceding frame is selected. On the other hand, when the degree of compression is relatively small, multiple frame correlation is selected. When the degree of compression is relatively small, the displacement of the tissue at the diagnosis site is small. For example, the multi-frame correlation using the most reliable past frame is selected from the three past frames including the immediately preceding frame.

  For example, the forming means forms an elasticity image of a diagnostic region based on the selected elasticity information obtained by the multiple frame correlation or the minority frame correlation, and based on the elasticity information obtained by the minority frame correlation. It is desirable to form a strain graph of the diagnostic site.

  For example, the forming unit forms a strain graph of a diagnostic region based on the selected elasticity information obtained by the multiple frame correlation or the small frame correlation, and the multiple frame correlation or the small frame is formed on the strain graph. It is desirable to perform a display process that indicates a frame that is a correlation calculation target.

  For example, it is desirable that the determination means determine the degree of pressure on the diagnostic region using an amount of calculation obtained by correlation calculation between the frame data of the target frame and the frame data of the correlation frame as an index.

  For example, it is preferable that the ultrasonic diagnostic apparatus further includes means for determining an interval from the target frame to the correlation frame according to a frame rate.

  Further, another ultrasonic diagnostic apparatus suitable as a specific example of the present invention acquires RF frame data based on data obtained from a region including a diagnostic part by transmitting and receiving ultrasonic waves, and from the RF frame data, In the ultrasonic diagnostic apparatus that generates at least one displacement image and generates an elasticity image from the displacement image, the type of the compression technique for the diagnosis site is sequentially determined from the calculation result obtained by the correlation calculation based on the RF frame data. Depending on the result of the sequential determination, the number of displacement images used when generating an elastic image from the RF frame data is switched. When the number of displacement images is two or more, the two or more displacement images A displacement image satisfying the determination condition is identified from the images, and an elastic image is generated based on the identified displacement image.

  With the above configuration, the number of displacement images used when generating an elastic image can be switched according to the type of compression technique for the diagnostic region.

  In addition, another ultrasonic diagnostic apparatus suitable as a specific example of the present invention acquires RF frame data based on data obtained from a region including a diagnostic part by transmitting and receiving ultrasonic waves, and in the RF frame data In an ultrasonic diagnostic apparatus that generates a pair from two different temporally, generates at least one displacement image based on the pair, and generates an elastic image from the displacement image, the correlation based on the pair of RF frame data From the calculation result obtained by the calculation, the type of the compression technique for the diagnosis part is sequentially determined, and the number of pairs of the RF frame data used for generating the elastic image is switched according to the result of the sequential determination, and the RF frame data Of two or more displacement images obtained from the two or more pairs of RF frame data. Identify the determination condition is satisfied displacement image from, and generating an elastic image based on the identified displacement image.

  With the configuration described above, the number of pairs of RF frame data used when generating an elastic image can be switched according to the type of compression technique for the diagnostic region.

  For example, the compression technique includes a plurality of types having different degrees of compression, and it is desirable to determine the type of the compression technique based on the degree of compression evaluated based on the calculation result.

  For example, when the degree of compression is small, the ultrasonic diagnostic apparatus increases the number of displacement images or the number of pairs of RF frame data used when generating the elastic image than when the degree is high. Is desirable.

  For example, the compression technique includes a plurality of types having different changes in the size of the compression per unit time, and is based on the change in the size of the compression per unit time evaluated based on the calculation result. Thus, it is desirable to determine the type of the compression procedure.

  For example, when the change in the size of the compression per unit time is small, the number of displacement images or the number of pairs of RF frame data used when generating the elastic image is larger than when the change is large. Is desirable.

  For example, the compression technique preferably includes at least one of a NO Manual Compression technique, a Minimal Vibration technique, and a Significant Compression technique as a plurality of types of compression techniques.

  For example, when the number of displacement images or the number of pairs of RF frame data used when generating the elastic image is two or more, the ultrasonic diagnostic apparatus temporally updates the latest RF frame data one by one. When the displacement images are generated one after another based on a combination of retrospective RF frame data and the number of displacement images or the number of pairs of RF frame data used when generating the elastic image is one, It is desirable to generate the displacement image based on a pair of a combination of the latest RF frame data and RF frame data that is traced back one time.

  For example, the ultrasonic diagnostic apparatus can determine the type of the compression technique from the calculation result obtained by the correlation calculation based on the combination of the latest RF frame data and the RF frame data retroactive to one time. desirable.

  According to the present invention, there is provided a technique for selecting a frame correlation mode according to the degree of compression on a diagnosis site when obtaining elasticity information. Further, the present invention provides a technique for switching the number of displacement images or the number of pairs of RF frame data used when generating an elastic image according to the type of compression technique for the diagnostic region.

1 is a diagram illustrating an overall configuration of an ultrasonic diagnostic apparatus that is preferable in the practice of the present invention. It is a figure which shows the specific example of a process until an elastic image is formed. It is a figure which shows the specific example of a compression technique. It is a figure which shows the specific example of the elasticity diagnosis using the ultrasonic diagnosing device of FIG. It is a figure which shows the specific example of the elasticity diagnosis by multiple types of compression technique. It is a figure which shows the example of a display of a strain graph.

  FIG. 1 is a diagram showing an overall configuration of an ultrasonic diagnostic apparatus suitable for implementing the present invention. The probe 10 is an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject including a diagnosis target (diagnosis site). The probe 10 includes a plurality of vibration elements that transmit and receive ultrasonic waves, and transmission of the plurality of vibration elements is controlled by the transmission / reception unit 12 to form a transmission beam. Further, the plurality of vibration elements receive ultrasonic waves from within the region including the diagnosis target, and a signal obtained thereby is output to the transmission / reception unit 12, and the transmission / reception unit 12 forms a reception beam along the reception beam. Received signals (echo data) are collected. It should be noted that techniques such as transmission aperture synthesis may be used in transmission / reception of ultrasonic waves.

  The tomographic image forming unit 20 forms image data of an ultrasonic tomographic image based on the reception signal obtained from the transmission / reception unit 12. The tomographic image forming unit 20 performs signal processing such as gain correction, log compression, detection, contour enhancement, and filter processing on the received signal as necessary, for example, in a subject including a diagnostic region. Image data (tomographic image data) of a B-mode image in the cross section is formed. The tomographic image forming unit 20 forms tomographic image data of a plurality of frames (a plurality of time phases).

  The frame storage unit 30 stores frame data based on the received signal obtained from the transmission / reception unit 12. The frame storage unit 30 stores frame data of a plurality of frames (a plurality of time phases) corresponding to a plurality of time phases. For example, frame data corresponding to a tomographic image is stored in the frame storage unit 30 one after another over a plurality of time phases.

  The frame acquisition unit 32 acquires a target frame and a plurality of pair candidate frames to be subjected to displacement calculation from frame data of a plurality of frames corresponding to a plurality of time phases stored in the frame storage unit 30. For example, the frame acquisition unit 32 selects the current frame that is the latest frame as the target frame, and selects a plurality of past frames as a plurality of pair candidate frames.

  The displacement calculation unit 40 obtains a displacement frame for each pair candidate frame by a displacement calculation based on the target frame and each pair candidate frame. The displacement calculation unit 40 performs, for example, a one-dimensional or two-dimensional correlation calculation process on two frames (two frame data) configured by a pair of the current frame and each past frame, thereby performing intraframe (frame For each measurement point in the tomographic image, a displacement vector indicating the displacement of the tissue at the measurement point, that is, a one-dimensional or two-dimensional displacement vector related to the direction and magnitude of the displacement is derived, A displacement frame indicating a distribution of displacement vectors at a plurality of measurement points in the inside (in the tomographic image) is formed. In deriving the displacement vector, for example, a block matching method or a phase gradient method is used.

  In the block matching method, a frame, that is, a tomographic image, is divided into a plurality of blocks by blocks each consisting of several pixels in the vertical direction and several pixels in the horizontal direction, and each block is divided into blocks in one frame. The most similar block is searched in the other frame. Thereby, the displacement between time phases (between two frames) is calculated for each measurement point (each block) in each frame, and for example, a two-dimensional displacement vector is obtained. Note that a displacement vector at each measurement point may be obtained by referring to search results of a plurality of blocks and performing a process such as predictive encoding, that is, a process of determining a sample value based on a difference.

  In the phase gradient method, the phase information of the wave of the received signal is obtained from the received signal constituting each frame, and the amount of movement of the wave of the received signal is calculated from the change of the phase information between time phases (between two frames). By calculating and deriving the displacement of each measurement point in the frame, for example, a one-dimensional displacement vector in the reception beam direction (depth direction) or a two-dimensional displacement vector in the frame may be obtained.

  The displacement vector may be derived over the entire frame or may be derived only within the region of interest set in the frame. The region of interest is set according to an operation from a user such as a doctor or a laboratory technician.

  The displacement calculation unit 40 forms a displacement frame based on the current frame and each past frame. Each time the current frame is selected, the displacement calculator 40 forms a plurality of displacement frames corresponding to a plurality of past frames paired with the current frame. For example, the displacement calculation unit 40 may form a plurality of displacement frames based on the RF frame data before the detection process, or may form a plurality of displacement frames based on the frame data after the detection process. Good.

  The compression determination unit 50 determines the degree of compression or the like on the diagnosis site, using the calculation amount obtained by the correlation calculation based on the frame data as an index. The compression determination unit 50 determines, for example, the degree of compression with respect to the diagnosis region by using the amount of displacement obtained from the displacement frame formed in the displacement calculation unit 40 by correlation calculation based on the frame data as an index, and performs the compression procedure for the diagnosis region. Determine the type.

  The displacement frame selection unit 60 selects a representative displacement frame according to the determination result in the compression determination unit 50. The displacement frame selection unit 60 selects, for example, one set of frame correlations or three sets of frame correlations according to the determination result in the compression determination unit 50, and is obtained by one set of frame correlations or three sets of frame correlations. A representative displacement frame is selected from the displacement frames.

  The elastic image forming unit 70 forms an elastic image for each time phase over a plurality of time phases based on the representative displacement frames of a plurality of time phases selected one after another by the displacement frame selecting unit 60. For example, based on the displacement vector at each measurement point in the representative displacement frame, the elasticity image forming unit 70 calculates elasticity information such as tissue strain and elastic modulus for each measurement point for a plurality of measurement points. Then, the elastic image forming unit 70 forms image data of an elastic image that visually indicates elasticity information obtained based on the representative displacement frame.

  The elastic image can be formed by a known technique. The elastic image forming unit 70 forms, for example, elastic image data (elastic image frame data) indicating elastic values (tissue strain and elastic modulus) of each measurement point in the region of interest set in the frame. In the elasticity image data, hue information corresponding to the elasticity value at the measurement point is given to each measurement point, and red (R) which is the three primary colors of light for each measurement point based on the elasticity image data. Elastic images with green (G) and blue (B) are formed. For example, in each frame, a tissue part having an average hardness is expressed by a color based on green (G), and a relatively hard tissue part is expressed by a color based on blue (B). A soft tissue portion is expressed in a color based on red (R).

  The strain graph forming unit 72 displays a strain graph showing elasticity information obtained for each time phase over a plurality of time phases based on the representative displacement frames of a plurality of time phases selected one after another by the displacement frame selecting unit 60. Form. The strain graph can be formed by a known technique. The strain graph forming unit 72 forms, for example, a strain graph in which the horizontal axis represents the time axis and the vertical axis represents the strain (distortion).

  The display processing unit 80 is based on the tomographic image data obtained from the tomographic image forming unit 20, the elastic image data obtained from the elastic image forming unit 70, and the strain graph data obtained from the strain graph forming unit 72. A display image related to the diagnosis is formed. For example, the display processing unit 80 forms a display image in which a B-mode image based on tomographic image data and an elastic image based on elastic image data are arranged side by side. Further, the display processing unit 80 forms a display image including a strain graph. The display image formed in the display processing unit 80 is displayed on the display unit 82.

  The control unit 100 generally controls the inside of the ultrasonic diagnostic apparatus shown in FIG. The overall control by the control unit 100 also reflects an instruction received from a user such as a doctor or a laboratory technician via the operation device 90.

  Among the configurations shown in FIG. 1 (respectively marked parts), the transmission / reception unit 12, the tomographic image forming unit 20, the frame acquisition unit 32, the displacement calculation unit 40, the compression determination unit 50, the displacement frame selection unit 60, and elastic image formation Each unit of the unit 70, the strain graph forming unit 72, and the display processing unit 80 can be realized by using, for example, hardware such as an electric / electronic circuit or a processor, and a device such as a memory is used as necessary for the realization. May be. In addition, all or a part of the functions corresponding to the above-described units may be realized by cooperation of hardware such as a CPU, a processor, or a memory, and software (program) that defines the operation of the CPU or the processor.

  The frame storage unit 30 can be realized by a storage device such as a semiconductor memory or a hard disk drive. A preferable specific example of the display unit 82 is a liquid crystal display, an organic EL (electroluminescence) display, or the like, and the operation device 90 is, for example, at least one of a mouse, a keyboard, a trackball, a touch panel, and other switches. It can be realized by one. The control unit 100 can be realized by, for example, cooperation between hardware such as a CPU, a processor, and a memory, and software (program) that defines the operation of the CPU and the processor.

  The overall configuration of the ultrasonic diagnostic apparatus in FIG. 1 is as described above. Next, a specific example of a diagnostic function realized by the ultrasonic diagnostic apparatus will be described. In addition, about the structure (each part which attached | subjected the code | symbol) shown in FIG. 1, the code | symbol of FIG. 1 is utilized in the following description.

  FIG. 2 is a diagram illustrating a specific example of processing until an elastic image is formed. In FIG. 2, the frame sequence is a plurality of frames stored in the frame storage unit 30. FIG. 2 shows a plurality of frames corresponding to a plurality of time phases from time phase N−3 to time phase N + 2 as a specific example of the frame sequence.

  The frame acquisition unit 32 acquires a current frame and a plurality of past frames from a plurality of frames corresponding to a plurality of time phases stored in the frame storage unit 30. In the specific example shown in FIG. 2, a current frame N corresponding to time phase N and three past frames N corresponding to time phase N-1, time phase N-2, and time phase N-3 are selected from the frame sequence. -1, N-2, and N-3 are selected.

  The displacement calculation unit 40 forms a displacement frame based on the current frame N and the past frames N-1, N-2, and N-3. FIG. 2 shows a displacement frame N-1 obtained from the current frame N and the past frame N-1, a displacement frame N-2 obtained from the current frame N and the past frame N-2, a current frame N and a past frame N. The displacement frame N-3 resulting from -3 is shown.

  The compression determination unit 50 determines the degree of compression with respect to the diagnostic region by using the amount of displacement obtained from the displacement frame formed by the displacement calculation unit 40 as an index, and determines the type of compression technique for the diagnostic region.

  FIG. 3 is a diagram showing a specific example of the compression technique. In elastography, for example, a user such as a doctor or a laboratory technician presses the tissue in the subject from the body surface of the subject with the probe 10, and the displacement of the tissue caused by the compression is measured with ultrasound. In the diagnostic guidelines by elastography, for example, the following three types of compression techniques are proposed.

<Procedure A> NMC: NO Manual Compression
This is a technique in which the user does not perform spontaneous pressurization. A user such as a doctor or a laboratory technician does not perform positive pressurization simply by lightly touching the probe 10 against the body surface of the subject. Displacement that occurs in the diagnosis site due to movement (breathing or pulsation) is used. Of the three types of compression techniques, the degree of compression (the degree of compression) is the smallest, and is used, for example, for diagnosis near the body surface of the subject.

<Procedure B> SC: Significant Compression
This is a technique in which a user performs pressure with a certain degree of strength. Users such as doctors and laboratory technicians positively pressurize with a certain degree of strength by placing the probe 10 against the body surface of the subject. Of the three types of compression techniques, the degree of compression (the degree of compression) is the largest, and is used, for example, for deep diagnosis relatively far from the body surface of the subject.

<Procedure C> MV: Minimal Vibration
This is a technique of applying compression vibration with a medium strength, and the degree of compression (degree of compression) is medium among the three types of compression techniques.

  Returning to FIG. 2, the compression determination unit 50 determines the degree of compression with respect to the diagnosis region using the displacement amount obtained from the displacement frame N-1 as an index, and determines the type of compression technique for the diagnosis region. The displacement amount serving as an index is preferably an average value within the region of interest for elastic images, for example. Note that the amount of displacement at an arbitrary location within the region of interest for the elastic image may be used as an index.

  When the amount of displacement is large, for example, when the amount of displacement is equal to or greater than a threshold, the compression determination unit 50 determines that the degree of compression is large, and determines that the compression technique is SC (see FIG. 3). Further, when the amount of displacement is small, for example, when the amount of displacement is smaller than a threshold value, the compression determination unit 50 determines that the degree of compression is small and determines that the compression technique is NMC (see FIG. 3). In the specific example shown in FIG. 2, SC or NMC is determined as the type of the compression procedure. However, for example, any of the three types of SC, NMC, and MV (see FIG. 3) may be determined.

  Note that the compression determination unit 50 may determine the degree of compression with respect to the diagnosis site using the distortion or correlation coefficient obtained from the displacement frame N-1 as an index. For example, when the strain is greater than or equal to a threshold, the compression determination unit 50 determines that the degree of compression is large and the compression technique is SC, and when the distortion is less than the threshold, the degree of compression is small and the compression technique is NMC. You may determine that there is. Further, for example, when the correlation coefficient is equal to or less than the threshold, the compression determination unit 50 determines that the degree of compression is large and the compression technique is SC, and when the correlation coefficient is greater than the threshold, the degree of compression is It may be determined that the compression technique is a small NMC.

  The displacement frame selection unit 60 selects a representative displacement frame according to the determination result in the compression determination unit 50. The displacement frame selection unit 60 selects, for example, the minority frame correlation or the majority frame correlation according to the determination result in the compression determination unit 50, and selects the displacement frame obtained by the minority frame correlation or the majority frame correlation as the representative displacement frame. To do.

  For example, in the specific example shown in FIG. 2, when it is determined that the compression technique is SC, a set of frame correlations by a pair (one pair) of the current frame N and the past frame N-1 is selected, and the current frame is selected. The displacement frame N-1 obtained from N and the past frame N-1 is selected as the representative displacement frame N. Then, an elastic image N is formed from the displacement frame N-1.

  In addition, in the specific example shown in FIG. 2, when it is determined that the compression technique is NMC, three sets of frame correlations based on a pair (three pairs) of the current frame N and the three past frames N-1 to N-3. Is selected. In the three sets of frame correlations, the representative displacement frame N is selected from the three displacement frames N-1 to N-3. The displacement frame selection unit 60 selects the representative displacement frame N from among the three displacement frames N-1 to N-3, for example, according to the continuity determination condition.

  The displacement frame selection unit 60, for example, satisfies a matching condition between a statistical index value obtained from representative displacement frames of a plurality of time phases selected in the past and an index value obtained from each displacement frame by three sets of frame correlations. In this case, it is determined that the displacement frame satisfies the continuity determination condition. For example, the statistical index value of the displacement distribution or the elasticity information distribution related to the representative displacement frames of a plurality of time phases selected in the past and the index value of the displacement distribution or the elasticity information distribution of each displacement frame are matched (for example, two indices When the value difference satisfies the tolerance range), it is determined that the displacement frame satisfies the continuity determination condition.

  In the specific example shown in FIG. 2, when the compression procedure is determined to be NMC and three sets of frame correlations are selected, the displacement frame N-2 is selected as the representative displacement frame N and is the representative displacement frame N. An elastic image N is formed from the displacement frame N-2.

  In the specific example shown in FIG. 2, the amount of calculation (displacement amount, distortion, correlation coefficient) serving as an index for determining the degree of compression from the displacement frame N-1 based on the current frame N and the past frame N-1. ) That is, in the specific example illustrated in FIG. 2, the current frame N and the immediately preceding past frame N−1 are used in the determination of the degree of compression. For example, the interval from the current frame N to the past frame to be correlated is determined according to the frame rate, and the degree of compression (type of compression technique) is determined using the current frame N and the past frame. May be.

  FIG. 4 is a diagram (flow chart) showing a specific example of elasticity diagnosis using the ultrasonic diagnostic apparatus of FIG. First, a user such as a doctor or a laboratory technician operates the operation device 90, for example, sets the ultrasonic diagnostic apparatus to an elastography mode (elasticity diagnosis mode), and starts elastography (S1). For example, a user such as a doctor or a laboratory technician applies the probe 10 to the body surface of the subject, compresses the tissue in the subject body from the body surface of the subject, and measures the displacement of the tissue due to the compression. The

  When elastography is started and frame data of a plurality of frames corresponding to a plurality of time phases is stored in the frame storage unit 30, a plurality of frames corresponding to the plurality of time phases stored in the frame storage unit 30 are stored by the frame acquisition unit 32. From the frame, the current frame N and the past frames N-1, N-2, and N-3 that are the targets of the displacement calculation are acquired (S2).

  Subsequently, the displacement calculation unit 40 generates a displacement frame N-1 based on the current frame N and the past frame N-1 (S3). In step S3, the displacement calculation unit 40 calculates displacement frames N-1, N-2, and N-3 based on the current frame N and the past frames N-1, N-2, and N-3. May be generated.

  Then, the compression determination unit 50 determines the degree of compression with respect to the diagnosis region using the displacement amount obtained from the displacement frame N-1 as an index, and determines the type of compression technique for the diagnosis region (S4). In the specific example shown in FIG. 4, SC (see FIG. 3) or NMC (see FIG. 3) is determined as the type of the compression procedure.

  If it is determined that the type of the compression technique is NMC, three sets of frame correlations are selected, and the displacement calculation unit 40 based on the current frame N and the past frames N-1, N-2, N-3, Displacement frames N-1, N-2, and N-3 are generated (S5). Note that if the displacement frames N-1, N-2, and N-3 have already been generated in step S3, step S5 may be omitted. Then, the representative displacement frame N is selected from among the plurality of displacement frames N-1, N-2, N-3, for example, according to the continuity determination condition (S6).

  On the other hand, when it is determined that the type of the compression technique is SC, one set of frame correlation is selected, and the displacement frame N-1 based on the current frame N and the past frame N-1 is selected as the representative displacement frame N. (S7).

  Then, the elastic image forming unit 70 forms the elastic image N based on the representative displacement frame N, and the display image of the elastic image N formed by the display processing unit 80 is displayed on the display unit 82 (S8). The processes from S1 to S8 are repeated every time the current frame N is updated, and a plurality of time-phase elastic images N are displayed on the display unit 82.

  A user such as a doctor or a laboratory technician can perform an elasticity diagnosis in which a plurality of types of compression techniques are mixed by using the ultrasonic diagnostic apparatus of FIG.

  FIG. 5 is a diagram illustrating a specific example of the elasticity diagnosis using a plurality of types of compression procedures. FIG. 5 shows a specific example of a strain graph obtained in elasticity diagnosis using the ultrasonic diagnostic apparatus of FIG. In FIG. 5, the horizontal axis of the strain graph is the time axis, and the vertical axis indicates the strain (strain) ε.

  In the specific example shown in FIG. 5, the diagnosis period 1 is a period in which the magnitude (amplitude value) of the strain ε is relatively large and the degree of compression on the diagnosis region is relatively large. In the diagnosis using the ultrasonic diagnostic apparatus of FIG. 1, it is determined that the type of compression technique is SC (see FIG. 3) in the diagnosis period 1, and a set of frame correlations is selected. For example, in a breast diagnosis, a deep tumor is diagnosed by SC.

  In the specific example shown in FIG. 5, the diagnosis period 2 is a period in which the magnitude (amplitude value) of the strain ε is relatively small and the degree of compression on the diagnosis region is relatively small. In the diagnosis using the ultrasonic diagnostic apparatus of FIG. 1, it is determined that the type of compression technique is NMC (see FIG. 3) in the diagnosis period 2, and three sets of frame correlations are selected. For example, in breast diagnosis, a shallow tumor is diagnosed by NMC.

  In the specific example shown in FIG. 5, the diagnosis period 3 is a period in which the magnitude (amplitude value) of the strain ε is relatively large and the degree of pressure on the diagnosis region is relatively large. Similar to the diagnosis period 1, in the diagnosis period 3, it is determined that the type of compression technique is SC, and a set of frame correlations is selected.

  When the degree of compression is relatively large, the tissue displacement at the diagnostic site is large, so it is desirable that the interval between the two frames to be subjected to correlation calculation is not too wide. In the elastic diagnosis using the ultrasonic diagnostic apparatus of FIG. 1, in the case of a compression technique (for example, SC) in which the degree of compression on the diagnosis site is relatively large, a set of frame correlations is selected. The elastic image can be obtained by the correlation calculation with the past frame N-1.

  On the other hand, when the degree of compression is relatively small, the displacement of the tissue at the diagnosis site is small, and it is expected that a good calculation result can be obtained even if the interval between two frames to be subjected to correlation calculation is increased to some extent. The In the elasticity diagnosis using the ultrasonic diagnostic apparatus of FIG. 1, three sets of frame correlations are selected in the case of a compression technique (for example, NMC) in which the degree of compression on the diagnostic region is relatively small. For example, the current frame N and the past frame An elastic image is obtained by adopting the most reliable displacement frame from among the displacement frames N-1, N-2, N-3, which are the results of the correlation operation with N-1, N-2, N-3. Can do.

  As described above, the ultrasonic diagnostic apparatus of FIG. 1 selects the mode of frame correlation (one set of frame correlations or three sets of frame correlations) according to the degree of compression (type of compression technique) and is elastic. Form an image. On the other hand, in the formation of the strain graph, the same frame correlation as that of the elastic image may be selected according to the degree of compression (type of compression technique), or the same regardless of the degree of compression (type of compression technique). Frame correlation may be used.

  For example, the strain graph forming unit 72 may form a strain graph based on a displacement frame obtained by using a set of frame correlations regardless of the degree of compression (type of compression technique). Thus, for example, the current frame N and the past frame N-1 are subject to correlation calculation regardless of the degree of compression (the type of compression technique), so the past frames N-1 to N-3 are selectively used. Compared to the case, the temporal continuity of the strain graph is improved.

  Further, the strain graph forming unit 72 forms a strain graph based on a set of frame correlations selected according to the degree of compression (type of compression technique) or a displacement frame obtained by three sets of frame correlations. May be. In this case, since the displacement frame is obtained by selectively using any of the past frames N-1 to N-3 as the correlation calculation target of the current frame N, for example, the selected displacement frame (time phase) ) Should be clearly indicated on the strain graph.

  FIG. 6 is a diagram illustrating a display example of a strain graph. FIG. 6 shows a specific example of a strain graph clearly showing the selected displacement frame. For example, as in the specific example shown in FIG. 6, different display processes were performed in the period using the displacement frame N-1, the period using the displacement frame N-2, and the period using the displacement frame N-3. A strain graph is formed. For example, different display processes can be realized by changing at least one of the line type, color, brightness, and the like of the strain graph.

  The preferred embodiment of the present invention has been described above, but according to the above-described embodiment, the apparatus determines the degree of compression (type of compression technique) and selects an appropriate frame correlation. Even if a user such as an engineer does not perform an operation for selection, a highly accurate elastic image suitable for the degree of compression (type of compression technique) can be obtained. The above-described embodiments are merely examples in all respects, and do not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

  DESCRIPTION OF SYMBOLS 10 probe, 12 transmission / reception part, 20 tomographic image formation part, 30 frame memory | storage part, 32 frame acquisition part, 40 displacement calculation part, 50 compression determination part, 60 displacement frame selection part, 70 elastic image formation part, 80 display processing part, 82 display unit, 90 operation device, 100 control unit.

Claims (14)

Acquisition means for acquiring frame data based on data obtained from an area including a diagnostic site by transmitting and receiving ultrasonic waves;
A determination means for determining the degree of compression on the diagnosis site, using the calculation amount obtained by correlation calculation based on frame data as an index,
A selection means for selecting a majority frame correlation when it is determined that the degree of compression is small, and a selection means for selecting a minority frame correlation when it is determined that the degree of compression is large;
Forming means for forming an image relating to a diagnostic region based on elasticity information obtained by the selected multiple frame correlation or the small frame correlation;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The forming means includes
Forming an elasticity image of the diagnostic region based on the elasticity information obtained by the selected multiple frame correlation or the few frame correlation;
Forming a strain graph of the diagnostic site based on the elasticity information obtained by the minority frame correlation;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The forming means forms a strain graph of a diagnostic region based on the selected elasticity information obtained by the multiple frame correlation or the small frame correlation, and the multiple frame correlation or the small frame correlation is formed on the strain graph. Apply display processing to indicate the frame to be calculated,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The determination means determines the degree of compression with respect to the diagnostic region, using as an index the amount of calculation obtained by correlation calculation between the frame data of the target frame and the frame data of the correlation frame.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 4,
Means for determining an interval from the target frame to the correlation frame according to a frame rate;
An ultrasonic diagnostic apparatus. RF frame data is acquired based on data obtained from an area including a diagnostic site by sending and receiving ultrasound,
In the ultrasonic diagnostic apparatus that generates at least one displacement image from the RF frame data and generates an elastic image from the displacement image,
Displacement used to sequentially determine the type of compression technique for the diagnostic region from the calculation result obtained by the correlation calculation based on the RF frame data, and to generate an elastic image from the RF frame data according to the result of the sequential determination When the number of images is switched and the number of displacement images is two or more, a displacement image that satisfies the determination condition is identified from the two or more displacement images, and elasticity is determined based on the identified displacement image. Generate images,
An ultrasonic diagnostic apparatus. RF frame data is acquired based on data obtained from an area including a diagnostic site by sending and receiving ultrasound,
In the ultrasonic diagnostic apparatus that generates a pair from two temporally different RF frame data, generates at least one displacement image based on the pair, and generates an elastic image from the displacement image,
RF frame data used for sequentially determining the type of compression technique for the diagnostic region from the calculation result obtained by the correlation calculation based on the pair of RF frame data, and generating the elastic image according to the result of the sequential determination When the number of pairs of the RF frame data is two or more, the displacement satisfying the determination condition is selected from two or more displacement images obtained from the two or more pairs of the RF frame data. Identify an image and generate an elastic image based on the identified displacement image;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 6 or 7,
The compression technique includes a plurality of types with different degrees of compression,
Determining the type of the compression technique based on the degree of compression evaluated based on the calculation result;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 8,
When the degree of compression is small, the number of displacement images or the number of pairs of RF frame data used when generating the elastic image is larger than when the degree is large.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 6 or 7,
The compression procedure includes a plurality of types with different changes in size per unit time of compression,
Determining the type of the compression technique based on the change in the size of the compression per unit time evaluated based on the calculation result;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 10,
When the change in the size per unit time of the compression is small, the number of displacement images or the number of pairs of RF frame data used when generating the elastic image is larger than when the change is large.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 6 to 11,
The compression procedure includes at least one of a NO Manual Compression procedure, a Minimal Vibration procedure, and a Significant Compression procedure as a plurality of types of compression procedures.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 6 to 12,
When the number of displacement images or the number of pairs of RF frame data used when generating the elastic image is two or more, the latest RF frame data and the RF frame data retroactive in time are combined. Generate the displacement image one after another based on the pair,
When the number of displacement images or the number of pairs of RF frame data used when generating the elastic image is one, the pair is the combination of the latest RF frame data and the RF frame data that is traced back one time. Generating the displacement image based on,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 6 to 13,
The type of the compression technique is determined from the calculation result obtained by the correlation calculation based on the combination of the latest RF frame data and the RF frame data retroactive to one time.
An ultrasonic diagnostic apparatus.