JP2013198635A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide improved technology for obtaining information about a cycle from an ultrasonic image of an object which cyclically moves.SOLUTION: A reference image designating section 30 designates the tomographic image of a reference frame to be used as a reference of computation of the degree of similarity from among a plurality of frames of tomographic images sequentially acquired from an image forming section 20. A similarity computing section 40 computes the degree of similarity between the designated tomographic image of the reference frame and the tomographic image of each of the frames sequentially acquired from the image forming section 20. A similar image selecting section 50 selects a similar image similar to the tomographic image of the reference frame from among the tomographic images of the plurality of frames on the basis of the degree of similarity computed for each frame in the similarity computing section 40. A cycle information computing section 60 acquires the information about a cycle of heartbeat of a fetus on the basis of a time-phase interval between the tomographic image of the reference frame and the similar image.

Description

  The present invention relates to an ultrasonic diagnostic apparatus that obtains diagnostic information of an object that moves periodically.

  2. Description of the Related Art An ultrasonic diagnostic apparatus that obtains diagnostic information on a tissue such as a heart with periodic motion is known. In particular, it is extremely difficult for the fetal heart to directly measure a heart rate or the like using an electrocardiograph or the like, but information such as a heart rate can be obtained by using an ultrasonic diagnostic apparatus.

  For example, Patent Literature 1 discloses an ultrasonic diagnostic apparatus that sets a point of interest in a fetal heart in image data and measures a heartbeat cycle of the fetal heart from a displacement of the point of interest obtained by tracking processing between image data. Has been proposed. However, with this technique, the accuracy of measurement decreases unless a point of interest is set at a location that moves relatively greatly according to the heartbeat.

  It is also possible to obtain a waveform related to the heartbeat of the fetus using the ultrasonic M mode or Doppler mode, and to set the cursor or the like on the waveform to measure the heartbeat period or the like. However, since the measurement depends on the setting by the user, there is a concern that the measurement result varies from user to user.

JP 2010-233966 A

  In view of the background art described above, the inventor of the present application has repeatedly researched and developed a technique for obtaining diagnostic information from an ultrasonic image of an object that periodically moves.

  The present invention has been made in the course of its research and development, and an object thereof is to provide an improved technique for obtaining periodic information from an ultrasonic image of an object that periodically moves.

  An ultrasonic diagnostic apparatus suitable for the above-described object is a probe that transmits and receives ultrasonic waves to an object that periodically moves, and obtains an ultrasonic reception signal by scanning the ultrasonic waves by controlling the probe. A reference image is designated from among a plurality of time-phase ultrasonic images, a transmission / reception unit, an image forming unit that forms a plurality of time-phase ultrasonic images related to the object based on reception signals obtained over a plurality of time phases, and A reference image designating unit, a similarity calculation unit that calculates the similarity of the image between the reference image and the ultrasonic image obtained for each time phase, and a plurality of values based on the similarity obtained for each time phase Periodic information on the motion of the object is obtained based on a similar image selection unit that selects a similar image similar to the reference image from ultrasonic images in the time phase and a time phase interval between the reference image and the similar image. A periodic information calculation unit. The features.

  In the above configuration, a suitable example of an object that periodically moves is an in-vivo heart, and in particular, the ultrasonic diagnostic apparatus can be directly measured using an electrocardiograph or the like. Difficult fetal heart can be targeted. The ultrasonic image is preferably a two-dimensional B-mode image (tomographic image), for example, from the viewpoint of similarity calculation, but may be a color Doppler image or a three-dimensional image. In the similarity calculation, for example, a pattern matching process between images or a correlation value between images may be used.

  According to the said structure, the improvement technique for obtaining period information from the ultrasonic image of the target object which carries out a periodic motion is provided. For example, without forcing the user to perform complicated setting operations, it is possible to obtain period information such as heartbeats related to the heart of the fetus while reducing measurement variations among users.

  In a preferred embodiment, the similar image selection unit first selects a time phase ultrasonic image having a maximum similarity from a plurality of ultrasonic images obtained for each time phase after the reference image. The similar image is used.

  In a preferred embodiment, the reference image specifying unit specifies the selected similar image as a new reference image, and the similar image selecting unit is similar to the updated reference image every time the reference image is updated. An image is selected, and the period information calculation unit obtains the period information by statistically processing the time phase intervals obtained one after another when the reference image is updated.

  In a preferred embodiment, the reference image designating unit designates a plurality of reference images corresponding to mutually different time phases from among a plurality of time phase ultrasonic images, and the similarity calculating unit determines the reference image for each reference image. The image similarity between the reference image and the ultrasonic image of each time phase is calculated, and the similar image selection unit selects a similar image similar to the reference image for each reference image, and calculates the period information The unit is characterized in that the period information is obtained by statistically processing the time phase interval obtained from each of a plurality of reference images based on the time phase interval between each reference image and its similar image. To do.

  In a preferred embodiment, the probe transmits and receives ultrasonic waves to and from the fetal heart, and the image forming unit transmits ultrasonic waves of a plurality of time phases related to the fetal heart based on reception signals obtained over a plurality of time phases. An image is formed, and the period information calculation unit obtains period information of the fetal heartbeat as the period information.

  According to the present invention, an improved technique for obtaining periodic information from an ultrasonic image of an object that periodically moves is provided. For example, according to a preferred aspect of the present invention, it is possible to obtain periodic information such as heartbeats related to the heart of the fetus without forcing the user to perform complicated setting operations, thereby reducing variations in measurement for each user. Is possible.

1 is an overall configuration diagram of an ultrasonic diagnostic apparatus suitable for implementing the present invention. It is a figure for demonstrating the process after a reference | standard frame is designated until period information is obtained. It is a flowchart which shows the process in the ultrasonic diagnosing device of FIG.

  Hereinafter, preferred embodiments of the present invention will be described.

  FIG. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus (present ultrasonic diagnostic apparatus) suitable for implementing the present invention. The probe 10 transmits and receives ultrasonic waves in a region including an object. The probe 10 includes a plurality of vibration elements that transmit and receive ultrasonic waves, and the plurality of vibration elements are transmission-controlled by the transmission / reception unit 12 to form a transmission beam. Further, the plurality of vibration elements receive the ultrasonic waves reflected from the object, and signals obtained thereby are output to the transmission / reception unit 12, and the transmission / reception unit 12 forms a reception beam.

  The transmission / reception unit 12 outputs a transmission signal corresponding to each of the plurality of vibration elements included in the probe 10, thereby forming an ultrasonic transmission beam and scanning the transmission beam. Further, the transmission / reception unit 12 forms a reception beam corresponding to the transmission beam to be scanned by performing a phasing addition process or the like on the reception signal obtained from each of the plurality of vibration elements included in the probe 10, and receives the reception beam. Echo data (received signal) obtained along the beam is output.

  An object to be diagnosed by the ultrasonic diagnostic apparatus is a periodically moving tissue, for example, a fetal heart. Therefore, in the following, a case where the fetal heart, which is one of preferred examples, is used as an object will be described.

  The image forming unit 20 forms an ultrasonic image of a plurality of time phases related to the fetal heart based on echo data (received signal) obtained over a plurality of time phases. The image forming unit 20 forms, for example, a tomographic image (B-mode image) relating to the fetal heart over a plurality of frames for each frame (for each time phase). The tomographic images formed in the image forming unit 20 are output to the reference image designating unit 30 and the similarity calculating unit 40 one after another for each frame. The tomographic image formed in the image forming unit 20 is output and displayed on the display unit 70 such as a monitor.

  The reference image designating unit 30 designates a tomographic image of a reference frame serving as a reference for calculating similarity from among a plurality of frames of tomographic images obtained one after another from the image forming unit 20. The similarity calculation unit 40 calculates the image similarity between the tomographic image of the designated reference frame and the tomographic images of each frame obtained one after another from the image forming unit 20. The similar image selection unit 50 selects a similar image similar to the tomographic image of the reference frame from the tomographic images of a plurality of frames based on the similarity calculated for each frame in the similarity calculation unit 40. Then, the cycle information calculation unit 60 obtains the cycle information of the fetal heartbeat based on the time phase interval (frame interval) between the tomographic image of the reference frame and the similar image.

  Therefore, in the following, a process from when the reference frame is specified by the reference image specifying unit 30 until the period information is obtained by the period information calculating unit 60 will be described in detail. In the following description, the reference numerals shown in FIG. 1 are used.

  FIG. 2 is a diagram for explaining processing from when a reference frame is designated until period information is obtained.

  FIG. 2 (1) shows the processing related to the first reference frame, and the horizontal axis shows the frame number of the tomographic image obtained over a plurality of frames (multiple time phases), and the vertical axis shows Indicates the degree of similarity calculated for each frame.

  The reference image designating unit 30 first designates a tomographic image of the first reference frame from a plurality of frames of tomographic images obtained one after another from the image forming unit 20. For example, the first frame immediately after the tomographic image regarding the fetal heart is obtained is set as the first reference frame. Of course, the frame at the timing designated by the user may be the first reference frame. FIG. 2A shows an example in which the tomographic image of the frame F1 is designated as the first reference frame.

  When the first reference frame is designated, the similarity calculation unit 40 calculates the image similarity between the tomographic image of the first reference frame and the tomographic images of each frame obtained one after another from the image forming unit 20. To do. That is, the similarity between the frames F1 and F2, which are the first reference frames, the similarity between the frames F1 and F3, the similarity between the frames F1 and F4, and the similarity for each frame is calculated based on the frame F1. .

  The similarity is an index indicating how similar the contents of two images are to each other. The higher the similarity (the larger), the more similar the contents of the two images, and the lower the similarity. The contents of the two images are different from each other (smaller). In evaluating the similarity between images, various known methods can be used. For example, a pattern matching process between images or a correlation value between images may be used.

  The similar image selection unit 50 selects a similar image similar to the tomographic image of the first reference frame from the multiple frames of tomographic images based on the similarity calculated for each frame in the similarity calculation unit 40. . The similar image selection unit 50 first sets a tomographic image of a frame having the maximum similarity as a similar image among a plurality of tomographic images obtained for each frame successively after the first reference frame. For example, in the example shown in FIG. 2A, since the similarity of the frame F5 has the first maximum value, the tomographic image of the frame F5 is a similar image. For example, since the similarity between the frame F5 and the frame F6 is higher than the similarity between the frames F4 and F6 after the similarity up to the frame F6 is calculated, it is determined that the frame F5 has a maximum value, and the tomographic image of the frame F5 Are similar images.

  Then, the cycle information calculation unit 60 obtains the cycle information of the fetal heartbeat based on the time phase interval (frame interval) between the tomographic image of the reference frame and the similar image. The shape and the like of the fetal heart that moves according to the heartbeat cycle changes periodically according to the heartbeat cycle. For this reason, it is highly possible that the tomographic image and the similar image in the reference frame correspond to the same period in the heartbeat, and therefore the time phase interval between these images corresponds to one period of the heartbeat. . For example, in the example shown in FIG. 2A, the time between the frame F1 that is the first reference frame and the frame F5 that is a similar image, that is, the time for four frames is one cycle of the heartbeat. The time of one cycle may be used as the cycle information, and the heart rate per unit time may be calculated as the cycle information from the time of the one cycle.

  When a similar image is selected, the reference image designating unit 30 designates the selected similar image as a tomographic image of a new first reference frame. In the example shown in FIG. 2A, since the frame F5 is selected as the similar image, the tomographic image of the frame F5 is designated (updated) as a new first reference frame tomographic image.

  When a new first reference frame is designated, the similarity calculation unit 40 calculates the similarity based on the tomographic image of the new first reference frame. That is, the similarity between the frames F5 and F6, which are new first reference frames, the similarity between the frames F5 and F7, the similarity between the frames F5 and F8, and the similarity for each frame based on the frame F5. calculate.

  Furthermore, the similar image selection unit 50 selects a similar image similar to the tomographic image of the new first reference frame based on the similarity calculated for each frame. The similar image selection unit 50 first selects a tomographic image of a frame having the maximum similarity as a similar image from among a plurality of tomographic images obtained for each frame after the frame F5 which is the first reference frame. To do. In the example shown in FIG. 2A, since the similarity of the frame F10 is the first maximum value, the tomographic image of the frame F10 is a similar image.

  Then, the cycle information calculation unit 60 further obtains fetal heartbeat cycle information based on the time phase interval (frame interval) between the tomographic image and the similar image of the new reference frame. In the example shown in FIG. 2A, the time between the frame F5, which is a new first reference frame, and the frame F10, which is a similar image, that is, the time corresponding to five frames is one cycle of the heartbeat.

  Each time a similar image is selected, the reference image designating unit 30 updates the selected similar image to a new tomographic image of the first reference frame, and the similar image selecting unit 50 determines that the tomographic image of the first reference frame is A similar image similar to the updated tomographic image is selected every time the tomographic image is updated, and the period information calculation unit 60 calculates the difference between the tomographic image of the reference frame and the similar image every time the tomographic image of the first reference frame is updated. Get the information of the time interval between. In this way, since the time phase intervals are obtained one after another over a plurality of cycles of the heartbeat, the cycle information calculation unit 60 statistically processes the time phase intervals obtained one after another to obtain cycle information. For example, an average value of a plurality of time phase intervals obtained one after another may be used as the cycle information, and a heart rate per unit time may be calculated as the cycle information from the average value.

  As described above, since the cycle information is obtained by statistical processing over a plurality of cycles of the heartbeat, relatively reliable cycle information is obtained only by the processing related to the first reference frame shown in FIG. be able to. However, the present ultrasonic diagnostic apparatus can set the second reference frame, the third reference frame and a desired number of reference frames in addition to the first reference frame to obtain more accurate periodic information. it can.

  FIG. 2 (2) shows the processing related to the second reference frame, where the horizontal axis shows the frame number of the tomographic image obtained over a plurality of frames (multiple time phases), and the vertical axis shows Indicates the degree of similarity calculated for each frame. Note that the tomographic image in FIG. 2A and the tomographic image in FIG. 2B are the same image. For example, the tomographic image from frame F2 to frame F20 in FIG. 2 (2) is the tomographic image from frame F2 to frame F20 in FIG. 2 (1).

  However, in FIG. 2B, the tomographic image of the frame F2 is designated as the second reference frame. As shown in FIG. 2A, the reference image designating unit 30 designates the tomographic image of the first reference frame, and designates the tomographic image of the second reference frame in the subsequent frames. FIG. 2B shows an example in which the tomographic image of the frame F2 is designated as the second reference frame. Note that the second reference frame may be designated after one or more frames are sandwiched between them instead of the frame immediately after the first reference frame.

  When the second reference frame is designated, the same processing as that for the first reference frame is executed. That is, the similarity calculation unit 40 calculates the image similarity between the tomographic image of the second reference frame and the tomographic images of each frame obtained one after another from the image forming unit 20. In addition, the similar image selection unit 50 selects a similar image similar to the tomographic image of the second reference frame from the multiple frames of tomographic images based on the similarity calculated for each frame by the similarity calculation unit 40. Select. Then, the period information calculation unit 60 obtains fetal heartbeat period information based on the time phase interval (frame interval) between the tomographic image and the similar image of the second reference frame.

  Further, every time a similar image is selected, the reference image designating unit 30 updates the selected similar image to a tomographic image of a new second reference frame, and the similar image selecting unit 50 selects a tomographic image of the second reference frame. Each time the image is updated, a similar image similar to the updated tomographic image is selected, and the period information calculation unit 60 updates the tomographic image of the reference frame and the similar image every time the tomographic image of the second reference frame is updated. Get the information of the time interval between. Thus, even in the processing related to the second reference frame, since the time phase intervals are obtained one after another over a plurality of cycles of the heartbeat, the cycle information calculation unit 60 statistically processes the time phase intervals obtained one after another. To obtain periodic information.

  Further, a third reference frame may be set in addition to the second reference frame. FIG. 2 (3) shows the processing related to the third reference frame, and the horizontal axis shows the frame number of the tomographic image obtained over a plurality of frames (multiple time phases), and the vertical axis shows Indicates the degree of similarity calculated for each frame. The tomographic image in FIG. 2 (3) is also the same image as the tomographic images in FIGS. 2 (1) and 2 (2).

  In FIG. 2 (3), the tomographic image of the frame F3 is designated as the third reference frame. As shown in FIG. 2B, the reference image designating unit 30 designates the tomographic image of the second reference frame, and designates the tomographic image of the third reference frame in the subsequent frames. FIG. 2 (3) shows an example in which the tomographic image of the frame F3 is designated as the third reference frame. Note that the third reference frame may be designated after one or more frames are sandwiched between them instead of the frame immediately after the second reference frame. When the third reference frame is designated, the same processing as that for the first reference frame and the second reference frame is executed. In addition to the third reference frame, a fourth reference frame, a fifth reference frame, and a desired number of reference frames may be added.

  Thus, since the heartbeat period information can be obtained for each reference frame for the plurality of reference frames, the period information calculation unit 60 further statistically processes the period information obtained from each of the plurality of reference frames. Thus, for example, averaging can be performed to obtain final cycle information.

  FIG. 3 is a flowchart showing processing in the ultrasonic diagnostic apparatus of FIG. First, ultrasonic waves are transmitted and received, a tomographic image is formed for each frame (S301), and the image state of the formed tomographic image is confirmed (S302). For example, if the transmission / reception surface of the probe 10 is pointed in the air, a reflected wave of ultrasonic waves cannot be obtained, and a black tomographic image with low luminance can be obtained. Therefore, for example, the image state is determined based on the average value of luminance in the tomographic image. For example, if the average value is equal to or greater than the threshold value, it is determined that the image state is good, and if the average value is smaller than the threshold value, it is determined that the image state is bad. Then, the determination is repeated until it is determined that the image state is good. For example, when the probe 10 is directed toward the heart of the fetus, the image state is determined to be good and the subsequent processing proceeds.

  When the probe 10 is pointed at the fetal heart, first, the reference image designating unit 30 designates the tomographic image of the first reference frame (S303-1), and the similarity calculation unit 40 successively produces the tomographic image of the first reference frame one after another. The similarity of the image between the tomographic images of each frame obtained is calculated (S304-1). Further, the similar image selection unit 50 selects a similar image similar to the tomographic image of the first reference frame from the tomographic images of a plurality of frames based on the similarity calculated for each frame (S305-1). Then, the cycle information calculation unit 60 uses the heart rate (first frequency) based on the first reference frame as the cycle information of the fetal heartbeat based on the time phase interval between the tomographic image and the similar image of the reference frame. Heart rate) is calculated (S306-1). That is, the process described with reference to FIG.

  When the tomographic image of the first reference frame is designated, the reference image designating unit 30 designates the tomographic image of the second reference frame in the subsequent frames, and the same processing as in the case of the first reference frame is executed ( S303-2) to (S306-2). That is, the processing described with reference to FIG. 2B is executed, and the heart rate (second heart rate) based on the second reference frame is calculated as the period information of the fetal heart rate.

  Furthermore, a desired number of reference frames may be added, and the same processing as in the case of the first reference frame or the second reference frame may be executed (S303-N) to (S306-N).

  Then, the cycle information calculation unit 60 further statistically processes the heart rate obtained from each of the plurality of reference frames to calculate, for example, an average value (S307), and the average value of the calculated heart rate is displayed on the display unit 70. Is displayed.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above is only a mere illustration in all the points, and does 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 image formation part, 30 reference | standard image designation | designated part, 40 similarity calculation part, 50 similar image selection part, 60 period information calculation part, 70 display part

Claims (5)

A probe for transmitting and receiving ultrasonic waves to an object that periodically moves; and
A transmitting / receiving unit that obtains an ultrasonic reception signal by scanning an ultrasonic wave by controlling a probe;
An image forming unit that forms ultrasonic images of a plurality of time phases related to the object based on reception signals obtained over a plurality of time phases;
A reference image designating unit for designating a reference image from ultrasonic images of a plurality of time phases;
A similarity calculator that calculates the similarity of the image between the reference image and the ultrasonic image obtained for each time phase;
A similar image selection unit that selects a similar image similar to the reference image from the ultrasonic images of a plurality of time phases based on the similarity obtained for each time phase;
A periodic information calculation unit that obtains periodic information related to the motion of the object based on a time phase interval between a reference image and a similar image;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The similar image selection unit first selects a time-phase ultrasonic image having a maximum similarity among the plurality of ultrasonic images obtained for each time phase after the reference image as the similar image. ,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1 or 2,
The reference image designating unit designates the selected similar image as a new reference image,
The similar image selection unit selects a similar image similar to the updated reference image every time the reference image is updated,
The period information calculation unit statistically processes the time interval obtained one after another each time a reference image is updated to obtain the period information.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The reference image designating unit designates a plurality of reference images corresponding to different time phases from among a plurality of time phase ultrasonic images,
The similarity calculation unit calculates an image similarity between the reference image and each time phase ultrasonic image for each reference image,
The similar image selection unit selects a similar image similar to the reference image for each reference image,
The period information calculation unit obtains the period information by statistically processing the time phase interval obtained from each of a plurality of reference images based on the time phase interval between each reference image and its similar image. ,
An ultrasonic diagnostic apparatus. In the ultrasonic diagnostic apparatus according to any one of claims 1 to 4,
The probe sends and receives ultrasound to the fetal heart,
The image forming unit forms an ultrasonic image of a plurality of time phases related to a fetal heart based on reception signals obtained over a plurality of time phases,
The period information calculation unit obtains period information of the fetal heartbeat as the period information.
An ultrasonic diagnostic apparatus.

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