JP2014068980A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus which achieves elimination of resetting of a sample gate even when an object tissue moves, and also which can set a plurality of sample gates.SOLUTION: Two sample gates can be set on a tomographic image 52, and follow-up control can be performed according to the movement of object tissues 58A, 64A in each sample gate. To be concrete, in each follow-up control, a template is obtained at a point of time when a sample gate is set first, and a two-dimensional movement vector is calculated by pattern matching between the template and each reference area on a current frame. A new setting position for the sample gate is calculated on the basis of such a two-dimensional movement vector.

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a technique for setting a sample gate.

  In the pulse Doppler method, Doppler components obtained by transmitting an ultrasonic pulse to a target part and receiving a reflected wave from the target part are subjected to frequency analysis, and the analysis result is displayed on a screen as a Doppler waveform. In order to designate a part from which the Doppler component is acquired, a sample gate (observation part or measurement point) is set on the tomographic image using a marker or a cursor. Specifically, the Doppler beam direction is designated, and the sample gate is set to a specific depth on the direction. Conventionally, the spatial position of the sample gate is fixed in time, and the spatial position of the sample gate does not change even if the target site moves. If the sample gate is removed from the target site, the sample gate must be manually set again. If the target part does not move almost like an adult, once the sample gate is set, the sample gate is not likely to be detached from the target part, and it is necessary to reset the sample gate as an examiner. There are few cases, and stress does not occur much in the examiner.

  However, in recent years, the fetal heart has been observed, and it often occurs that the fetus being observed moves relative to the probe. In other words, once the sample gate is set, if the fetus moves (even if the mother moves), it is necessary to start over from the beginning. In other words, when the sample gate has deviated from the target site, an operation for appropriately resetting the sample gate with respect to the target site on the tomographic image must be performed. Recently, an ultrasonic diagnostic apparatus capable of performing Doppler measurement simultaneously at two locations has been put into practical use. In such an apparatus, after the first sample gate is set, if the fetus moves during the setting of the second sample gate, the first sample gate is set after the setting of the second sample gate is completed. The setting must be re-executed, and the fetus may move during that time, and the work of setting the two sample gates is very heavy, especially when targeting the fetus. Yes. Of course, if the fetus moves before the measurement is completed after setting the two sample gates, the two sample gates must be set again from the beginning.

  Patent Documents 1 and 2 disclose ultrasonic diagnostic apparatuses that can simultaneously display a plurality of Doppler waveforms. Patent Documents 3 and 4 disclose ultrasonic diagnostic apparatuses that execute the B mode and the D mode. Patent Document 5 describes a sub-template method in inter-frame pattern matching processing.

JP-A-11-76237 JP 2009-136446 A JP-A-6-7348 JP 2005-58332 A JP 2012-115387 A

  Conventionally, if the sample gate is detached from the target part due to the movement of the target part, the sample gate must be set again, which is cumbersome. The problem was particularly noticeable when multiple sample gates were set for the fetal heart.

  An object of the present invention is to realize an ultrasonic diagnostic apparatus in which it is not necessary to reset a sample gate even if the positional relationship between a probe and a target site changes. Alternatively, it is to improve workability when setting the sample gate. Alternatively, it is to realize a lock-on type sample gate or a motion corresponding Doppler waveform display.

  The present invention provides movement information calculation means for calculating movement information for an observation site in the target tissue based on data obtained by performing beam scanning on the target tissue, and a beam scanning region based on the movement information. Control means for dynamically moving the sample gate in accordance with the movement of the observation site by dynamically changing the spatial position of the sample gate in the inside, and an ultrasonic beam for Doppler observation according to the spatial position of the sample gate. And Doppler waveform generation means for generating a Doppler waveform based on a Doppler component extracted by processing and processing a received signal.

  According to the above configuration, scanning of the ultrasonic beam is repeatedly performed on the target tissue, thereby acquiring a series of data such as a frame data string. Desirably, movement information is calculated in units of frame data by a pattern matching process between frames using a frame data sequence. In that case, the pattern matching process may be executed between the reference frame and each subsequent frame data, or the pattern matching process may be executed between adjacent frame data. In the case of an organ that moves periodically, it is desirable to adopt the former. In the pattern matching process, it is preferable to use frame data before scan conversion, but frame data after scan conversion may be used. The movement information may be calculated by applying a process other than the pattern matching process. For example, there are an echo tracking method, a method using tissue Doppler information, and the like. It is desirable to calculate two-dimensional movement information as movement information. Three-dimensional movement information may be calculated. The control means dynamically changes the spatial position of the sample gate based on the movement information. As a result, the sample gate moves following the movement of the target tissue (lock-on state). Therefore, a situation where Doppler information is obtained from outside the target organization can be prevented. In particular, in the case of a small blood flow part, it can be pointed out that the sample gate is easily detached from the blood flow part by the movement, but according to the above configuration, even in such a case, the movement of the blood flow part can be matched. Since the sample gate moves, the measurement reliability can be improved. The sample gate represents a measurement site or measurement point from which a Doppler component is extracted in the beam scanning region. It is sometimes expressed as a sample volume. Generally, a gate mark or a cursor representing a sample gate is displayed on the tomographic image at the time of setting the sample gate and thereafter. In the transmission / reception process, an ultrasonic beam for Doppler observation is formed so as to pass through the sample gate. In the received signal processing, the range gate is set at a position on the time axis corresponding to the depth of the sample gate. In general, the range gate is a signal extraction gate, and a signal cut out by the range gate is sent to an FFT operation unit to form a Doppler waveform. The time length of the sample gate, that is, the range gate may be variable by the user.

  Conventionally, once the sample gate is set, it is fixed on the beam scanning plane, and when the sample gate is reset by the user, the Doppler waveform is reset. This is because when the sample gate is changed, the beam forming conditions and received signal processing conditions up to that point cannot be maintained. In other words, when the sample gate is changed, the velocity range (vertical axis scaling of the Doppler waveform) usually changes as a result of changes in the crossing angle of the blood flow direction and the ultrasound beam. It can be said that it is natural to update.

  On the other hand, the above configuration actively changes the spatial position of the sample gate in accordance with the movement of the target tissue, and does not reset the Doppler waveform due to such a change in the spatial position. The Doppler waveform is continuously formed and displayed as a growth display. Therefore, in that sense, it can be said that the above configuration employs a system that is completely opposite to the conventional system, or can acquire information with temporal continuity that cannot be obtained in the past. In the above configuration, the problem that the scaling at each time in the Doppler waveform is different will be described. Unless the movement amount of the target tissue is excessive, the change in scaling due to the change in the beam angle is expected to be negligible. It is. If the movement amount becomes excessive, it can be dealt with as an error. Since the change amount of the beam angle is known in the apparatus, the waveform size can be corrected (vertical axis correction) if necessary. Further, the movement amount (particularly, the movement amount component in the beam scanning direction) may be displayed as a graph together with the Doppler waveform. According to such a configuration, it is possible to obtain an advantage that the Doppler waveform can be observed while recognizing the presence or degree of the flow velocity error with reference to the graph.

  The above configuration is particularly useful in diagnosis of the fetal heart. That is, for example, the left ventricle in the fetal heart is very small, and it is not easy to set the sample gate accurately there. In addition, if the fetus itself subsequently moves or the mother moves due to breathing, etc., the positional relationship between the probe and the left ventricle changes, that is, the sample gate moves away from the left ventricle. become. This forces the resetting of the sample gate, and if such cases occur frequently, the burden on the doctor or laboratory technician becomes very large. Further, when Doppler measurement is performed for a plurality of target parts by setting a plurality of sample gates, a process of setting the second sample gate to the second target part after setting the first sample gate to the first target part Therefore, the first sample gate often deviates from the first target region, and the stress of the doctor or the laboratory technician in such a case is very large. With respect to such a problem, according to the above configuration, once the sample gate is set for the target portion, a lock-on state is formed, so that even if the target portion subsequently moves, the sample gate follows and moves. Therefore, the problem of detachment of the sample gate from the target site does not occur. In addition, if the above configuration is expanded so that sample gate tracking control is performed independently for a plurality of target parts, even if sample gates are set in order for a plurality of target parts, Since there is no situation where the sample gate set up to this point is detached from the target region, the workability can be made extremely good. The follow-up control is basically applied to the pulse Doppler method, but may be applied to the continuous wave Doppler method. However, in that case, the tomographic image is formed intermittently, and the sample gate is considered as a cross part of the transmission beam and the transmission beam.

  Preferably, the movement information calculation means calculates a movement component in the beam scanning direction and a movement component in the depth direction along the beam as the movement information, and the control means moves in the beam scanning direction. A transmission / reception control means for changing a beam address of the Doppler observation ultrasonic beam based on a component; and a means for setting a Doppler component extraction range gate as a gate corresponding to the sample gate for the received signal. And range gate control means for changing the position of the range gate on the time axis based on the moving component in the depth direction. According to this configuration, the direction of the ultrasonic beam for Doppler observation is adaptively set based on the moving component in the beam scanning direction, and the range gate set for the received signal based on the moving component in the depth direction. The position on the time axis is set adaptively. That is, both the beam direction and the sample depth are adaptively changed with the movement of the target portion. The time width of the range gate may be further dynamically changed. In that case, for example, not only the parallel movement amount between frames but also the rotational movement amount may be calculated, and the time width of the range gate may be changed according to the rotational movement amount.

  Preferably, image forming means for forming a tomographic image as a moving image based on a frame sequence obtained by performing beam scanning on the target tissue, and an ultrasonic beam azimuth for Doppler observation on the tomographic image. A means for combining and displaying a direction marker to be displayed and a gate marker representing the sample gate, and dynamically changing a relative display position of the direction marker and the gate marker with respect to the tomographic image based on the movement information. Display processing means. According to this configuration, it is possible to visually confirm the position of the sample gate on the tomographic image in relation to the target portion that moves. The orientation marker and the gate marker may be configured to move in accordance with the movement of the target tissue on the tomographic image. It is desirable to adopt such a configuration when a plurality of sample gates are set. It is also possible to move the tomographic image side so that the orientation marker and the gate marker are fixedly displayed on the display screen, that is, the target tissue is fixedly displayed. In that case, usually, the cut-out area to be displayed in the tomographic image is dynamically changed.

Preferably, the movement information calculation means includes a registration means for registering data in a sample gate-containing area in a reference frame obtained by performing beam scanning on the target tissue as a template, and the target tissue. Matching processing means for calculating the movement information in units of frame data by applying a matching process using the template to each target frame data after the reference frame obtained by performing beam scanning on the frame; The template is divided into a plurality of sub-templates, and the matching processing means sequentially sets a reference area while changing a setting position for each of the target frame data, and the plurality for each setting position. Sub-templates and multiple sub-areas within the reference area Means for determining a plurality of effective sub-pairs from a sub-pair group with the data, means for calculating a correlation value based on the plurality of effective sub-pairs for each set position, and corresponding to the plurality of set positions Means for calculating the movement information by obtaining an optimal combination setting position based on a plurality of correlation values. According to this configuration, in the inter-frame pattern matching process, the entire template is not subjected to comparison, for example, a portion with very low similarity is excluded and the remaining area is set as an effective area, and the correlation value for the effective area is determined. (Similarity) can be calculated. Thereby, the influence of the heart wall boundary etc. from which a form changes with time phases can be reduced, for example. It is desirable to set the template so that the real tissue is included beyond the blood flow part. This is because even if pattern matching is performed between blood flow portions, an effective correlation value cannot often be obtained.

  The present invention provides a movement for calculating first movement information and second movement information for a first observation site and a second observation site in the target tissue based on data obtained by performing beam scanning on the target tissue. The first sample gate is moved along with the movement of the first observation site by dynamically changing the spatial position of the first sample gate in the beam scanning region based on the information movement means and the first movement information. In accordance with the movement of the second observation region, the first follow-up control for following movement is executed, and the spatial position of the second sample gate in the beam scanning region is dynamically changed based on the second movement information. Control means for performing a second follow-up control for making the second sample gate follow-up, and a first Doppler observation ultrasonic beam according to a spatial position of the first sample gate. And generating a first Doppler waveform based on the Doppler component extracted by processing the first received signal and forming a second Doppler observation ultrasonic beam according to the spatial position of the second sample gate. And Doppler waveform generation means for generating a second Doppler waveform based on the Doppler component extracted by processing the second received signal.

  In the above configuration, the first tracking control and the second tracking control (and the first Doppler waveform processing and the second Doppler waveform processing) are configured as independent processes. That is, immediately after the setting of the first sample gate is completed, the execution of the first follow-up control is started, and the first follow-up control is continued without being affected by the subsequent setting work of the second sample gate. The reverse is also true. According to such a configuration, when the sample gates are sequentially set for a plurality of target parts, it is possible to avoid the sample gate set in the past from being removed from the target part. Therefore, workability can be made extremely good.

  Preferably, the control means includes the first follow-up control and the second follow-up control when there is a user operation to change a spatial position of one of the first sample gate and the second sample gate. Is interrupted and the other of the first follow-up control and the second follow-up control is continued. According to this configuration, even when manual resetting is required for one sample gate among a plurality of sample gates, the setting state of other sample gates can be maintained. Don't return.

  According to the present invention, it is not necessary to reset the sample gate even if the positional relationship between the probe and the target region changes. Alternatively, workability when setting the sample gate can be improved. Alternatively, a lock-on type sample gate or a motion-compatible Doppler waveform display can be realized.

1 is a block diagram showing a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention. It is a figure which shows the setting state of two sample gates before a tissue movement. It is a figure which shows the setting state of two sample gates after tissue movement. It is a figure for demonstrating tracking control of two sample gates. It is a figure for demonstrating the pattern matching process using a template. It is a flowchart for demonstrating tracking control of a sample gate. It is a flowchart for demonstrating a subtemplate method. It is a conceptual diagram for demonstrating the subtemplate method. It is a figure which shows the movement amount graph displayed with a Doppler waveform. It is a figure for demonstrating the Doppler waveform after reset. It is a figure for demonstrating the transmission / reception sequence which consists of formation of the beam for B modes, and the formation of the beam for D modes.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration thereof. This ultrasonic diagnostic apparatus is installed in a medical institution, and performs ultrasonic diagnosis of a fetus particularly in obstetrics. Of course, ultrasonic diagnosis may be performed on other tissues.

  The probe 10 is used in contact with the body surface. In the present embodiment, the probe 10 is contacted with the abdominal surface of the mother body. The probe 10 includes a 1D array transducer including a plurality of vibration elements. An ultrasonic beam is formed by the array transducer, and the ultrasonic beam is electronically scanned. As electronic scanning methods, electronic sector scanning, electronic linear scanning, and the like are known. A scanning surface is formed by electronic scanning of the ultrasonic beam, and a B-mode image, that is, a tomographic image, is formed based on frame data corresponding to the scanning surface. When the D mode (pulse Doppler mode) is selected, the Doppler observation ultrasonic beam is repeatedly formed with respect to the set Doppler beam azimuth. In this embodiment, as will be described later, the B mode and the D mode are executed simultaneously. A transmission / reception sequence for that purpose will be described later with reference to FIG. A 2D array transducer that forms a three-dimensional echo data capturing space may be provided for the probe 10.

  The transmission unit 12 is a transmission beam former, and at the time of transmission, a plurality of transmission signals are supplied from the transmission unit 12 to the array transducer, thereby forming a transmission beam. The reflected wave from the living body is received by the array transducer, and a plurality of reception signals are sent from the array transducer to the receiving unit 14. The reception unit 14 is a reception beam former, and generates a reception signal after phasing addition, that is, beam data, by phasing addition processing for a plurality of reception signals, and outputs it.

  The transmission / reception control unit 18 provided in the control unit 16 performs transmission / reception control in accordance with an operation mode designated by the user, and specifically controls the operations of the transmission unit 12 and the reception unit 14. When the B / D mode is selected, a predetermined transmission / reception sequence is executed. Specifically, transmission / reception control is performed so that the ultrasonic beam is repeatedly scanned electronically with respect to the B mode. In the D mode, transmission / reception control is performed so that an ultrasonic beam is repeatedly formed in the Doppler observation direction. Although the B-mode ultrasonic beam and the D-mode ultrasonic beam are usually different, they may be configured by the same beam. In realizing the D mode, a sample gate is set for a target region (for example, the left ventricle in the fetal heart) on the tomographic image, and the Doppler observation ultrasonic beam is obtained so that Doppler information can be obtained from the sample gate. And the position of the range gate on the time axis with respect to the received signal obtained thereby is set. These techniques are known. In the present embodiment, as will be described later, a plurality of sample gates are simultaneously set on the same beam scanning plane.

  The Doppler signal processing unit 20 includes, for example, a quadrature detection circuit, a range gate circuit, a sample hold circuit, an FFT calculator, and the like, and executes a process of extracting a Doppler component in the sample gate. The extracted signal component is sent to the Doppler waveform forming unit 22. The Doppler waveform forming unit 22 includes an FFT calculator and an image processing unit that generates a Doppler waveform based on an output signal thereof. Information representing the Doppler waveform is sent to the display processing unit 24. In the present embodiment, the Doppler signal processing unit 20 executes signal processing corresponding to two sample gates, and the Doppler waveform forming unit 22 has a function of generating two Doppler waveforms corresponding to two sample gates. It has. For example, it is possible to set a sample gate for each of two blood flow parts in the fetus, for example, an arterial vascular part and a venous vascular part.

  The luminance signal processing unit 26 is a module that executes signal processing for forming a B-mode image, that is, processing of beam data. The luminance signal processing unit 26 includes a detector, a logarithmic compressor, a gain adjuster, and the like. Has been. The tomographic image forming unit 28 is a module that forms a B-mode image as a tomographic image based on the beam data after signal processing. The tomographic image forming unit 28 is constituted by a digital scan converter in this embodiment. The formed tomographic image data is sent to the display processing unit 24.

  The display processing unit 24 has an image composition function, a color coding function, and the like. In the present embodiment, the display processing unit 24 composes a display image by combining one tomographic image and two Doppler waveforms, and sends the image data to the display unit 30. The control unit 16 includes a graphic plane creation unit (not shown), and image data representing the created graphic plane is sent to the display processing unit 24. As will be described later, the graphic plane includes a marker indicating a Doppler direction, a cursor indicating a sample gate, a baseline constituting a Doppler waveform, and the like. When the position information is displayed as a graph on the screen as will be described later, such a graph also constitutes a part of the graphic image.

  Next, the movement vector calculation module 32 will be described. The beam data output from the luminance signal processing unit 26 is sent to the movement vector calculation module 32. That is, the beam data according to the polar coordinate system before the scan conversion is given to the movement vector calculation module 32. The movement vector calculation module 32 is realized, for example, as a software function or configured as hardware. It calculates the two-dimensional movement vector of the target part for each sample gate by inter-frame pattern matching processing. In the present embodiment, the sub-template method is used as the pattern matching process. This will be described later with reference to FIGS.

  Specifically, the motion vector calculation module 32 stores two templates corresponding to two sample gates in the frame memory 34. More specifically, in the present embodiment, one or a plurality of reference frames including two templates are stored. It is stored in the frame memory 34. The reference frame is frame data at the time when the sample gate is set. Usually, when the first sample gate is set and when the second sample gate is set, two reference frames are defined, and their frame data is stored in the frame memory 34. However, since only the template is used as the data portion, only two template portions may be stored in the frame memory 34. The frame memory 36 sequentially stores frame data for subsequent frames after the reference frame. That is, the frame memory 34 and the frame memory 36 constitute a storage unit for performing pattern matching between frames. The frame memory 34 is a memory for registering a template first, and the frame memory 36 is a memory for sequentially storing current frames. In the present embodiment, the pattern matching process is executed between the reference frame and the current frame, but the pattern matching process may be executed between adjacent frames.

  The first matching processing unit 38 performs pattern matching processing with the current frame using the first template. The first matching processing unit 38 includes a first movement vector calculator 40. As will be described later, the first movement vector calculator 40 is a module that calculates a two-dimensional movement vector from a position of a reference area that best matches the template as a result of pattern matching processing. . In this embodiment, as the two-dimensional movement vector, the moving amount in the azimuth direction, that is, the beam scanning direction, and the moving amount in the beam direction, that is, the depth direction are separately calculated, and the information is the first position adjustment. Sent to section 46.

  The second matching processing unit 42 performs inter-frame pattern matching processing on the second sample gate. Specifically, the matching processing is performed between the template and data in the reference area set on the current frame. Is to execute. The second movement vector computing unit 44 obtains a two-dimensional movement vector in the same manner as described above based on the position where the reference area having the highest correlation value with respect to the template exists, and the amount of movement in the azimuth direction representing it The movement amount in the depth direction is output to the second position adjustment unit 48.

  The first position adjustment unit 46 adaptively changes the spatial position of the first sample gate based on the first movement vector calculated by the first movement vector calculator 40. The two-position adjusting unit 48 adaptively changes the spatial position of the second sample gate based on the two-dimensional movement vector calculated for the second sample gate. Since the first movement vector indicates the amount of movement of the first target region and the second movement vector indicates the amount of movement of the second target region, the first position adjustment unit 46 and the second position adjustment unit 48 function. As a result, two sample gate lock-in states are formed for two target parts. That is, if the target part moves, the sample gate set on the target part also follows and moves together.

  Based on the new spatial positions of the two sample gates set by the first position adjustment unit 46 and the second position adjustment unit 48, the transmission / reception control unit 18 generates two Doppler observation ultrasonic beams. The transmitter 12 and the receiver 14 are controlled so that two range gates are formed, and the Doppler signal processor 20 is controlled. The input unit 50 represents an operation panel.

  FIG. 2 shows a first display example. FIG. 2 shows a state before the two target parts move. Specifically, reference numeral 52 indicates a tomographic image, reference numeral 54 indicates a first Doppler waveform, and reference numeral 56 indicates a second Doppler waveform. On the tomographic image 52, the first blood flow part 58 and the second blood flow part 64 appear. For example, the first blood flow part 58 is an arterial blood vessel part, and the second blood flow part 64 is a venous blood vessel part. The angle of the first Doppler beam orientation marker 60 is manipulated on the screen by the examiner, and the angle of the first Doppler beam orientation marker 60 is set so as to pass through the first blood flow part 58. Then, the position of the first cursor 62 on the first Doppler beam direction marker 60 is determined by the examiner, and specifically, the first cursor 62 is determined so as to be positioned at the center of the first blood flow part 58. In addition, when the 1st cursor 62 is moved to an azimuth | direction direction, you may comprise so that the 1st Doppler beam azimuth | direction marker 60 may move interlockingly. Similarly, the second Doppler beam direction marker 66 is set so as to pass through a specific part in the second blood flow part 68, and the second cursor 68 is set at a specific depth thereon. Each of the first cursor 62 and the second cursor 68 represents a spatial position of the sample gate on the beam scanning plane. The length of each cursor 62, 68 in the depth direction represents the size of the sample gate in the depth direction.

  When the position of the first cursor 62 is determined, the pulse Doppler method for the first sample gate is executed, and as a result, the first Doppler waveform 54 is generated. There are several display methods for the Doppler waveform 54. In this embodiment, the display form is determined so that the Doppler waveform 54 grows from the left end to the right end. Of course, a scroll method may be adopted. Similarly, when the position of the second cursor 68 is determined, that is, when the spatial position of the second sample gate is determined, the pulse Doppler method is executed, and the second Doppler waveform 56 is displayed as described above. Will be.

  In the conventional ultrasonic diagnostic apparatus, the sample gate does not follow the movement even when the target tissue moves, and thus a problem as shown in FIG. 3 may occur. That is, the first blood flow part 58 has moved to the position indicated by reference numeral 58A on the tomographic image 52 due to the movement of the fetus, the mother's breathing, and the like, and similarly, the second blood flow part 64 is indicated by reference numeral 64A. It has moved to the position shown. If the spatial positions of the two sample gates remain fixed with respect to such body movement, the respective sample gates will be disengaged from the target blood flow, and the Doppler waveforms 54 and 56 are inappropriate. It becomes a thing.

  On the other hand, according to the apparatus of the present embodiment, the follow-up control according to the movement of the target part is realized for each of the two sample gates. It is possible to maintain. That is, when the first blood flow portion moves on the tomographic image 52 as indicated by reference numeral 58A, the movement amount is detected by the inter-frame pattern matching processing, and the first sample gate is detected based on the movement amount. It is possible to change the spatial position. Specifically, the cursor 62A moves together with the first blood flow part 58A, and the spatial position of the first sample gate is maintained in an appropriate state in relation to the first blood flow part 58A. At that time, the Doppler observation beam azimuth is also changed. Specifically, the angle of the marker 60A representing it is automatically changed. Similarly, even when the second blood flow part moves as indicated by reference numeral 64A, the movement amount is detected by the inter-frame pattern matching process, and the spatial position of the second sample gate is determined according to the movement amount. Has been reset. As a result, the position of the cursor 68A in the azimuth direction and the depth direction is updated, and the angle of the marker 66A indicating the Doppler observation beam azimuth is changed accordingly. Thereby, it is possible to always set the second sample gate correctly for the second blood flow portion. By realizing the follow-up control for each of the first sample gate and the second sample gate as described above, it is possible to continuously display the Doppler waveform display as indicated by reference numerals 54 and 56. Inspection efficiency can be increased. Incidentally, when the amount of movement of the target part becomes excessive, it is sufficient to determine that and apply error processing. In the follow-up control, the positions of the cursors 62A and 68A and the markers 60A and 66A are dynamically changed on the tomographic image 52 individually following the movements of the two target tissues. When setting a single sample gate, the tomographic image display position is dynamically changed so that the cursor and marker are fixedly displayed on the display screen, that is, the display position of the target tissue is fixed. Also good. In that case, it is also possible to dynamically change the position of the cutout region (partial region including the target tissue) from the tomographic image.

  Incidentally, even if the Doppler beam azimuth is changed as the target part moves, that is, even if the beam angle changes, the amount of change is not so large as shown in the figure, so the scaling error on the Doppler waveform is not a big problem. However, since the changed angle is known, the scaling in the vertical axis direction, that is, the mapping, in the Doppler waveform can be changed from the angle. Further, as will be described later, it is also possible to observe the Doppler waveform while confirming the degree of error by displaying the amount of movement, particularly the moving component in the beam scanning direction, in a graph.

  In the present embodiment, two sample gates are set in order, and when the first sample gate is set in advance, the first sample gate is not waited for completion of setting the second sample gate. Follow-up control is being executed immediately. Therefore, even when the fetus moves during the setting of the second sample gate, it is possible to maintain the setting state of the first sample gate, and the problem of re-setting the sample gate does not occur. Further, as will be described later, even when the spatial position of any sample gate is manually corrected by an inspector during diagnosis, the setting state of the sample gate that is not the correction target is maintained, that is, Since the follow-up control is continuously executed, the complexity of having to reset all the sample gates is also eliminated.

  FIG. 5 shows the concept of the inter-frame pattern matching process. Reference numeral 68 represents a reference frame. Normally, two reference frames are generated, but one reference frame 68 is shown in FIG. 5 for convenience. On the other hand, reference numeral 77 represents the current frame. The current frame to be compared is sequentially switched according to the progress of the time axis.

  Two sample gates 70 and 72 are set on the reference frame 68. A first template 74 is set as an area containing the sample gate 70 as a center, and the sample gate 74 is set as a center. A second template 76 is set as an included area. The horizontal direction in the reference frame 68 represents the beam direction, and the vertical direction represents the depth direction. Therefore, the first template 72 is constituted by data over a specific depth range among a plurality of beam data arranged in the beam direction, and the same applies to the second template 76. Incidentally, the first template 72 and the second template 74 are expressed in a rectangular shape when the beam orientation and the depth direction are represented on the orthogonal coordinate system, while the trapezoidal shape is displayed on the sector-shaped ultrasonic image. It is considered as an area.

  The pattern matching process using the first template 72 will be described. The corresponding area 72A can be conceived at the same position as the first template 72 on the current frame 77, and the search area is a region extending from the center with a predetermined size. 78 is defined. In the search area 78, for example, the reference area 80 is sequentially set while changing the setting position like a raster scan. Then, a matching process such as a correlation calculation is performed between the area data in the reference area at each position and the first template 72, and a correlation value representing the degree of similarity is obtained. Therefore, a plurality of correlation values corresponding to a plurality of setting positions are obtained. Among them, the best correlation value is specified. A two-dimensional movement vector 82 is defined as a movement amount from the center position of the corresponding area 72A to the center of the reference area 80 where the best correlation value is obtained. Actually, the two-dimensional movement vector 82 is composed of a movement component in the azimuth direction and a movement component in the depth direction. Similarly to the above, for the second template, that is, the second sample gate, the corresponding area 76A is defined on the current frame 77, the search area 84 is set as an area having a certain spread from the center, and each position within the range is set. A reference area 86 is set, and a correlation value calculation is executed between the second template 76 and the data in the reference area 86 for each position, and a plurality of correlation values corresponding to a plurality of setting positions are obtained. Then, the best correlation value is identified from among them. A two-dimensional movement vector 88 is obtained as a vector connecting the center of the corresponding area 76A to the reference area center position where the best correlation value is generated.

  The sizes of the search areas 78 and 84 can be changed according to various conditions. In addition, each frame may be preprocessed prior to the pattern matching process. When a sample gate is set for the heart and pattern matching processing is performed for follow-up control, the pattern matching processing may not be performed properly due to the influence of the beating heart wall boundary. Therefore, in this embodiment, a sub-template method described later is adopted.

  FIG. 6 shows a flowchart representing the follow-up control in the ultrasonic diagnostic apparatus shown in FIG. This flowchart is executed for each sample gate, and each process is independent in this embodiment. In S10, the cursor is initially set on the target part on the B-mode image. That is, the sample gate is initialized. In this case, the sample gate is specified by the azimuth θ, the depth d, and the width w in the depth direction. In S12, a template is defined as an area having a certain spread from the center of the sample gate, and is registered in the memory. You may comprise so that the size of a template can be variably set. It is also possible to adopt a one-dimensional template or the like as a template. In S14, conditions for performing the D-mode process are set based on the above-described initial setting. Specifically, transmission / reception conditions and reception signal processing conditions are determined. The Doppler observation beam azimuth θ is determined as the transmission / reception condition, the diagnostic depth BD on the beam is determined, and the position RG of the range gate set for the reception signal is set as the reception signal processing condition. The diagnostic depth BD may be the same as the diagnostic depth in the B mode, but since it is not necessary to perform Doppler measurement for a portion deeper than the sample gate, the depth up to the end of the sample gate may be determined as the diagnostic depth. Good. Specifically, it is desirable that the pulse repetition frequency (PRF) is variably set according to the depth of the sample gate.

  In S16, it is determined whether or not the cursor has been manually moved by the examiner. When such movement is determined, the processes from S12 are executed again. That is, each process for registering a new sample gate corresponding to a new cursor position is executed.

  In S18, a matching process is executed. That is, as described above, the pattern matching process is sequentially executed between the template and the reference area in the current frame. As a result, a two-dimensional movement vector is obtained from the position where the best correlation value can be obtained. In S20, the amount of movement, that is, the size of the two-dimensional movement vector is referred to. If there is no movement, S26 is executed as it is. If it is determined that the movement is small, S22 is executed and the movement is large. If it is determined, S24 is executed. In S22, control for setting the cursor, that is, the sample gate to follow the movement of the target tissue is executed, that is, the orientation, depth, etc. of the sample gate are set again. On the other hand, in S24, the error process is executed because the movement is excessive. In that case, for example, the processing is interrupted and a certain message or the like is provided to the user. In S26, it is determined whether or not to continue this process, and in the case of continuing, each process from S16 is repeatedly executed.

  Therefore, the motion of the target tissue is detected by the inter-frame matching process, and if there is a motion, control is performed to move the cursor, that is, the sample gate in accordance with that motion. The sample gate can be moved according to the movement. As a result, since the sample gate does not deviate from the target tissue, the Doppler waveform can be made appropriate, and problems such as interruption of the Doppler waveform can be prevented. Thereby, it is possible to realize continuous Doppler waveform observation for a pulsating blood flow part that cannot be obtained in the past. When the user manually moves the cursor, the template is taken in again. Even in such a case, the processing for the other sample gates is continuously performed without any influence, so that the trouble of resetting the other sample gates does not occur.

  Next, the sub-template method described above will be described with reference to FIGS. The sub-template method corresponds to partial correction in the pattern matching process, and in particular, the matching process is performed for the remaining effective part where a part is excluded rather than the entire template. In S30 of FIG. 7, the initial value 1 is substituted for the parameter k. In S32, the reference area is set at the kth position in the search area. In S34, prior to the calculation of the correlation value of the entire template, the correlation value is calculated in units of individual sub-templates. That is, a correlation value is calculated in units of subpairs between a plurality of subarea data and a plurality of subtemplates constituting area data in the reference area. In S36, one or a plurality of sub-templates whose correlation values are lower than a predetermined value are excluded from the plurality of sub-templates, and the remaining ones are regarded as an effective sub-template group. That is, sub-pairs having a low correlation value among a plurality of sub-pairs are excluded, and the remaining sub-pairs are regarded as effective sub-pair groups. In S36, correlation values are calculated for those effective sub-template groups, that is, sub-pair groups. The correlation value can be said to be an overall correlation value for the entire template. In S38, it is determined whether or not k has reached the maximum value. If the maximum value has not been reached, k is incremented by 1 in S40, and the steps after S32 are repeatedly executed. In S42, the reference area having the maximum overall correlation value is determined, and a two-dimensional movement vector is calculated from the position.

  FIG. 8 conceptually shows the above processing contents. Reference numeral 90 denotes a template, and reference numeral 100 denotes a search area in the current frame. A reference area 94 is set at a certain position. The template 90 includes a plurality of sub-templates 92, that is, is divided into a plurality of sections. Similarly, the reference area 94 is divided into a plurality of areas, thereby defining a plurality of sub areas 96. Correlation values are calculated for each sub-pair between the plurality of sub-templates 92 and the plurality of sub-area data, and sub-pairs with low correlation values are excluded as described above. Here, the gray expression is excluded, specifically, the sub-template 92a is excluded from the template 90, and the sub-area 96a is excluded from the reference area 94. The excluded portions 102 and 106 are, for example, a beating heart wall. Pattern matching processing is executed using the remaining effective areas 104 and 108, and as a result, a representative correlation value is calculated.

  FIG. 9 shows a modification of the display. Reference numeral 110 indicates a Doppler waveform, and reference numerals 112 and 114 indicate graphs representing movement amounts. Specifically, reference numeral 112 is a graph showing the temporal change of the moving component in the azimuth direction, and reference numeral 114 is a graph showing the temporal change of the moving component in the depth direction. By observing such a graph, it is possible to intuitively recognize how much movement has occurred in association with the time phase of the Doppler waveform, and it is possible to obtain reference information when evaluating the Doppler waveform. is there. For example, if there is a portion where the Doppler orientation has changed greatly, it can be recognized that the error in scaling is large.

  FIG. 10 shows a case where a reset for one Doppler waveform occurs. Reference numeral 114 denotes a Doppler waveform corresponding to the first sample gate, in which a position change by the user has occurred, that is, a reset of the Doppler waveform has occurred. Reference numeral 118 denotes a blank period caused by the reset. On the other hand, continuous waveform growth is observed for the second Doppler waveform indicated by reference numeral 116, that is, even if one sample gate is manually reset, the processing for the other sample gate is not affected. As a result, there is no need to reset the sample gate.

  FIG. 11 shows some transmission / reception sequence examples in the B / D mode. Here, the block including the letter B indicated by reference numeral 128 represents one transmission / reception for the B mode, and the block including the letter D indicated by reference numeral 130 represents one transmission / reception in the D mode. In executing the B mode, it is necessary to form an ultrasonic beam for each beam direction, and in executing the D mode, it is necessary to repeatedly form an ultrasonic beam for a specific beam direction.

  In the first example shown in (A), the B mode transmission / reception 128 and the D mode transmission / reception 130 are executed alternately in each frame 120, 122, 124, 126. In this example, only one sample gate is set.

  In the second example shown in (B), transmission / reception in the B mode is continuously executed repeatedly within the period indicated by reference numeral 132, thereby forming one or more B-mode frames. The same applies to the period 136. On the other hand, the periods 134 and 138 are periods having an arbitrary time length, and transmission / reception for the D mode is continuously repeated within the period.

  In the third and fourth examples shown in (C) and (D), two sample gates are set. In the third example, in the period 140, transmission / reception is sequentially performed in the order of B-mode transmission / reception, first sample gate transmission / reception, D-mode transmission / reception, and second sample gate transmission / reception. The same applies to 144 and 146. Each of the periods 140 to 146 corresponds to one frame, for example.

  In the fourth example shown in (D), transmission / reception for B mode is repeatedly executed continuously in two periods 148 and 154, which correspond to one or a plurality of frames. In the period 150, transmission / reception for the first sample gate is continuously repeated, and in the subsequent period 152, transmission / reception for the second sample gate is continuously repeated. All the transmission / reception sequences shown in FIG. 11 are examples, and it is desirable to set an optimal transmission / reception sequence according to the purpose and various conditions. For example, it is desirable to determine a desired transmission / reception sequence from the viewpoint of the frame rate of the B-mode image, the maximum flow velocity at which Doppler observation is performed, and the like.

  According to the configuration of the embodiment described above, it is possible to lock on the sample gate with respect to the target tissue, that is, to move the sample gate following the target tissue so that it does not come off with the movement of the target tissue. It is possible to display the growth of the Doppler waveform without interruption even during such a movement process. Therefore, it is different from the conventional Doppler waveform display in that the target tissue to be moved is expressed as one Doppler waveform regardless of the movement. In the present embodiment, since two sample gates are set and tracking control is realized for each of them, there is an advantage that a plurality of Doppler waveforms as described above can be displayed simultaneously.

  In addition, according to the present embodiment, when a plurality of sample gates are set, the tracking control for each sample gate is independent, so when one sample gate is set, the setting of the other sample gate is set. The tracking control for one of the sample gates can be started without waiting for completion. Therefore, even if the fetus moves during the setting of the other sample gate, it is possible to maintain the setting state of one of the sample gates that has been set so far, so that workability can be improved and the stress of the examiner can be greatly reduced Is obtained. In addition, even if the sample gate is changed manually by the user, it is possible to continue the tracking control for the sample gate that is not the target of change, so it is necessary to reset it even in that case. Therefore, there is an advantage that workability can be improved.

  DESCRIPTION OF SYMBOLS 10 Probe, 12 Transmission part, 14 Reception part, 18 Transmission / reception control part, 20 Doppler signal processing part, 22 Doppler waveform formation part, 26 Luminance signal processing part, 28 Tomographic image formation part, 32 Movement vector calculation module, 46 1st position Adjustment unit, 48 Second position adjustment unit.

Claims (6)

Movement information calculating means for calculating movement information for an observation site in the target tissue based on data obtained by performing beam scanning on the target tissue;
Control means for dynamically moving the spatial position of the sample gate in the beam scanning region based on the movement information to cause the sample gate to follow the movement of the observation site;
Doppler waveform generation means for generating a Doppler waveform based on a Doppler component extracted by forming a Doppler observation ultrasonic beam according to a spatial position of the sample gate and processing a received signal;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
The movement information calculation means calculates, as the movement information, a movement component in the beam scanning direction and a movement component in the depth direction along the beam,
The control means includes
A transmission / reception control means for changing a beam address of the ultrasonic beam for Doppler observation based on a moving component in the beam scanning direction;
A means for setting a range gate for Doppler component extraction as a gate corresponding to the sample gate with respect to the received signal, and changing the position of the range gate on the time axis based on the moving component in the depth direction Range gate control means,
An ultrasonic diagnostic apparatus comprising: The apparatus according to claim 1 or 2,
An image forming means for forming a tomographic image as a moving image based on a frame sequence obtained by performing beam scanning on the target tissue;
A means for combining and displaying an orientation marker representing an ultrasonic beam orientation for Doppler observation and a gate marker representing the sample gate on the tomographic image, and based on the movement information, the orientation marker and the gate for the tomographic image Display processing means for dynamically changing the relative display position of the marker;
An ultrasonic diagnostic apparatus comprising: The device according to any one of claims 1 to 3,
The movement information calculation means includes
Registration means for registering data in a sample gate-containing area in a reference frame obtained by performing a beam scan on the target tissue as a template;
Matching that calculates the movement information in units of frame data by applying a matching process using the template to each target frame data after the reference frame obtained by performing beam scanning on the target tissue Processing means;
Including
The template is divided into a plurality of sub-templates,
The matching processing means includes
Means for sequentially setting reference areas while changing the setting position for each target frame data;
Means for determining a plurality of effective sub-pairs from a sub-pair group between the plurality of sub-templates and a plurality of sub-area data in the reference area for each set position;
Means for calculating a correlation value based on the plurality of effective sub-pairs for each set position;
Means for calculating the movement information by obtaining an optimal combination setting position based on a plurality of correlation values corresponding to the plurality of setting positions;
An ultrasonic diagnostic apparatus comprising: Movement information calculation means for calculating first movement information and second movement information for the first observation site and the second observation site in the target tissue based on data obtained by performing beam scanning on the target tissue; ,
First moving the first sample gate in accordance with the movement of the first observation site by dynamically changing the spatial position of the first sample gate in the beam scanning region based on the first movement information. Tracking control is performed, and the second sample gate is moved in accordance with the movement of the second observation region by dynamically changing the spatial position of the second sample gate in the beam scanning region based on the second movement information. Control means for executing second follow-up control for following the gate;
A first Doppler waveform is generated based on a Doppler component extracted by forming a first Doppler observation ultrasonic beam according to a spatial position of the first sample gate and processing a first received signal, Doppler waveform generation means for generating a second Doppler waveform based on a Doppler component extracted by forming a second Doppler observation ultrasonic beam according to the spatial position of the sample gate and processing the second received signal;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 5.
The control means performs one of the first follow-up control and the second follow-up control when there is a user operation to change a spatial position of one of the first sample gate and the second sample gate. Suspending and continuing the other of the first follow-up control and the second follow-up control,
An ultrasonic diagnostic apparatus.