JP2016097256A - Ultrasonic image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select a suitable frame set used for measurement from a frame array without a particular burden on an inspector.SOLUTION: A frame array analysis part 32 acquires cardiac cycle information indicating the cardiac cycle of the heart on the basis of brightness information of each frame included in the frame array acquired from the unborn child's heart being a measurement object tissue. A frame specification part 34 specifies frame sets consisting of a telediastolic frame and an end-systolic frame from the frame array on the basis of the cardiac cycle information. A display processing part 22 displays the specified frame sets side by side on a display part 24. When the frame set displayed first is not appropriate for measurement, the display processing part 22 performs switching display of the frame sets by a cardiac cycle unit in accordance with the user's operation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic image processing apparatus, and more particularly to display processing of a frame sequence acquired by transmission / reception of ultrasonic waves.

  An ultrasonic diagnostic apparatus is an apparatus that transmits and receives ultrasonic waves to and from a subject and forms an ultrasonic image based on data obtained thereby. For example, in the B mode, a frame data string is acquired by transmitting / receiving ultrasonic waves to / from the target tissue. The acquired frame data sequence is temporarily stored in an image memory (cine memory) and processed by a scan converter or the like to be displayed in real time as a B-mode moving image. When a freeze operation is performed by the user due to the need for measurement, printing, etc., real-time display of the moving image is stopped, and the image displayed at the time of the freeze operation is displayed as a still image. Thereafter, the frame data sequence stored in the image memory is reproduced as necessary. When the store operation is performed by the user, the frame data string temporarily stored in the image memory or specific frame data is stored in the nonvolatile storage device. In this specification, the term “frame” is a simplified expression of frame data, and the concept includes frame data obtained by electronic scanning of an ultrasonic beam and after processing by a scan converter. Frame data.

  Ultrasonic images are used for various measurements. The measurement is performed using a still image displayed by a freeze operation or a still image or a moving image obtained by reproducing a frame sequence stored in a cine memory. Measurement may be performed in the information processing apparatus that has received the frame sequence from the ultrasonic diagnostic apparatus. The types of measurement include distance measurement in which a distance between two predetermined points on the B-mode image is measured, and a distance between the two predetermined points in the target tissue is calculated from the measured value, and a predetermined range on the B-mode image There is an area measurement for measuring the cross-sectional area of the target tissue from the area.

  For example, when measuring a tissue that moves periodically, such as the heart, measurement may be performed at a plurality of time phases within the movement cycle, and changes in a plurality of obtained measurement results may be observed. For example, the measurement called FS measurement is to measure the shortening rate (FS value) of the left ventricular diameter of the heart, and calculates the left ventricular diameter at the end diastole of the heart and the left ventricle diameter at the end systole of the heart, The FS value is calculated based on these measurement results.

  In the measurement as described above, a frame set composed of an end-diastolic frame and an end-systolic frame within the same heartbeat is specified, and these are simultaneously displayed on the screen. That is, a frame sequence is acquired by transmitting / receiving ultrasonic waves to the target tissue in advance over one or more motion cycles, and used for measurement from the acquired frame sequence at a plurality of predetermined time phases within the same heartbeat. In general, a plurality of corresponding frames (frame sets) are selected afterwards.

  For example, in the above-described FS measurement, it is necessary to measure the left ventricular diameter at the end diastole and end systole of the heartbeat cycle. That is, the frame acquired at the end diastole and the frame acquired at the end systole must be appropriately selected from the frame sequence.

  Conventionally, selection of a frame set used for measurement has been manually performed by a user such as a doctor. For example, in the FS measurement, a frame obtained by the user visually at the end diastole while displaying a frame sequence obtained one by one with a plurality of heartbeats transmitted and received with respect to the heart of the subject. And selected frames acquired at end systole.

  The selection method based on visual judgment as described above can point out the problem that the burden on the inspector is large and takes time. It can also be pointed out that such a selection method depends on the subjectivity of the user. That is, it can be pointed out that even if the frame sequence is the same, a different frame set is selected depending on the user.

  An object of the present invention is to select a suitable frame set to be used for measurement from a frame sequence without requiring a special burden on an inspector.

The ultrasonic image processing apparatus according to the present invention acquires period information indicating a motion period of the target tissue by analyzing a frame sequence obtained by transmitting and receiving ultrasonic waves to the target tissue that periodically moves. A period information acquisition means for performing a first time phase frame corresponding to a first time phase in the motion cycle and a second time phase in the motion cycle from the frame sequence based on the cycle information. Frame set specifying means for specifying a frame set including a second temporal phase frame;
Display control means for displaying the frame sets side by side on a display unit.

  According to the above configuration, the period information is acquired by analyzing the acquired frame sequence by the period information acquisition unit. Since the target tissue moves periodically, a periodic change corresponding to the motion cycle of the target tissue also appears in a frame sequence obtained by transmitting and receiving ultrasonic waves to and from the target tissue. For example, since the luminance information of each frame included in the frame sequence (for example, the average luminance of a specific region in the frame) changes according to the motion of the target tissue, the period information acquisition unit is based on the change in the luminance. Period information can be acquired. The period information acquisition method is particularly effective when period information of a target tissue cannot be directly acquired, for example, by performing FS measurement on a fetal heart for which an electrocardiograph cannot be used.

  A frame set comprising a plurality of frames corresponding to a plurality of specific time phases is selected from the frame sequence by the frame set specifying means and displayed by the display control means. That is, according to the measurement to be performed, a plurality of frames having a predetermined time phase relationship that are measurement target candidates are displayed simultaneously. Therefore, since individual observation or contrast observation can be performed and the quality of the contents can be collectively evaluated in units of sets, the evaluation can be performed accurately, and the time until the measurement target is specified can be determined. Can be shortened. The user does not need to visually check each frame included in the frame sequence in order to select a measurement frame set. That is, the user can more easily select a measurement frame set from the frame sequence. According to the above configuration, since the measurement target candidates are automatically associated (pairing and grouping) according to the measurement to be performed, the burden on the user is greatly reduced and the measurement efficiency can be increased. .

  Preferably, the display control means first displays a frame set corresponding to the most recent motion cycle in the past from the measurement start operation time point using the frame sequence. In general, a user visually observes a moving image displayed in real time during acquisition of a frame sequence and starts measurement by performing a freeze operation at the moment when an image suitable for measurement is taken. That is, there is a high possibility that a frame set corresponding to the most recent motion cycle from the measurement start operation time point is appropriate as a frame set used for measurement. Therefore, by first displaying the frame set corresponding to the most recent motion cycle from the measurement start operation time point, it is possible to preferentially display a frame set that is more likely to be suitable for measurement. Thereby, the effort or time concerning selection of the measurement frame set by the user can be further reduced.

  Preferably, the display control means switches and displays a plurality of frame sets corresponding to a plurality of motion cycles in accordance with a user instruction. When the user determines that the initially displayed frame set is not appropriate as the measurement frame set, the user needs to select another frame set. At this time, the candidate is a frame set corresponding to a motion cycle other than the motion cycle corresponding to the currently displayed frame set. Therefore, the display control unit switches and displays a plurality of frame sets corresponding to each motion cycle in accordance with a user operation. That is, only a plurality of measurement target candidates are sequentially displayed by jumping a plurality of frames not used for measurement. Accordingly, when the frame set displayed first is a frame set that is not suitable for measurement and when another frame set is selected, the user's trouble in selecting the frame set for the next measurement candidate or Time can be further reduced.

  Preferably, the target tissue is a fetal heart, and the motion cycle is a cardiac cycle. Desirably, the first time phase is an end diastole in the heartbeat cycle, and the second time phase is an end systole in the heartbeat cycle.

  According to the present invention, a suitable frame set to be used for measurement can be selected from the frame sequence without requiring a special burden on the inspector.

1 is a schematic configuration diagram of an ultrasonic diagnostic apparatus according to the present embodiment. It is the B mode image of the heart acquired in the end diastole and the end systole. It is a graph which shows the luminance change of each frame contained in a frame sequence. It is a conceptual diagram which shows a mode that a frame set is selected based on a heartbeat period waveform. It is a figure which shows a mode that a frame set is displayed. It is a figure which shows the result of having implemented FS measurement using the displayed frame set. It is a flowchart which shows the flow of operation | movement of the ultrasonic diagnosing device which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described. In the present embodiment, a tomographic image (B-mode image) of a fetal heart that is a measurement target tissue is formed in the ultrasonic diagnostic apparatus 10, and FS measurement is performed using this.

  FIG. 1 is a schematic configuration diagram of an ultrasonic diagnostic apparatus 10 as an ultrasonic image processing apparatus according to the present embodiment. The ultrasonic diagnostic apparatus 10 is a medical device generally installed in a medical institution such as a hospital.

  The probe 12 is an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject. The probe 12 has a transducer array composed of a plurality of transducers. A plurality of transmission signals from the transmission unit 14 are supplied to the plurality of transducers. Thereby, an ultrasonic beam is formed. The plurality of vibration elements constituting the transducer array receive the reflected echo from the transmission / reception region, and thereby a plurality of reception signals are output to the receiving unit 16. In this embodiment, the probe 12 is brought into contact with the mother's abdomen, and ultrasonic waves are transmitted to and received from the fetal heart via the mother's abdominal wall.

  The transmission unit 14 transmits a plurality of transmission signals for exciting them to a plurality of transducers included in the probe 12 in accordance with control from the control unit 26. When the freeze operation is performed by the user at the input unit 30, the transmission unit 14 temporarily stops the supply of the transmission signal to the probe 12. When the freeze release operation is performed by the user, the transmission signal is supplied again.

  The receiving unit 16 forms beam data by phasing and adding a plurality of reception signals output from the plurality of transducers of the probe 12. Along with electronic scanning of the ultrasonic beam, a plurality of beam data are sequentially output. A plurality of beam data for one frame is obtained per electronic scan. Each beam data is composed of a plurality of reflected echo signals arranged in the depth direction. A reception frame sequence is generated by repeatedly performing the electronic scanning.

  The image forming unit 18 is, for example, a digital scan converter (DSC), and converts the received frame sequence from the receiving unit 16 into a display frame sequence. Specifically, the image forming unit 18 has a coordinate conversion function, an interpolation processing function, and the like. In the present embodiment, the image forming unit 18 forms a display frame sequence that is displayed on the display unit 24 as a B-mode image. Note that when an image memory 20 described later is provided in the preceding stage of the image forming unit 18, the image forming unit 18 may convert the received frame sequence stored in the image memory into a display frame sequence.

  The volatile image memory 20 provided in the front stage or the rear stage of the image forming unit 18 temporarily stores the received frame sequence output from the receiving unit 16 or the display frame sequence processed by the image forming unit 18. The image memory 20 has a ring buffer structure, for example, and stores each frame input in time series order. That is, the image memory 20 stores a frame sequence acquired from the present time in a past fixed period. When a store operation is performed by the user in the input unit 30, the frame sequence stored in the image memory 20 is transferred to a non-volatile image storage unit (not shown). In the present embodiment, the image memory 20 is provided in the subsequent stage of the image forming unit 18, and a display frame sequence processed by the image forming unit 18 is stored in the image memory.

  The display processing unit 22 processes the display frame sequence formed by the image forming unit 18 and causes the display unit 24 to display a B-mode image as an ultrasonic image. In addition, the display unit 24 displays a plurality of B-mode images corresponding to the frame set specified by the frame specifying unit 34 described later. Further, measurement result information (for example, measurement value data and graph data) output from the measurement unit 36 described later is processed, and the measurement value and graph are displayed on the display unit 24. An ultrasonic image and a measurement result may be combined and displayed. The display unit 24 is configured by a liquid crystal display, for example.

  The control unit 26 can be realized by, for example, cooperation with hardware such as a CPU or a microprocessor, or software (program) that defines the operation of the CPU or the microprocessor. The control unit 26 controls each component of the ultrasonic diagnostic apparatus 10.

  The storage unit 28 is non-volatile and includes, for example, a hard disk, a ROM, or a RAM. The storage unit 28 stores a program for operating each component of the ultrasonic diagnostic apparatus 10. Further, the storage unit 28 may store a measurement result of the measurement unit 36 to be described later.

  The input unit 30 includes buttons, switches, a dial type knob, a trackball, and the like, and is used for inputting user instructions to the control unit 26. The user can perform various operations such as a freeze operation, a freeze release operation, a store operation, a measurement start operation, or a measurement point input operation using the input unit 30.

  Next, a configuration that functions for measurement will be described. The measurement is performed in a frozen state after the real-time operation. In the illustrated configuration example, the frame sequence analysis unit 32 analyzes the frame sequence stored in the storage unit 28. Thereby, the period information which shows the movement period of the object tissue which moves periodically is acquired. That is, the frame sequence analysis unit 32 has a function as period information acquisition means. In this embodiment, since the target tissue is a fetal heart, the frame sequence analysis unit 32 acquires fetal heartbeat cycle information as cycle information.

  Specifically, the frame sequence analysis unit 32 calculates heartbeat cycle information based on a change in luminance information (luminance value) of each frame included in the frame sequence, which occurs according to the pulsation of the heart of the fetus that is the target tissue. get. As the luminance information, the sum or average of the luminance values of each pixel included in each frame can be used. Since the luminance information obtained from each frame has periodicity according to the heartbeat of the fetus, the heartbeat cycle information of the fetus can be obtained based on this. Further, in order to acquire heartbeat cycle information with high accuracy, a luminance value in a predetermined region in the frame may be used as luminance information. Details of the processing of the frame sequence analysis unit 32 will be described later with reference to FIGS.

  Note that the period information acquisition method is not limited to a technique of analyzing a change in luminance value of each frame. For example, a technique may be used in which a target tissue contour extraction process is performed on each frame included in the frame sequence, and period information is acquired based on the shape or size of the extracted contour. In addition, when the measurement target is an adult heart, the heart rate information may be directly acquired by an electrocardiograph.

  The frame specifying unit 34, based on the heartbeat period information acquired by the frame sequence analysis unit 32, from among a plurality of frames constituting the frame sequence, a plurality of frames acquired at a plurality of time phases in the heartbeat cycle of the target tissue. (Frameset) is specified. That is, the frame specifying unit 34 has a function as a frame set specifying unit. Each frame included in the frame set is selected from within the same cardiac cycle. Specifically, a plurality of frames satisfying the required temporal relationship are specified as a frame set according to the measurement contents.

  The specific time phase is a time phase at which a frame necessary for measurement is acquired. Therefore, the specific time phase varies depending on the measurement contents. Which phase of the frame the frame specifying unit 34 specifies may be specified in advance by the user or may be automatically determined according to the measurement content. In the present embodiment, in order to perform FS measurement, the frame specifying unit 34 specifies a frame set including a frame acquired at the end diastole and a frame acquired at the end systole in the heartbeat cycle. Alternatively, in addition to this, a frame in another time phase (for example, a frame acquired at an intermediate point between end diastole and end systole) may be included in the frame set. Details of the processing of the frame specifying unit 34 will be described later with reference to FIG.

  The measurement unit 36 performs various measurements on the ultrasonic image displayed on the display unit 24 by the display processing unit 22. Measurements that can be performed by the measurement unit 36 include distance measurement that measures the distance between two predetermined points of the target tissue, area measurement that measures the area of a predetermined region of the target tissue, and the like. The measurement position (measurement point) on the ultrasonic image is designated by the user. The measuring unit 36 performs these measurements on the frame set specified by the frame specifying unit 34 to obtain a plurality of measurement values. Then, a value for evaluating the motor function of the target tissue is calculated based on the plurality of measurement values. For example, in addition to the FS measurement described above, an EF (Ejection Fraction) value, which is an index of the left ventricular contraction function, is calculated based on the left ventricular volume at the end diastole and the left ventricular volume at the end systole. The In the calculation of the EF value, the left ventricular area is measured by the above-described area measurement in the frames acquired at the end diastole and the end systole, and the respective left ventricular volumes are calculated based on the area. In addition, TAPSE (Tricuspid Annular Plane Systolic Excursion) measurement for measuring the moving distance of the tricuspid annulus on the right ventricular free wall side can be performed. In TAPSE measurement, a target distance is measured based on the distance between the position of the tricuspid annulus in the frame acquired at the end diastole and the position of the tricuspid annulus in the frame acquired at the end systole.

  Since the target tissue performs a periodic motion, the position of the target region of the target tissue is different in each frame in the frame sequence. The tracking processing unit 38 follows the site of interest that changes from frame to frame, and changes the position of the measurement point set on the site of interest for each frame (that is, maintains the position of the measurement point on the site of interest). Perform tracking processing. As a tracking method, for example, a known technique such as a pattern matching technique can be used.

  In the present embodiment, the ultrasonic diagnostic apparatus 10 is used as the ultrasonic image processing apparatus. However, as the ultrasonic image processing apparatus, a computer other than the ultrasonic diagnostic apparatus 10, for example, a personal computer (PC) may be used. Is possible. In this case, the computer receives the frame sequence formed by the ultrasonic diagnostic apparatus and performs the above processing.

  1, the transmitting unit 14, the receiving unit 16, the image forming unit 18, the display processing unit 22, the frame sequence analyzing unit 32, the frame specifying unit 34, and the measuring unit 36. Each unit of the tracking processing unit 38 can be realized by using hardware such as an electric / electronic circuit or a processor, and a device such as a memory may be used as necessary in the realization. In addition, functions corresponding to the above-described units may be realized by 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 details of the processing of the frame sequence analysis unit 32 will be described below with reference to FIG. 1 and FIG. 2 and FIG.

  FIG. 2 shows a B-mode image showing a four-chamber cross section of the fetal heart. 2A shows an end-diastolic image 50 formed from a frame acquired at the end diastole, and FIG. 2B shows an end-systolic image 56 formed from a frame acquired at the end systole. It is shown. In the following description, a B-mode image is used for the sake of simplicity, but the processing of the frame sequence analysis unit 32 is actually performed on the frame.

  As can be seen by comparing FIG. 2A and FIG. 2B, the cross section of the heart shown in the B-mode image is also expanded and contracted in accordance with the expansion and contraction of the heart. Specifically, in the end diastole image 50 of FIG. 2A, the heart cross section 52 is expanded to the maximum during the cardiac cycle, the heart wall is extended, and the area of each cavity is increased. On the other hand, in the end systole image 56 of FIG. 2B, the heart cross section 58 contracts to the maximum during the cardiac cycle, the heart wall contracts, and the area of each cavity is reduced. In the present embodiment, the heart wall portion (hatched portion in FIG. 2) is a high-luminance portion.

  As described above, the frame sequence analysis unit 32 acquires heartbeat period information based on the change in the luminance value of each frame. Although it is possible to acquire the heart cycle information based on the change of the luminance value of the entire region of one frame for each frame, in this embodiment, in order to acquire the heart cycle information with higher accuracy, each frame Is divided into a plurality of regions, a region where the luminance value change cycle is most stable among the regions is specified, and heartbeat cycle information is acquired based on the change of the luminance value acquired from the region for each frame.

  First, the frame sequence analysis unit 32 divides each frame included in the frame sequence into 16 regions (divided into 4 equal parts in length and width) (see FIG. 2). Then, for each of the 16 regions of one frame, the sum of luminance values of pixels included in the region (which may be an average value) is calculated. That is, 16 luminance values are calculated for one frame. Then, this process is performed for all frames included in the frame sequence. Thereby, 16 luminance value sequences (luminance value waveforms) corresponding to each region are formed.

  The frame sequence analysis unit 32 performs filter (low-pass filter) processing for noise removal on each formed luminance value waveform, and generates 16 post-filter waveforms. Furthermore, a secondary differential process is performed on each post-filter waveform to generate 16 secondary differential waveforms. FIG. 3 shows an example of the luminance value waveform 70, the filtered waveform 72, and the secondary differential waveform 74. In the example of FIG. 3, each waveform for one area divided into 16 areas is shown. In FIG. 3, the horizontal axis indicates frame numbers (numbers assigned in the order of acquisition to the frames constituting the frame sequence). In other words, the horizontal axis can be viewed as the time axis. The vertical axis represents the luminance value with the lower end being 0 for the luminance value waveform 70 and the filtered waveform 72, and the secondary differential value with the center being 0 for the secondary differential waveform 74.

  Hereinafter, the description will be given focusing on the processing for one region. The frame sequence analysis unit 32 generates a reference sine waveform based on the filtered waveform. Specifically, the period is first extracted from one post-filter waveform. Here, when the period of the filtered waveform is unstable, a large number of periods are extracted. Then, the average value (AvgHR) of the extracted periods is calculated. In the present embodiment, the average value for 1σ in the period obtained from the post-filter waveform is AvgHR (that is, calculated by excluding extreme values). A sine wave having the calculated AvgHR as a period is set as a reference sine waveform.

Then, the frame sequence analysis unit 32 calculates a correlation value between the reference sine waveform shape and the secondary differential waveform corresponding to the region. In calculating the correlation value, first, the cross-correlation waveform is calculated by the equation (1).
Here, g (x) is a second-order differential waveform, and FPS indicates a frame rate [Hz]. Further, x indicates a frame number, and y indicates a phase adjustment amount (how many frames the phase is shifted). N is the number of frames included in the frame sequence.

The cross-correlation waveform calculated by Expression (1) takes a maximum value when the phase of the reference sine waveform and the secondary differential waveform g (x) is the same phase, and the reference sine waveform and the secondary differential waveform g (x ) Is a periodic function having a minimum value when the phase is opposite to the phase. Therefore, the frame sequence analysis unit 32 calculates the effective value RMS of the cross-correlation waveform by Equation (2), and sets the calculated value as the correlation value.

  The large calculated correlation value means that the similarity between the reference sine waveform and the second-order differential waveform is high, which means that the period of the luminance value waveform in the region is stable. . Conversely, in a region where the period of the luminance value waveform is unstable, the similarity between the reference sine waveform and the secondary differential waveform is low, and the correlation value is calculated low.

  The frame sequence analysis unit 32 calculates correlation values for all 16 regions by the method described above. Then, the largest correlation value is specified from among the plurality of calculated correlation values. Then, the post-filter waveform or the second-order differential waveform in the region where the specified maximum correlation value is calculated is used as heartbeat cycle information (heartbeat cycle waveform). In the present embodiment, the correlation value calculated for the region 54 shown in FIG. 2 is the maximum, and the filtered waveform in the region 54 is used as the heartbeat cycle waveform. As can be seen from FIG. 2, in the region 54, the sum of the luminance values of the pixels in the region 54 is minimized at the end diastole, and the sum of the luminance values is maximized at the end systole. Therefore, the time when the maximum value is obtained in the heartbeat cycle waveform indicates the end systole, and the time when the minimum value is obtained indicates the end diastole.

  Hereinafter, the processing of the frame specifying unit 34 will be described with reference to FIG. FIG. 4 shows a heartbeat period waveform 80 acquired by the frame sequence analysis unit 32 and a corresponding frame sequence. The frame specifying unit 34 specifies a frame acquired at the end diastole (end diastole frame) and a frame acquired at the end systole (end systole frame) from the frame sequence based on the heartbeat cycle waveform. Specifically, the frame acquired when the heartbeat period waveform 80 becomes the minimum value is specified as the end diastole frame, and the frame acquired when the heartbeat period waveform 80 becomes the maximum value is specified as the end systole frame. . In the example of FIG. 4, end diastole frames 82a and 82c and end systole frames 82b and 82d are specified.

  A set of end diastole frames and end systole frames are defined as a frame set. Specifically, one end diastole frame and the first end systole frame acquired after the end diastole frame is acquired are defined as one frame set. In the example of FIG. 4, a frame set 84a composed of an end diastole frame 82a and an end systole frame 82b, and a frame set 84b composed of an end diastole frame 82c and an end systole frame 82d are defined.

  Hereinafter, the display mode and measurement of the frame set will be described with reference to FIGS. 5 and 6.

  As shown in FIG. 5, the display processing unit 22 arranges two B-mode images corresponding to the end-diastolic frame and end-systolic frame (frame set) selected from the acquired frame sequence on the display unit 24. indicate. This eliminates the need for the user to look at each frame row one by one and find a frame set obtained at a desired time phase. Further, the two B-mode images corresponding to the frame set are displayed side by side, so that the user can determine whether or not the image is suitable for measurement at a glance without requiring a display switching process.

  In addition, the display processing unit 22 first displays a frame set corresponding to the heartbeat cycle closest to the measurement start time or the freeze time among the plurality of frame sets specified by the frame specifying unit 34. Referring to FIG. 4, in this embodiment, the end-diastolic frame 82c, the end-systolic frame 82d, the end-diastolic frame 82a, and the end-systolic frame 82b are acquired in the order of time series. ) Measurement starts. Therefore, in this embodiment, two B-mode images corresponding to the frame set 84a corresponding to the heartbeat cycle immediately before the freeze operation are displayed first. Specifically, the B mode image 86a corresponding to the end diastole frame 82a and the B mode image 86b corresponding to the end systole frame 82b are displayed first (see FIG. 5).

  In general, a user visually observes a real-time moving image displayed on the display unit while acquiring a frame, and performs a freeze operation at the moment when an appropriate image is taken for use in measurement. Therefore, there is a high possibility that the frame set 84a is suitable as a frame set used for measurement. Therefore, displaying the frame set corresponding to the heartbeat period immediately before the freeze operation first means that the frame set that is likely to be appropriate as a measurement target is displayed first. As a result, the user can quickly select a frame set to be measured, and can reduce the trouble of switching the display of the frame set.

  There may be a case where the user determines that the frame set displayed first is not a frame set suitable for measurement. Therefore, the display processing unit 22 switches and displays frame sets corresponding to other heartbeat cycles in accordance with user operations. Specifically, for example, when the user rotates the dial type knob one graduation, the end diastole frame 82c and the end systole included in the frame set 84b (see FIG. 4) acquired in a heartbeat period different from the frame set 84a. Frames 82d are displayed side by side. Of course, when three or more frame sets are specified, the frame sets may be switched one after another according to a user operation. Thereby, when the frame set displayed first is not an appropriate frame set to be used for measurement, it is possible to reduce time and effort required for the user to search for another frame set.

FIG. 6 is a diagram illustrating a result of performing FS measurement. When the user selects a frame set to be used for FS measurement, FS measurement is performed using the frame set. The FS value is calculated by Expression (3).
Here, LVDd is the left ventricular diameter at the end diastole, and LVDs is the left ventricular diameter at the end systole. Therefore, for the FS measurement, the left chamber diameter is measured on each of the B mode image 86a corresponding to the end diastole frame 82a and the B mode image 86b corresponding to the end systole frame 82b.

  The user moves the cursor to be displayed on the B-mode image 86a and designates the start point 90a and the end point 90b of the left chamber diameter measurement. Then, the distance between the start point 90a and the end point 90b is measured by the measuring unit 36. The left interior diameter is calculated based on the distance on the B-mode image 86a and the display magnification of the B-mode image 86b. Similarly, the left chamber diameter is calculated on the B-mode image 86b, and the FS value is calculated based on the two left chamber diameters.

  The start point and end point of the left chamber inner diameter measurement on the two B-mode images may be manually specified by the user, but in the present embodiment, the tracking processing unit 38 is specified on one of the B-mode images. By performing tracking processing for each frame included in the frame sequence for each of the start point and end point, the start point and end point in the other B-mode image are automatically specified.

  For example, when the start point 90a and the end point 90b of the left chamber diameter measurement are designated by the user in the B-mode image 86a, the tracking processing unit 38 moves from the end diastole frame 82a toward the end systole frame 82b in the acquired frame sequence ( Refer to FIG. 4) Tracking is performed for each of the start point 90a and the end point 90b. Specifically, pattern matching processing is performed between the end diastole frame 82a and a frame acquired after the end diastole frame 82a (hereinafter referred to as “next frame”). By this processing, it is possible to grasp to which position the predetermined part in which the start point and end point of the end diastole frame 82 are designated has moved in the next frame. Then, a start point and an end point are designated at the position of the predetermined part in the next frame. By repeating this process up to the end systole frame 82b, the tracking processing unit 38 designates the positions of the start point 90a and the end point 90b in the end systole frame 82b.

  When the start point and the end point in one B-mode image are designated by the tracking process, it is necessary for the user to check whether the designated start point and end point are appropriate positions. Therefore, the display processing unit 22 displays each frame from the end diastole frame to the end systole frame as a moving image in the area where one of the two B-mode images is displayed. In the moving image, the positions of the start point and the end point in each frame designated by the tracking process are shown. Therefore, when the moving image is reproduced, it is possible to grasp how the positions of the start point and the end point change every moment. The user can easily confirm whether the tracking has been performed correctly by confirming the moving image.

  When the start point and end point of distance measurement are specified in the two B-mode images, the measurement unit 36 calculates the FS value. As shown in FIG. 6, the calculated FS value 94 is displayed on the display unit 24.

  Alternatively, tracking processing may be performed on the entire acquired frame sequence, a start point and an end point may be specified for each frame included in the frame sequence, and the left chamber diameter may be measured for each frame. Then, as shown in FIG. 6, the transition of the left chamber diameter in the frame sequence may be displayed on the display unit 24 as a transition graph 96. The horizontal axis of the transition graph 96 indicates the frame number (time), and the vertical axis indicates the left chamber diameter. It is also preferable to highlight the position in the transition graph 96 of the frame set currently displayed at the top of the screen. In FIG. 6, a part of the transition graph 96 is displayed with a thick line 96a, which indicates a frame set currently displayed. By displaying the transition graph 96, the user can easily grasp the transition of the left chamber diameter in the frame sequence.

  Hereinafter, the flow of processing of the present embodiment will be described using the flowchart shown in FIG. 7 with reference to FIG.

  In step S10, ultrasonic waves are transmitted / received from the probe 12 to the fetal heart to be measured for a certain period (over a plurality of heartbeats). Thereby, a frame sequence is acquired. When ultrasonic wave transmission / reception is performed for a certain period of time, the user performs a freeze operation and frame acquisition is stopped. The acquired frame sequence is stored in the image memory 20.

  In step S12, the frame sequence analysis unit 32 acquires heart cycle information indicating the heart cycle of the fetal heart based on the luminance value of each frame included in the acquired frame sequence.

  In step S14, the frame specifying unit 34 specifies the end diastole frame acquired in the end diastole and the end systole frame (frame set) acquired in the end systole from the frame sequence based on the cardiac cycle information in step S12. To do. Since the frame sequence is a frame acquired over a plurality of heartbeats, a plurality of frame sets are specified.

  In step S <b> 16, the display processing unit 22 causes the display unit 24 to display two B-mode images corresponding to the end diastole frame and the end systole frame included in the specified frame set. Here, the first frame set displayed is a frame set corresponding to the heartbeat cycle most recently from the measurement start operation (freeze operation).

  In step S <b> 18, the control unit 26 determines whether or not there is a frame set display switching instruction from the user. The instruction to switch the display of the frame set from the user means that the frame set displayed first is not appropriate as a measurement target. Therefore, in this case, in step S20, the display processing unit 22 displays another frame set. The processing in steps S18 and S20 is repeatedly executed until there is no display switching instruction from the user, that is, until the frame set used for measurement is determined.

  In step S22, the control unit 26 determines whether or not the start point and the end point of the left chamber diameter measurement are designated in one of the displayed frame sets, that is, two B-mode images.

  When the start point and the end point of distance measurement are designated in any one of the B-mode images, in step S24, the tracking processing unit 38 uses the one B-mode image (in this example, the B-mode image at the end diastole). Tracking is performed for the designated start point and end point, and the start point and end point of the left chamber diameter measurement are designated on the B-mode image at the end systole.

  In step S <b> 26, the display processing unit 22 performs loop reproduction of each frame from the end diastole frame to the end systole frame as a moving image. At this time, the start point and the end point of the left chamber diameter measurement designated for each frame from the end diastole frame to the end systole frame are displayed together by the tracking process.

  In step S28, the control unit 26 determines whether or not there is an FS value calculation execution instruction from the user. The absence of the instruction from the user means that the positions of the start point and end point specified by the tracking process are not appropriate, and therefore the start point and end point on the B-mode image at the end systole are corrected in step S30. The correction may be performed by the user, or tracking may be performed again by changing the conditions of the tracking process.

  When the FS value calculation execution instruction is given by the user, in step S32, the measurement unit 36 measures the left ventricular diameter on the B-mode images at the end diastole and the end systole, and calculates the FS value based thereon. The calculated FS value is displayed on the display unit 24 by the display processing unit 22.

  As described above, according to the present embodiment, a frame set to be used for measurement is selected from the frame sequence and displayed. For this reason, the user can select the frame set used for measurement from the frame sequence without taking extra time. Even if the frame set displayed first is not suitable for measurement, the frame sets that are measurement candidates are switched and displayed one after another, so that the user can easily select the measurement frame set. it can.

  In the above description, the embodiment of the present invention has been described using an example in which FS measurement is performed on a fetal heart, but the present invention is not limited to this embodiment. INDUSTRIAL APPLICABILITY The present invention is effective for an ultrasonic image processing apparatus that measures a target tissue that moves periodically and performs measurement using a plurality of frames of a specific time phase from the motion cycle of the target tissue. be able to.

  DESCRIPTION OF SYMBOLS 10 Ultrasonic diagnostic apparatus, 12 Probe, 14 Transmission part, 16 Reception part, 18 Image formation part, 20 Image memory, 22 Display processing part, 24 Display part, 26 Control part, 28 Storage part, 30 Input part, 32 Frame sequence Analysis unit, 34 frame identification unit, 36 measurement unit, 38 tracking processing unit.

Claims (6)

Periodic information acquisition means for acquiring periodic information indicating the motion period of the target tissue by analyzing a frame sequence obtained by transmitting and receiving ultrasonic waves to the target tissue that periodically moves;
Based on the period information, a first time phase frame corresponding to the first time phase in the motion cycle and a second time phase frame corresponding to the second time phase in the motion cycle are selected from the frame sequence. A frame set identifying means for identifying a frame set to include,
Display control means for displaying the frame sets side by side on a display unit;
An ultrasonic image processing apparatus comprising: The display control means first displays a frame set corresponding to the most recent motion cycle in the past from the start operation time point of the measurement using the frame sequence,
The ultrasonic image processing apparatus according to claim 1, wherein: The display control means is configured to switch and display a plurality of frame sets corresponding to a plurality of motion cycles according to a user instruction.
The ultrasonic image processing apparatus according to claim 2, wherein: The target tissue is a fetal heart;
The exercise cycle is a heartbeat cycle;
The ultrasonic image processing apparatus according to any one of claims 1 to 3, wherein The first time phase is the end diastole in the heartbeat cycle;
The second time phase is the end systole in the heartbeat cycle.
The ultrasonic image processing apparatus according to claim 4, wherein: Computer
Periodic information acquisition means for acquiring periodic information indicating the motion period of the target tissue by analyzing a frame sequence obtained by transmitting and receiving ultrasonic waves to the target tissue that periodically moves;
Based on the period information, a first time phase frame corresponding to the first time phase in the motion cycle and a second time phase frame corresponding to the second time phase in the motion cycle are selected from the frame sequence. A frame set identifying means for identifying a frame set to include,
Display control means for displaying the frame sets side by side on a display unit;
An ultrasonic image processing program which is made to function as: