JP6193449B1 - Ultrasonic diagnostic equipment - Google Patents

Abstract

An improved technique for appropriately setting scanning conditions in reconstruction scanning is provided. A transmission / reception processing unit (12) controls a probe (10) to repeat a scan for forming a scanning plane over a plurality of heartbeats while changing a position in a scanning direction in a three-dimensional space including a fetal heart. Perform a configuration scan. The reconstruction processing unit 50 forms a reconstruction volume of a plurality of time phases constituting one heartbeat period of the fetal heart based on a plurality of frames obtained by the reconstruction scan. The scan condition setting unit 40 sets a scan repetition condition in the reconstruction scan based on the depth of the fetal heart. [Selection] Figure 1

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a technique for obtaining a reconstruction volume of the heart.

  2. Description of the Related Art An ultrasonic diagnostic apparatus that forms a three-dimensional ultrasonic image of a tissue that accompanies motion such as the heart is known. For example, an ultrasonic beam is scanned three-dimensionally in a three-dimensional space, echo data is collected from the three-dimensional space, a three-dimensional ultrasonic image is formed based on the collected echo data, and is displayed in real time. Technology is known. However, real-time display has a fundamental limitation that the scan rate, beam density, and beam range are in a trade-off relationship with each other.

  Techniques for avoiding the fundamental limitations in real-time display of 3D ultrasound images have also been proposed. For example, in Patent Document 1, a plurality of tomographic image data is collected by collecting a plurality of tomographic image data at a plurality of scanning positions while moving a scanning plane at a low speed in a three-dimensional space including a target tissue such as a fetal heart. An innovative technique (reconstruction process) is described in which three-dimensional image data (reconstructed volume data) of a target tissue is formed by rearranging and reconstructing the tomographic image data. Patent Documents 2 and 3 also describe techniques relating to reconstruction processing (volume reconstruction).

Japanese Patent No. 5525748 JP 2014-23928 A JP 2014-36848 A

  For example, when a three-dimensional image of the fetal heart is obtained by the reconstruction process described above, the scan direction is extended over a relatively long period of, for example, several seconds to 20 seconds within a period including a plurality of fetal heartbeats. A reconfiguration scan is performed in which the scan for forming the scan plane is repeated while changing the position. As described above, since a relatively long period is required for the reconstruction scan, it is desirable that processing re-execution does not occur.

  For example, if the quality of the reconstruction volume data obtained by the reconstruction scan is not suitable for diagnosis, the reconstruction scan may have to be performed again for the diagnosis. Therefore, for example, it is desirable that the scanning conditions in the reconstruction scan can be appropriately set so that a reconstruction volume suitable for diagnosis can be obtained.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an improved technique for appropriately setting a scanning condition in reconstruction scanning.

  An ultrasonic diagnostic apparatus suitable as a specific example of the present invention performs a reconstruction scan that repeats a scan that forms a scan plane over a plurality of heartbeats of the heart while changing the position in the scan direction within a three-dimensional space including the heart. A scanning processing unit to be executed, and a reconstruction processing unit for obtaining a reconstructing volume of a plurality of time phases constituting one heartbeat period of the heart based on a plurality of frames obtained from a scanning surface formed one after another by repeating the scanning. And a condition setting unit that sets the scanning repetition condition based on the depth of the heart.

  According to the ultrasonic diagnostic apparatus having the above-described configuration, it is possible to set a repetition condition according to the depth of the heart as a scanning condition in the reconstruction scan. For example, the resolution in the scan direction of the reconstruction volume may be affected by the depth. In this case, for example, by setting an appropriate repetition condition based on the depth of the heart and the target resolution, it is desirable to reduce the influence of the depth of the heart while preferably not depending on the depth of the heart. Can be achieved. Since the target resolution is realized, it is expected to improve the accuracy of cardiac diagnosis. In addition, since the reconstruction scan is executed under an appropriate repetition condition, for example, the trouble of the reconstruction scan is reduced, and it is possible to eliminate the re-execution of the reconstruction scan, and it is possible to reduce the inspection burden. For example, the burden on pregnant women in the examination is reduced.

  In a preferred embodiment, the condition setting unit sets the scanning repetition condition based on the depth of the heart and the target resolution in the scanning direction of the reconstruction volume.

  In a preferred embodiment, the condition setting unit, based on the depth of the heart, the target resolution, and the scan range in the scan direction of the reconstruction scan, as the scan repeat condition, The repetition time is set.

  In a preferred embodiment, the condition setting unit derives an inter-frame angle based on the depth of the heart and the target resolution, and a plurality of target frames constituting a reconstruction volume based on the scanning range and the inter-frame angle. A number is derived, and the number of repetitions of the scan or the repetition time of the scan is derived based on the target number of frames.

  In a preferred embodiment, the ultrasonic diagnostic apparatus includes a scan range setting unit that sets a scan range in the scan direction of the reconstruction scan based on data obtained by performing a pre-scan prior to the reconstruction scan. Furthermore, it is characterized by having.

  In a preferred embodiment, the scanning range setting unit forms the projection data of the heart based on data obtained by pre-scanning, and sets the scanning range based on the projection data.

  In a preferred embodiment, the ultrasonic diagnostic apparatus detects the feature time phases one after another based on echo data obtained from the heart over a plurality of heartbeats, thereby detecting the features successively over the plurality of heartbeats. The scan processing unit further includes a trigger generation unit that generates a trigger signal indicating the timing of the time phase, and the scan processing unit stepwise in the scan direction according to the timing of the characteristic time phase indicated by the trigger signal in the reconstruction scan. The scanning surface is formed while changing the position.

  In a preferred embodiment, the scan processing unit executes the reconstruction scan while forming a plurality of scan planes by parallel reception at each position while changing the position in the scan direction.

  According to the present invention, an improved technique for appropriately setting scanning conditions in reconstruction scanning is provided. For example, according to a preferred aspect of the present invention, it is possible to set a repetition condition according to the depth of the heart as the scanning condition in the reconstruction scan.

1 is an overall configuration diagram of an ultrasonic diagnostic apparatus suitable for implementing the present invention. It is a figure for demonstrating the specific example of a region of interest. It is a figure for demonstrating the scanning of a three-dimensional ultrasonic wave. It is a figure for demonstrating a pre scan. It is a figure which shows the specific example of the three-dimensional data obtained by the prescan. It is a figure which shows the specific example of a projection image and a scanning range. It is a figure which shows the specific example 1 of a reconstruction scan. It is a figure for demonstrating collection and the reconstruction process of frame data. It is a figure which shows the specific example 2 of a reconstruction scan. It is a figure for demonstrating the repetition conditions in a reconstruction scan. It is a figure for demonstrating the setting of the repetition condition according to the depth of a diagnostic object. It is a figure which shows the specific example of the production | generation of a trigger signal. It is a figure which shows the internal structural example of a trigger production | generation part.

  FIG. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus suitable for implementing the present invention. The probe 10 is an ultrasonic probe that transmits and receives ultrasonic waves in a three-dimensional space including the heart of a fetus to be diagnosed. A preferred specific example of the probe 10 is a 2D array probe (matrix array probe) provided with a plurality of vibration elements arranged two-dimensionally. The probe 10 may be, for example, a mechanical 3D probe that mechanically moves the position of a scanning surface that is electronically formed by a plurality of vibration elements (1D array transducers) arranged one-dimensionally. .

  The transmission / reception processing unit 12 functions as a scanning processing unit that performs scanning processing such as reconstruction scanning by controlling the probe 10. The transmission / reception processing unit 12 performs transmission control by outputting a transmission signal corresponding to each of the plurality of vibration elements included in the probe 10. By the transmission control, an ultrasonic transmission beam is formed, and the transmission beam is scanned in the three-dimensional space. In addition, the transmission / reception processing unit 12 performs beam forming processing such as phasing addition processing on signals (acoustic wave reception signals) obtained from a plurality of vibration elements included in the probe 10. As a result, an ultrasonic reception beam is formed and scanned in the three-dimensional space.

  The frame forming unit 20 forms frame data based on the received beam data obtained from the transmission / reception processing unit 12. For example, based on line data (beam data) obtained from a plurality of reception beams constituting the scanning plane, frame data corresponding to the scanning plane is formed. The line data obtained from the transmission / reception processing unit 12 is obtained in a coordinate system suitable for transmission / reception of ultrasonic waves, for example, an rφ coordinate system expressed by the ultrasonic beam depth direction r and the scanning direction φ in the scanning plane. It is done. The frame forming unit 20 may form rφ coordinate system frame data from rφ coordinate system line data, but performs scan conversion processing (coordinate conversion processing, interpolation processing, etc.) on the rφ coordinate system line data. By applying, it is desirable to form frame data of an xy coordinate system (orthogonal coordinate system).

  The ultrasonic diagnostic apparatus of FIG. 1 performs a reconstruction scan on a three-dimensional space including a fetal heart, executes a reconstruction process based on frame data of a plurality of frames obtained by the reconstruction scan, A three-dimensional moving image of the fetal heart is formed. Prior to the reconstruction scan, the region of interest is set and pre-scanned. Therefore, in the following, setting of the region of interest, pre-scanning, and reconstruction scanning by the ultrasonic diagnostic apparatus of FIG. 1 will be described in order, and further setting of scanning conditions and generation of a trigger signal in the reconstruction scanning will be described. In addition, about the structure (part) shown in FIG. 1, the code | symbol of FIG. 1 is utilized in the following description.

<Setting of region of interest>
When diagnosing the fetal heart using the ultrasonic diagnostic apparatus of FIG. 1, for example, a user such as a doctor or a laboratory technician holds the probe 10 in his / her hand and probes the body surface (eg, abdomen) of a pregnant woman (maternal body) The ultrasonic wave is transmitted / received by bringing the 10 transmission / reception wave surfaces into contact with each other to confirm the position of the fetal heart. When confirming the position of the fetal heart, for example, an ultrasonic tomographic image formed in the tomographic image forming unit 30 is used.

  The tomographic image forming unit 30 forms ultrasonic tomographic image data based on the frame data obtained from the frame forming unit 20. For example, the tomographic image forming unit 30 forms image data of a B-mode image in the mother body. The ultrasonic tomographic image formed in the tomographic image forming unit 30 is subjected to display processing in the display processing unit 60 and displayed on the display unit 62. The user adjusts the position and orientation of the probe 10 so that the fetal heart is displayed in the tomographic image while confirming the tomographic image in the mother body displayed on the display unit 62. In the tomographic image including the fetal heart, the region of interest setting unit 32 sets the region of interest.

  FIG. 2 is a diagram for explaining a specific example of the region of interest. FIG. 2A shows a specific example of the scanning plane S and the probe 10 used for setting the region of interest. The probe 10 has a function of transmitting and receiving ultrasonic waves three-dimensionally in a three-dimensional space. However, in setting a region of interest, an ultrasonic beam (transmission beam and reception beam) in the depth direction r is scanned in the scanning direction φ. A two-dimensional (one) representative scanning plane S formed by scanning in a straight line is used.

  In setting the region of interest, a user such as a doctor or a laboratory technician adjusts the position and posture of the probe 10 appropriately so that the entire cross section of the fetal heart is included in the scanning plane S. For example, the position and posture of the probe 10 are adjusted so that four cross sections of the left ventricle, left atrium, right ventricle, and right atrium of the fetal heart fall within the typical scanning plane S shown in FIG. Is done.

  FIG. 2B shows a specific example of the tomographic image 30B corresponding to the scanning plane S of FIG. A cross section of the fetal heart (Fh) is projected in the tomographic image 30B, and a region of interest (ROI) is set so as to surround the fetal heart in the tomographic image 30B. FIG. 2B shows a trapezoidal region of interest as a specific example of the region of interest. That is, a trapezoidal region of interest in which the upper base and the lower base are deformed into a bow corresponding to the scanning direction φ is illustrated.

  For example, the position of the region of interest (ROI) so as to surround the fetal heart (Fh) in the tomographic image 30B when the user operates the operation device 80 while viewing the tomographic image 30B displayed on the display unit 62. Specify the shape and size. In response to the operation, the region-of-interest setting unit 32 sets a region of interest in the tomographic image 30B.

  The region-of-interest setting unit 32 detects the boundary of the heart (Fh) (for example, the boundary between the heart cavity and the myocardium) by image processing on the image data of the tomographic image 30B, for example, and surrounds the region of interest (ROI) ) May be set.

  FIG. 2B shows a trapezoidal region of interest (ROI) in which the range in the depth direction r is D1 to D2 and the range in the scanning direction φ is φ1 to φ2. 2B shows a trapezoidal region of interest as a specific example of the shape, the region of interest may have a shape other than the trapezoid (for example, a rectangle or an ellipse). Good. When a region of interest (ROI) is set for the fetal heart (Fh), a three-dimensional ultrasound scan is performed in the three-dimensional space including the fetus.

  FIG. 3 is a diagram for explaining three-dimensional ultrasonic scanning. As shown in FIG. 3, for example, an ultrasonic beam (transmission beam and reception beam) having the r direction as the beam direction (depth direction) is formed, and the ultrasonic beam is electronically scanned in the φ direction and scanned. A surface S is formed. That is, a plurality of line data corresponding to a plurality of beam addresses are formed in the scanning plane S while changing the beam address of the received beam in the φ direction. Frame data corresponding to the scanning plane S is constituted by a plurality of line data in the scanning plane S.

  Furthermore, the ultrasonic beam is scanned in the scanning plane S while moving the scanning plane S in the θ direction, that is, while changing the position and angle of the scanning plane S (which may be either position or angle) in the θ direction. . Thereby, the ultrasonic beam is scanned three-dimensionally in the three-dimensional space, and, for example, as shown in a specific example shown in FIG. 3, frame data of a plurality of frames arranged in the θ direction is formed.

  The ultrasound diagnostic apparatus in FIG. 1 performs reconstruction processing on frame data of a plurality of frames obtained by three-dimensionally scanning an ultrasound beam in a three-dimensional space including a fetal heart to be diagnosed. A three-dimensional image that reflects the three-dimensional shape of the heart is formed. Prior to the reconstruction process, that is, prior to the reconstruction scan for collecting the frame data necessary for the reconstruction process, a pre-scan is performed.

<Pre-scan>
FIG. 4 is a diagram for explaining pre-scanning. The prescan is performed prior to the reconstruction scan. FIG. 4A shows a specific example of pre-scanning, and FIG. 4B shows a specific example of reconstruction scanning.

  For example, as in the specific example shown in FIG. 4, in both the pre-scan and the reconstruction scan, an ultrasonic beam having the beam direction (depth direction) as the r direction is formed, and the ultrasonic beam is electronically The scanning surface S is formed by scanning. Furthermore, the ultrasonic beam is scanned in the scanning surface S while moving the scanning surface S in the θ direction electronically or mechanically. Thereby, frame data of a plurality of frames arranged in the θ direction are successively formed. However, the scan range and the scan density (scanning speed) in the θ direction are different between the pre-scan and the reconstruction scan.

  The purpose of the pre-scan is to confirm the position and size of the fetal heart (Fh) in the three-dimensional space, and the scanning range and scanning density (scanning speed) are determined according to the purpose. For example, in the pre-scan, the scanning surface S is scanned in a wider range than the reconstruction scan in the angle θ direction, and the scanning surface S is scanned with a coarser scanning density (faster scanning speed) than the reconstruction scan. Then, for example, the scanning plane S has a relatively wide range (angle range in the θ direction) around the position (angle in the θ direction) of the representative scanning plane S (see FIG. 2) where the region of interest is set. Scanned. The scanning surface S may be scanned in the angle θ direction within the maximum scanning range that can be scanned by the probe 10.

  On the other hand, the reconstruction scan is executed within a limited scan range set according to the position and size of the fetal heart (Fh) confirmed by the pre-scan. For example, as in the specific example shown in FIG. 4B, the scanning plane S is scanned in the angle θ direction within the smallest possible range including the fetal heart. A specific example of the reconstruction scan will be described in detail later.

  Based on the frame data of a plurality of frames obtained by the prescan, that is, the three-dimensional data obtained from the three-dimensional space by the prescan, the scan range of the reconstruction scan is determined.

  FIG. 5 is a diagram illustrating a specific example of the three-dimensional data obtained by the pre-scan. For example, pre-scanning is performed in a three-dimensional space including the fetal heart (Fh) (see FIG. 4), and the ultrasonic beam is scanned three-dimensionally while changing the beam address in the φ direction and the θ direction ( In FIG. 3, the transmission / reception processing unit 12 forms a plurality of line data corresponding to a plurality of beam addresses. Further, in the frame forming unit 20, frame data corresponding to the scanning plane is constituted by a plurality of line data in the scanning plane composed of the r direction and the φ direction.

  Each line data is composed of a plurality of data arranged in the r direction, and each line data is arranged at a position corresponding to the beam address of the line data, that is, a plurality of line data is arranged in the rφθ coordinate system. Thus, the three-dimensional data shown in FIG. 5 is obtained. In the specific example shown in FIG. 5, each beam address is associated with a coordinate value in the two-dimensional coordinate system in the φ direction and the θ direction.

  For example, the three-dimensional data shown in FIG. 5 is stored in the data storage unit 22 as the scan result of the pre-scan. For example, frame data of a plurality of frames arranged in the θ direction is stored in the data storage unit 22 one after another for each frame. Then, based on the three-dimensional data obtained by the pre-scan, the position and size of the fetal heart (Fh) are confirmed, and the scan range of the reconstruction scan is determined. That is, the projection data forming unit 34 forms a projection image based on the three-dimensional data obtained by the pre-scan, and the scan range setting unit 36 determines the scan range of the reconstruction scan based on the projection image.

  FIG. 6 is a diagram illustrating a specific example of a projected image and a scanning range. The projection data forming unit 34 forms a projection image based on the three-dimensional data (FIG. 5) stored in the data storage unit 22 as a scan result of the prescan. For example, as shown in FIG. 6, a projection image is formed by projecting the fetal heart (Fh) on a plane including the φ direction and the θ direction.

  The projection data forming unit 34 obtains projection data for each line data from a plurality of line data constituting the three-dimensional data obtained by the pre-scan, and thereby based on a plurality of projection data corresponding to the plurality of line data. To form a projected image. For example, the projection data forming unit 34 integrates (adds) a plurality of data constituting each line data, and sets the integrated value as projection data of the line data. Note that the projection data forming unit 34 may select, for example, the minimum data corresponding to the minimum echo intensity from a plurality of data constituting each line data, and use the selected data as the projection data of the line data.

  When the line data passes through the heart chamber in the fetal heart (Fh) in the three-dimensional data, the data corresponding to the heart chamber is included in the line data. Since blood flow is dominant in the heart chamber, the reflection of ultrasonic waves from the heart chamber is weaker than that of tissues such as the myocardium. That is, the echo intensity in the heart chamber is smaller than in other parts such as the myocardium.

  Therefore, when each line data passes through the heart chamber in the fetal heart (Fh), since the echo intensity corresponding to the heart chamber is small, projection data obtained by integrating a plurality of data constituting the line data is also included. Relatively small. In addition, when selecting the minimum data corresponding to the minimum echo intensity from among a plurality of data constituting each line data as projection data, when the line data passes through the heart cavity in the fetal heart Fh, If the data with very small echo intensity corresponding to the heart chamber is selected and the line data does not pass through the heart chamber, data with relatively strong echo intensity corresponding to the tissue such as the myocardium is selected.

  Therefore, the heart chamber portion in the fetal heart (Fh) is composed of a data group (pixel group) having a small echo intensity, and the portion other than the fetal heart is composed of a data group (pixel group) having a relatively strong echo intensity. A projected image is formed.

  In the projected image, for example, an image portion having an area smaller than the reference value in an image portion (pixel group) having a small echo intensity is considered as noise that is not the fetal heart Fh and is removed. desirable. In removing noise, any of various known processes may be used.

  The scan range setting unit 36 determines the scan range of the reconstruction scan in the reconstruction process based on the projection image obtained from the projection data forming unit 34. The scan range setting unit 36 extracts an image region of the fetal heart (Fh) in the projection image, and determines a scan range based on the image region. For example, the image region of the fetal heart (Fh) is specified in the projection image by a binarization process using a threshold value that identifies a pixel corresponding to the heart chamber and other pixels.

  When the image area of the fetal heart (Fh) is specified, the scan range setting unit 36 sets a search line L that passes through the center of the image area of the fetal heart (Fh) (for example, the area centroid or its vicinity). . For example, as shown in FIG. 6, a search line L parallel to the θ direction is set.

  Then, the scan range setting unit 36 searches the boundary of the fetal heart (Fh) on the search line L. For example, the boundaries of one side and the other side in the θ direction are searched for on the search line L from the center of the image area of the fetal heart (Fh) (for example, the area center of gravity point or its neighboring point). For example, a pixel position that changes from a pixel corresponding to a fetal heart (heart chamber) to a pixel corresponding to a myocardium or the like is searched. Thereby, on the search line L, the two boundaries of the one side boundary and the other side boundary of the fetal heart (Fh) are specified. In the specific example of FIG. 6, the position of θ1 and the position of θ2 are two boundaries.

  The scan range setting unit 36 determines the scan range in the reconstruction scan according to the projection range of the fetal heart (Fh) specified by the two boundaries specified on the search line. For example, in the specific example of FIG. 6, the scan range (Scan θ) in the θ direction in the reconstruction scan is determined according to the projection range of the heart (Fh) from the position of θ1 to the position of θ2.

  Since the fetal heart (Fh) periodically repeats the expansion and contraction motion, the projection range of the heart (Fh) is more reliably included in the scanning range in the reconstruction scan over a plurality of cycles. A range obtained by adding a blank area to the scanning range is a scanning range. For example, as in the specific example shown in FIG. 6, the scanning range (Scan θ) is a range from θs to θe with a margin Δ added to each of the θ1 side and θ2 side with respect to the projection range from θ1 to θ2. Is done. Note that the projection range from θ1 to θ2 shown in FIG. 6 may be used as the scan range in the θ direction as it is.

  In the specific example described above, the scan range (Scan θ) in the θ direction is determined based on the projection range in the θ direction of the fetal heart (Fh) obtained from the projection image in FIG. The scanning range in the φ direction may be determined by specifying the projection range in the φ direction of the fetal heart (Fh) from the image. For example, a two-dimensional scan range including a scan range in the φ direction and a scan range in the θ direction may be determined. Note that the range (φ1 to φ2) in the scanning direction φ of the region of interest (FIG. 2) set by the region of interest setting unit 32 may be used as the scanning range in the φ direction. 6 may be displayed on the display unit 62, and the user may specify the scan range in the θ direction and the scan range in the φ direction in the projection image while confirming the display.

  Further, the depth of the fetal heart may be determined based on the line data obtained by the prescan. For example, along the line data obtained by the pre-scan, a search is made by searching for a portion (corresponding to the heart chamber) where the echo data is smaller than the threshold value from the shallow side (probe 10 side) to the deep side. The position may be the depth of the heart. For example, the depth of the heart is determined for each line data in a plurality of line data obtained by the pre-scan, and a plurality of statistical values (for example, average values) obtained from the plurality of line data are obtained. It may be good.

<Reconfiguration scan>
FIG. 7 is a diagram illustrating a specific example 1 of the reconstruction scan. FIG. 7 shows a specific example of reconstruction scanning when the probe 10 is a 2D array probe. The transmission / reception processing unit 12 controls the probe 10 to scan the heart (Fh) while changing the position in the θ direction (scan direction) in the three-dimensional space including the fetal heart (Fh). A reconstruction scan that repeats over multiple heartbeats is performed.

  In the reconstruction scan, an ultrasonic beam having the r direction as a beam direction (depth direction) is formed, and the ultrasonic beam is electronically scanned to form a scanning surface. Further, in the case of a 2D array probe, the scanning plane is electronically moved stepwise in the θ direction, and an ultrasonic beam is scanned within the scanning plane.

  The reconstruction scan is executed in the scan range set by the scan range setting unit 36. For example, the scan plane is formed within the angle range in the φ direction set by the scan range setting unit 36. The angle range in the φ direction may be the range (φ1 to φ2) in the scanning direction φ of the region of interest (FIG. 2) set by the region of interest setting unit 32. Further, the reconstruction scan is executed while the scanning plane is moved stepwise in the θ direction within the scanning range (Scan θ in FIG. 6) from θs to θe in the θ direction set by the scan range setting unit 36.

  In Specific Example 1 shown in FIG. 7, that is, in the reconstruction scan in the case of the 2D array probe, the scan range in the θ direction is divided into a plurality of scan regions (R1 to R8). A plurality of scanning planes are formed by parallel reception for each scanning area. For example, an ultrasonic beam (transmission beam and reception beam) is scanned in the φ direction (see FIG. 2 and FIG. 3) while performing parallel reception to obtain a plurality of reception beams from one transmission beam. A plurality of (for example, four) scanning planes constituting the scanning region are collectively formed (in parallel).

  Then, the scanning area is switched in accordance with the trigger timing indicated by the trigger signal output from the trigger generation unit 70 (which will be described in detail later), and scanning surfaces are successively formed in the plurality of scanning areas (R1 to R8). Frame data is collected. Further, a reconstruction process is executed based on the collected frame data.

  FIG. 8 is a diagram for explaining frame data (frame set) collection and reconstruction processing. FIG. 8A shows a specific example of the frame data collected by the reconstruction scan of the 2D array probe (FIG. 7).

  In the specific example shown in FIG. 8 (A), for example, four scanning planes are formed together by parallel reception in the scanning region R1 from the timing of the trigger (1), and the frame is composed of four frame data corresponding to the four scanning planes. A set is obtained. In the scanning region R1, the frame sets are collected over a plurality of time phases until the timing of the next trigger (2) without moving the positions of the four scanning planes.

  Thereby, for example, as shown in FIG. 8A, in the scanning region R1, a frame set R1 (T1) consisting of four frame data corresponding to time phase 1 and four frame data corresponding to time phase 2 are used. Frame set R1 (T2), frame set R1 (T3) consisting of four frame data corresponding to time phase 3, and frame set R1 (T4) consisting of four frame data corresponding to time phase 4 are obtained one after another. .

  Then, at the timing of the trigger (2), the position of the scanning surface is moved from the scanning region R1 to the scanning region R2. Also, for example, four scanning planes are formed collectively by parallel reception in the scanning region R2 from the timing of the trigger (2), and a frame set composed of four frame data corresponding to the four scanning planes is obtained. Furthermore, the frame sets are collected over a plurality of time phases until the timing of the next trigger (3) without moving the positions of the four scanning planes in the scanning region R2.

  Thereby, for example, as shown in FIG. 8A, in the scanning region R2, the frame set R2 (T1) composed of four frame data corresponding to time phase 1 and the four frame data corresponding to time phase 2 are used. Frame set R2 (T2), frame set R2 (T3) consisting of four frame data corresponding to time phase 3, frame set R2 (T4) consisting of four frame data corresponding to time phase 4, and time phase 5 A frame set R2 (T5) consisting of four corresponding frame data is obtained one after another.

  Even after the trigger (3), the scanning area is switched according to the trigger timing, and the positions of the four scanning planes are not moved in each scanning area, and the frames are transmitted over a plurality of time phases until the next trigger timing. A set is collected. Thus, for example, as in the specific example shown in FIG. 8A, in each of the scanning regions (R1 to R8), that is, within the scanning range in the θ direction (from θs to θe in FIG. 7). A frame set is collected over a plurality of time phases. The collected frame set is stored in the data storage unit 22.

  A trigger indicated by a trigger signal (described in detail later) is generated for each fetal heartbeat cycle. The fetal heart cycle may fluctuate within multiple heartbeats. Therefore, for example, as in the specific example shown in FIG. 8A, the number of time phases (T1, T2,...) Between adjacent triggers may also vary.

  The reconstruction processing unit 50 forms a reconstruction volume by performing a reconstruction process on the frame set stored in the data storage unit 22. FIG. 8B shows a specific example of a reconstructed volume obtained from the frame set (collected frame data) of FIG.

  In the reconstruction process, frame sets corresponding to the same time phase are collected from a plurality of scanning regions (R1 to R8), and a reconstruction volume corresponding to the time phase is configured. For example, as in a specific example shown in FIG. 8B, a frame set R1 (T1), a frame set R2 (T1), a frame set R3 (corresponding to the time phase T1) from a plurality of scanning regions (R1 to R8). T1),..., A frame set R8 (T1) is collected. Then, the collected frame sets are arranged in association with the positions of the corresponding scanning regions, and a reconstructed volume T1 corresponding to the time phase T1 is formed.

  Similar to the reconstruction process in time phase 1, in time phase 2 and later, frame sets corresponding to the same time phase are collected from the plurality of scanning regions (R1 to R8), and a reconstruction volume corresponding to the time phase is obtained. Composed. Thus, in the specific example shown in FIG. 8B, a reconstructed volume (T1 to T4) having a plurality of time phases corresponding to a plurality of time phases (T1 to T4) constituting one heartbeat period of the fetal heart is formed. .

  FIG. 9 is a diagram illustrating a specific example 2 of the reconstruction scan. FIG. 9 shows a specific example of reconstruction scanning when the probe 10 is a mechanical 3D probe. The transmission / reception processing unit 12 controls the probe 10 to scan the heart (Fh) while changing the position in the θ direction (scan direction) in the three-dimensional space including the fetal heart (Fh). A reconstruction scan that repeats over multiple heartbeats is performed.

  In the reconstruction scan, an ultrasonic beam having the r direction as a beam direction (depth direction) is formed, and the ultrasonic beam is electronically scanned to form a scanning surface. Further, in the case of a mechanical 3D probe, a scanning surface electronically formed by a plurality of vibration elements (1D array transducers) arranged one-dimensionally is mechanically moved relatively slowly in the θ direction. An ultrasonic beam is scanned in the scanning plane.

  The reconstruction scan is executed in the scan range set by the scan range setting unit 36. For example, the scan plane is formed within the angle range in the φ direction set by the scan range setting unit 36. The angle range in the φ direction may be the range (φ1 to φ2) in the scanning direction φ of the region of interest (FIG. 2) set by the region of interest setting unit 32. Further, the scanning plane is moved slowly (continuously or stepwise) in the θ direction within the scanning range (Scan θ in FIG. 6) from θs to θe in the θ direction set by the scan range setting unit 36. A reconfiguration scan is performed.

  In the specific example 2 shown in FIG. 9, that is, in the reconstruction scan in the case of the mechanical 3D probe, from the θs scanning range in the θ direction to θe, the fetal heart (Fh) is relatively slowly over a plurality of heartbeats. While mechanically moving the scanning plane, frame data of a plurality of frames is collected and stored in the data storage unit 22.

  Also in the case of a mechanical 3D probe, a plurality of (for example, four) scanning planes (scanning plane sets) may be collectively (in parallel) formed by parallel reception. Then, for example, the reconstruction scan is executed while slowly moving the scan plane set continuously (or stepwise) in the θ direction.

  The reconstruction processing unit 50 forms a reconstruction volume by reconstructing frame data of a plurality of frames stored in the data storage unit 22. As the reconstruction process in the case of the mechanical 3D probe, for example, a known process described in Patent Document 1 is used. That is, the frame data of a plurality of frames obtained by the reconstruction scan is rearranged to reconstruct three-dimensional data (reconstruction volume), and the fetus is generated by the three-dimensional image forming unit 52 based on the reconstructed three-dimensional data. A reconstructed image that three-dimensionally represents the heart is formed.

<Setting scan conditions>
The scan condition setting unit 40 sets a scan condition (scan condition) in the reconstruction scan (FIGS. 7 and 9). The scan condition is set, for example, after the pre-scan and before the reconstruction scan.

  The scan condition setting unit 40 sets a scan repetitive condition for forming a scan plane while changing the position in the scan direction (θ direction) as the scan condition in the reconstruction scan (FIGS. 7 and 9). As a scanning repetition condition, in the case of a 2D array probe, the number of scanning repetitions (scanning number) is set, and in the case of a mechanical 3D probe, a scanning repetition time (scanning time) is set.

  FIG. 10 is a diagram for explaining the repetition condition in the reconstruction scan. FIG. 10A shows a comparative example in which the scan range (θ direction) and the depth are the same, and the number of scans or the scan time is different.

  In the comparative example of FIG. 10A, when the number of scans is small or the scan time is short, the total number of frames constituting the reconstructed volume obtained after the reconstructing process is small, and the adjacent frame interval is widened. On the other hand, when the number of scans is large or the scan time is long, the total number of frames constituting the reconstructed volume obtained after the reconfiguration process is increased, and the interval between adjacent frames is reduced. If the frame interval of a plurality of frames constituting the reconstruction volume is narrow, the resolution in the scanning direction of the three-dimensional image obtained based on the reconstruction volume is increased.

  FIG. 10B shows a comparative example in which the scan range in the scan direction (θ direction) and the number of scans (scan time) are the same, and the depth of the diagnosis target (fetal heart) is different. In the comparative example of FIG. 10B, when the diagnosis target is shallow, the frame interval of the plurality of frames constituting the reconstruction volume obtained after the reconstruction process is relatively narrow, but when the diagnosis target is deep, The frame interval becomes relatively wide. Therefore, when the diagnosis target is deep, the resolution in the scanning direction of the three-dimensional image obtained based on the reconstruction volume is lower than when the diagnosis target is shallow. Therefore, the scan condition setting unit 40 sets a repetition condition in the reconstruction scan according to the depth of the heart of the fetus that is the diagnosis target.

  FIG. 11 is a diagram for explaining the setting of the repetition condition according to the depth of the diagnosis target. The scan condition setting unit 40 sets the repetition condition so that the frame intervals of a plurality of frames constituting the reconstruction volume become the target frame interval d corresponding to the target resolution. That is, the repetition condition is set so that the frame interval of a plurality of frames constituting the reconstructed volume becomes the target frame interval d regardless of whether the heart of the fetus to be diagnosed is shallow or deep.

In setting the repetition condition, first, based on the target frame interval d and the depth D, the frame interval angle Δθ relating to a plurality of frames constituting the reconstructed volume after the reconstructing process is determined by, for example, Equation 1. .
[Formula 1] Δθ = arcsin (d / D)

  The target frame interval d is determined so that the resolution in the scanning direction of the three-dimensional image obtained based on the reconstruction volume becomes the target resolution. For example, the resolution of the tomographic image (B mode image) formed in the tomographic image forming unit 30 is set as the target frame interval d. For example, when the resolution of the B-mode image is switched, it is desirable to change the set value of the target frame interval d accordingly. In addition, a user such as a doctor or a laboratory technician may be able to adjust the target frame interval d so that a desired resolution can be obtained in accordance with, for example, the contents of diagnosis.

  The depth D is the depth of the fetal heart, and is determined based on, for example, the region of interest (FIG. 2) set for the fetal heart. For example, the depth of the lower base of the region of interest (depth D2 in FIG. 2) is the depth D of the fetal heart. Note that the fetal heart depth D may be determined based on other positions based on the region of interest, such as the depth of the upper base of the region of interest (depth D1 in FIG. 2) or the center position of the region of interest. .

Next, based on the scan range (Scan θ) in the scan direction (θ direction) and the frame interval angle Δθ, the target frame number Fn required for the reconstruction volume is determined by, for example, Equation (2). The scan range (Scan θ) in the scan direction is set by the scan range setting unit 36 (see FIG. 6).
[Expression 2] Fn = (Scanθ / Δθ) +1

Then, the scan condition setting unit 40 sets the number of scans or the scan time in the reconstruction scan as a repetition condition so that the target number of frames Fn necessary for the reconstruction volume is realized. When the probe 10 is a 2D array probe, the scan condition setting unit 40 determines the number of scans according to Equation 3, and when the probe 10 is a mechanical 3D probe, determines the scan time according to Equation 4.
[Expression 3] Number of scans = (Fn / parallel reception number) +1
[Formula 4] Scan time = Fn × average period / number of parallel receptions

  The number of parallel receptions of Equation 3 and Equation 4 is the number of scan planes (for example, 4) formed collectively by parallel reception in the reconstruction scan. In addition, the average period of Formula 4 is an average (general) period time regarding the heartbeat of the fetus, and for example, a preset value determined in advance is used. Of course, the preset value may be changed as appropriate.

  The control unit 100 performs transmission / reception processing so that the reconstruction scan (FIGS. 7 and 9) is executed in accordance with the scan condition set by the scan condition setting unit 40 within the scan range set by the scan range setting unit 36. The unit 12 is controlled.

  For example, when the probe 10 is a 2D array probe, the scan set by the scan condition setting unit 40 within the scan range from θs to θe in the θ direction set by the scan range setting unit 36 (see FIG. 7). The reconstruction scan is executed with the number of triggers corresponding to the number of times (Equation 3). Incidentally, the specific examples of FIGS. 7 and 8 correspond to a reconstruction scan with the number of triggers (number of scans) 9 from the trigger (1) to the trigger (9). In the case of the 2D array probe, the scanning range in the θ direction in the reconstruction scan is divided into (the number of triggers−1) scanning regions. For example, it is desirable that the scanning range in the θ direction is equally divided into (the number of triggers−1) scanning regions. Then, a number of scanning surfaces corresponding to the number of parallel receptions is formed for each scanning region. For example, a plurality of scanning surfaces are formed at equal intervals (same scanning surface pitch) in each scanning region. Note that the scanning surface interval (scanning surface pitch) in each scanning region is not necessarily the same (equal interval), but the scanning surface interval (scanning surface pitch) is determined according to a certain rule over a plurality of scanning regions. It is desirable to do.

  When the probe 10 is a mechanical 3D probe, the scan time set by the scan condition setting unit 40 within the scan range from θs to θe in the θ direction set by the scan range setting unit 36 (see FIG. 7) ( The reconstruction scan is executed by multiplying (Equation 4).

<Trigger signal generation>
In the reconstruction scan (FIGS. 7 and 8) when the probe 10 is a 2D array probe, line data (consisting of a plurality of echo data) obtained from the heart of the fetus over a plurality of heartbeats while performing the reconstruction scan. The characteristic time phases are detected one after another based on the above, and a trigger signal indicating the timing of the characteristic time phases detected successively over a plurality of heartbeats is generated. The trigger signal is generated by the trigger generation unit 70.

  The line data used for generating the trigger signal is a center frame (for example, a typical scanning plane on which the region of interest is set (see FIG. 2)) or a center beam (for example, the center in the region of interest (see FIG. 2)). Obtained from an ultrasound beam passing through the fetal heart).

  FIG. 12 is a diagram illustrating a specific example of generation of a trigger signal. The transmission / reception processing unit 12 controls the probe 10 (2D array probe) and executes a reconstruction scan (FIGS. 7 and 8), for example, simultaneously with the beam formation of the reconstruction scan or periodically with the beam formation of the reconstruction scan. The center frame (or center beam) is formed to obtain line data. The trigger generation unit 70 generates a trigger signal based on the center frame (or center beam) line data obtained from the transmission / reception processing unit 12.

  First, the total sum (luminance sum) of echo data constituting line data obtained from the center frame (or center beam) is calculated. The trigger generation unit 70 generates a luminance sum signal indicating the luminance sum for each time phase (each time) over a plurality of time phases (a plurality of times) (S1). Next, the trigger generation unit 70 applies, for example, a low-pass filter (LPF) having a cutoff frequency of about 3 Hz to the luminance sum signal (S1) to obtain a luminance sum signal (S2) after LPF.

  Then, the trigger generation unit 70 detects a time phase at which the luminance sum reaches a maximum value (peak) in the luminance sum signal (S2) after LPF. For example, the luminance sum i (t) after LPF obtained for each time phase t is referred to, and the luminance sum i (t−1) satisfying i (t−2) ≦ i (t−1)> i (t). ) Is detected as a peak. In this specific example, the timing at which the peak is detected is time t immediately after time (t−1).

  Since there is a lot of blood flow in the fetal heart (heart chamber), echo data is relatively small in the heart. Therefore, the total echo data (luminance sum) is relatively small when the fetal heart is relatively large, and the echo data sum (luminance sum) is relatively small when the fetal heart is relatively small. Is relatively large. Therefore, the time phase corresponding to the end systole of the fetal heart is detected by detecting the time phase at which the total sum of the echo data (luminance sum) reaches the maximum value (peak).

  The trigger generation unit 70 sequentially detects time phases in which the luminance sum reaches a maximum value (peak) in the luminance sum signal (S2) after LPF. Then, the trigger generation unit 70 generates a trigger signal indicating the time phases detected one after another (rising at that time phase) (S3). Thus, for example, a trigger signal indicating the timing of the end systole is generated as the characteristic time phase timing of the fetal heartbeat. Note that, for example, a trigger signal indicating a timing shifted by a certain time from the time phase at which the luminance sum reaches the maximum value (peak) may be generated.

  Frame data (frame set) is collected by a reconstruction scan using the trigger signal generated in this way (see FIG. 8). That is, the reconstruction scan is executed while switching the scanning area at the trigger (rising edge) indicated by the trigger signal.

  FIG. 13 is a diagram illustrating an internal configuration example of the trigger generation unit 70. The trigger generation unit 70 generates a trigger signal based on line data obtained from the center frame or the center beam. The line data is output from the transmission / reception processing unit 12. The clock (CLK) serves as a trigger indicating the timing of each time phase (time phase t in FIG. 12) of a plurality of time phases.

  The adder circuit calculates the total sum (luminance sum) of echo data constituting the line data obtained from the center frame (or center beam). The luminance sum calculated for each time phase (each time) over a plurality of time phases (a plurality of times) in the adder circuit is shifted step by step by one time phase in the three buffers at the subsequent stage. Luminance sums corresponding to the three time phases to be output are sent to the LPF circuit.

  The LPF circuit obtains a luminance sum after LPF (low-pass filter) processing from luminance sums corresponding to three time phases. For example, an addition value or an average value of luminance sums corresponding to three time phases is output as the luminance sum after LPF. The luminance sum after LPF calculated for each time phase (each time) over a plurality of time phases (a plurality of times) in the LPF circuit is shifted step by step by one time phase in the subsequent three buffers. The luminance sum after LPF corresponding to the three time phases output from one buffer is sent to the peak detection circuit.

  The peak detection circuit detects a time phase at which the luminance sum reaches a maximum value (peak) from the luminance sum after LPF corresponding to the three time phases. In the peak detection circuit, time phases in which the luminance sum after LPF reaches a maximum value are detected one after another, and a detection trigger indicating the detection timing is output. The pulse circuit generates a trigger signal that rises at the detection timing based on the detection trigger obtained from the peak detection circuit.

  Returning to FIG. 1, the control unit 100 generally controls the inside of the ultrasonic diagnostic apparatus in FIG. 1. 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 80.

  Among the configurations (respectively assigned parts) shown in FIG. 1, the transmission / reception processing unit 12, the frame forming unit 20, the tomographic image forming unit 30, the region of interest setting unit 32, the projection data forming unit 34, the scan range setting unit 36, and the scan conditions The setting unit 40, the reconstruction processing unit 50, the three-dimensional image forming unit 52, the display processing unit 60, and the trigger generation unit 70 can be realized by using hardware such as an electric / electronic circuit or a processor, for example. In the implementation, a device such as a memory may be used as necessary. Further, at least a part of the functions corresponding to the above-described units may be realized by a computer. That is, at least a part of the 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 data storage unit 22 can be realized by a storage device such as a semiconductor memory or a hard disk drive. A preferred specific example of the display unit 62 is a liquid crystal monitor or the like. The operation device 80 can be realized by at least one of a mouse, a keyboard, a trackball, a touch panel, and other switches, for example. And the control part 100 is realizable by cooperation with hardwares, such as CPU, a processor, a memory, and the software (program) which prescribes | regulates operation | movement of CPU, a processor, for example.

  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.

  10 probe, 12 transmission / reception processing unit, 20 frame forming unit, 22 data storage unit, 30 tomographic image forming unit, 32 region of interest setting unit, 34 projection data forming unit, 36 scan range setting unit, 40 scan condition setting unit, 50 re Configuration processing unit, 52 3D image forming unit, 60 display processing unit, 62 display unit, 70 trigger generation unit, 80 operation device, 100 control unit.

Claims (8)

A scan processing unit that executes a reconstruction scan that repeats a scan that forms a scan plane while changing a position in a scan direction in a three-dimensional space including the heart over a plurality of heartbeats of the heart;
A reconstruction processing unit for obtaining a reconstruction volume of a plurality of time phases constituting one heartbeat period of the heart based on a plurality of frames obtained from a scanning plane formed one after another by repeating the scanning;
A condition setting unit for setting a repetition condition of the scan based on the depth of the heart;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The condition setting unit sets the scanning repetition condition based on the depth of the heart and the target resolution in the scanning direction of the reconstruction volume.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 2,
The condition setting unit sets the number of repetitions of the scan or the repetition time of the scan as the scanning repetition condition based on the depth of the heart, the target resolution, and the scanning range in the scanning direction of the reconstruction scanning. ,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 3.
The condition setting unit derives an inter-frame angle based on the heart depth and the target resolution, derives a target frame number of a plurality of frames constituting a reconstruction volume based on the scanning range and the inter-frame angle, Deriving the number of repetitions of the scan or the repetition time of the scan based on a target number of frames;
An ultrasonic diagnostic apparatus. In the ultrasonic diagnostic apparatus according to any one of claims 1 to 4,
An ultrasonic diagnostic apparatus, further comprising: a scan range setting unit that sets a scan range in a scan direction of the reconstruction scan based on data obtained by executing a pre-scan prior to the reconstruction scan. . The ultrasonic diagnostic apparatus according to claim 5,
The scan range setting unit forms projection data of the heart based on data obtained by prescan, and sets the scan range based on the projection data.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 6,
A trigger for generating a trigger signal indicating the timing of characteristic time phases detected successively over the plurality of heartbeats by detecting characteristic time phases one after another based on echo data obtained from the heart over a plurality of heartbeats. A generator,
The scan processing unit forms a scan surface while changing the position stepwise in the scan direction according to the timing of the characteristic time phase indicated by the trigger signal in the reconstruction scan.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 7,
The scan processing unit executes the reconstruction scan while forming a plurality of scan planes by parallel reception at each position while changing the position in the scan direction.
An ultrasonic diagnostic apparatus.