JP2017136251A - Ultrasonic imaging apparatus and ultrasonic imaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for acquiring an effect of high picture quality by aperture synthesis even when an imaging object moves.SOLUTION: An ultrasonic wave is transmitted to a range 33 which should be imaged of an imaging object 20 from a transmission opening 110 of an ultrasonic probe 108. An echo of the ultrasonic wave from the imaging object 20 is received by a reception area 130 of the ultrasonic probe, then phasing processing is performed on an output of the reception area 130, and acquiring a reception signal on a desired reception focus of the imaging object 20. A plurality of reception signals for a same reception focus are subjected to addition processing, the plurality of reception signals being acquired by a reception part 105 from the echoes of the ultrasonics transmitted at different transmission timings and from different transmission apertures 111. At this time, when the ultrasonics are transmitted, the ultrasonics are sequentially transmitted from the different plurality of transmission apertures 110, 111 at timings in which, a spatial position of the reception focus on the imaging object 20 matches according to movement of the imaging object 20 with respect to a same area out of the plurality of areas obtained by dividing the range 33 which should be imaged of the imaging object 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for performing high-quality imaging by performing transmission-to-transmission synthesis in an ultrasonic imaging apparatus.

  An imaging apparatus using ultrasonic waves is configured by transmitting ultrasonic waves to an object, receiving an echo reflected by the object as an electrical signal, and displaying the received signal on a monitor as image data. Ultrasound is generated by inputting an electrical signal to an ultrasonic transducer (transducer) provided in the apparatus. The echo is converted into an electrical reception signal by being received by the ultrasonic transducer. The imaging device depicts the internal structure of the imaging target by displaying the intensity of the received signal as a tomographic image or a stereoscopic image. Such an imaging technique is widely used as a diagnostic apparatus that captures a tomographic image of a living body with minimal invasiveness.

  The ultrasonic imaging apparatus scans an ultrasonic beam from an ultrasonic transducer over an imaging region, and receives an echo generated by each transmission. The echo received in each transmission is received by a plurality of ultrasonic transducers and converted into a plurality of received signals. The plurality of received signals are delayed (phased) by a delay time set for each element according to the reception focus, and then added, and converted into focus data in a target imaging region. Furthermore, the ultrasonic imaging apparatus creates image data of the entire object by arranging the focus data for different imaging points obtained respectively by different transmissions.

  Also, by combining the focus data obtained by transmitting ultrasonic transducers from different directions to a certain imaging point, the resolution of the point image is increased, and the robustness against inhomogeneity is given. can do. Such a synthesis process is called an inter-transmission aperture synthesis method or the like as an image quality improvement imaging method. Patent Document 1 is known as a prior patent relating to the aperture synthesis method.

JP-A-11-212214

  Since the focus data superimposed by the aperture synthesis method described in Patent Document 1 is obtained by transmitting ultrasonic waves from a plurality of different directions to the same imaging point, the transmission time is different. For this reason, when there is a motion in the imaging target, the spatial positional relationship between the imaging point of the imaging target and the transducer is different at a plurality of transmission times when the focus data to be superimposed is obtained. For this reason, when the imaging point is set in the same manner as when there is no movement in the imaging target, focus data cannot be obtained for the same imaging point, so the signals cannot be correctly superimposed by the aperture synthesis method, and high image quality is achieved. The effect cannot be obtained. Further, when the positional relationship is greatly different, there is a possibility that the image quality is deteriorated by causing image blurring after the composition.

  An object of the present invention is to obtain an effect of improving image quality by aperture synthesis even in a case where there is a movement in an imaging target in ultrasonic imaging.

  In order to solve the above problems, one of the representative ultrasonic imaging apparatuses of the present invention includes an ultrasonic probe having a plurality of transmission apertures and one or more reception areas, and an imaging target for each transmission aperture. A phasing process is performed on the output of the receiving area that receives the ultrasonic echo from the imaging target, and a transmission unit that performs an operation of transmitting ultrasonic waves toward the range to be imaged, and the imaging target A reception unit that obtains a reception signal for a desired reception focal point and an addition process for a plurality of reception signals for the same reception focal point respectively obtained by the reception unit receiving ultrasonic echoes transmitted from different transmission apertures A combining unit; and a setting unit that sets transmission timing of the transmitting unit. The setting unit divides the range to be imaged of the imaging target into a plurality of areas, and the timing at which the spatial position of the reception focus in the imaging target matches within the predetermined range for the same area according to the movement of the imaging target Thus, ultrasonic waves are transmitted in order from a plurality of different transmission openings.

  According to the present invention, an image quality improvement effect by aperture synthesis can be obtained even when there is a movement in the imaging target. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is a diagram illustrating an overall configuration of an ultrasonic imaging apparatus according to a first embodiment of the present invention. The figure which shows schematic structure of the ultrasonic transmission / reception surface of an ultrasonic probe. (A) Explanatory drawing which shows irradiation area | region of transmission aperture of 1st embodiment, (b) Explanatory drawing which shows a phasing range and a receiving focus, (c) Explanatory drawing which shows the range of the receiving focal point after a synthesis | combination. Explanatory drawing which shows a response | compatibility with each area | region of the range which should be imaged, and the group of the transmission opening of the ultrasonic probe of 1st embodiment. The figure explaining transmitting an ultrasonic wave from a transmission opening at the timing of the same time phase t1 of a different heartbeat. The figure explaining the signal (electrocardiogram signal) showing the motion of the imaging target of 1st embodiment. The figure explaining the signal (blood-flow velocity signal) showing the motion of the imaging target of 1st embodiment. Explanatory drawing which shows the example which set multiple time phases t1-t4 to the heartbeat period of 1st embodiment. Explanatory drawing which shows the receiving scanning line set to the range which should be imaged. (A)-(c) The figure which shows the response | compatibility with the example of the pattern (map) of the group set to the transmission opening arranged in one dimension, and the time phase set to the heartbeat period. (A) Explanatory drawing which shows the relationship between the transmission aperture arranged in two dimensions, and the range which should be imaged, (b) Explanatory drawing which shows the relationship between each area | region of the range which should be imaged, and a transmission aperture. (A), (b) The figure which shows a response | compatibility with the example of the pattern (map) of the group set to the transmission opening arranged in two dimensions, and the time phase set to the heartbeat period. (A), (b) The figure which shows a response | compatibility with the example of the pattern (map) of the group set to the transmission opening arranged in two dimensions, and the time phase set to the heartbeat period. The figure which shows the whole structure of the ultrasonic imaging device of 2nd embodiment. 15 is a flowchart showing operations of a setting unit and a combining unit of the ultrasonic imaging apparatus in FIG. Explanatory drawing which shows the relationship between the transmission opening of 2nd embodiment, its phasing range, and the synthesis | combination of a phasing range.

<< First Embodiment >>
An ultrasonic imaging apparatus (ultrasonic transmission / reception apparatus) according to a first embodiment will be described with reference to the drawings. FIG. 1 is a diagram illustrating an overall configuration of the ultrasonic imaging apparatus 100 according to the first embodiment, and FIG. 2 illustrates a schematic configuration of an ultrasonic transmission / reception surface of the ultrasonic probe 108 (an arrangement example of transmission openings). FIG. 3A is an explanatory diagram showing the irradiation area 33 of the transmission aperture in the first embodiment, FIG. 3B is an explanatory diagram showing the phasing range 35 and the reception focus, and FIG. 3C is a range of the reception focus after synthesis. It is explanatory drawing. FIG. 4 is an explanatory diagram showing a correspondence between a group of transmission apertures of the ultrasonic probe 108 of the first embodiment and each region of the range 219 to be imaged. FIG. 5 is a diagram for explaining that ultrasonic waves are transmitted from the transmission openings 110 to 113 at the same time phase t1 of different heartbeats.

  As illustrated in FIG. 1, the ultrasonic imaging apparatus 100 includes an ultrasonic probe 108, a transmission unit 102, a reception unit 105, a setting unit 104, and a synthesis unit 25.

As shown in FIG. 2, the ultrasonic probe 108 has transmission openings 110 to 113 that are areas of ultrasonic transducers that irradiate ultrasonic waves in a plurality of predetermined directions, and one or more reception areas 130. The plurality of transmission openings 110 to 113 and the like and the reception area 130 are each configured by one or more ultrasonic transducers (transducers). The ultrasonic transducer has a function of converting an electric signal into a sound wave and a sound wave into an electric signal. In the example of FIG. 2, the reception region 130 is configured by a channel 109 that is a set of one or more ultrasonic transducers, and the transmission openings 110 to 113 and the like are configured by a plurality of channels 109. In addition, the ultrasonic transducer is virtually or physically divided into a plurality (P) of channels 109 _{1 to} 109 _P. Each of the channels 109 _{1 to} 109 _P is composed of one or a plurality of ultrasonic transducers.

  Not limited to this configuration, each of the transmission apertures 110 to 113 may be configured by one channel. A plurality of transmission openings 110 to 113 may be overlapped with each other. In addition, the ultrasonic probe of FIG. 2 has a configuration in which one channel 109 performs both transmission and reception. However, the configuration is not limited to this, and the channels of the transmission apertures 110 to 113 and the reception area 130 are separated. May be.

  The transmission unit 102 performs an operation of transmitting the ultrasonic wave 31 toward the range (imaging range) 219 to be imaged of the imaging target 20 of the subject for each of the transmission apertures 110 and 111 and the like. The ultrasonic wave 31 may be focus-transmitted toward a predetermined transmission focus of the imaging target 20, or may be diffusely transmitted as shown in FIG. Thereby, an ultrasonic wave is irradiated to the irradiation area 33 of the range 219 to be imaged for each transmission aperture.

  The reception area 130 receives an ultrasonic echo from the imaging target 20 and outputs an electrical reception signal. The receiving unit 105 applies a phasing process to the output of the reception area 130, and receives a received signal for the reception focus (for example, 52) in the phasing range 35 set in the irradiation area 33 as shown in FIG. (Focus data) is obtained. As shown in FIG. 3C, the synthesizer 25 obtains focus data obtained from ultrasonic echoes transmitted at different transmission timings from different transmission apertures (for example, 110 and 111) with respect to the same reception focus 52. Addition processing (combination between transmissions) is performed. For example, an image is constructed in a range 135-n where a phasing range 35-110 corresponding to the position of the transmission opening 110 and a phasing range 35-111 corresponding to the position of the transmission opening 111 adjacent to the transmission opening 110 overlap. A reception scanning line 241 that is a line in which a plurality of points are collected and a reception focal point (hereinafter also referred to as “imaging point”) 52 that is each point for constructing an image overlap. The combining unit 25 adds the respective focus data of 35-110 and 35-111 for the range of 135-n.

  At this time, the setting unit 104 divides the imaging range 219 of the imaging target 20 into a plurality of areas 219-1 to 219-4 as shown in FIG. The setting unit 104 then sets the timing (for example, the spatial position of the reception focus 52 or the like on the imaging target 20 within a predetermined range in accordance with the movement of the imaging target 20 with respect to the same region (for example, 219-1) (for example, At time t1) in FIG. 5, ultrasonic waves are transmitted in order from a plurality of different transmission openings 110 to 113 as shown in FIG. Note that the timing that matches within the predetermined range is not only the timing that completely matches, but also the timing that deviates within the predetermined range due to characteristic fluctuations of the imaging target, errors in the measurement system that detects the signal, and the like. Is also included.

  Thereby, the synthetic | combination part 25 can carry out aperture composition between the transmissions of the focus data obtained from the echo of the ultrasonic wave transmitted at the timing when the spatial position of the reception focus 52 in the region (for example, 219-1) matches. . Therefore, even when the imaging target 20 moves and the imaging target 20 moves while repeating the transmission of ultrasonic waves, the spatial position of the imaging target 20 matches, so image blurring occurs during aperture synthesis. The effect of high image quality by aperture synthesis can be obtained without causing any problems.

  For example, as illustrated in FIGS. 1 and 5, the setting unit 104 receives the signal 12 corresponding to the periodic movement of the imaging target 20 and has the same time phase (for example, t1) with respect to the received signal 12. And outputs a signal instructing to transmit ultrasonic waves and a signal instructing a transmission aperture used for transmitting ultrasonic waves to the transmitting unit 102. As a result, the transmission unit 102 transmits ultrasonic waves from the transmission opening of the ultrasonic probe 108 instructed by the setting unit 140 to the same region 219-1 in the imaging range 219 at the instructed timing. Let

  FIG. 6 is a diagram illustrating a signal (electrocardiogram signal) representing the movement of the imaging target 20 according to the first embodiment. FIG. 7 is a diagram illustrating a signal (blood flow velocity signal) representing the movement of the imaging target 20 according to the first embodiment.

  As the signal 12 corresponding to the periodic movement of the imaging target 20, an electrocardiogram signal, a signal indicating blood flow velocity, or a signal indicating respiratory motion can be used. Specifically, for example, as shown in FIG. 6, an electrocardiogram signal (electrocardiogram waveform) 61 of the imaging target 20 obtained by an electrocardiograph (electrocardiogram monitor) 60 can be used as the signal 12. Further, for example, as shown in FIG. 7, the blood flow velocity of the blood vessel 73 of the imaging target 20 is measured by an ultrasonic Doppler blood flow meter (blood flow velocity monitor) 70, and the obtained blood flow velocity signal 62 is obtained as a signal 12. Can be used as

  As a reference for determining the timing of the temporary phase, a signal indicating a signal period is detected and used. In the case of the electrocardiographic waveform 61, for example, an R wave 71 can be used. In the case of the blood flow velocity signal 62, the rise time 72 synchronized with the pulsation can be used.

  Note that the time of the R wave 71 and the rise time 72 may not be a completely periodic signal due to characteristic fluctuations of the imaging target, errors in the measurement system that detects the signal, and the like. Even in such a case, performing aperture synthesis using a plurality of signals 12 is equivalent to transmitting at a timing that matches within a range of fluctuation or error (that is, a timing that matches within a predetermined range). .

  As shown in FIG. 4, the plurality of transmission openings 110 to 113 that transmit ultrasonic waves to the same region (for example, 219-1) in the imaging range 219 are preferably adjacent to each other in the transmission order. Thereby, since the wide range of the irradiation region 33 of the ultrasonic wave 31 can be overlapped with each other, the focus data of the reception focus 52 in the overlapping irradiation region 33 can be aperture-synthesized.

  Moreover, FIG. 8 is explanatory drawing which shows the example which set multiple time phases t1-t4 to the heartbeat period of 1st embodiment. FIG. 9 is an explanatory diagram showing the reception scanning line 241 set in the imaging range 219. As shown in FIG. 8, the setting unit 104 has a plurality of different time phases t1 within the same period (for example, 81-1) based on the periods 81-1 to 81-4 of the signal 12 from the imaging target 20. , T2, t3, and t4 can be set. In this case, ultrasonic waves are transmitted in order from different transmission openings to different regions for different time phases. For example, as illustrated in FIG. 4, in the time phase t1, the ultrasonic waves 31 are transmitted from the four different transmission openings 110 to 113 to the region 219-1 of the imaging target 20, respectively, and in the time phase t2, the ultrasonic waves 31 are different to the region 219-2. The ultrasonic waves 31 are transmitted from the four transmission openings 114 to 117, respectively, and at the time phase t3, the ultrasonic waves 31 are transmitted from the four transmission openings 118 to 121 to the area 219-4, respectively, and to the area 219-4 at the time phase t4. The ultrasonic waves 31 are transmitted from the transmission openings 122 to 125, respectively. As described above, by transmitting ultrasonic waves from a plurality of different time phases within the same period, the focus data (that is, the image) of the reception focus for the reception scanning line 241 in the entire imaging range 219 is obtained as shown in FIG. Time until it can be obtained can be shortened.

  When transmitting ultrasonic waves from a plurality of time phases within the same cycle, adjacent regions (for example, the regions 219-1 and 219-2) among the plurality of regions 219-1 to 219-4 have a plurality of different times. It is desirable that the ultrasonic wave 31 is transmitted at the timing of successive time phases (for example, t1 and t2) among the phases t1 to t4. This is because the effect of improving the resolution by aperture synthesis is obtained even in the vicinity of the boundary between adjacent regions. When the synthesizing unit 25 synthesizes the focus data of the reception focus 52 on the reception scanning line 241 near the boundary between the adjacent regions 219-1 and 219-2, the echo of the ultrasonic wave 31 transmitted at the time phase t1 is used. In order to synthesize the obtained focus data and the focus data obtained by the echo of the ultrasonic wave 31 transmitted at the time phase t2, the position of the reception focus 52 is not completely matched by the movement of the imaging target 20, Since the time phases t1 and t2 are continuous, the amount of displacement due to the body movement of the imaging target 20 is minimal. Therefore, aperture synthesis can be performed while minimizing the amount of positional deviation of the reception focal point 52 in the vicinity of the boundary between adjacent areas, and the disturbance in resolution near the boundary between the adjacent areas 219-1 and 219-2 can be reduced. While suppressing, the effect of improving the resolution by aperture synthesis can be obtained.

  FIG. 10 is a diagram showing a correspondence between an example of a group pattern (map) set in the transmission openings arranged in one dimension and a time phase set in the heartbeat cycle.

  For example, as illustrated in FIGS. 10A to 10C, the setting unit 104 may determine the number of time phases to be set in the same period 81 according to the length of the period 81 of the signal 12. Thereby, for example, aperture synthesis can be performed according to the period 81 of the signal 12 of the imaging target 20.

  The setting unit 104 may be configured to set the patterns (shape and arrangement) of the regions 219-1 to 219-4 of the imaging range 219 according to the number of time phases set within the same period 81. . Specifically, for example, the setting unit 104 includes a memory 104a that stores a pattern (region pattern) of one or more regions that are predetermined for each number of time phases set in the same period 81. Configure. The memory 104a stores the area pattern as a map, for example, but is not limited thereto. The setting unit 104 can read and set the corresponding area pattern from the memory 104a based on the number of time phases set within the same period 81.

  For example, the setting unit 104 divides the plurality of transmission apertures of the ultrasound probe 108 into a plurality of groups corresponding to the shapes of the plurality of regions 219-1 to 219-4, and the same region (for example, 219). In (1), the ultrasonic waves 31 can be transmitted in order at the same time phase from a plurality of transmission apertures included in the group corresponding to the region. FIGS. 10A to 10C show specific examples when the transmission apertures of the ultrasonic probe 108 are a one-dimensional array in which the transmission apertures are arranged one-dimensionally and the signal 12 is an electrocardiogram signal 61. FIG. A plurality of patterns in which the groups 220-1 to 220-6 including the number of transmission apertures corresponding to the number of the ultrasonic waves 31 transmitted to one region 219-1 to 219-4 are set in the ultrasonic probe 108. Are prepared in advance as shown in FIGS. 10A to 10C and stored in the memory 104 a in the setting unit 104.

  The pattern of FIG. 10A is a pattern when the period 81 of the electrocardiogram signal 12 is long and six time phases t1 to t6 can be set in the same period 81. Six groups 220-1 to 220-6 are set in the ultrasound probe 108 having the transmission apertures 110 to 125, and each group includes three transmission apertures, and the ultrasound probe 108 in a period of 3 heartbeats. The transmission is completed from all the transmission apertures 110 to 125, and the focus data for the reception scanning lines 241 in the areas 219-1 to 219-6 of the imaging target 20 corresponding to the groups 220-1 to 220-6 is acquired.

  The group 220-6 includes one transmission aperture 125. As a result of setting each group in the ultrasonic probe 108, the remaining transmission apertures 125 constitute one group. Indicates that In this case, since the transmission opening for transmitting the ultrasonic wave 31 does not exist in the time phase t6-2 and the time phase t6-3, the ultrasonic wave 31 is not transmitted.

  The pattern of FIG. 10B is a pattern when the period of the electrocardiogram signal 12 is shorter than that of FIG. 10A and four time phases t1 to t4 can be set within the same period 81. Four groups 220-1 to 220-4 are set in the ultrasound probe 108, and each group includes four transmission apertures. All the transmission apertures 110 to 110 of the ultrasound probe 108 in a period of four heartbeats. The transmission is completed from 125, and the focus data for all the reception scanning lines 241 in the areas 219-1 to 219-4 corresponding to the groups 220-1 to 220-4 is acquired.

  On the other hand, the pattern of FIG. 10C is a pattern when the period of the electrocardiogram signal 12 is further shorter than that of FIG. 10B and three time phases t1 to t3 can be set in the same period 81. Three groups 220-1 to 220-3 are set in the ultrasound probe 108, each group including six transmission apertures, and all the transmission apertures 110 to 110 of the ultrasound probe 108 in a period of three heartbeats. The transmission is completed from 125, and the focus data for all the reception scanning lines 241 in the areas 219-1 to 219-3 corresponding to the groups 220-1 to 220-3 is acquired.

  As in FIG. 10A, the group 220-3 includes four transmission openings 122 to 125.

  Note that as shown in FIG. 10B, when the number of times of transmission is constant within each period, a waiting time during which transmission cannot be performed does not occur, so that imaging efficiency can be increased. As described above, the setting unit 104 may automatically select a pattern diagram 10 (b) that does not generate a waiting time.

  FIGS. 11A and 11B are (a) an explanatory diagram showing a relationship between two-dimensionally arranged transmission apertures and the imaging range 219, and (b) an explanatory diagram showing a relationship between each region of the imaging range 219 and the transmission apertures. is there. FIG. 12 and FIG. 13 are diagrams showing a correspondence between an example of a group pattern (map) set for two-dimensionally arranged transmission apertures and a time phase set for a heartbeat cycle.

  FIG. 11A shows a relationship in which the transmission aperture is two-dimensionally arranged in the xy axis direction, and ultrasonic waves are transmitted from the transmission aperture toward the imaging range 219 set in a three-dimensional space. FIG. 11B shows an xy-axis cross section of FIG. 11A, and the ultrasonic waves 31-110 irradiated to the transmission apertures 110 to 113 in the image pickup range 219 set to four are set to 219-1. The positional relationship of etc. is shown.

  When the transmission aperture of the ultrasonic probe 108 is a two-dimensional array arranged two-dimensionally as shown in FIG. 11, an example of a pattern such as a group 220-1 set in the ultrasonic probe 108 is illustrated. 12 (a) and 12 (b) and FIGS. 13 (a) and 13 (b). The pattern of FIG. 12A is a pattern when four time phases t1 to t4 can be set in the same period 81. Four groups 220-1 to 220-4 are set in the ultrasonic probe 108 having 16 transmission apertures 110 to 125, and each group includes four transmission apertures, and the ultrasonic probe is in a period of 4 heartbeats. The transmission of the ultrasonic wave 31 is completed from all the transmission openings 110 to 125 of the touch element 108, and the focal points of the regions 219-1 to 219-4 corresponding to the groups 220-1 to 220-4 as shown in FIG. Get the data.

  The pattern of FIG. 12B is a pattern when five time phases t1 to t5 can be set in the same period 81. Five groups 220-1 to 220-5 are set in the ultrasonic probe 108 having 25 transmission apertures 110 and the like, and each group includes five transmission apertures, and the ultrasonic probe is performed in a period of 5 heartbeats. The transmission of the ultrasonic waves 31 is completed from all 25 transmission apertures 110 and the like of the child 108, and the focus data of the areas 219-1 to 219-5 corresponding to the groups 220-1 to 220-5 are acquired.

  The pattern of FIG. 13A is a pattern when six time phases t1 to t6 can be set in the same period 81. Six groups 220-1 to 220-6 are set in the ultrasonic probe 108 having 24 transmission apertures 110 and the like, and each group includes four transmission apertures, and the ultrasonic probe in a period of 4 heartbeats. The transmission of the ultrasonic wave 31 is completed from all 24 transmission apertures 110 and the like of the child 108, and the focus data of the areas 219-1 to 219-6 corresponding to the groups 220-1 to 220-6 are acquired.

  The pattern of FIG. 13B is a pattern when eight time phases t1 to t8 can be set in the same period 81. Eight groups 220-1 to 220-8 are set in the ultrasonic probe 108 having 24 transmission apertures 110 and the like, and each group includes three transmission apertures, and the ultrasonic probe is performed in a period of 3 heartbeats. The transmission of the ultrasonic wave 31 is completed from all 24 transmission apertures 110 and the like of the child 108, and the focus data of the regions 219-1 to 219-8 corresponding to the groups 220-1 to 220-8 are acquired.

  The setting unit 104 detects the period of the signal 12 corresponding to the movement of the imaging target 20, sets the number of time phases set within one period according to the length of the period, and sets the number of time phases according to the number of time phases. The pattern of the group of transmission apertures can be selected from the patterns of 10 or FIGS.

  The setting unit 104 preferably transmits ultrasonic waves in the order of adjacent transmission apertures among the plurality of transmission apertures 110, 111, 112, and the like in the group 220-1. This is because by transmitting ultrasonic waves in the order of adjacent transmission apertures, it is possible to largely overlap ultrasonic irradiation regions, and it is possible to synthesize apertures in a wide range that overlaps each time transmission is performed.

  As described above, by using the ultrasonic imaging apparatus according to the first embodiment, even when there is a motion in the imaging target, it is possible to suppress the influence of the motion and obtain an image with high resolution by aperture synthesis. it can. For example, in living body imaging, not only the heart, which is a spontaneously moving organ, is the imaging target, but also other parts, such as the carotid artery and liver, which are affected by the heartbeat, are considered as imaging targets. In this case, a high resolution image can be obtained by aperture synthesis.

<< Second Embodiment >>
A specific configuration example of the ultrasonic imaging apparatus according to the second embodiment will be described.

<Overall configuration of device>
FIG. 14 is a diagram illustrating an overall configuration of the ultrasonic imaging apparatus 100 according to the second embodiment. In FIG. 14, the same components as those of the first embodiment shown in FIG. Similar to the first embodiment, the ultrasonic imaging apparatus 100 includes an ultrasonic probe 108, a transmission unit 102, a reception unit 105, a synthesis unit 25, and a setting unit 104. The embodiment includes a control unit 106, a user interface (UI) 121, a transmission / reception switching unit 101, an image processing unit 107, and a display unit 122.

  The control unit 106 controls the overall operation of the ultrasonic imaging apparatus 100. The UI 121 is an interface that accepts an instruction from a user who uses the ultrasonic imaging apparatus 100, input of various parameters, and the like. The transmission / reception switching unit 101 is a switch for selecting the connection destination of the ultrasonic probe 108 so that the ultrasonic probe 108 is connected to the transmission unit 102 at the time of ultrasonic transmission and to the reception unit 105 at the time of ultrasonic reception. Is performed under the control of the control unit 106. The image processing unit 107 generates an ultrasonic image using the focus data after the synthesis unit 25 performs aperture synthesis. The display unit 122 displays an ultrasonic image.

  The ultrasonic probe 108 includes a plurality of ultrasonic transducers (transducers) arranged one-dimensionally or two-dimensionally in a predetermined arrangement. The ultrasonic probe 108 is tailored to have an outer shape suitable for use by bringing the surface on which the ultrasonic transducer is disposed (ultrasonic transmission / reception surface) into contact with the imaging target 20.

Etc. transmit aperture 110 can be the same size as the one channel 109 _1, such as may constitute a single transmit aperture by a plurality of channels as shown in FIG. In the following description, an example in which a plurality of adjacent channels (four in FIG. 2) are used as one transmission aperture 110 will be described. The plurality of transmission apertures (110, 111, 112, 113) may be set so as to partially overlap.

In the following description, each of the channels 109 _{1 to} 109 _P is used as the reception area 109. Of course, it is possible to use two or more channels as one reception area 109.

<Imaging range 219>
The ultrasonic imaging apparatus 100 automatically determines the imaging range 219 of the imaging target 20 based on designation from the UI 121 or input parameters from the UI 121.

<Transmitter 102>
The transmission unit 102 selects a predetermined transmission opening (for example, 110) of the ultrasonic probe 108 in accordance with an instruction from the setting unit 104, and generates a transmission signal for transmitting the ultrasonic wave 31 to the selected transmission opening 110. . Specifically, the waveform type, delay time, amplitude modulation, weighting, and the like are determined, and a transmission signal corresponding to the waveform type is generated. The transmission unit 102 delivers the generated transmission signal to each of the ultrasonic transducers of the channels constituting the transmission opening 110, and the ultrasonic wave 31 is transmitted from the transmission opening 110 to the irradiation region 33 as shown in FIG. 3A, for example. Send it. The transmission unit 102 causes the transmission openings 110 to 113 to execute this operation at the timing set by the setting unit 104 described later.

<Receiving unit 105>
When the ultrasonic wave 31 is transmitted to the imaging range 219 from any one of the transmission openings 110 to 113, an echo is generated in the imaging range 219. The reception aperture (channel) 109 of the ultrasonic probe 108 receives the echo and converts it into an electrical signal. As illustrated in FIG. 14, the reception unit 105 includes a memory 40 and a delay addition unit 21. The received signal obtained each time transmission is temporarily stored in the memory 40. The delay adder 21 reads out the received signal from the memory 40, delays it by a predetermined delay value for each channel, and then performs addition processing to generate focus data focused on a predetermined imaging point 52 (reception). Beam forming). The receiving unit 105 passes the generated focus data to the synthesizing unit 25. For reception beam forming, reception signals of all the channels 109 _{1 to} 109 _P of the ultrasonic probe 108 may be used, or only reception signals of channels within a predetermined reception aperture (active channel) may be used. Good.

  Note that the control unit 106 sets a plurality of reception scanning lines 241 at predetermined positions in the imaging range 219 as shown in FIG. Further, the control unit 106 sets a predetermined phasing range 35-110 corresponding to the position of the transmission opening 110 at the time of transmission to the receiving unit 105 as shown in FIG. Focus data is generated for all the reception focal points 52 on the plurality of reception scanning lines 241 included in. Thus, at least in the range 135-n where the phasing range 35-111 corresponding to the adjacent transmission aperture 111 and the phasing range 35-110 corresponding to the transmission aperture 110 overlap, the reception scanning line 241 and the imaging point Since 52 overlaps, the synthesizing unit 25 can add the focus data.

<Synthesis unit 25>
As shown in FIG. 3C, the synthesizer 25 synthesizes by adding a plurality of pieces of focus data having the same coordinates transferred. At this time, the focus data to be combined is selected according to the range set by the setting unit 104. As shown in FIG. 9, after the combined focus data of the reception scanning lines 241 in all the areas of the imaging range 219 are collected, the combined data is transferred to the image processing unit 107, and the image processing unit 107 Data received as image data for processing is processed, transferred to the display unit 122, and displayed on the display unit 122.

<Setting unit 104>
The setting unit 104 divides the imaging range 219 of the imaging target 20 into a plurality of areas, and at a timing when the spatial position of the reception focus in the imaging target matches the same area according to the movement of the imaging target 20. The operation of transmitting the ultrasonic waves 31 in order from the transmission opening is performed. In order to realize this by software, the setting unit 104 includes a memory 104a and a CPU (Central Processing Unit) 104b. The CPU 104b reads and executes a program stored in advance in the memory 104a, so that FIG. Behaves like Of course, part or all of the operation of the setting unit 104 may be realized by hardware such as ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

  The operations of the setting unit 104 and the combining unit 25 will be described with reference to FIGS. 15 and 16. FIG. 15 is a flowchart showing the operations of the setting unit and the synthesizing unit of the ultrasonic imaging apparatus of FIG. 14, and FIG. 16 shows the relationship between the transmission aperture, its phasing range, and the phasing range synthesis of the second embodiment. It is explanatory drawing which shows. Here, as an example, the electrocardiogram signal 61 of the imaging target 20 is used as the signal 12. In the memory 104a, maps (for example, FIGS. 10 (a) to 10 (c) and FIGS. 12 (a), 12 (b) and 13 (a), (a), which define a pattern (arrangement pattern) of the transmission aperture group 220, b) is stored in advance for each combination of the number of transmissions (number of time phases N) during one heartbeat period 81 and the total heart rate M used for generating one image, which can be input by the user. ing.

  First, the setting unit 104 causes the display unit 122 to display a predetermined input screen for accepting input of imaging conditions from the user, and accepts imaging parameters on the input screen (step 140). Specifically, the setting unit 104 includes an imaging range 219, an imaging depth D, a transmission numerical aperture S used to construct an image, a total heart rate M used until image update (one image generation), and An input for selecting whether the ultrasonic probe 108 used for imaging is a one-dimensional array or a two-dimensional array is received as an imaging parameter (step 140). The imaging range 219, the imaging depth D, and the transmission numerical aperture S may use predetermined values, or may be calculated by the setting unit 104 by a predetermined calculation method based on other imaging conditions. . Whether the ultrasonic probe 108 is a one-dimensional array or a two-dimensional array, when the control unit 106 has a function of discriminating the type of the ultrasonic probe 108, a determination result is set from the control unit 106. You may grasp | ascertain by 104 receiving.

  The setting unit 104 receives the electrocardiogram signal 12 from the electrocardiograph 60 of the imaging target 20 and calculates a cycle T of one heartbeat (step 141). The setting unit 104 divides the calculated heartbeat period T by a predetermined minimum time interval at which ultrasound can be transmitted, and the number of transmissions (number of time phases) that can be transmitted during one heartbeat from one heartbeat period T. A certain maximum number of transmissions Nmax is calculated (step 142). Specifically, for example, the imaging depth received in step 140 is D [mm], the sound speed of the medium is C [mm / s], and the time required for processing such as delivery of a predetermined transmission / reception signal is α [s]. In this case, the maximum number of transmissions Nmax = T / (2 * D / C + α).

  Next, the setting unit 104 receives the transmission numerical aperture S used for constructing one image received in step 140 and the total heart rate M used until image update (one image generation). The number N of times of transmission to be transmitted is calculated by N = S / M (where N ≦ Nmax). The setting unit 104 displays the calculated number of transmissions N and Nmax on the display unit 122. The user confirms the displayed value of Nmax, and under the constraint of N ≦ Nmax, if importance is attached to high image quality, the number S of transmission apertures used for constructing one image is increased, and real-time characteristics are emphasized. Adjustment such as lowering M is performed, and the setting unit 104 accepts this adjustment. Thereby, the setting unit 104 sets the number N of transmissions transmitted during one heartbeat and the total heart rate M used until image update (one image generation, imaging) (step 143).

  Next, the setting unit 104 selects a group such as the transmission aperture 110 according to the number of transmissions (number of time phases) N, the total heart rate M, and whether the ultrasonic probe 108 is a one-dimensional array or a two-dimensional array. An arrangement pattern (map) such as 220-1 is selected from the maps stored in the memory 104a (step 144).

When the setting unit 104 receives a scan start instruction via the UI 121, the setting unit 104 detects, for example, an R wave of the electrocardiogram signal 12 in order to generate an i-th image (captured image number i). The time is t0, the heart rate m and the number of transmissions n are counted, and the ultrasonic wave 31 is transmitted at the time tn-m in the selected map at the timing of the time phase tn-m determined in advance with respect to the time t0. A signal instructing the transmitting unit 102 to transmit the ultrasonic wave 31 from the transmission aperture determined to be output is output (steps 145 to 148). Specifically, for example, when the map of N = 4 and M = 4 shown in FIG. 12A is selected in step 144, the setting unit 104 takes an image to generate the first image. An image number i = 1 is set (step 145), for example, an R wave of the electrocardiogram signal 12 is detected, and at time t0, scanning is started and a heart rate m = 1 is counted (step 146). The setting unit 104 counts the number of transmissions n = 1 (step 147), and is set to transmit the ultrasonic wave 31 at time t1-1 in the time phase tn-m = t1-1 of the map selected in step 144. The transmission unit 102 is instructed to transmit the ultrasonic wave 31 from the transmission aperture 110 (group 220-1) (step 148). Thereby, the transmission unit 102 transmits the ultrasonic waves 31 from the transmission opening 110a of the ultrasonic probe 108. Echoes from the subject are received by the plurality of receiving areas 109 _{1 to} 109 _P of the ultrasonic probe 108. As shown in FIGS. 3B and 16, the receiving unit 105 sets a predetermined phasing range 35-110 around the transmission aperture 110, and sets the reception focus on the reception scanning line in the phasing range 35-110. Focus data is generated and stored in the built-in memory 40 in association with heart rate m = 1. In the memory 40, for each transmission aperture, an area for storing focus data obtained by transmission from the transmission aperture is prepared.

  Next, the setting unit 104 determines whether the number of transmissions n has reached the upper N (= 4) (whether n = N) (step 149), and if not, increments the number of transmissions n ( n = 2) (step 150), and at the time phase tn-m = t2-1 of the map selected in step 144, the transmission aperture 114 (group 220-) set to transmit the ultrasonic wave 31 at time t2-1. The transmitting unit 102 is instructed to transmit the ultrasonic wave 31 from 2) (step 148). Similarly, the setting unit 104 transmits the ultrasonic wave 31 from the transmission opening 118 (group 220-3) at the time phase t3-1 and from the transmission opening 122 (group 220-4) at the time phase t4-1. To instruct. Thereby, the transmission unit 102 transmits the ultrasonic wave 31 from the designated transmission opening at the designated timing. Each time transmission is performed, the receiving unit 105 generates focus data of a predetermined phasing range 35 around the transmission aperture, and stores the focus data in the memory 40 in association with the heart rate m = 1.

  If the number of transmissions n reaches the upper N (= 4) in step 149, the setting unit 104 determines whether the heart rate m has reached the total heart rate M (whether m ≧ M) (step 149). 151) If not reached, the heart rate m is incremented (m = 2) (step 152), and if the next R wave of the electrocardiogram signal 12 is detected, the time is set to t0 and the number of transmissions n = 1 Is counted (step 147). Then, steps 148 to 150 are repeated. As a result, the transmitter 102 is instructed to transmit the ultrasonic waves 31 from the transmission apertures 111, 115, 119, and 123 of the groups 220-1 to 220-4 at the timings t1-2, t2-2, t3-2, and t4-2, respectively. Then, the receiving unit 105 stores the focus data of the predetermined phasing range 35 each time in the memory 40 in association with the heart rate = 2. This operation is repeated until the heart rate m reaches the total heart rate M (step 151). As a result, as shown in FIG. 16, the focus data of the phasing range 35 corresponding to the transmission aperture transmitted at the heart rate for each heart rate m is stored in the memory 40 in correspondence with the heart rate m.

  If the heart rate m reaches the total heart rate M, the synthesizer 25 receives all the focus data (m = 1 to M) stored in the memory 40 (step 154), and the focus of the same reception focus 52 The data is added and aperture synthesis is performed (step 155). Thereby, as shown in FIG. 16, the composition unit 25 generates one piece of image data for the imaging range 219 (step 156). The image data generated in step 156 is displayed as an image on the display unit 122.

  At this time, since the ultrasonic waves transmitted from the same group 220-1 or the like to the corresponding region 219-1 or the like are transmitted in the same time phase, the reception focus is not affected by the body movement of the imaging target 20. Match. Therefore, the focus data can be synthesized with high positional accuracy without being affected by the position shift due to the body movement, so that the effect of improving the resolution by aperture synthesis can be obtained. Moreover, since adjacent groups (for example, 220-1 and 220-2) are transmitted in continuous time phases, the time difference is about 1 PRT (pulse-repetition-time). Since this is a very small time for one cycle of cardiac vibration, the entire movement of the imaging target is so small that it can be ignored. Therefore, the amount of displacement due to body movement at the boundary between adjacent groups that transmit ultrasonic waves in successive time phases is minimal, and image blurring is minimized in the synthesis process, and an image quality improving effect is obtained.

  10 (a) to 10 (c) and FIGS. 12 (a), 12 (b) and FIGS. 13 (a) and 13 (b), the order in which transmission is performed within the groups of the transmission openings is shown in the figure. Not limited to. As described above, since the ultrasonic waves transmitted from the same group 220-1 and the like to the corresponding region 219-1 and the like are transmitted in the same time phase, the group 220-1 is reached by the time when the total heart rate M is reached. It is only necessary that transmission is performed from all transmission apertures arranged in the same position, and any transmission aperture is transmitted at any time phase (that is, the arrangement of transmission apertures that perform transmission sequentially within one group is randomly selected). The effect of improving the resolution can be obtained even if it is arranged. The arrangement of groups is the same.

  However, when it is possible to improve the image quality by synthesizing with the focus data obtained at close heartbeat timings, it is useful to make the transmission order adjacent to each other in the group of transmission apertures. For example, the arrangement of the transmission openings performed in order includes clockwise rotation. In the case of such a fixed arrangement, in order to avoid variation in aperture synthesis between adjacent groups, the arrangement of transmission apertures performed in order between adjacent groups may be the same, or may be arranged in line symmetry or point symmetry. . The arrangement of groups is the same.

  If one image is generated, the setting unit 104 increments the heart rate m (m = m + 1), increments the captured image number i (i = i + 1), and generates the next image. Return to 147. Then, the setting unit 104 repeats steps 147 to 150 until n = N is reached, and the time phases t1- (m + 1), t2- (m + 1), t3- (m + 1), t4- ( Transmission is performed at m + 1), focus data of each phasing range 35 is obtained, and focus data in the memory area for the corresponding transmission aperture in the memory 40 is overwritten. In step 151, since the current heart rate m + 1 exceeds the total heart rate M, the process proceeds to step 154, and the synthesis unit 25 receives all focus data from the current state in the memory 40 of the reception unit 105 (step 154), Aperture synthesis is performed (step 155). As a result, transmission is performed with the current heart rate (m + 1) at the time phases t1- (m + 1), t2- (m + 1), t3- (m + 1), t4- (m + 1). The focus data and the focus data obtained at the previous three (= M-1) heart rates are combined to generate one image (step 156). Every time the heart rate m is incremented (m = m + 1) (step 157), an updated image is generated for each heartbeat based on the focus data of the region corresponding to the transmission aperture transmitted in that heartbeat. Can do.

  In the flow of FIG. 15, the transmission aperture group pattern (map) is selected in step 144 based on the transmission numerical aperture S and the total heart rate M set in step 143. The user selects a group pattern first, and the setting unit 104 determines a transmission numerical aperture S, a total heart rate M, and a time phase number N that are adapted to the pattern, and determines whether N ≦ Nmax is satisfied. It is also possible to do.

  In the above description, the composition unit 25 performs composition for the same reception focus even at the boundary between adjacent groups (for example, 220-1 and 220-2). However, the present invention is limited to this structure. Instead, the combining unit 25 may combine only the focus data obtained by transmission from the transmission aperture of the same group. In addition, when the time phases transmitted by adjacent groups (for example, 220-1 and 220-2) are continuous (for example, the time phases t1-m and t2-m), synthesis is performed at the boundary, When the time phases transmitted by adjacent groups (for example, 220-1 and 220-3) are not continuous (for example, the time phases t1-m and t3-m), the synthesis may not be performed at the boundary. Good.

  In FIG. 16, transmission openings 110 to 117 (transmission openings 118 to 125 are not shown) for each heart rate m counted by the setting unit 104 and their phasing ranges 35-110 to 35-117 (phasing ranges 35-118 to 35-125 indicates an imaging range 219 that is a combination of a phasing range at a total heart rate M = 4.

  As described above, according to the ultrasonic imaging devices of the first and second embodiments, the spatial positional relationship of the imaging target can be matched even when the imaging target has a movement. The effect of high image quality can be obtained by aperture synthesis.

DESCRIPTION OF SYMBOLS 12 ... Signal, 20 ... Imaging object, 25 ... Synthesis | combination part, 31 ... Ultrasound, 33 ... Irradiation area | region, 35 ... Phase adjustment range, 100 ... Ultrasonic imaging device, 102 ... Transmission part, 104 ... Setting part, 104a ... Memory 104b ... CPU 105 ... receiving unit 108 ... ultrasonic probe 109 ... reception area 110-125 ... transmission aperture 219 ... imaging range 219-1 to 219-4 ... area 220-1 to 220 -4 ... Group

Claims (11)

An ultrasound probe having a plurality of transmission apertures and one or more receiving areas;
A transmission unit that performs an operation of transmitting ultrasonic waves from the transmission opening toward a range to be imaged of the imaging target;
A receiving unit that performs a phasing process on the output of the reception area that has received the ultrasonic echo from the imaging target, and obtains a reception signal for a desired reception focus of the imaging target;
A synthesizing unit that adds the plurality of reception signals for the same reception focus obtained by the reception unit from echoes of the ultrasonic waves transmitted at different transmission timings from different transmission apertures;
A setting unit for setting the transmission timing of the ultrasonic wave in the transmission unit,
The setting unit divides the imaging range of the imaging target into a plurality of areas, and a spatial position of the reception focus in the imaging target is predetermined for the same area according to the movement of the imaging target. The ultrasonic waves are transmitted in order from a plurality of different transmission apertures at the same timing within the range of
An ultrasonic imaging apparatus. 2. The ultrasonic imaging apparatus according to claim 1, wherein the setting unit divides the plurality of transmission openings of the ultrasonic probe into a plurality of groups corresponding to the shapes of the plurality of regions, and the same. In the region, the ultrasonic waves are transmitted in order from the plurality of transmission apertures included in the group corresponding to the region,
An ultrasonic imaging apparatus. 2. The ultrasonic imaging apparatus according to claim 1, wherein the setting unit receives a signal corresponding to a periodic movement of the imaging target, and is the same at a timing that is in the same time phase with respect to the received signal. The ultrasonic waves are transmitted in order from a plurality of different transmission openings with respect to the region of
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 3, wherein the plurality of transmission apertures that allow the setting unit to transmit ultrasonic waves to the same region are adjacent to each other in the order of transmission. In the transmitting aperture that fits, the irradiation area of the ultrasonic wave partially overlaps,
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 3, wherein the setting unit detects a period of the received signal, sets a plurality of different time phases within the same period, and sets each different time phase. To transmit the ultrasonic waves sequentially from the different transmission openings to the different regions,
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 5, wherein the setting unit includes a plurality of different time phases in the same period in a region adjacent in at least one direction among the plurality of regions. Among them, the ultrasonic wave is transmitted at the timing of the continuous time phase.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 5, wherein the setting unit determines the number of the time phases to be set in the same cycle according to a length of a cycle of the signal.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 7, wherein the setting unit sets a pattern of the region in the range to be imaged according to the number of time phases set in the same cycle.
An ultrasonic imaging apparatus. 9. The ultrasonic imaging apparatus according to claim 8, wherein the setting unit includes a storage unit that stores a pattern of one or more of the regions that is predetermined for each number of time phases. In accordance with the number of time phases set within the period, the corresponding pattern of the region is read from the storage unit and set.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 3, wherein the signal corresponding to the periodic movement of the imaging target is a signal indicating an electrocardiographic waveform.
An ultrasonic imaging apparatus. Transmitting ultrasonic waves from the transmission opening of the ultrasonic probe toward the imaging range of the imaging target;
The ultrasonic echo from the imaging object is received by the reception area of the ultrasonic probe, and the phasing process is performed on the output of the reception area to receive the desired reception focus of the imaging object. Obtaining a signal;
A step of adding a plurality of received signals for the same reception focus obtained by the receiving unit from echoes of the ultrasonic waves transmitted at different transmission timings from different transmission apertures, and
In the step of transmitting the ultrasonic wave, the spatial position of the reception focus in the imaging target according to the movement of the imaging target with respect to the same area among a plurality of areas obtained by dividing the imaging range of the imaging target. Transmitting the ultrasonic waves in order from a plurality of different transmission apertures at a timing that coincides within a predetermined range,
And an ultrasonic imaging method.

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