JP2019000150A - Ultrasonic diagnostic device and sample gate setting method - Google Patents

Abstract

To allow a sample gate to be set at an appropriate position automatically in an ultrasonic diagnostic device.SOLUTION: A center point P1 and a maximum flow speed point P2 are calculated based on blood flow data. Flow directions φ1 and φ2 are calculated based on the blood blow data on the center point P1 and the maximum flow speed point P2, and front wall directions φF1 and φF2, and rear wall directions φR1 and φR2 are calculated based on tissue data. After that, angular differences ΔφF11, ΔφR11, ΔφF22, and ΔφR22 indicating the parallelism are calculated, and, based on them, either one point is selected as a sample gate position from the center point P1 and the maximum flow speed point P2.SELECTED DRAWING: Figure 16

Description

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

  An ultrasonic diagnostic apparatus is a medical apparatus that forms an ultrasonic image based on a reception signal obtained by transmitting / receiving ultrasonic waves to / from a living body. As an operation mode (or diagnosis mode) in the ultrasonic diagnostic apparatus, a B mode, a CFM (Color Flow Mapping) mode, a Doppler mode, and the like are known. As the Doppler mode, a PW (Pulsed Wave Doppler) mode and a CW (Continuous Wave Doppler) mode are known. Furthermore, a harmonic component imaging mode and a three-dimensional mode are also known.

  In the CFM mode, a color blood flow image is superimposed and displayed on a black and white tomographic image (tissue image). A blood flow image is an image representing a two-dimensional velocity distribution or power distribution. In the following, ultrasonic examination of blood vessels (carotid artery, lower limb artery, etc.) will be described.

  In the execution state of the B mode, the position and posture of the probe are adjusted so that the cross section of the target blood vessel appears appropriately in the tomographic image displayed on the screen. Thereafter, the CFM mode is executed, whereby a color blood flow image is superimposed and displayed on a black and white tomographic image. In the CFM mode, the scanning of the ultrasonic beam for tissue observation and the scanning of the ultrasonic beam for blood flow observation are executed in parallel. The blood flow observation ultrasonic beam is usually tilted (steered) by a certain angle from the central axis of the probe. That is, the steered blood flow observation ultrasonic beam is scanned. The scanning range is defined by a region of interest (ROI). The region of interest defines a scanning direction range and a depth direction range in which blood flow is observed.

  Subsequently, when a predetermined operation is performed by the examiner, a marker (or cursor) representing the sample gate is displayed on the image (tomographic image and blood flow image) displayed in real time. By moving the marker on the image, the marker is positioned at a desired observation point in the blood vessel. Typically, a marker is set inside the stenosis site. The sample gate is a section for acquiring or extracting Doppler information. Ideally, it is set inside the bloodstream in the living body, but in practice it is a signal extraction section in the received signal. A power spectrum is generated by frequency analysis of a signal (Doppler information) extracted from the sample gate. A Doppler waveform is generated by expressing each power spectrum generated at each time as a luminance sequence. The horizontal axis of the Doppler waveform is the time axis, and the vertical axis represents the Doppler shift frequency, that is, the blood flow velocity. A power component for each frequency in the power spectrum is expressed by luminance.

  There are cases where the CFM mode automatically ends when the Doppler mode is turned ON during execution of the CFM mode, and cases where the CFM mode and the Doppler mode are executed concurrently. The sample gate is also called a sample volume or range gate. The region of interest is also referred to as a color ROI or color box.

  Patent Document 1 discloses an ultrasonic diagnostic apparatus that automatically sets a sample volume and a color box. In the apparatus, the position closest to the center of mass in the blood flow center path is specified, and the position is specified as the sample volume position. Subsequently, the color box is set so that the center of mass coincides with the center of the color box.

  Patent Document 2 discloses an ultrasonic diagnostic apparatus that automatically sets a sample gate. In the apparatus, a blood vessel region (blood vessel segment) is extracted based on color data or black and white data, and a sample gate is set at or near the center position. The sample gate size is determined based on the blood vessel size.

  In paragraph 0054 and subsequent paragraphs of Patent Document 3, an ultrasonic diagnostic apparatus that automatically sets a sample gate based on a tissue image and a blood flow image is disclosed. In the apparatus, first, a reference part is specified based on a tissue image, and an analysis range is specified based on the reference part. The maximum flow velocity point within the analysis range is specified based on the blood flow image. The maximum flow velocity point is the sample gate position.

  Patent Document 4 discloses an ultrasonic diagnostic apparatus that automatically adjusts the position of a range gate according to a blood vessel wall.

  Patent Document 5 discloses an ultrasonic diagnostic apparatus having an automatic transition function to the Doppler mode. In the apparatus, after the start of execution of the composite mode (combination of the Doppler mode and the B mode, etc.), the elapsed time is measured by a timer, and when the measured elapsed time reaches a predetermined time, the Doppler mode Control to automatically transition to is executed. During the measurement of the elapsed time, the timer is reset when a motion is detected in the B-mode image or the like.

Special table 2014-528266 gazette JP 2002-52026 A JP2015-156960A Special table 2003-523250 gazette JP 2005-296253 A

  According to the manual setting of the sample gate, a burden is caused on the inspector and the inspection time is prolonged. Objectivity and reproducibility may be a problem. Therefore, it is desirable to automate the setting of the sample gate. However, all of the techniques described in Patent Documents 1 to 4 determine the position of the sample gate uniformly or uniformly, depending on the situation. This causes a problem that the sample gate cannot be set at an appropriate position. For example, when a stenosis site exists, there is a need to set a sample gate inside the stenosis site. On the other hand, there is another need to set the sample gate stably. It is desired to realize an ultrasonic diagnostic apparatus capable of meeting those needs depending on the situation.

  An object of the present invention is to provide an apparatus and a method capable of automatically setting a sample gate at an appropriate position according to a situation.

  (1) An ultrasonic diagnostic apparatus according to an embodiment includes a wave transmitting / receiving unit that acquires tissue data and blood flow data by transmitting / receiving ultrasonic waves to / from a living body, and a blood flow region based on the blood flow data Calculating means for calculating a plurality of candidate points, selecting means for selecting specific candidate points from the plurality of candidate points based on the tissue data and the blood flow data, and based on the specific candidate points Setting means for setting a sample gate for measuring Doppler information.

  According to the above configuration, a plurality of candidate points are calculated based on the blood flow data. That is, one point is not specified uniformly or uniformly, but a plurality of candidate points are specified from a plurality of viewpoints. Subsequently, specific candidate points are selected from a comprehensive point of view in consideration of tissue data in addition to blood flow data. The specific candidate point may be used as the sample gate position as it is, or another position based on the specific candidate point may be used as the sample gate position.

  For example, since the maximum flow velocity point is likely to occur inside the stenosis region, it is desirable to include the maximum flow velocity point in the candidate point group. Since the center point of the blood flow region is a relatively stable point, it is desirable to include the center point in the candidate point group. The candidate point group may include a turbulent point or the like. The candidate point group may be composed of three or more candidate points.

  In the embodiment, the selection unit corresponds to the plurality of candidate points based on the tissue data and the flow direction calculation unit that calculates a plurality of flow directions corresponding to the plurality of candidate points based on the blood flow data. Wall direction calculating means for calculating a plurality of wall directions, and evaluation means for evaluating the plurality of flow directions and the plurality of wall directions in order to select the specific candidate point.

  According to the above configuration, a plurality of flow directions and a plurality of wall directions (direction set for each candidate point) corresponding to a plurality of candidate points are evaluated, and as a result, specific candidate points are selected. In general, the flow direction is specified as the flow angle, which can be calculated from blood flow data. Also, the wall direction is specified as the edge angle, which can be calculated from the tissue data. It is possible to evaluate the possibility of parallelism or a stenosis site for each candidate point from the mutual relationship between a plurality of directions (or a plurality of angles) for each candidate point.

  In the embodiment, the wall direction calculation means calculates a front wall direction and a rear wall direction for each candidate point as the plurality of wall directions, and the evaluation means calculates the plurality of flow directions, the plurality of front directions. The plurality of candidate points are evaluated based on the wall direction and the plurality of rear wall directions. According to this configuration, the front wall direction and the rear wall direction are calculated for each candidate point, and the possibility of being a stenosis site is evaluated based on them. The front wall is a blood vessel wall closer to the probe, and the rear wall is a blood vessel wall farther from the probe. Although it is possible to refer to only one of the front wall direction and the rear wall direction, plaque or the like can occur on either the front wall or the rear wall. It is a reference target.

  In the embodiment, the evaluation means, for each candidate point, the front side angle difference between the flow direction and the front wall direction, and the rear side angle difference between the flow direction and the rear wall direction, And means for selecting the specific candidate point from the plurality of candidate points based on a plurality of front angle differences and a plurality of rear angle differences for the plurality of candidate points. . The front angle difference and the rear angle difference are information indicating the degree of difference between the blood flow direction and the wall direction, respectively, and the possibility of being a stenosis site is determined using the information.

  In the embodiment, the plurality of candidate points include a maximum flow velocity point and a center point in the blood flow region. The concept of the center point includes a barycentric point, an average coordinate point, and the like.

  In an embodiment, it includes means for calculating a gate size based on at least one of the tissue data and the blood flow data, and the setting means sets the sample gate based on the specific candidate point and the gate size. . According to this configuration, not only the position of the sample gate but also the size of the sample gate is automatically set. Furthermore, the correction angle may be set automatically.

  In an embodiment, it includes means for creating a graph showing a periodic change in blood flow based on at least one of the tissue data and the blood flow data, and the update timing of the sample gate is determined based on the graph . According to this configuration, it is possible to determine the update timing even in a situation where an electrocardiogram signal is not obtained.

  (2) The sample gate setting method according to the embodiment is a method for setting a sample gate based on tissue data and blood flow data obtained by transmitting and receiving ultrasonic waves to and from a blood vessel in a living body, Calculating a plurality of candidate points in a blood flow region based on the blood flow data; calculating a flow direction based on the blood flow data for each candidate point; and calculating a wall direction based on the tissue data. A step of calculating, a step of selecting a specific candidate point from the plurality of candidate points based on a plurality of flow directions and a plurality of wall directions calculated for the plurality of candidate points, and the specific candidate point And setting a sample gate for Doppler information measurement based on the above.

  According to this configuration, after a plurality of candidate points in the blood flow region are calculated, candidate points are selected from them. When selecting, not only blood flow data but also tissue data is taken into account, so that the possibility of selecting candidate points suitable for the situation can be increased. The above method can be realized as a hardware function or as a software function. In the latter case, the sample gate setting program is installed in the ultrasonic diagnostic apparatus via a network or a portable storage medium.

  In the embodiment, the method further includes calculating a gate size based on the specific candidate point based on the blood flow data, and in the step of setting the sample gate, the specific candidate point and the specific point The sample gate is set based on the gate size, and an angle for Doppler information correction is set based on the flow direction for the specific candidate point.

  According to the present invention, the sample gate can be automatically set at an appropriate position according to the situation.

It is a block diagram which shows the structure of the ultrasonic diagnosing device which concerns on embodiment. It is a block diagram which shows the structural example of the calculation control part shown in FIG. It is a block diagram which shows the operation example of the ultrasonic diagnosing device shown in FIG. It is a figure which shows the beam scanning surface for a tissue observation, and the beam scanning surface for a blood flow observation. It is a figure for demonstrating the synthesis | combination of several blood-flow data. It is a figure for demonstrating the process of synthetic blood flow data. It is a figure for demonstrating the setting of a region of interest (ROI). It is a figure for demonstrating a removal process. It is a figure for demonstrating the specific example of a removal process. It is a figure for demonstrating the center point calculation for every flame | frame. It is a figure which shows an example of a graph. It is a figure for demonstrating update determination conditions. It is a flowchart which shows a ROI setting method. It is a flowchart which shows a ROI update method. It is a figure which shows the two flow directions (flow angle) corresponding to two candidate points. It is a figure which shows the calculation method of a front side angle difference and a rear side angle difference. It is a figure which shows the center point and maximum flow velocity point which were calculated in presence of a stenosis site | part. It is a figure which shows the evaluation method of a center point and the highest flow velocity point. It is a flowchart which shows the sample gate setting method. It is a figure which shows the other evaluation method. It is a figure for demonstrating the stability determination method. It is an enlarged view which shows an example of the stability determination range. It is a timing chart which shows a stability determination method. It is a flowchart which shows the stability determination method. It is a figure which shows the operation example when there exists sample gate update. It is a figure which shows the other example of the stability determination range. It is a figure which shows the 1st modification of a stability determination method. It is a figure which shows the 2nd modification of a stability determination method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Configuration and operation of ultrasonic diagnostic apparatus (FIGS. 1 to 3)
FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus. This ultrasonic diagnostic apparatus is an apparatus that is installed in a medical institution such as a hospital and performs ultrasonic diagnosis on a subject. In the present embodiment, the test site is, for example, the carotid artery. Other blood vessels such as lower limb arteries may be the object of diagnosis.

  In FIG. 1, a probe 10 functions as an ultrasonic transducer, and its transmission / reception surface is brought into contact with the surface of a living body 14 (for example, the neck). A blood vessel 16 to be examined exists inside the living body 14, and the inside thereof is a blood flow 17. The probe 10 has an array transducer 12 that functions as a wave transmitting / receiving unit. The array transducer 12 is composed of a plurality of vibration elements arranged linearly. As the array transducer 12, a 2D array transducer may be provided. As the array transducer 12, cMUT (Capacitive Micro-machined Ultrasonic Transducers) may be used.

  In the B mode, the array transducer 12 forms an ultrasonic beam for tissue observation (for B mode), which is electronically scanned. In this embodiment, an electronic linear scanning method is employed. The ultrasound beam for tissue observation is not normally steered and is formed parallel to the y 'direction in FIG. Note that the x direction is an electronic scanning direction, and the y direction is a direction in which a steered blood flow observation ultrasonic beam described below is directed, which is a depth direction. An electronic scanning method other than the electronic linear scanning method may be applied.

  In the CFM mode, the array transducer 12 forms an ultrasonic beam 20 for blood flow observation in addition to an ultrasonic beam for tissue observation. The ultrasonic beam 20 is typically steered, that is, it is a deflected beam. In FIG. 1, the deflection angle is θ1. The ultrasonic beam 20 is linearly scanned while maintaining the deflection angle θ1.

  As will be described in detail later, a region of interest (ROI) 18 is automatically set based on blood flow data obtained by the initial scanning control of the ultrasonic beam 20. After the ROI 18 is set, the scanning of the ultrasonic beam 20 is controlled based on the scanning range and depth range defined by the ROI 18. As will be described in detail later, the sample gate 24 has two-dimensional blood flow data obtained by scanning the ultrasonic beam 20 in the region of interest 18 and two-dimensional data obtained by scanning the ultrasonic beam according to the B mode. Automatically set based on organizational data. The sample gate 24 is set in the blood flow region. The substance is a section in which Doppler information is cut out from the received signal. Reference numeral 22 denotes an orientation passing through the sample gate 24.

  After the setting of the sample gate 24, control for automatically transitioning to the Doppler mode is executed. This will also be described in detail later. The Doppler mode includes a PW mode and a CW mode. The CFM mode may be executed concurrently in the execution process of the PW mode.

  The transmission / reception unit 26 is an electronic circuit that functions as a transmission beam former and a reception beam former. At the time of transmission, a plurality of transmission signals are supplied from the transmission / reception unit 26 to the array transducer 12. As a result, a transmission beam is formed. At the time of reception, the reflected wave from the living body is received by the array transducer 12. As a result, a plurality of reception signals are output in parallel from the array transducer 12 to the transmission / reception unit 26. The transmission / reception unit 26 includes a plurality of amplifiers, a plurality of A / D converters, a plurality of delay circuits, an addition circuit, and the like. In the transmission / reception unit 26, a plurality of reception signals are subjected to phasing addition (delay addition), and beam data corresponding to the reception beam is generated. In the illustrated configuration example, the transmission / reception unit 26 also includes a circuit for detecting a reception signal. The transmission / reception unit is also provided with a transmission / reception circuit for the PW mode.

  Usually, one received frame data (two-dimensional tissue data or two-dimensional blood flow data) is acquired per one scan of the ultrasonic beam. One reception frame data is composed of a plurality of beam data arranged in the scanning direction. Each beam data is composed of a plurality of echo data arranged in the depth direction. When the PW mode is executed, beam data corresponding to the beam direction passing through the sample gate is repeatedly acquired.

  The tomographic image forming unit 28 functions in the B mode, and includes a first beam data processing circuit, a first DSC (digital scan converter), and the like. The first beam data processing circuit includes a logarithmic conversion circuit, a correlation processing circuit, a filter processing circuit, and the like. The beam data string (that is, received frame data) output from the first beam data processing circuit is sent to the first DSC and simultaneously sent to the arithmetic control unit 38 (see “B” in FIG. 1). . The first DSC is an electronic circuit that performs coordinate conversion, interpolation processing, and the like, from which display frame data (B-mode tomographic image data) is output. The display frame data is sent to the display processing unit 34. The reception frame data input to the first DSC and the display frame data output from the first DSC are both tissue data corresponding to a two-dimensional image. However, the former is data according to a transmission / reception coordinate system (B-mode transmission / reception coordinate system), and the latter is data according to a display coordinate system. Individual pixel data constituting the tissue data represents echo intensity.

  The blood flow image forming unit 30 functions in the CFM mode (color Doppler mode), which includes a second beam data processing circuit, a second DSC, and the like. The second beam data processing circuit includes a wall motion filter, an autocorrelation circuit, a speed calculation circuit, a power calculation circuit, and the like. The beam data string (that is, received frame data) output from the second beam data processing circuit is sent to the second DSC and simultaneously sent to the arithmetic control unit 38 (see “C” in FIG. 1). . The second DSC has the same function as the first DSC. The reception frame data input to the second DSC and the display frame data output from the second DSC are both blood flow data corresponding to a two-dimensional image. However, the former is data according to a transmission / reception coordinate system (steering transmission / reception coordinate system), and the latter is data according to a display coordinate system. Individual pixel data constituting the blood flow data is data representing the blood flow velocity. Individual pixel data may be data representing the power of Doppler information.

  A cine memory (ring buffer) for temporarily storing data is provided in each of the tomographic image forming unit 28 and the blood flow image forming unit 30. Instead of the tissue data and blood flow data before the coordinate conversion, the tissue data and blood flow data after the coordinate conversion may be sent to the arithmetic control unit 38 (see two broken lines in FIG. 1).

  The Doppler waveform forming unit 32 functions in the Doppler mode (specifically, the PW mode), and includes a gate circuit, an FFT circuit, a waveform memory, and the like. The gate circuit is a circuit that extracts a signal (Doppler information) within a period corresponding to the sample gate from each beam data obtained in the Doppler observation direction (see reference numeral 22 in FIG. 1). The extracted Doppler information is subjected to frequency analysis in the FFT circuit. Thereby, a power spectrum is obtained. A Doppler waveform is generated by expressing each power spectrum sequentially obtained on the time axis as a luminance sequence. Data indicating the Doppler waveform is sent to the display processing unit 34. The data is also sent to the calculation control unit 38 as necessary. The arithmetic control unit 38 has a function of performing auto-trace processing and analysis of Doppler waveforms.

  The display processing unit 34 has a graphic image generation function, an image composition function, a color processing function, and the like. The graphic image is an image including a marker, a cursor, and the like. A graphic image may be generated in the arithmetic control unit 38. The display 36 displays a two-dimensional tissue image (monochrome tomographic image) in the B mode. In the CFM mode, a two-dimensional color blood flow image is superimposed and displayed on the two-dimensional tissue image. In the PW mode, the Doppler waveform is displayed on the display 36. The analysis result of the Doppler waveform and the measurement result are also displayed on the display 36. The display device 36 is configured as an LCD or an organic EL device, for example.

  In this embodiment, the arithmetic control unit 38 is constituted by a CPU and an operation program. It may be composed of one or more devices, one or more processors, electronic circuits, etc. The arithmetic control unit 38 controls the operation of each component shown in FIG. The arithmetic control unit 38 has a plurality of functions described below with reference to FIG. An operation panel 40 is connected to the arithmetic control unit 38. The operation panel 40 is an input device including a trackball, a plurality of buttons, a plurality of switches, a keyboard, and the like.

  In FIG. 2, a plurality of functions of the arithmetic control unit 38 are expressed by a plurality of blocks. Individual blocks may be configured by dedicated processors or devices. The arithmetic control unit 38 has a transmission / reception control function, an ROI setting function, a sample gate setting function, a mode transition control function, and the like. These functions will be specifically described below.

  The transmission / reception control unit 42 is means for controlling transmission / reception of ultrasonic waves through control of the transmission / reception unit shown in FIG. The transmission / reception control unit 42 controls transmission / reception of ultrasonic waves so that beam scanning or the like according to the selected operation mode is executed. The transmission / reception control unit 42 includes a scanning control unit 42A. The scanning control unit 42A executes initial scanning control prior to automatic ROI setting, and performs scanning control according to the ROI after automatic ROI setting. In that case, the preset steering angle θ1 is referred to. The steering angle θ1 may be automatically set based on blood flow data and tissue data. The steering direction may be reversed by a user operation, or the steering angle θ1 may be changed.

  In the automatic setting of ROI (initial ROI, ROI), the preprocessing unit 44, the center point calculation unit 46, and the ROI setting unit (update unit) 48 function. The preprocessing unit 44 functions as a synthesis unit, a processing unit, and a removal unit. Specifically, the preprocessing unit 44 synthesizes a plurality of blood flow data obtained under the initial scanning control to generate synthetic blood flow data, and processes the combined blood flow data to change its form in the scanning direction. And a function of removing the protruding portion when an apparent protrusion of the blood flow image occurs. In this embodiment, the blood flow data is received frame data obtained by scanning the Doppler observation ultrasonic beam, and corresponds to a blood flow image before coordinate conversion.

  The center point calculation unit 46 is a means for calculating the center point of the blood flow region in the combined blood flow data and the center point of the blood flow region in each blood flow data. These center points are representative points of the blood flow region. The ROI setting unit (update unit) 48 is a means for setting the ROI while setting the center point of the blood flow region as the ROI center point, and updating the ROI. In setting the ROI, the preset scanning direction ROI width Wx, depth direction ROI width Wy, and steering angle θ1 are referred to. Those parameters may be automatically determined based on blood flow data and tissue data. The tissue data is received frame data obtained by scanning an ultrasonic beam for tissue observation, and corresponds to a tissue image before coordinate conversion.

  The waveform generation unit 50 is a means for generating a waveform (graph) to be described later based on a plurality of blood flow data on the time axis. The peak determination unit 52 is a means for determining a predetermined time phase (for example, a time phase slightly after the end diastole) in units of heartbeats by determining individual peaks in the waveform. In the illustrated configuration example, a trigger signal indicating a predetermined time phase is output from the peak determination unit 52 to the ROI setting unit 48 and the gate setting unit 62. The trigger signal is a signal indicating update timing or determination timing.

  In the automatic setting of the sample gate, the maximum flow velocity point calculation unit 54, the center point calculation unit 56, the selection unit 58, the gate size calculation unit 60, and the gate setting unit (update unit) 62 function. The maximum flow velocity point calculator 54 and the center point calculator 56 function as candidate point calculators, the selector 58 functions as candidate point selectors, and the gate setting unit 62 functions as sample gate setting means. In the present embodiment, a plurality of candidate points belonging to the blood flow region are calculated on a frame basis, and any candidate point is selected from the evaluation results of the plurality of candidate points. The selected candidate point becomes the sample gate position (center position of the sample gate). Based on the selected candidate point, the sample gate position may be determined as a different point.

  More specifically, in the present embodiment, the highest flow velocity point as the first candidate point and the center point as the second candidate point are calculated, and any one of them is set as the sample gate position. When a stenosis site exists, it is desirable to set a sample gate inside the stenosis region. From such a viewpoint, the maximum flow velocity point is included in the candidate point group. In order to avoid the spatial variation of the sample gate position, it is necessary to prepare a candidate point that is stably generated. From such a viewpoint, the center point is included in the candidate point group. It is after the transition to the Doppler mode that the sample gate performs its original function.

  The maximum flow velocity point calculator 54 is a means for calculating the maximum flow velocity point in the blood flow region based on the blood flow data. However, what can actually be observed in the ultrasonic diagnostic apparatus is generally a component in the ultrasonic beam direction in a true Doppler signal. The center point calculation unit 56 is a means for calculating the center point of the blood flow region based on the blood flow data. The center point is, for example, a barycentric point of the blood flow region or a point defined as an intermediate coordinate in the blood flow region. The selection unit 58 functions as a selection unit, and the selection unit is a concept including a direction calculation unit and an evaluation unit. The selection unit 58 evaluates the maximum flow velocity point and the center point based on the blood flow data and the tissue data, and selects one of the evaluation results.

  The gate size calculation unit 60 functions as a size calculation unit, which specifies the width of the blood flow image in the direction passing through the selected point, and calculates the gate size based on the width. The gate setting unit 62 functions as sample gate setting means, which sets a sample gate having a calculated gate size while setting the selected point as the sample gate center position. In that case, the preset steering angle θ1 is referred to. The setting (updating) of the sample gate is executed as necessary at the timing when the trigger signal is obtained from the peak determination unit 52.

  The maximum flow velocity point calculation unit 54, the center point calculation unit 56, the selection unit 58, and the gate size calculation unit 60 operate in units of frames, but the above trigger signal is input when the gate setting unit 62 performs the setting operation. That is, a predetermined time phase in each heartbeat. Control may be performed so that the maximum flow velocity point calculator 54 and the like operate only during a predetermined time phase in each heartbeat. Note that the sample gate may be calculated and set not at a predetermined time phase but at a designated timing.

  In the mode transition control, the maximum flow velocity point calculation unit 54, the center point calculation unit 56, the selection unit 58, and the gate setting unit 62 function as sample gate information calculation means. A stability determination unit 66 and a transition control unit 68 described below function as control means. In the present embodiment, the sample gate position is referred to as the sample gate information in determining whether the sample gate is stable, but other information indicating that the sample gate position is stable may be referred to.

  Information indicating a plurality of sample gate positions is sequentially input to the stability determination unit 66, and the stability determination unit 66 monitors them, and based on the fact that the temporal change in the sample gate position is small, mode transition is performed. Determine. Here, each sample gate position is a point in time when the trigger signal is generated, and two sample gate positions separated by one heartbeat are compared. Specifically, a stability determination range is determined based on the previous sample gate position, and stability is determined when the current sample gate position belongs to the stability determination range. When the stability is determined n times continuously (when the stable state continues for n heartbeats), the mode transition is determined. The transition control unit 68 is means for determining such a situation and actually executing the mode transition. The display of the Doppler waveform is started with the start of execution of the Doppler mode.

  The angle correction unit 70 is a unit that specifies the correction angle at the sample gate position and corrects the vertical axis of the Doppler waveform based on the correction angle. In this embodiment, the flow direction is calculated for each candidate point, and the correction angle is specified from the flow direction. On the display screen, a correction angle marker crossing the center is displayed together with a gate marker indicating the sample gate. Note that the sample gate position, the correction angle, and other parameters can be manually corrected as necessary.

  FIG. 3 shows an operation example of the ultrasonic diagnostic apparatus as a flowchart. In S10, the B mode is selected by the inspector, or the B mode is automatically selected as the default operation mode. The examiner adjusts the position and posture of the probe so that the cross section of the target blood vessel is included in the tomographic image while viewing the displayed tomographic image. Thereafter, in S12, an operation for instructing the start of the operation in the CFM mode is performed by the inspector. In S14, the ROI is automatically set based on the blood flow data, and then the set ROI is updated as necessary. In S16, the steering angle is changed by the inspector as necessary. Along with this, the form of the ROI changes. In S18, the inspector performs an operation of causing a cursor (marker) that simulates the sample gate to appear on the screen. With this as a trigger, in S20, the sample gate is automatically set based on the blood flow data and the tissue data. The sample gate is automatically updated when certain requirements are met. In S24, it is determined whether or not the sample gate is in a stable state. If the sample gate is in a stable state, a transition is automatically made to the PW mode in S26. You may automatically transition to CW mode. In S28, auto-trace on the Doppler waveform, measurement based on the auto-trace result, etc. are executed.

  Conventionally, manual setting for ROI manual setting, sample gate manual setting, and Doppler mode execution were necessary. However, in the above embodiment, all of them are automatically executed. The burden on the person is greatly reduced. This provides the advantage that the examiner can concentrate on image observation. In addition, since the examination time can be shortened, the burden on the subject can be reduced. Furthermore, the ROI and the sample gate can be set objectively, and the advantage that the reproducibility can be improved in those settings can be obtained.

(2) Automatic ROI setting (FIGS. 4 to 14)
The ROI automatic setting method will be described in detail below. The method is executed in S14 shown in FIG.

  In FIG. 4, two beam scanning planes are shown. The beam scanning surface 71 is formed by electronically scanning a tissue observation ultrasonic beam. A cross section 74 of the blood vessel is included in the beam scanning plane 71. Reference numeral 73 indicates the entire range in the scanning direction. The beam scanning surface 72 is formed by electronically scanning the steered ultrasonic beam 75 for blood flow observation. The steering angle is θ1. In the CFM mode, the beam scanning surface 71 and the beam scanning surface 72 are generally formed simultaneously or alternately.

  As shown in FIG. 5, in the initial scanning control, an ultrasonic beam for blood flow observation is repeatedly scanned over a predetermined period T1. Thereby, a plurality of blood flow data (a plurality of received frame data) F1 to Fn arranged on the time axis are obtained. The predetermined period T1 is determined as, for example, approximately half of an average one heartbeat period, which is, for example, 0.5 seconds. In general, the appearance (position and range) of a blood flow image changes greatly within one heartbeat. For example, a blood flow image appears best at the end phase of diastole or just after that. The predetermined period T1 is determined so that such a best blood flow image can be acquired and the initial ROI setting is not delayed so much. In the initial scanning control, in this embodiment, the blood flow observation ultrasonic beam is scanned over the entire range in the scanning direction. However, the scanning may be performed over the main part in the entire range.

  Each blood flow data F1 to Fn includes blood flow images R1 to Rn. The blood flow images R1 to Rn correspond to color portions having a certain speed or power. Among them, the blood flow image R2 extends throughout the blood vessel, and the blood flow image Rn has almost no substance. In the present embodiment, blood flow data F1 to Fn obtained within a predetermined period T1 are synthesized. Specifically, it is added. Thereby, synthetic blood flow data is generated. The combined blood flow data includes an added image 78 composed of a plurality of blood flow images. At the time of addition, a cumulative addition method may be employed, or an addition method according to an OR condition may be employed. In any case, the entire blood flow image generation area is specified as a premise for specifying the ROI center point.

  Subsequently, as shown in FIG. 6, the combined blood flow data 76 is processed in accordance with the steering direction and the steering angle so as to be symmetrical on the display coordinate system. Specifically, a portion 84 of the synthetic blood flow data 76 is cut out to generate synthetic blood flow data 76A having a symmetrical form (symmetric in the scanning direction). In the illustrated example, the steering angle is θ1, and the portion 84 is a portion corresponding to 2 × θ1 or + θ1 and −θ1. Specifically, a portion 84 to be cut off includes an area 86 corresponding to an angle θ1 on one side of the vertical line 82 when the vertical line 82 is dropped from the end point 80 on the cut side (the side where the ultrasonic beam is tilted). And an area 88 corresponding to the angle θ1 on the other side of the perpendicular line 82. The processed combined blood flow data 76A has a symmetrical form with the center line 90 as a boundary.

  The center point C is calculated based on the processed combined blood flow data 76A. Specifically, in the combined blood flow data 76A, the maximum value and the minimum value in the x direction of the blood flow image 78A and the maximum value and the minimum value in the y direction (or y ′ direction) of the blood flow image 78A are specified. Based on these, an intermediate value (average value) in the x direction and an intermediate value (average value) in the y direction (or y ′ direction) are calculated. They specify the coordinates of the center point. The center point is a point representing the blood flow image and corresponds to the center of gravity point. The center point may be calculated in consideration of individual pixel values.

  When the center point is obtained without performing the above processing, for example, the position Ca is specified. The position Ca is shifted in the tilt direction of the ultrasonic beam due to the influence of the steering of the ultrasonic beam. When the ROI is set based on such a position Ca, the ROI is set at a shifted position. According to the above processing, it is possible to avoid such a problem. As long as left-right symmetry is obtained, other forms may be generated by processing.

  As shown in FIG. 7, the initial ROI 92 is generated so that the center point C calculated as described above coincides with the ROI center. In that case, the preset Wx, Wy (or Wy ') is referred to. Wx designates the width of the ROI 92 in the x direction, and Wy designates the width of the ROI 92 in the y direction. Reference numeral 94 represents a center line parallel to the y direction, and reference numeral 96 represents a center line parallel to the x direction. For example, Wx is 1/2 of the entire scanning range, and Wy is 1/2 of the currently set B-mode diagnosis range (diagnosis depth). Each numerical value described in the present specification is merely an example.

  After the initial ROI is set, the initial ROI defines a scanning range of an ultrasonic beam for blood flow observation and a diagnostic range for blood flow observation. As a result, blood flow data inside the initial ROI is obtained repeatedly. Based on the blood flow data, the position of the ROI is updated as necessary. Prior to updating the ROI, a process of removing the protruding portion is applied to each blood flow data inside the ROI. This will be described with reference to FIGS.

  A state 100 before the removal process is shown on the left side of FIG. 8, and a state 102 after the removal process is shown on the right side of FIG. The tissue image 106 includes a blood vessel cross-sectional image 110. The blood flow image 108 in the ROI 92 includes a protruding portion 112. In the illustrated example, the protruding portion 112 bulges from the inside of the blood vessel to the deep side in the steering direction 116. The protruding portion 112 includes a portion superimposed on the blood vessel wall. The protruding portion 112 is caused by various factors such as low distance resolution. If the center point is calculated based on the blood flow image 108 including the protruding portion 112, the center point cannot be obtained correctly. For example, a situation occurs in which the center point is calculated outside the stenosis site. Therefore, in this embodiment, the removal process described below is applied, and the center point is calculated based on the blood flow image 118 after the removal process.

  FIG. 9 shows an example of the removal process. In this removal process, blood flow data and tissue data are virtually converted into display data in order to determine superiority or inferiority in units of pixels on the display coordinate system. Coordinate conversion necessary for the conversion is also executed.

  Specifically, the conversion table 120 converts each velocity value constituting the blood flow data into display data (RGB values). In that case, positive and negative signs are also considered. The conversion table 122 converts each luminance value constituting the tissue data into display data (RGB values). Reference numeral 124 indicates the converted blood flow data, which is data existing in the ROI 126. Reference numeral 128 represents the converted tissue data, and reference numeral 130 represents an area corresponding to the ROI. A process for matching the coordinate system is applied between the converted blood flow data and tissue data, and comparison and determination are performed between the two display data 132 and 134 for each pixel. For example, assuming that the luminance value of the tissue is a certain value or more and the blood flow velocity value is not 0, the converted blood flow RGB value satisfies a predetermined condition with respect to the converted tissue RGB value, The blood flow RGB values are adopted (the original velocity values are maintained), otherwise the tissue RGB values are adopted (the original velocity values are excluded). Various conditions can be adopted as the condition.

  Incidentally, in the present embodiment, as shown in FIG. 10, the center points C11, C12, and C13 are calculated for each frame in the series of frames F11, F12, and F13. Further, the sum of velocity values (absolute values) is calculated for each frame unit, and as a result, a graph (waveform) 144 shown in FIG. 11 is generated. In FIG. 11, the horizontal axis is the time axis, and the vertical axis is the sum of the velocity values (absolute values). The graph 144 changes periodically in conjunction with the heartbeat. In other words, it is possible to specify a predetermined time phase within each heartbeat period from the graph 144. In the present embodiment, a peak (maximum point) 146 that occurs in the heartbeat unit is specified in the graph 144, and a trigger signal is generated at the peak detection timing. The center point calculated or specified at the trigger signal generation timing is used in determining whether or not the ROI needs to be updated, and is used as the center point of the updated ROI. In addition, referring to a plurality of center points before and after the trigger signal is generated, it may be determined whether or not the ROI needs to be updated, or the center point of the updated ROI may be determined. Good.

  FIG. 12 shows conditions for determining whether or not the ROI update is necessary. Reference numeral 148 indicates an already set ROI. C15 is the center point. A dead area 150 is defined with the center point C15 as a reference. The width 154 in the scanning direction of the insensitive area 150 is determined by multiplying the width 152 in the scanning direction of the ROI 148 by a constant coefficient (for example, 0.6), and the width 158 in the depth direction of the insensitive area 150 is determined by the ROI 148. It is determined by multiplying the width 156 in the depth direction by a constant coefficient (for example, 0.6). If the current center point C16 calculated at the time of the trigger signal generation belongs to the dead area 150, the ROI update is postponed. On the other hand, when the current center point C16 calculated at the trigger signal generation time does not belong to the dead area 150, it is determined that the ROI is updated. Specifically, a new ROI centered on the center point C16 is generated. In that case, the transmission / reception conditions are usually reset, and transmission / reception is performed under the new transmission / reception conditions. The center point C17 may be used as the center of the ROI, or the initial ROI may be set by applying the initial scanning control under new transmission / reception conditions.

  In any case, when a large change occurs such that the center point of the blood flow image exceeds the insensitive region 150, it is not appropriate to maintain the current ROI, so the ROI is updated. On the other hand, if transmission / reception conditions are reset frequently, a psychological burden is placed on the inspector and the inspection time is prolonged. Considering this, the current ROI is maintained when the center point of the blood flow image does not change so much. In order to satisfy the two needs as described above, the size and form of the insensitive area 150 are appropriately determined.

  FIG. 13 is a flowchart showing the initial ROI setting method. In S30, scanning of the steered ultrasonic beam for blood flow observation is started in accordance with the initial scanning condition. In that case, the ultrasonic beam is scanned over the entire scanning range. In S32, a plurality of blood flow data (a plurality of frame data) obtained by the repeated scanning of the ultrasonic beam are combined to generate combined blood flow data. If necessary, in S34, the process for removing the protruding portion may be applied to the synthetic blood flow data. In S36, the synthetic blood flow data is processed. Specifically, the combined blood flow data is processed so that the form of the combined blood flow data is symmetric with respect to the center line. The above S34 may be applied after the execution of S36. In S38, the center point is calculated based on the synthesized blood flow data after processing. In S40, the initial ROI is set so that the center point coincides with the initial ROI center. Thereafter, the transmission / reception conditions for blood flow observation are reset according to the initial ROI.

  FIG. 14 shows an ROI update method executed after setting an initial ROI. S50 and S52 are executed for each frame. In S50, the processing for removing the protruding portion is applied to the blood flow data. Then, in S52, a center point is calculated based on the blood flow data after processing. In S54, it is determined whether or not a peak is detected in the graph. If no peak is detected, that is, if it is determined that the current time is not a predetermined time phase for performing update determination, the processes after S50 are executed. . If a peak is detected in S54, that is, if it is determined that the current time is a predetermined time phase, it is determined in S56 whether or not the update condition based on the dead area is satisfied, and if the update condition is not satisfied Each process after S50 is performed. If the update determination condition is satisfied in S56, the ROI position is updated in S58. That is, the ROI is reset. Thereafter, the transmission / reception conditions for blood flow observation are reset according to the ROI.

  According to the embodiment, it is possible to automatically set the region of interest for observing Doppler information at an appropriate position. In particular, the data processing as the pre-processing makes it possible to calculate the center point without being affected by the steering direction and the steering angle. Furthermore, since the synthetic blood flow data is used for the calculation of the center point, even if the individual instantaneous blood flow image changes greatly depending on the time phase, the center point is calculated at an inappropriate position. Absent.

  In the above embodiment, the combined blood flow data is processed after generating the combined blood flow data. However, after processing each blood flow data individually, the processed blood flow data is synthesized. Alternatively, the processing may be performed simultaneously with the synthesis. As a result, it is only necessary to obtain synthetic blood flow data having left-right symmetry.

(3) Automatic sample gate setting (FIGS. 15 to 20)
The automatic setting method of the sample gate will be described in detail below. It is executed in S20 shown in FIG.

  FIG. 15 shows blood flow data in the ROI. In the illustrated example, the blood flow image 160 appears relatively large in the blood vessel. In the present embodiment, the center point P1 and the maximum flow velocity point P2 are calculated as a plurality of candidate points based on the blood flow data. The center point P1 is, for example, a center of gravity point. The barycentric point is, for example, an intermediate coordinate between the maximum coordinate and the minimum coordinate in the scanning direction of the blood flow image (color portion) and an intermediate point between the maximum coordinate and the minimum coordinate in the depth direction of the blood flow image (color portion). And coordinates. The barycentric point may be calculated in consideration of the velocity value of each pixel, or the barycentric point may be calculated in consideration of the form of the blood flow image. The maximum flow velocity point P2 is a point having the largest velocity value as an absolute value. The third point may be a candidate point. Further, the center point or the maximum flow velocity point may be replaced with another point.

  For the blood flow data, a plurality of reference lines 164 are set in parallel to the beam direction, and an intermediate point 166 of the blood flow image 160 is calculated on each reference line. A center line 168 is formed by connecting a plurality of intermediate points 166 arranged in the scanning direction. The center line 168 is not the center line of the blood vessel but the center line of the blood flow image 160.

  On the basis of the center line 168, the flow directions (flow angles) φ1 and φ2 are calculated for each of the center point P1 and the maximum flow velocity point P2. Specifically, for example, an intersection 170 where a line L1 passing through the center point P1 and parallel to the beam direction intersects with the center line 168 is specified. In the center line 168, a constant section 172 extending in the scanning direction around the intersection 170 is referred to, and the flow direction is specified from the line segment defined by the section 172. For example, the flow direction is calculated by applying a least square method to the line segment or by applying a tangent calculation. Other methods may be used. Specifically, the flow direction is specified as a flow angle φ1. As for the maximum flow velocity point P2, as described above, a constant section 178 is defined on the center line 168 with reference to the intersection 176 between the center line 168 and the line L2, and the flow direction is calculated based on the line segment in the section 178. Is done. The flow direction is specifically specified as a flow angle φ2.

  The wall direction of the blood vessel wall is also specified with reference to the lines L1 and L2. For example, as shown in FIG. 16, the front wall direction, that is, the front wall angle φF1 can be specified as the edge direction at the point where the line L1 intersects the front wall (for example, the outer membrane in the front wall). Further, it is possible to specify the rear wall direction, that is, the rear wall angle φR1 as the edge direction at the point where the line L1 intersects with the rear wall (for example, the outer membrane in the rear wall). Similarly, the front wall angle φF2 and the rear wall angle φR2 can be specified for the maximum flow velocity point P2. Various known techniques can be used as the edge direction calculation method.

  In the present embodiment, the flow angle φ1, the front wall angle φF1 and the rear wall angle φR1 about the center point P1, and the flow angle φ2, the front wall angle φF2 and the rear wall about the maximum flow velocity point P2 calculated as described above. Based on the angle φR2, either the center point or the highest flow velocity point is selected. The selected point is set as the sample gate position. Specifically, with respect to the center point P1, an angle difference ΔφF11 (see reference numeral 180) between the flow angle φ1 and the front wall angle φF1 and an angle difference ΔφR11 (reference sign) between the flow angle φ1 and the rear wall angle φR1. 182) is calculated. Regarding the maximum flow velocity point P2, there are an angle difference ΔφF22 (see reference numeral 184) between the flow angle φ2 and the front wall angle φF2 and an angle difference ΔφR22 (see reference numeral 186) between the flow angle φ2 and the rear wall angle φR2. Calculated. The angle differences ΔφF11 and ΔφR11 indicate the parallelism between the center point P1 and the blood vessel wall near the center point P1. That is, they serve as indices indicating whether or not the center point P is stably generated. The angle differences ΔφF22 and ΔφR22 indicate the parallelism between the highest flow velocity point P2 and the blood vessel wall in the vicinity of the highest flow velocity point P2. They serve as indicators for determining whether or not the site is a stenosis site. Therefore, in consideration of the four angular differences, any one of the center point and the maximum flow velocity point is selected (see reference numeral 188).

  In the example shown in FIG. 17, the center point P <b> 1 is specified approximately at the center of the inner region of the blood vessel 190. On the other hand, the maximum flow velocity point P2 is specified inside the stenosis site (reference numeral 192 schematically shows a plaque). In such a case, the highest flow velocity point P2 is generally selected. In addition, when the stenosis part does not exist, the position of the maximum flow velocity point P2 is not stable. In particular, when the frame rate is low, the maximum flow velocity point P2 is generated at various positions. In such a case, the center point P1 is selected. If so-called folding occurs, it is desirable to specify the maximum flow velocity point after correcting it.

  FIG. 18 shows the selection conditions. Reference numeral 194 indicates an evaluation of the center point. Reference numeral 196 indicates an evaluation on the maximum flow velocity point. Reference numeral 198 indicates a selection result. Considering in detail, the center point is selected when the first condition that the angle difference ΔφF11 is equal to or smaller than the predetermined value α1 and the angle difference ΔφR11 is equal to or smaller than the predetermined value α2 is satisfied, and at the same time, the angle difference ΔφF22 is equal to or smaller than the predetermined value α3. Only when the second condition that the angle difference ΔφR22 is equal to or smaller than the predetermined value α4 is satisfied. In other cases, the maximum flow velocity point P2 is selected. This is based on the idea that the highest flow velocity point is preferentially selected when the highest flow velocity point is generated to a certain degree of stability. When the first condition and the second condition are satisfied at the same time, there is a high possibility that a stenosis site has not occurred, and the position of the maximum flow velocity point may change greatly. In this case, the center point is selected. I try to do it. The same numerical value may be set as α1 to α4. For example, those values may be 10 degrees.

  As described above, the selected point (center point or maximum flow velocity point) is set as the center position of the sample gate. For the selected point, the already calculated flow angle is the correction angle. On the line passing through the selected point, the width of the blood flow image is specified (for example, the previously calculated width is referred to), and the width is multiplied by a predetermined coefficient (for example, 1/2 or 2/3). Thus, the sample gate size is automatically set. The sample gate size may be determined by other methods.

  The selection conditions shown in FIG. 18 are an example, and other selection conditions may be adopted depending on the purpose and situation. The automatically selected points may be changed manually. In the above embodiment, not only blood flow data but also tissue data are referred to when selecting candidate points (because the front and rear walls are taken into account), so that candidate points can be selected more accurately. Is possible.

  FIG. 19 shows a sample gate setting method as a flowchart. A series of steps from S70 to S78 are executed in units of frames. In S70, the center point and the maximum flow velocity point are calculated based on the blood flow data. In S72, the flow direction (flow angle) for the center point and the flow direction (flow angle) for the highest flow velocity point are calculated based on the blood flow data. Also, based on the tissue data, the front wall direction (front wall angle) and rear wall direction (rear wall angle) for the center point, and the front wall direction (front wall angle) and rear wall direction ( The rear wall angle) is calculated. In S74, based on those directions (angles), the center point and the maximum flow velocity point are evaluated, and as a result, any point is selected. In S76, the flow angle for the selected point is set as the correction angle. In S78, the gate size is calculated from the width of the blood flow image on the line passing through the selected point. In S80, it is determined whether or not a peak in the graph is detected. If no peak is detected, the processes in and after S70 are executed via the determination in S88. If a peak is detected in S80, it is determined in S82 whether or not the first sample gate is set. If YES, the sample gate is automatically set in S86 without going through S84. At that time, a marker representing the set sample gate is displayed on the screen. In S88, it is determined whether or not to continue this processing.

  On the other hand, if it is determined in S82 that it is not the first sample gate setting (in the case of No), it is determined in S84 whether the update condition is satisfied. For example, a predetermined dead area is set around the previously set sample gate position, and it is determined whether or not the currently selected point has exceeded the dead area (whether the update condition is satisfied). Only when the update condition is satisfied, the sample gate update in S86 is allowed. In S86, for example, a dead area shown in FIG. 12 may be set as the dead area. By providing the update condition, it is possible to avoid that the sample gate position is frequently updated and the transmission / reception condition is reset each time. However, when the selection target is switched from the highest flow velocity point to the center point, the situation has changed greatly, and the sample gate should be updated. In such a case, S86 is executed. It is desirable to set update conditions as appropriate. In the case of the first sample gate setting, as indicated by reference numeral 199, S86 may be executed immediately after S78.

  FIG. 20 shows a modification. In this modification, in addition to the flow angle φ1, the front wall angle φF1, and the rear wall angle φR1, the wall angle difference ΔφFR1 is also calculated for the center point P1 (see reference numeral 200). In addition to the flow angle φ2, the front wall angle φF2, and the rear wall angle φR2, the wall angle difference ΔφFR2 is also calculated for the maximum flow velocity point P2 (see reference numeral 202). The both-wall angle difference ΔφFR1 is an angle difference between the front wall angle φF1 and the rear wall angle φR1. Both wall angle difference ΔφFR2 is an angle difference between front wall angle φF2 and rear wall angle φR2. The selection accuracy can be further improved by performing selection (see reference numeral 204) in consideration of both wall angle differences ΔφFR1 and ΔφFR2. Further, other information may be referred to.

  According to the embodiment, the sample gate can be automatically set at an appropriate position according to the situation. In particular, since both blood flow data and tissue data are used for the setting, the reliability of the setting result can be improved. Note that if the transition to the Doppler mode is delayed after setting the sample gate, the sample gate update is repeated and stress may be applied to the inspector. Therefore, mode transition control can be performed quickly under certain conditions after setting the sample gate. Is preferably performed.

(4) Automatic transition to Doppler mode (FIGS. 21 to 27)
The mode automatic transition method will be described in detail below. It is executed in S24 and S26 shown in FIG.

  FIG. 21 shows the current frame 210. A sample gate 218 is set based on the previous frame. Reference numeral 214 denotes the center position (sample gate position) of the sample gate 218. A bar 219 passing there represents a correction angle for correcting the blood flow velocity. Reference numeral 212 indicates the ROI. The ROI 212 is set based on the previous frame or a past frame. Reference numeral 223 indicates a dead area that satisfies the sample gate update condition.

  Based on the current frame 210 (specifically, current blood flow data), the sample gate position 222 is calculated as the center point or the maximum flow velocity point. The sample gate position 222 is currently calculated and is actually adopted as long as the update condition is satisfied.

  In the present embodiment, a neighborhood area 220 for determining a stable state is set based on the previous sample gate position 214. Stability is determined when the currently calculated sample gate position 222 belongs within the neighborhood area 220. Then, when the stability is determined n times continuously, the mode transition is determined, and the mode transition control is executed. n is an integer of 1 or more, and is preferably 2 or more, but n may be 1. You may comprise so that n can be variably set according to a condition. The neighborhood area 220 is a smaller area included in the dead area 212. The radius can be variably set.

  In FIG. 22, the neighborhood area 220 is shown as an enlarged view. The neighborhood area 220 is a circular area in the display coordinate system, and its radius is β. Stability is determined when the currently calculated computational gate position 224 that is currently determined belongs within the neighborhood area 220, and when the currently calculated computational gate position 226 that is currently determined is outside the neighboring area 220, the stability is Not judged. The sensitivity of stability determination can be adjusted by the size of the radius β. In actual comparison and determination, distances r1 and r2 between the previous sample gate position 214 and the calculated current sample gate positions 224 and 226 are calculated on the display coordinate system, and then the distances r1 and r2 are calculated. It is determined whether or not the radius is within β. In such calculation, since it is not necessary to consider the direction, comparative determination can be performed relatively easily. But you may judge whether it is stable according to other conditions. For example, β is set to several mm or less, and preferably 0.5 mm to 1.0 mm.

  FIG. 23 shows the contents described above as a timing chart. As indicated at 230, individual peaks in the graph are detected. Thereby, the predetermined time phase in each heartbeat is specified. Between two adjacent heartbeats, two sample gate positions corresponding to the same time phase are compared. As indicated by reference numeral 231, sample gate positions (calculated sample gate positions) q 1 to q 7 at the time of detecting each peak are specified. In the illustrated example, the sample gate position q1 calculated at the timing t1 is actually adopted in the sample gate setting (see reference numeral 234), and thereafter, the set sample gate position is maintained. As indicated by reference numeral 233, in this embodiment, two sample gate positions are compared between two adjacent heartbeats.

  Specifically, a neighborhood area is set based on the sample gate position calculated for the previous heartbeat, and it is determined whether or not the currently calculated sample gate position belongs to the neighborhood area. In the illustrated example, as indicated by reference numeral 235, when it is determined that the stability is continued three times, control for automatically transitioning to the Doppler mode is executed. Prior to the distance calculation, coordinate transformation is applied to each sample gate position. It is also possible to obtain the distance without performing coordinate conversion. For example, the neighborhood range may be defined on the transmission / reception coordinate system.

  FIG. 24 shows a mode automatic transition method as a flowchart. In S90, 0 is substituted into the counter M, and M is initialized. In S92, the distance between the previous sample gate position and the current sample gate position is calculated, and it is determined whether or not the distance is within β. If the distance is not within β, S90 is executed and M is reset. If it is determined in S92 that the distance is within β, M is incremented by one in S92. After that, in S96, it is determined whether or not M has reached the determination value N. If not, S92 is executed. If it is determined that the distance is within β continuously N times, S98 is executed, that is, execution of the Doppler mode is started. If N is 1, the mode automatically shifts to the Doppler mode when the condition of S92 is satisfied.

  According to the above-described embodiment, it is possible to automatically shift to the Doppler mode when a stable state is obtained after setting the sample gate. As a result, the burden on the inspector can be reduced and the inspection time can be shortened.

  FIG. 25 shows an operation example including sample gate update. At timing t1, the sample gate position q1 is adopted. Thereafter, at timing t2, two sample gate positions q1 and q2 with one heartbeat are compared, and NG (unstable) is determined. At the next timing t3, the two sample gate positions q2 and q3 are compared, and OK (stable) is determined (see reference numeral 250). However, at the subsequent timing t4, the sample gate position is updated to q4 (see reference numeral 252). In that case, the counter M is reset. Then, the comparison of two adjacent sample gate positions is repeated.

  As shown in FIG. 26, a neighborhood area (determination area) 244 having a parallelogram shape on the display coordinate system may be set based on the previous sample gate position 240. The neighborhood area 244 corresponds to a reduced figure of ROI. According to such a configuration, the neighborhood area 244 can be set without performing coordinate conversion.

  In the above stability determination, other information may be referred to instead of or together with the sample gate position. For example, the flow angle, gate size, sample gate velocity distribution, and the like may be referred to. They are also included in the concept of sample gate information. In any case, it is desirable to determine the stability determination condition based on the previous sample gate information, and determine whether the subsequent sample gate information corresponds thereto.

  FIG. 27 shows a first modification. In the first modification, the sample gate position that is actually adopted is the comparison target. Specifically, the sample gate position q1 is employed at timing t1 (see reference numeral 254). The sample gate position calculated thereafter is sequentially compared with the sample gate position q1. For example, the calculated sample gate position q2 is compared with the sample gate position q1 at timing t2 (see reference numeral 258), and then, at timing t3, the calculated sample gate position is compared with the sample gate position q1. The position q3 is compared (see reference numeral 259).

  FIG. 28 shows a second modification. In this example, the calculated sample gate position is specified every arbitrary period Δt. Then, it is determined whether or not it is stable by comparing two sample gate positions that are temporally adjacent.

(5) Other Embodiments When setting a sample gate, three or more candidate points may be included in the candidate point group. Further, points other than the maximum flow velocity point and the center point may be used as candidate points. In any case, by preparing a plurality of candidate points and evaluating and selecting them, it is possible to avoid a problem that occurs when the sample gate position is defined uniformly.

  In the sample gate setting, the parallelism may be evaluated from another viewpoint, instead of comparing the flow angle and the wall angle. For example, a plurality of candidate points may be evaluated based on a change in blood flow width or blood vessel diameter in the scanning direction.

  In the mode transition control, a freeze state may occur before the transition to the Doppler mode. The waveform (graph) may be generated based on the average velocity value or the blood flow area in each frame. You may make it employ | adopt independently the some feature matter contained in the said embodiment.

10 probe, 28 tomographic image forming unit, 30 blood flow image forming unit, 32 Doppler waveform forming unit, 34 display processing unit, 44 preprocessing unit, 46 center point calculation unit, 48 ROI setting unit, 50 waveform generation unit, 52 peak Determination unit, 54 Maximum flow velocity point calculation unit, 56 Center point calculation unit, 58 Selection unit, 60 Gate size calculation unit, 62 Gate setting unit, 66 Stability determination unit, 68 Transition control unit, 70 Angle correction unit.

Claims (9)

Wave transmitting / receiving means for acquiring tissue data and blood flow data by transmitting / receiving ultrasonic waves to / from a living body;
Computing means for computing a plurality of candidate points in the blood flow region based on the blood flow data;
A selection means for selecting a specific candidate point from the plurality of candidate points based on the tissue data and the blood flow data;
Setting means for setting a sample gate for Doppler information measurement based on the specific candidate point;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
The selection means includes
A flow direction calculation means for calculating a plurality of flow directions corresponding to the plurality of candidate points based on the blood flow data;
Wall direction calculating means for calculating a plurality of wall directions corresponding to the plurality of candidate points based on the tissue data;
An evaluation means for evaluating the plurality of flow directions and the plurality of wall directions to select the specific candidate points;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 2.
The wall direction calculating means calculates a front wall direction and a rear wall direction for each candidate point as the plurality of wall directions,
The evaluation means evaluates the plurality of candidate points based on the plurality of flow directions, the plurality of front wall directions, and the plurality of rear wall directions;
An ultrasonic diagnostic apparatus. The apparatus of claim 3.
The evaluation means includes
Means for calculating, for each candidate point, a front angle difference between the flow direction and the front wall direction, and a rear angle difference between the flow direction and the rear wall direction;
Means for selecting the specific candidate point from the plurality of candidate points based on a plurality of front angle differences and a plurality of rear angle differences for the plurality of candidate points;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
The plurality of candidate points include a maximum flow velocity point and a center point in the blood flow region,
An ultrasonic diagnostic apparatus. The apparatus of claim 1.
Means for calculating a gate size based on at least one of the tissue data and the blood flow data;
The setting means sets the sample gate based on the specific candidate point and the gate size;
An ultrasonic diagnostic apparatus. The apparatus of claim 1.
Means for creating a graph showing periodic changes in blood flow based on at least one of the tissue data and the blood flow data;
The update timing of the sample gate is determined based on the graph.
An ultrasonic diagnostic apparatus. In a method of setting a sample gate based on tissue data and blood flow data obtained by transmitting and receiving ultrasound to and from a blood vessel in a living body
Calculating a plurality of candidate points in a blood flow region based on the blood flow data;
For each candidate point, calculating a flow direction based on the blood flow data and calculating a wall direction based on the tissue data;
Selecting specific candidate points from the plurality of candidate points based on the plurality of flow directions and the plurality of wall directions calculated for the plurality of candidate points;
Setting a sample gate for Doppler information measurement based on the specific candidate point;
A sample gate setting method comprising: The method of claim 8, wherein
Calculating a gate size based on the specific candidate point based on the blood flow data,
In the step of setting the sample gate, the sample gate is set based on the specific candidate point and the gate size, and an angle for Doppler information correction is set based on the flow direction for the specific candidate point. To be
A sample gate setting method characterized by that.