JPWO2017119301A1 - Ultrasonic imaging device - Google Patents

Abstract

In vector Doppler measurement, aliasing is automatically specified for Doppler shift amounts measured from a plurality of directions.
The ultrasonic imaging apparatus includes a signal processing unit that processes echo signals received at a plurality of openings formed in the ultrasonic probe, and the signal processing unit receives tissue signals from reception signals received at the individual openings. A Doppler velocity calculation unit that calculates the Doppler velocity of the above and an aliasing processing unit that detects aliasing (phase aliasing) caused by the Doppler velocity calculation. The aliasing processing unit detects aliasing by fitting the Doppler phase shift amount of each opening calculated by the Doppler velocity calculation unit, and performs processing such as removal or correction.

Description

  The present invention relates to an ultrasonic imaging apparatus, and more particularly to an ultrasonic imaging apparatus having a Doppler calculation function based on a vector Doppler method.

  In an ultrasonic imaging apparatus, an ultrasonic Doppler method is widely known as a technique for measuring the velocity of a tissue including blood flow in a target portion. In the ultrasonic Doppler method, only the velocity component (Doppler velocity) in the transmission direction of the ultrasonic beam can be directly measured. On the other hand, a method has been proposed in which a Doppler velocity is obtained from two or more different directions for one point (measurement point) of a target tissue, and a velocity vector is calculated using the Doppler velocities having different angles. (Non-Patent Document 1). This method is called a vector Doppler method. By using this method, the velocity vector of the tissue to be measured, that is, the tissue velocity vector, is calculated, and the velocity of the tissue can be measured.

  As is well known, the ultrasonic Doppler method calculates the Doppler velocity using the fact that a frequency shift is caused by moving or moving away from the ultrasonic blood flow. In the calculation, an RF (Radio Frequency) signal is orthogonally detected, and a frequency shift is detected and calculated as a Doppler phase shift amount (hereinafter simply referred to as a Doppler shift amount). At this time, the problem of phase folding occurs depending on the sampling time (pulse repetition frequency PRF in the pulse Doppler method).

  This is a problem that the speed exceeding the upper limit of the measurement speed cannot be measured, and at this time, the measured value is measured with a phase shift of 2π in the Doppler shift amount, which is called aliasing (phase folding). However, in normal inspection, Doppler velocity measurement is performed while displaying the measurement result, so that aliasing can be specified from experience and physical consistency. Therefore, in general, since the inspector performs correction manually, aliasing is not preferable but is not an inevitable problem. There has also been proposed a method for correcting aliasing using continuity of two-dimensional phase change in an ultrasonic Doppler image, that is, spatial continuity (for example, Patent Document 1).

JP 2009-207613 A

A. Pastorelli et al, "A Real-Time 2-D Vector Doppler System for Clinical Experimentation", IEEE TRANSACTIONS OF MEDICAL IMAGEING, VOL. 27, NO. 10, OCTOBER 2008

  In a general color Doppler, as described above, aliasing is visualized by an ultrasonic Doppler image and can be easily corrected. Further, since the Doppler shift amount is obtained as an average value of the values of a large number of elements constituting the ultrasonic probe, aliasing inherent in the signal of each element does not become a problem.

  On the other hand, in the vector Doppler method described above, since the Doppler shift amount is calculated using the received signal obtained by measuring echoes from a predetermined measurement point at a plurality of angles, aliasing exists even in one of the received Doppler shift amounts. In this case, the calculated vector accuracy is significantly reduced. The solution of this problem is indispensable when performing various clinical applications using the vector Doppler method.

  An object of the present invention is to solve the above-described problem when the vector Doppler method is applied. Specifically, it is an object to provide a technique for automatically correcting aliasing for Doppler shift amounts measured from a plurality of directions.

In order to solve the above-described problem, one of the representative ultrasonic imaging apparatuses of the present invention is configured to individually measure a plurality of openings set in an ultrasonic probe and the plurality of openings and a measurement target region. Based on the geometric relationship with the point, aliasing of the Doppler shift amount calculated for each opening is detected.
That is, the present invention is based on detecting aliasing using Doppler shift information measured from a plurality of directions with respect to a velocity vector at one measurement point, and the spatial continuity of the tissue itself with respect to the Doppler shift amount in a specific direction. The prior art (for example, the invention described in Patent Document 1) that detects aliasing by using the method is completely different from the technical idea.

  Specifically, an ultrasonic imaging apparatus of the present invention transmits an ultrasonic wave to an inspection object and receives an echo signal (received signal) reflected from the inspection object, and an ultrasonic probe. And a signal processing unit for processing a reception signal received at each of the plurality of set openings. The signal processing unit calculates tissue Doppler velocity information that is information regarding the velocity of the tissue to be examined for each opening from the received signal, and detects aliasing included in the calculated tissue Doppler velocity information.

  According to the present invention, the tissue velocity can be calculated with high accuracy. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an overall block diagram illustrating an embodiment of an ultrasonic imaging apparatus. It is a figure which shows the outline | summary of the process by 1st embodiment. It is a figure explaining the relationship between the arrangement direction of an element, and tissue velocity. It is a figure explaining the element group used for one measurement, and the division | segmentation of an opening part. It is explanatory drawing regarding the Doppler shift amount for every opening part, (a) shows the case where aliasing has not occurred, and (b) shows the case where aliasing has occurred. It is a flowchart figure of the process of the signal processing part (mainly aliasing process part) by 1st embodiment. FIGS. 4A and 4B are diagrams illustrating linear fitting. FIG. 4A illustrates a case where fitting is performed including data that causes aliasing, and FIG. 5B illustrates a case where fitting is performed using data in the vicinity of a reference value. It is a figure explaining the threshold value for aliasing determination. It is a figure which shows the flow of the data in a signal processing part. It is a flowchart figure of the process of the signal processing part by the modification 1 of 1st embodiment. It is a flowchart figure of the aliasing correction | amendment by 2nd embodiment. It is a figure explaining an aliasing correction | amendment. It is a functional block diagram of the signal processing part by 3rd embodiment. (A), (b) shows the example of a display screen by 3rd embodiment, respectively. FIGS. 4A and 4B are diagrams showing examples of display images, where FIG. 5A shows a case where the effect of the aliasing process is insufficient, and FIG. 6B shows a case where the effect of the process by the aliasing processing unit is obtained.

  The ultrasonic imaging apparatus (ultrasonic transmitting / receiving apparatus) of the present embodiment includes an ultrasonic probe (2) that transmits an ultrasonic wave to the inspection object (3) and receives an echo reflected from the inspection object as a reception signal; And a signal processing unit (15) for processing a reception signal received by the ultrasonic probe. The ultrasonic probe is formed with a plurality of openings each composed of one or more elements, and the signal processing unit processes a received signal for each opening. The signal processing unit (15) calculates the frequency change amount or phase change amount (referred to as Doppler shift amount) of the transmitted ultrasonic wave from the echo signal, and uses the Doppler shift amount, the sound velocity, and the wavelength to transmit the transmitted ultrasonic wave of the tissue velocity. A Doppler velocity calculation unit (153) that calculates a Doppler velocity that is a transmission direction component and a velocity vector of a measurement target tissue, and an aliasing process that detects aliasing based on the Doppler shift amount calculated by the Doppler velocity calculation unit Part (155). The Doppler velocity is calculated using the sound velocity and the wavelength as the frequency change or phase change amount (Doppler shift amount) of the transmitted ultrasonic wave. Since this is a known technique, details are omitted.

  The aliasing processing unit (155) updates the data set composed of the measured Doppler shift amount calculated from the received signals at the individual openings to a new data set composed of the Doppler shift amount not including aliasing, and performs the Doppler velocity calculation unit (153). ) Calculates the Doppler velocity and the tissue velocity vector using the new data set updated by the aliasing processing unit. The processing by the aliasing processor and the calculation of the tissue velocity by the Doppler velocity calculator can take various forms.

  In addition, the ultrasonic imaging apparatus of the present embodiment includes an input unit for a person who performs an inspection using the apparatus (hereinafter referred to as an inspector) to input conditions and instructions, a display unit for displaying processing results to the inspector, and the like May be provided.

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

  An apparatus configuration example of an ultrasonic imaging apparatus to which the present invention is applied is shown in FIG. As shown in FIG. 1, the ultrasonic imaging apparatus 100 of the present embodiment includes an apparatus main body 1 and an ultrasonic probe 2.

  The apparatus main body 1 generates an ultrasonic image while controlling the ultrasonic probe 2, and includes an input unit 10, a control unit 11, an ultrasonic signal generator 12, an ultrasonic reception circuit 13, a display unit 14, and A signal processing unit 15 is provided.

  The ultrasonic probe 2 is in contact with the living body (subject) 3 and irradiates the irradiation area 30 in the living body with ultrasonic waves according to the signal generated by the ultrasonic signal generator 12. An echo signal that is a reflected wave of the signal is received. The ultrasonic probe 2 has a large number (for example, about 30 to 10,000) of driving elements arranged in a one-dimensional direction or a two-dimensional direction. The driving elements (hereinafter also simply referred to as elements) Ultrasonic waves can be transmitted and received, and some or all of them are used depending on the measurement.

  The ultrasonic probe 2 generates a continuous wave or a pulse wave according to the scanning method. In addition, a two-dimensional imaging method for imaging a two-dimensional cross section or a three-dimensional imaging method for imaging a three-dimensional region can be appropriately selected according to the scanning method of the ultrasonic probe 2.

Each component of the apparatus main body 1 will be described.
The ultrasonic signal generator 12 includes an oscillator that generates a signal having a predetermined frequency, and sends a drive signal to the ultrasonic probe 2. By controlling the timing of the drive signal sent to each element constituting the ultrasonic probe 2 by a known method, a convergent beam, a plane wave for high-speed imaging, a diffused wave, or the like can be transmitted.

  In addition to the receiving circuit, the ultrasonic receiving circuit 13 includes a circuit that performs signal processing such as amplification and delay processing on the reflected echo signal received by the ultrasonic probe 2. Furthermore, the ultrasonic reception circuit 13 may include a reception data memory 131 that stores a time-series reception signal in each element. The reception signal stored in the reception data memory 131 is a time-series RF signal, and is hereinafter also referred to as reception data.

  In the case of storing the reception data for each element, the same number of reception data memories as the number of elements are required, so the memory becomes enormous. In this case, the memory may be reduced by bundling the reception data of a plurality of elements by the conventional delay addition method to obtain the reception data of one opening.

  When the elements are bundled, the number of elements constituting one opening and the number of openings may be set in advance, or may be set by the user via the input unit 10 described later.

  The signal processing unit 15 has a function of generating an ultrasound image from an echo signal from the ultrasound probe 2 and includes an envelope detection unit and a unit that performs log compression. Details of the signal processing unit 15 will be described later.

  Although not shown, the apparatus main body 1 includes a scan converter and an A / D (Analog-to-digital) converter. The A / D converter is provided before the signal processing unit 15. The sampling frequency is usually between 20 MHz and 50 MHz. The scan converter may be included in the ultrasonic receiving circuit 13 or may be provided in the subsequent stage of the signal processing unit 15. When the ultrasonic receiving circuit 13 includes a scan converter, there is an advantage that the amount of data handled by the signal processing unit 15 is reduced. In addition, when the scan converter is not included in the ultrasonic receiving circuit 13, a large amount of data can be handled by the signal processing unit 15, and a highly accurate measuring device can be realized.

  The control unit 11 controls the ultrasonic signal generator 12, the ultrasonic reception circuit 13, the display unit 14, and the signal processing unit 15 based on the operating conditions of the ultrasonic imaging apparatus 100 set by the input unit 10. It can be constructed in a CPU (Central Processing Unit) of a computer system. Note that some or all of the calculations performed by the signal processing unit 15 may be realized on the same CPU.

  The input unit 10 includes a keyboard and a pointing device in which a doctor or an engineer (hereinafter collectively referred to as an examiner) who operates the ultrasonic imaging apparatus 100 sets operating conditions of the ultrasonic imaging apparatus 100 to the control unit 11. Also, when information from an external device such as an electrocardiogram is used for the examination, it also functions as an external signal input unit.

  The display unit 14 outputs information obtained by the signal processing unit 15, for example, an ultrasonic image. The display unit 14 may constitute a UI (User Interface) for the inspector to set operation conditions and the like together with the input unit 10 and display a necessary GUI (Graphical User Interface).

  Next, components of the signal processing unit 15 will be described. The signal processing unit 15 includes a tomographic image forming unit 151, a Doppler speed calculation unit 153, an aliasing processing unit 155, a display image forming unit 156, and a memory 157 as main elements. Some or all of the arithmetic functions of the respective units included in the signal processing unit 15 may be realized by the CPU configuring the control unit 11 described above, or may be implemented by an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). It is also possible to realize with hardware such as).

  The tomographic image forming unit 151 uses, for example, a B-mode image, that is, a two-dimensional tissue shape image using a planar imaging method of an ultrasonic irradiation target, from a reception signal (echo signal) output from the ultrasonic reception circuit 13; Alternatively, a three-dimensional tissue shape image using a three-dimensional imaging method is formed.

  The tissue shape image created by the tomographic image forming unit 151 is an image for presenting the imaging target shape to the examiner, and is created using an echo signal acquired by imaging different from Doppler imaging. In the present embodiment on the premise of Doppler imaging, the tomographic image forming unit 151 is not an essential component, but it is more diagnostic by presenting a tissue shape image together with tissue Doppler velocity information that is information relating to the velocity of the tissue. Suitable information can be provided.

  The Doppler velocity calculation unit 153 performs planar imaging on various tissue Doppler velocity information such as color Doppler, tissue Doppler, pulse wave Doppler, and continuous wave Doppler from the echo signal output from the ultrasonic receiving circuit 13. Two-dimensional tissue Doppler velocity information using the method or three-dimensional tissue Doppler velocity information using the stereoscopic imaging method is extracted. Furthermore, in the present embodiment, the Doppler velocity calculation unit 153 performs reception processing for each element stored in the reception data memory 131 or reception data obtained by bundling it for each opening to perform processing based on the vector Doppler method. The tissue Doppler velocity information is calculated for each of a plurality of elements or openings.

  The aliasing processing unit 155 detects aliasing during the Doppler velocity calculation based on the tissue Doppler velocity information calculated for each opening. As described above, when the Doppler velocity calculation unit 153 calculates the Doppler shift amount, which is one of the tissue Doppler velocity information, for each opening, aliasing may exist in the Doppler shift amount due to calculation restrictions. The aliasing processing unit 155 specifies which aperture Doppler shift amount is aliased based on the relationship between the geometric position of the aperture portion and each Doppler shift amount, and performs a subsequent calculation using each Doppler shift amount. For example, in calculating the tissue velocity vector, a process for eliminating the influence of aliasing is performed. As such processing, for example, the aliasing processing unit 155 may reject the Doppler shift amount in which aliasing has occurred, or may perform aliasing correction processing. Further, the Doppler velocity may be obtained again based on the rejected or corrected Doppler shift amount, or the tissue velocity vector information may be calculated. The specific contents of the aliasing detection method and processing will be described in detail later.

  The display image forming unit 156 forms a display image displayed on the display unit 14, and is calculated by the tomographic image formed by the tomographic image forming unit 151, the Doppler waveform obtained by Doppler measurement, and the aliasing processing unit 155. A display image is formed in accordance with a predetermined format or an instruction input from the input unit 10 with the various amounts.

  The memory 157 stores an echo signal, information necessary for calculation in the signal processing unit 15 and a processing result of the signal processing unit 15.

  Based on the configuration of the apparatus described above, an embodiment of the operation of the signal processing unit 15 of the ultrasonic imaging apparatus of the present embodiment will be mainly described. In the following description, a case where the irradiation region 30 shown in FIG. 1 is a part including the carotid artery will be described as a specific example. However, the irradiation region 30 may be a blood vessel or other heart desired by the examiner. .

[First embodiment]
An outline of the processing of the ultrasonic imaging apparatus 100 of the present embodiment is shown in FIG. As shown in FIG. 2, a process of acquiring and receiving a reception signal for each element by transmitting and receiving an ultrasonic wave at each of the plurality of openings (S 0) , Processing for generating reception data composed of RF signals (S1), processing for calculating Doppler shift amount of each opening using reception data of each opening (S2), and using Doppler shift amount of each opening Then, processing for detecting aliasing (S3) is performed. The processing S0 is mainly performed by the ultrasonic signal generator 12 and the ultrasonic receiving circuit 13, and the processing S1 to S3 is performed by the signal processing unit 15.

The contents of each process will be described below.
<Processing S0>
First, imaging of ultrasonic Doppler is performed. Therefore, the ultrasonic signal generator 12 sends a drive signal having a predetermined frequency to the ultrasonic probe 2. When the ultrasonic probe 2 transmits an ultrasonic wave, a convergent beam may be transmitted as in a general-purpose medical ultrasonic diagnostic apparatus, or a plane wave or a diffused wave for high-speed imaging may be transmitted. May be. At the time of transmission, the apodization may be set to a Hanning window or a Hamming window using a delay addition method.

  The Doppler frequency is defined by the angle between the flow direction (tissue velocity (eg, blood flow velocity)) and the transmitted beam at one point (measurement point) in the measurement target tissue (eg, blood vessel), and the flow direction at the measurement point. Since it is determined by the angle with the receiving element direction, the transmission method is not limited as long as two angles can be defined. FIG. 3 shows an example in which the transmitted beam is a convergent beam. The angle β between the tissue velocity V (thick arrow) that is the flow direction at one measurement point P in the measurement target tissue and the transmitted beam 301 is measured. The relationship between the tissue velocity V which is the flow direction at the point P and the angle (referred to as a prospective angle) θi in the receiving element direction is shown. The prospective angle θi varies depending on the position of the elements 21 in the arrangement direction.

  After each of the plurality of openings of the ultrasonic probe 2 transmits an ultrasonic wave, each element 21 of the ultrasonic probe 2 receives the ultrasonic wave and detects an ultrasonic signal. The ultrasonic signal detected by each element 21 is stored in the reception data memory 131 for each element as an RF signal that is a time-series reception signal, and the ultrasonic reception circuit 13 acquires the reception signal for each element 21.

  Although not essential to the present embodiment, morphological imaging such as B mode may be performed separately from imaging of ultrasonic Doppler (S0). The morphological imaging is the same as that of a conventional ultrasonic imaging apparatus, and will be briefly described. For example, the ultrasonic frequency of the B-mode image is in the range of 1 MHz to 20 MHz that can be imaged. The frame rate is set within a range in which the movement of the heart that fluctuates depending on the heartbeat can be captured. Specifically, the frequency is set to 3 Hz or higher so that the time phase of the heart can be observed. The tomographic image forming unit 151 forms, for example, a B-mode image from the echo signal output from the ultrasonic receiving circuit 13. The ultrasound biological image may be either a two-dimensional image using a planar imaging method or a three-dimensional image using a stereoscopic imaging method, and acquires data in time series. A three-dimensional image can be obtained by scanning in the short axis direction using, for example, a two-dimensional array in the short axis direction or a mechanical probe.

<Process S1>
First, as a premise of the process S1, the relationship between the element group of the ultrasonic probe used for one measurement and the opening will be described with reference to FIG. In the example shown in this figure, in order to simplify the description, the case where the elements are arranged in a one-dimensional direction and planar imaging is performed is shown as in FIG. When performing measurement once, all the elements 21 (for example, 256 elements) may be used, or some elements may be selected and used due to restrictions of the apparatus. In FIG. 4, some elements, for example, about 96 elements are used as driving elements.

  These element groups used for one measurement may all be used as one opening, or as shown in FIG. 4, a plurality of elements (six elements in FIG. 4) are bundled to form one opening. Also good. The number N of openings may be at least 3 or more and may be 3 or more and the number of elements. The plurality of openings do not necessarily have to be continuous, but are preferably continuous. Such information on the number and position of the openings that bundle the elements of the ultrasonic probe 2 is set in advance in the ultrasonic receiving circuit 13 and the signal processing unit 15 (Doppler velocity calculation unit 153). However, the inspector can also set the number and position of the openings as one parameter of the operating condition.

  The Doppler speed calculation unit 153 stores the bundled openings in the reception data memory 131 based on the information about the openings set in this way, and measures the received signal that is the reception data of the bundled reception elements. By performing delay addition according to points, reception data for each opening is created. At this time, a sample gate is set for the reception signal, and reception data composed of an RF signal only in a specific region (referred to as a measurement region) is created.

<Process S2>
The Doppler velocity calculation unit 153 calculates the Doppler shift amount by performing quadrature detection on the reception data including the RF signal obtained in the processing S1 and detecting the phase difference between the transmissions of the ultrasonic signals transmitted. A technique for calculating the Doppler shift amount from the reception data subjected to the quadrature detection is known, and detailed description thereof is omitted here, but the outline is as follows. The I (t) signal and Q (t) signal obtained by quadrature detection of received data consisting of RF signals are subjected to LPF processing to remove high frequency components, and the phase is extracted by normalizing the amplitude components. From the phase obtained for each sampling, the phase difference (Doppler shift amount) between transmissions is calculated by the autocorrelation method or the like. When the Doppler shift frequency is fd, the phase difference φ is expressed by Expression (1). On the other hand, there is a relationship expressed by Expression (2) between the Doppler shift frequency fd and the carrier center frequency f0.
[Formula 1] φ = 2πfd · t (1)
[Formula 2] fd = f0 {2V / c} (2)
In formula (1), t represents time, in formula (2), V represents the tissue velocity, and c represents the speed of sound.

  In the conventional ultrasonic Doppler, the Doppler shift amount (φ) is calculated using all received signals, and the tissue velocity V is obtained from the equations (1) and (2). In the vector Doppler method, individual elements (opening portions) are obtained. ) The phase difference is obtained every time. In this case, the above equation (2) can be expressed by equation (3) when the angle β of the direction of blood flow at the measurement point P shown in FIG. 3 and the expected angle θi of each element are used.

式（３）中、ｆｄ^ｉはｉ番目の素子の受信信号から算出されたドプラシフト周波数である。式（３）は各素子に関しての記述であるが、各素子を束ねた開口部については、θiとして開口部の中心部の角度を用いることで各開口部でのドプラシフト周波数を算出できる。また式（３）のドプラシフト周波数は、実際には式（１）を加味した位相差（ドプラシフト量）が算出される。この各開口部のドプラシフト量からなるデータは、計測領域内の複数の計測点について得られる。その結果、ドプラ速度演算部１５３は、各開口部で実測し、算出したドプラシフト量である実測ドプラシフト量からなるデータのまとまりであるデータセット（実測データセット２００）を取得する。そしてドプラ速度演算部１５３は、実測データセット２００をエイリアシング処理部１５５に送る。

In Formula (3), fd ⁱ is a Doppler shift frequency calculated from the received signal of the i-th element. Equation (3) is a description for each element, but for the opening part where the elements are bundled, the Doppler shift frequency at each opening part can be calculated by using the angle of the center part of the opening part as θi. The Doppler shift frequency in Expression (3) is actually calculated as a phase difference (Doppler shift amount) taking into account Expression (1). Data including the Doppler shift amount of each opening is obtained for a plurality of measurement points in the measurement region. As a result, the Doppler speed calculation unit 153 obtains a data set (actual measurement data set 200) that is a collection of data that is actually measured at each opening and includes the calculated Doppler shift amount that is the calculated Doppler shift amount. Then, the Doppler speed calculation unit 153 sends the actual measurement data set 200 to the aliasing processing unit 155.

<Process S3>
The aliasing processing unit 155 receives the measured data set 200 including the measured Doppler shift amount of each opening calculated in the processing S2 (FIG. 6: S30), and performs processing using the fitting and the threshold value using this, and the aliasing is performed. Detect where it is happening and remove the data.

  FIG. 5 shows an image diagram in which the measured Doppler shift amount at each opening is plotted. In FIG. 5, the horizontal axis of the graph is the expected angle θ of the element, and the vertical axis is the Doppler shift amount. Here, the number of openings is set to 8, and the measured Doppler shift amount for each opening is calculated.

  When aliasing does not occur in the measured Doppler shift amount of each opening, as shown in FIG. 5A, the measured Doppler shift amount changes almost linearly (501), but when aliasing occurs, As shown in FIG. 5B, when the calculated actual Doppler shift amount exceeds the phase detection range, the polarity of the phase is reversed and aliasing occurs (509). The phase detection range differs depending on the calculation method used when calculating the measured Doppler shift amount. FIG. 5 shows the case of ± π / 2, but it may be ± π.

  In the conventional ultrasonic Doppler, the measured Doppler shift amount (fd) is calculated by using all the received signals. Therefore, even if there is a phase wrapping for each element or each of the plurality of openings, When the measured Doppler shift amount is obtained, individual phase wrap-around becomes obvious. For this reason, in this process S3, the process which excludes the data which has caused the aliasing is performed.

  Process S3 includes a step (S31) of fitting an actual measured Doppler shift amount of each opening with a predetermined opening among the plurality of openings as a reference point, a step (S32) of setting a threshold, an actual Doppler shift amount and a fitting function, It is determined whether the difference is within the threshold and updating the fitting function (S33), and calculating the tissue velocity vector using the finally obtained fitting function (S34). The aliasing processing unit 155 mainly performs S31 to S33, and the Doppler speed calculation unit 153 performs Step S34.

Hereinafter, the details of the processing S3 will be described with reference to the flow shown in FIG.
<< Step S30 >>
The aliasing processing unit 155 receives the actual measurement data set 200 including the actual measured Doppler shift amount for each opening obtained by the process S2 from the Doppler velocity calculation unit 153.
<< Step S31 >>
The aliasing processing unit 155 sets a reference and performs a fitting process (for example, a linear fitting process) based on the measured data set 200 including the measured Doppler shift amount for each opening obtained in the process S2. That is, the aliasing processing unit 155 fits the measured Doppler shift amount of each opening (determines a fitting function of the measured Doppler shift amount). If the fitting function of the measured Doppler shift amount for each opening is φi, the fitting function can be described as in Expression (4).

This equation corresponds to the straight line 501 in FIG. 5A, where α is the slope of the straight line and φ ^CFM is the intercept value. The phase difference is a relative value, and the intercept value (position on the vertical axis in FIG. 5) may change. Here, a predetermined opening is determined as a reference point (reference opening), and φ ^CFM is a reference point. The measured Doppler shift amount at. For this reason, first, a reference point is set. The position of the opening as the reference point is not particularly limited, but it is customary to set the color Doppler so that it does not fold when the inspector sets the color Doppler. It is premised that no wrapping has occurred. For example, a place where θ = 0 (opening position where the transmission beam is irradiated) may be used as a reference point, or the center of an element (opening) used for measurement may be used as a reference point. In the color Doppler, when the steering is performed at the tilt angle γ, an opening portion where θ = γ may be used as a reference. Hereinafter, the case where θ = 0 will be described as an example.

  In this step, the fitting function is obtained by obtaining the slope α which is an unknown in the equation (4). Specifically, when the Doppler shift amount is set with the location of θ = 0 as a reference point, the following simultaneous equations are obtained, and α can be obtained in the least squares.

即ち、αは全開口部の情報を平均的に用いれば下記のように記述できる。

That is, α can be described as follows if information on all openings is used on average.

Instead of equation (6), α may be calculated by weighting according to the angle of θ as in equation (7).

  In the expression (6) or (7), data of measured Doppler shift amounts of all elements (openings) is used, but fitting may be performed using data of measured Doppler shift amounts of some elements. Specifically, among the elements used for one measurement, the possibility of aliasing increases as it approaches the end, so that it is near the reference point, for example, half of all the openings near the reference point. The fitting may be performed using the region.

  The difference in the fitting result depending on the data used for fitting is shown in the image diagram of FIG. In the figure, ◯ is the individual measured Doppler shift amount, 500 is the fitting function, and 300 is the measured Doppler shift amount of the reference point. The vertical axis is an axis passing through the position of the reference point (here, θ = 0). FIG. 7A shows a case where all data including aliasing is used, and the fitting is remarkably displaced. On the other hand, as shown in FIG. 7B, when the vicinity of the reference point is used, good fitting is possible.

<< Step S32 >>
Next, the aliasing processing unit 155 calculates a threshold for determining whether or not the measured Doppler shift amount causes aliasing, and sets it in the ultrasonic imaging apparatus 100. As the threshold value, for example, any value of about 0.5 to 4 times the variance value may be used by using the variance σ of the difference between the fitting function and the measured Doppler shift amount. The threshold may be preset on the ultrasonic imaging apparatus 100 side in advance, or may be configured to be set by the inspector via the input unit 10.

<< Step S33 >>
The aliasing processing unit 155 has, at each measurement point, a fitting function (φi) (formula (4)) (fitting function (φi) of the measured Doppler shift amount of each opening and the measured Doppler shift amount for each opening that is each measurement point. ) Is calculated (S331), and it is determined whether or not the difference is equal to or smaller than the threshold set in step S32 (S332). When the threshold value is exceeded, the aliasing processing unit 155 determines that there is a high possibility that aliasing has occurred, rejects the data, and does not use it for subsequent calculations (S333). If the threshold value is less than or equal to the threshold value, the aliasing processing unit 155 uses data that is equal to or less than the threshold value (S334), and sets the measured Doppler shift amount of the opening portion that is less than or equal to the threshold value as a new data set 210 as shown in FIG. It passes to the calculating part 153 (S335).

  FIG. 8 shows the relationship between the measured Doppler shift amount and the threshold value. As indicated by dotted lines in FIG. 8, the threshold values 510 and 520 are set above and below the fitting function 500. In step S332, the aliasing processing unit 155 determines whether or not the measured Doppler shift amount (indicated by ◯) falls within a range between upper and lower dotted lines that are threshold values.

即ち、フィッティング関数が確定し、その傾きαが求まれば、βを計算することが可能となる。組織速度Ｖは、φ^CFMを用いて、前掲の式（１）、（２）から算出することができる。以上のようにして、ドプラ速度演算部１５３は、フィッティング関数を用いて組織速度ベクトルを算出する。<< Step S34 >>
Finally, the Doppler velocity calculation unit 153 uses the inclination of the determined fitting function and the measured Doppler shift amount of the reference point to obtain the gradient between the tissue velocity V at the measurement point and the transmission beam (transmitting beam) according to the following equation (8). (Angle) β is calculated.

That is, if the fitting function is determined and the slope α is obtained, β can be calculated. The tissue velocity V can be calculated from the above formulas (1) and (2) using φ ^CFM . As described above, the Doppler velocity calculation unit 153 calculates the tissue velocity vector using the fitting function.

Note that step S33 may be completed by a single process, but may be repeated twice or more as shown by the dotted arrow in FIG. 6 to update the fitting function and a new data set. . Specifically, after step S335, the aliasing processing unit 155 returns to step S31 and repeats the processes from steps S31 to S33 M times (S36).
Accordingly, it is possible to improve the accuracy of β calculated in S34. The repetition of the step ends when, for example, all the data that remains without being rejected falls below a predetermined threshold, or ends when the predetermined number of times is reached. When the step is repeated, the threshold value set in step S32 may be constant, or the threshold value may be changed for each repetition. When changing, for example, the threshold value is gradually changed to a smaller value.

  The aliasing processing unit 155 and the Doppler speed calculation unit 153 perform the process S3 illustrated in FIG. 6 for all measurement points included in the measurement region. Thereby, a velocity vector (a velocity value and a direction) is calculated for a tissue including blood flow included in the measurement region. The calculated velocity vector is stored in the memory 157 and then displayed on the display unit 14 as a display image in which an arrow indicating the vector is superimposed on a morphological image obtained separately or as a numerical value by the display image creation unit 156. be able to. The display mode will be described later.

An overview of the processes S2 and S3 of this embodiment is shown in FIG. As shown in FIG. 9, the Doppler calculation unit 153 calculates the measured Doppler shift amount for each opening using the reception data for each opening, obtains the measured data set 200 including the measured Doppler shift amount for each opening, and performs aliasing. The data is sent to the processing unit 155. The aliasing processing unit 155 detects aliasing present in the measured Doppler shift amount for each opening included in the measured data set 200, removes (rejects) the Doppler shift amount in which aliasing has been detected from the measured data set 200, and leaves the remaining openings. A new data set 210 consisting of the amount of Doppler shift is obtained and sent to the Doppler calculation unit 153. The Doppler calculation unit 153 calculates the velocity vector 250 of the measurement target region using the Doppler shift amount of the remaining opening that has not been removed by the aliasing processing unit 155 included in the new data set 210.
The display image forming unit 156 forms a display image of a new data set 210 or speed vector 250 displayed on the display unit 14.

  According to the present embodiment, when the velocity vector is calculated using the Doppler shift amount measured at different angles based on the vector Doppler method, the aliased data is removed from the Doppler shift amount for each opening. As a result, the accuracy of velocity vector calculation can be increased.

  In the present embodiment, an example of linear fitting with respect to planar imaging has been described. Needless to say, expansion can be performed by using fitting as a planar fitting for stereoscopic imaging. In this embodiment, a convergent beam is used. However, by setting the angle of transmission for all transmissions such as plane waves and diffusion waves, it can be dropped into equation (4). The invention can be applied.

Other typical modifications of the present embodiment are shown below.
[Variation 1 of the first embodiment]
This modification is different from the first embodiment in the processing (step S34) of the Doppler velocity calculation unit 153 after removing data with aliasing. The processing flow of this modification is shown in FIG. In FIG. 10, the same steps as those in FIG. The details of step S33 in FIG. 10 are the same as S331 to S334 in S33 shown in FIG. Alternatively, it may be the same as S330 (excluding S335) in FIG.

  In the flow shown in FIG. 6, after removing data with aliasing in step S34, the angle β is calculated using the slope α of the updated fitting function (Equation (8)). Using the measured Doppler shift amount included in the updated new data set 210, the Doppler speed is calculated in the same manner as in the conventional color Doppler method (S35). For this reason, first, the Doppler shift amount for each opening is averaged (S351). At that time, a weighted average may be performed as necessary, thereby further improving the accuracy of the color Doppler. As the weighting, for example, a weight inversely proportional to the size of the expected angle of the opening can be considered. After that, using the calculated Doppler shift amount, the Doppler speed is calculated by Equations (1) and (2) (S352). The tissue velocity vector can also be calculated using the Doppler velocity calculated as described above. Since this is described in a known technique (Non-Patent Document 1), it can be referred to.

  In this modification, the calculation of the Doppler speed is the same as in the conventional method, but the data after the average addition / weighting addition used for the calculation of the Doppler speed does not include the data with aliasing. The accuracy of color Doppler can be improved compared with the conventional method which does not remove.

[Modification 2 of the first embodiment]
In this modification, a step of automatically adjusting the speed range is added after the fitting function is obtained. This step can be inserted, for example, between steps S33 and S34 in FIG. 6 or after S34, or between steps S33 and S35 in FIG. 10 or after S35.

  When the fitting function is determined, the Doppler shift amount assumed in all openings, that is, the range of the Doppler shift amount can be estimated. In the added step, the speed range is automatically adjusted so that the Doppler shift amount of all the openings is within the threshold value. In general, the phase shift range is inversely proportional to the speed range. Therefore, for example, when the region determined by the fitting function and the threshold (the region sandwiched between the two dotted lines 510 and 520 in FIG. 8) is narrower than ± π / 2 in the total width of θ, the entire range of ± π / 2 is obtained. Narrow the speed range to spread out. As a result, the blood flow velocity distributed within the narrowed velocity range can be depicted with high resolution. On the contrary, when the fitting function calculated in the range of the prospective angle of the narrow opening and the threshold region are expanded from approximately −π / 2 to + π / 2, the speed range is set so that the Doppler shift amount of all the openings is within the threshold. To spread. As a result, a relatively slow blood flow to a fast blood flow can be depicted in a wide measurement region without phase wrapping.

  The calculation of the speed range adjustment amount is executed by adding a speed range correction unit as a function of the signal processing unit 15, for example, the aliasing processing unit 153 or the Doppler calculation unit 153.

  According to this modification, the speed range is automatically adjusted based on the determined fitting function, so that the speed range according to the blood flow velocity distribution in the measurement region can be adjusted without adjusting the speed range manually as in the past. Blood flow velocity can be depicted. Note that changing the speed range (changing the speed) is not always recommended because there is a trade-off that information in the low speed range is lost. Therefore, instead of automatically adjusting, a means or GUI for manual adjustment by the inspector may be provided.

[Second Embodiment]
In the ultrasonic imaging apparatus according to the present embodiment, the aliasing processing unit corrects the data (measured Doppler shift amount) determined to be aliasing by the threshold value instead of simply rejecting it. Other configurations are the same as those of the first embodiment, and hereinafter, the ultrasonic imaging apparatus of this embodiment will be described focusing on differences from the ultrasonic imaging apparatus 100 of the first embodiment.

  With reference to FIG. 11, the operation of the ultrasonic imaging apparatus of the present embodiment will be described. The ultrasonic imaging apparatus according to the present embodiment performs the processes S0 to S3 having the contents shown in FIG. 2 in the same manner as in the first embodiment, but the contents of the aliasing detection process S3 are changed. That is, in the first embodiment, in step S33 (FIG. 6) of process S3, the measured Doppler shift amount outside the range between the upper and lower thresholds of the fitting function is detected and removed as aliasing, but the second In the embodiment, the aliasing correction is performed on the removed one.

  Details of the processing S3 of the present embodiment will be described with reference to the flowchart of FIG. In FIG. 11, the same processes as those in FIG.

  As shown in FIG. 11, the aliasing processing unit 155 provides a reference for the measured data set 200 including the measured Doppler shift amount of each opening for each measurement point, performs fitting (S31), and calculates and sets a threshold value. (S32). Next, in step 330, the aliasing processing unit 155 calculates a difference between the measured Doppler shift amount of each opening and the fitting function (S331), and determines whether the difference is equal to or less than a threshold value (S332). Data equal to or less than the threshold value is used for the calculation of the velocity vector as it is as in the first embodiment (S334, S335). When the fitting function is updated by performing iterative calculation, it is added to the data set for iterative calculation (S334, S335).

  On the other hand, if the difference calculated in step S331 is outside the range defined by the threshold (the region sandwiched between 510 and 520 in FIG. 8), the aliasing processing unit 155 determines that aliasing has occurred and performs aliasing. A correction process is performed (S336). An outline of the aliasing correction will be described with reference to FIG.

  The aliasing processing unit 155 rotates the phase with respect to the actually measured Doppler shift amount group (Doppler shift data group) 301 that the aliasing processing unit 155 determines to be aliasing. Specifically, when the Doppler phase shift at the reference point (θ = 0) is positive, it is assumed that aliasing has occurred on the negative side, and π is added to the Doppler shift data group 301, as shown in FIG. When the Doppler phase shift at is negative, π is subtracted from the Doppler shift data group 301. As shown in FIG. 12, the Doppler shift data group 301 becomes the Doppler shift data group 303 as a result of the aliasing correction. When the phase shift range is ± π, the processing is to add or subtract 2π.

  Returning to FIG. 11, the aliasing processing unit 155 further determines whether or not the corrected Doppler shift data group 303 is equal to or smaller than the threshold (S337). If the corrected Doppler shift data group 303 is within the threshold region, the data is used (S338). If it is outside the threshold region, it is rejected (S339). As a result, a new data set 210 is created (S335). The threshold value used in step S337 may be the same as or different from the threshold value used in step S332, and is set in step S32.

  The aliasing processing unit 155 passes the new data set 210 to the Doppler velocity calculation unit 153, and the Doppler velocity calculation unit 153 calculates a tissue velocity vector (S34). Alternatively, the aliasing processing unit 155 repeats the processing from step S31 to S330 M times (S36), improves the accuracy of the data set, and then passes it to the Doppler speed calculation unit 153, as in the first embodiment. . Further, the Doppler velocity calculation unit 153 may calculate the velocity vector by calculating the angle β in the velocity direction by the calculation of the vector Doppler method, or the conventional color Doppler as in the first modification of the first embodiment. The velocity vector may be calculated by obtaining an average value of the Doppler shift amount of each opening based on the method.

  Also in the present embodiment, a data set with higher accuracy can be obtained by performing a series of processing one or more iterations. In the iterative calculation, it is considered that aliasing is corrected, and the area used for fitting may be gradually expanded. Further, the threshold value may be decreased stepwise.

  As described above, in the ultrasonic imaging apparatus according to the present embodiment, the aliasing processing unit corrects the measured Doppler shift amount determined to be aliasing out of the data set including the measured Doppler shift amount, and creates a new one. Get the dataset. In addition, if the difference between the corrected Doppler shift amount and the fitting function (the Doppler shift amount determined by the fitting function) is within a threshold value, the aliasing processing unit adds the corrected Doppler shift amount to the new data set and sets the difference outside the threshold value. You may add the processing to reject.

  According to the present embodiment, since the data can be corrected and used, the Doppler speed calculation can be performed without reducing the number of measured data.

[Third embodiment]
The ultrasonic imaging apparatus of the present embodiment is characterized by including means for enabling an inspector to select processing contents and conditions by the aliasing processing unit.
That is, the ultrasonic imaging apparatus of the present embodiment includes an input unit that receives selection of a processing mode by the aliasing processing unit. In addition, a display unit that displays the processing result of the aliasing processing unit or the calculation result of the Doppler velocity calculation unit reflecting the processing result is provided.

  The display image forming unit of the signal processing unit creates a UI that accepts selection by the examiner and displays the UI on the display unit. Other configurations are the same as those of the first and second embodiments, and the present embodiment will be described by appropriately using the elements in the drawings used in these embodiments.

  FIG. 13 shows a functional block diagram of the signal processing unit 15 of the present embodiment. In FIG. 13, only the Doppler velocity calculation unit 153, the aliasing processing unit 155, and the display image creation unit 156 among the components constituting the signal processing unit 15 are illustrated, and other elements are omitted, but FIG. Each part shown and other elements may be included.

  The Doppler speed calculation unit 153 includes a vector Doppler calculation unit 1533 and a color Doppler calculation unit 1535. The vector Doppler calculation unit 1533 calculates the velocity vector using the measured Doppler shift amount for each opening from which the influence of aliasing is removed by the aliasing processing unit 155. The color Doppler calculation unit 1535 calculates the Doppler speed by using the Doppler shift amount obtained by averaging or weighted addition of the measured Doppler shift amount for each aperture from which the influence of aliasing has been removed. The Doppler speed calculation unit 153 may further include a speed range setting unit 1531. A speed range used for speed calculation and display is set in the speed range setting unit 1531. The speed range is set via the UI unit 140. Alternatively, when the signal processing unit 15 includes the speed range automatic adjustment function described in the second modification of the first embodiment, the function is set by this function.

  The aliasing processing unit 155 includes an opening setting unit 1553, a first processing unit 1551, and a second processing unit 1552. The opening setting unit 1553 holds information on a preset or received through the UI unit 140. The first processing unit 1551 creates a new data set by removing the Doppler shift amount causing aliasing from the measured Doppler shift amount of each opening. The second processing unit 1552 creates a new data set by performing aliasing correction processing of the Doppler shift amount in which aliasing has occurred among the measured Doppler shift amounts of the respective openings.

  The UI unit 140 is a user interface device including the input unit 10 and the display unit 14 and operates interactively with the examiner. An example of a display screen in the UI unit 140 is shown in FIG. In the example shown in FIG. 14A, the display screen 400 includes a result display block (area) 410 that displays the calculation result of the Doppler velocity calculation unit 153, a menu selection block 420 that displays a menu selected by the examiner, and a menu selection. An operation block 430 for displaying objects such as buttons and knobs for setting or adjusting parameters in accordance with the imaging method (imaging technique) and operation mode (processing mode) selected via the block 420 is included. For example, when one menu in the menu selection block 420 is selected, a menu screen 450 as shown in FIG. 14B is displayed. In this exemplary menu screen 450, a GUI for receiving selection of an imaging method, selection of a processing mode in the vector Doppler method, setting of parameters (processing conditions) in the vector Doppler method, and the like is displayed.

  In the selection of the imaging method, for example, selection of color Doppler method or vector Doppler method is accepted. The selection of the imaging method may be alternative or combined.

Hereinafter, the operation of the ultrasonic diagnostic apparatus of this embodiment will be described.
First, when the inspector selects only the vector Doppler method processing via the UI unit 140, the Doppler velocity calculation unit 153 includes a new data set (each of which is updated by the aliasing processing unit 155 by the vector Doppler unit 1533). A calculation using equations (7) and (8) is performed using a measured data set of the Doppler shift amount of the opening to calculate a velocity vector. When the color Doppler method is selected, the color Doppler unit 1535 performs a normal color Doppler method calculation using the new data set updated by the aliasing processing unit 155. When the combined use with the color Doppler method is selected, the color Doppler unit 1535 performs the color Doppler method together with the vector Doppler method performed by the vector Doppler unit 1533. The blood flow vector directly obtained by the color Doppler method is a component in the direction parallel to the transmission beam. However, the color Doppler unit 1535 is a component in the orthogonal direction by an estimation method using a law of conservation of mass. In this case, a blood flow vector in the beam plane is calculated. A technique for calculating a blood flow vector in the color Doppler method is known, and a description thereof is omitted here.

  When the vector Doppler method is selected, a GUI for setting conditions such as the number of openings and a threshold value may be activated. At that time, if a value is preset, the value may be displayed. Alternatively, the buttons and knobs displayed on the operation block 430 are switched to a function of adjusting, for example, a threshold value and a speed range (width and upper limit value or lower limit value). The opening setting unit 1553 and the speed range setting unit 1531 accept the operation of the operation block 430 and set the number of openings and the speed range, respectively. The first processing unit 1551 and the second processing unit 1552 perform the respective processes (the processes in FIGS. 6 and 10) using the set threshold value.

  When the vector Doppler method is selected by the examiner, a UI for selecting a processing mode is displayed on another menu screen or a pull-down menu screen as shown in the figure. As a processing mode, for example, according to the first embodiment, a mode for removing data having a large difference from the fitting result (referred to as a normal mode), or a mode for correcting data having a large difference from the fitting result according to the second embodiment One of (correction mode) can be selected. These processing modes are determined by a processing program executed by the aliasing unit 155. Either processing mode may be preset in the apparatus, or the inspector can select any one.

  For example, when the normal mode is preset, if there is no instruction to change the processing mode, the first processing unit 1551 performs aliasing detection / removal and velocity vector calculation according to the flow of FIG. When the correction mode is selected or when the change of the processing mode is instructed, the second processing unit 1552 performs aliasing detection / correction and velocity vector calculation according to the flow of FIG.

  Further, regarding the calculation of the tissue Doppler velocity information using the updated new data set via the UI of the display unit 14, whether the calculation based on the vector Doppler method or the calculation based on the conventional color Doppler method is performed. A selection of whether to perform both may be accepted. Alternatively, the speed vector calculation method may be determined depending on whether the color Doppler method or the vector Doppler method is selected when the imaging method is selected.

  According to this embodiment, it is possible for the inspector to perform ultrasonic Doppler measurement under conditions more suitable for the target measurement based on his / her own judgment.

[Display Embodiment]
An embodiment of a technique for presenting information obtained by the ultrasonic imaging apparatus of the present invention to an examiner will be described.

  As described above, the ultrasonic imaging apparatus of the present invention can provide various diagnostic information reflecting the blood flow velocity vector. The method of providing diagnostic information is not particularly limited, but a typical providing method is a method of displaying as a display image on the display unit 14 of the ultrasonic imaging apparatus. The display image is generated by the display image generation unit 156. The diagnostic information image generated by the display image generation unit 156 is displayed on, for example, the result display block 410 of the screen 400 shown in FIG. A numerical value block 415 may be provided in the result display block 410 to display the blood flow velocity (average value) and the like. However, the display method is not limited to these, and various combinations and omission of elements that are not essential are possible.

  An example of a display image of blood flow vector information obtained by the Doppler velocity calculation unit 153 is shown in FIG. FIG. 15 shows a state where a color Doppler is displayed and a vector is superimposed on the flow of the blood vessel. In FIG. 15A, the vector direction and the blood vessel running direction are deviated, and it is highly possible that the vector calculation accuracy in aliasing is reduced. In such a case, it is expected that correction is performed as shown in FIG. 15B by using the aliasing correction mode.

  Further, when the aliasing is detected in the aliasing correction mode, the corrected information may be presented to the examiner. At this time, a mode for automatically increasing the speed range may be prepared on the apparatus side, or the inspector may be prompted to change the speed range.

  The examiner looks at this display and determines that the aliasing processing has not been performed properly if the blood flow velocity vector or blood flow velocity is unnatural or significantly different from the predicted result. The processing mode may be changed, or parameters used for the aliasing processing, such as the number of openings, the threshold value, and the speed range may be reset.

  According to the present embodiment, the ultrasonic Doppler measurement suitable for the measurement target, such as changing the processing mode when it is determined that the processing needs to be re-executed by looking at the result obtained in the preset normal mode processing. Can be implemented.

  As mentioned above, although explained using each embodiment of the present invention, the ultrasonic imaging apparatus of the present invention calculates the Doppler velocity of the tissue using the received signal received at each opening of the ultrasonic probe. And an aliasing processing unit for detecting aliasing at the time of calculating the tissue velocity vector at the time of calculating the tissue velocity vector (including the case of calculating based on the Doppler velocity). . According to the present invention, the tissue velocity can be calculated with high accuracy. Further, since the present invention does not assume spatial continuity, the present invention can also be applied to the speed of one measurement point.

  The ultrasonic imaging apparatus of the present invention is not limited to the above-described embodiments, and elements can be added or deleted as appropriate. The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit such as an FPGA. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as a program for realizing each function can be stored in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC (Integrated Circuit) card, an SD card, or a DVD. Various information does not depend on the data structure. Further, although the description has been given of recording each information in the memory by the expression “store”, it may be expressed as “register” or “set”.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

  According to the present invention, in the ultrasonic diagnostic apparatus that calculates the tissue velocity vector using the Doppler shift amounts from the plurality of openings, it is possible to improve the calculation accuracy of the tissue velocity vector. This can contribute to more reliable diagnosis.

DESCRIPTION OF SYMBOLS 100 ... Ultrasonic imaging apparatus 1 ... Apparatus main body 2 ... Ultrasonic probe 10 ... Input part 11 ... Control part 12 ... Ultrasonic signal generator 13 ... Ultrasound Receiving circuit 14 ... display unit 15 ... signal processing unit 151 ... tomographic image forming unit 152 ... tissue velocity calculation unit 153 ... Doppler velocity calculation unit 1533 ... vector Doppler calculation unit 1535. Color Doppler calculation unit 155 ... aliasing processing unit 1551 ... first processing unit 1552 ... second processing unit 1553 ... opening setting unit 157 ... memory 200 ... data set 210 ... New data set 250... Velocity vector 300... Reference value data 301... Data group 302 causing aliasing... Corrected data group 400... Display screen 410. Lock 420 ... menu selection block 430 ... operation block 500 ... fitting functions 510, 520 ... threshold

Claims (15)

An ultrasonic probe that transmits an ultrasonic wave to an inspection object and receives an echo reflected from the inspection object as a reception signal, and a reception signal received by each of a plurality of openings set in the ultrasonic probe A signal processing unit for processing
The signal processing unit calculates tissue Doppler velocity information that is information about the velocity of the tissue to be examined for each opening from the received signal, and detects aliasing included in the calculated tissue Doppler velocity information.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 1,
The tissue Doppler velocity information is a Doppler shift amount that is a frequency change amount or a phase change amount of the ultrasonic wave transmitted by the ultrasonic probe,
The signal processing unit designates one or more of the plurality of openings as a reference opening, and determines the presence or absence of aliasing in the other openings based on the Doppler shift amount in the reference opening. ,
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 2,
The reference opening is an opening located at or near the center of the opening used for transmitting ultrasonic waves.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 2,
The signal processing unit performs fitting on the relationship between the positions of a plurality of openings including the reference opening and the Doppler shift amount, calculates a fitting function, and determines the Doppler shift amount determined by the fitting function and the individual openings. If the difference from the measured Doppler shift amount calculated from the received signal is equal to or greater than a predetermined threshold, the measured Doppler shift amount is determined to be aliasing.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 1,
The tissue Doppler velocity information is a Doppler shift amount that is a frequency change amount or a phase change amount of the ultrasonic wave transmitted by the ultrasonic probe,
The signal processing unit includes a Doppler speed calculation unit that calculates the Doppler shift amount, and an aliasing processing unit that detects the aliasing,
The aliasing processing unit updates the data set composed of the measured Doppler shift amount calculated from the received signal at each opening by the Doppler velocity calculation unit to a new data set composed of the Doppler shift amount not including aliasing,
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 5,
The aliasing processing unit rejects the measured Doppler shift amount determined to be aliasing by a predetermined calculation from the data set including the measured Doppler shift amount, and obtains a new data set.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 5,
The aliasing processing unit corrects the measured Doppler shift amount determined to be aliasing by a predetermined calculation from the data set including the measured Doppler shift amount, and obtains a new data set.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 7,
The aliasing processing unit performs predetermined fitting on the measured Doppler shift amount, calculates a fitting function, and corrects the difference between the corrected Doppler shift amount and the Doppler shift amount determined by the fitting function within a threshold value. Adding the Doppler shift amount to the new data set, and rejecting it if it is outside the threshold,
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 5,
The Doppler velocity calculation unit calculates at least one of the tissue Doppler velocity and the tissue velocity direction using the new data set updated by the aliasing processor.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 9, wherein
The Doppler speed calculation unit calculates the Doppler speed using a Doppler shift amount obtained by averaging or weighting and adding a plurality of Doppler shift amounts constituting the new data set.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 9, wherein
The Doppler velocity calculation unit calculates the velocity direction based on the Doppler shift amount constituting the new data set.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 11,
The Doppler velocity calculation unit calculates the velocity direction from the slope of a line obtained by plotting the Doppler shift amount for each opening position.
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 1,
The signal processing unit includes a Doppler velocity calculation unit that calculates the tissue Doppler velocity information, an aliasing processing unit that detects the aliasing, and a speed range correction unit that corrects a velocity range using a processing result of the aliasing processing unit. And having
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 1, further comprising:
An input unit for receiving selection of a processing mode by the signal processing unit;
An ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 1,
The signal processing unit includes a Doppler velocity calculation unit that calculates the tissue Doppler velocity information, and an aliasing processing unit that detects the aliasing,
The ultrasonic imaging apparatus further includes:
A display unit for displaying a processing result by the aliasing processing unit or a calculation result of the Doppler speed calculation unit reflecting the processing result;
An ultrasonic imaging apparatus.

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