JP5409311B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that processes Doppler information from within a living body.

  The ultrasonic diagnostic apparatus has a function of displaying blood flow in a living body as a two-dimensional image. Actually, a color two-dimensional blood flow image is synthesized on the background two-dimensional monochrome tomographic image, and such a synthesized image is displayed as a moving image. This function is called a color Doppler function or a color flow mapping function. As the two-dimensional blood flow image, a two-dimensional blood flow velocity image and a two-dimensional blood flow power image are known. The former two-dimensional blood flow velocity image is an image in which the velocity at each point on the scanning plane (more precisely, the average velocity component in the beam direction) is displayed including positive and negative directions. The latter two-dimensional blood flow power image is an image displaying the power of Doppler information at each point on the scanning plane. The speed and power are obtained by calculating the Doppler information included in the received signal. Recently, it has also been proposed to generate a three-dimensional blood flow velocity image and a three-dimensional blood flow power image by processing three-dimensional volume data.

  Patent Document 1 discloses a technique for variably setting a beam scanning range for obtaining Doppler information. In this technique, the number of dots of blood flow data on each beam is counted, and the blood flow existence range is specified based on the count result. Patent Document 2 discloses a technique for specifying a region where no blood flow signal exists based on blood flow image information and reducing the number of times of transmission / reception for the region. None of the documents describes the concept of generating a frequency distribution in a measurement space corresponding to a transmission / reception space.

JP-A-2-172453 JP-A-4-250148

  For example, in the ultrasound diagnosis of the heart, in order to properly observe and display blood flow, or to reduce the operational burden on the user, the frame rate (or volume rate) and the depth of the transmission focus point It is desired that transmission / reception conditions such as these are set appropriately and automatically. For that purpose, it is necessary to specify the blood flow existence region (blood flow part) in the transmission / reception space, but it is difficult to specify the blood flow part simply by observing information of a certain time phase. This is because the range and degree of blood flow changes dynamically.

  An object of the present invention is to set an appropriate apparatus operating condition for observing a dynamically changing blood flow in an ultrasonic diagnostic apparatus.

  Another object of the present invention is to make it possible to automatically and appropriately set the size of the beam scanning range in accordance with a dynamically changing blood flow.

  Another object of the present invention is to enable the depth of the transmission focus point to be automatically and appropriately set according to the blood flow that dynamically changes.

  The ultrasonic diagnostic apparatus according to the present invention repeatedly forms a two-dimensional or three-dimensional beam scanning space, and acquires a plurality of Doppler information having a temporally different relationship for each coordinate in the beam scanning space. Blood flow information is determined for each coordinate in the measurement space corresponding to the beam scanning space, and determination means for determining whether the Doppler information is blood flow information based on each Doppler information Counting means for generating a two-dimensional or three-dimensional frequency distribution by counting frequencies individually, and condition setting means for setting ultrasonic transmission / reception conditions or image processing conditions based on the frequency distribution It is characterized by that.

  According to the above configuration, the number of times blood flow information is generated (existing number) is counted for each coordinate in the beam scanning space, and a two-dimensional or three-dimensional frequency distribution is generated. Since such a frequency distribution represents a general tendency (spatial existence probability) of a blood flow region in the beam scanning space, it is used to set apparatus operating conditions (transmission / reception conditions, image processing conditions, etc.). It can be useful. Particularly preferably, a frequency distribution is created based on a plurality of frame data, and a subsequent transmission / reception region (region of interest), a depth of a transmission focus point, and the like are determined from an analysis result of the frequency distribution by spatial processing. In the analysis of the frequency distribution, it is desirable to apply a process of dropping the dimension. For example, a process of projecting the two-dimensional distribution onto the one-dimensional distribution is executed. If such projection is performed from two different directions, it is possible to easily specify the existence range and distribution tendency of the blood flow part in each direction. In order to determine whether or not it is blood flow information, it is desirable to refer to a plurality of types of information instead of one type of information. For example, blood flow information may be selected from a combination of speed (or absolute value of speed) and power for a moving body. Conversely, clutter (unnecessary signal) may be specified from such a combination, and the rest may be regarded as blood flow information. Although at least Doppler information is desirably used, luminance information may be further taken into consideration.

  Preferably, an analysis unit that generates an integrated projection distribution that represents a spatial trend of the frequency distribution by an integrated projection process on the frequency distribution generated by the counting unit is included, and the condition setting unit includes the spatial trend of the frequency distribution. Condition setting is performed based on the integrated projection distribution to be expressed. According to the cumulative projection process, the n-dimensional distribution can be converted into, for example, an (n−1) -dimensional distribution, and thus it becomes easy to recognize the spatial tendency of the frequency distribution in a specific direction. It is desirable to perform a plurality of cumulative projection processes in a plurality of directions. In the case of two-dimensional processing, it is desirable to perform integral projection processing in both the beam address direction and the depth address direction. In the case of three-dimensional processing, the three-dimensional distribution is projected onto a two-dimensional distribution or a one-dimensional distribution. It is desirable that processing be performed. Performing a spatial search to specify the blood flow portion existence range in each direction also corresponds to the above-described integrated projection processing. According to the integrated projection processing, not only the presence or absence of blood flow but also the abundance or existence ratio can be evaluated.

  Preferably, the beam scanning space is a two-dimensional scanning plane, the frequency distribution represents a frequency at which blood flow information is determined at each coordinate on the scanning plane, and the analysis means includes the frequency distribution. The integrated projection distribution is generated by performing integrated projection processing on at least one of the depth direction and the beam scanning direction. Preferably, the analysis unit performs first integration projection processing in a beam scanning direction on the frequency distribution to generate a first integration projection distribution along a depth direction, and the frequency. And a second analysis unit that generates a second integrated projection distribution along the beam scanning direction by performing a second integrated projection process in the depth direction on the distribution, and the condition setting unit includes the first setting unit The condition is set based on the integrated projection distribution and the second integrated projection distribution. Preferably, the condition setting unit sets a region of interest based on the first integrated projection distribution and the second integrated projection distribution, and a new beam scanning space is set based on the region of interest. Preferably, the analyzing unit generates the integrated projection distribution along the depth direction by performing an integrated projection process in the beam scanning direction on the frequency distribution, and the condition setting unit adds the integrated projection distribution to the integrated projection distribution. Based on this, the transmission focus point is determined.

  Preferably, the analysis unit sets a plurality of sections in the beam scanning direction with respect to the frequency distribution, generates the integrated projection distribution for each section, and the condition setting unit sets the section for each section. The depth of the transmission focus point is determined for the section on the basis of the integrated projection distribution corresponding to. Preferably, each of the Doppler information includes speed information and power information, and when the speed information is smaller than the speed threshold value and the power information is larger than the power threshold value, the determination unit extracts the blood information. It is determined that it is stream information.

  According to the present invention, it is possible to set an appropriate apparatus operating condition for observing a dynamically changing blood flow in an ultrasonic diagnostic apparatus. Alternatively, the size of the beam scanning range, the depth of the transmission focus point, and the like can be automatically and appropriately set.

1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. It is a figure for demonstrating the frequency distribution produced | generated in measurement space. It is a conceptual diagram for demonstrating the production | generation process of frequency distribution. It is a figure which shows the integral projection distribution produced | generated on the beam address axis | shaft. It is a figure which shows the integrated projection distribution produced | generated on the depth address axis | shaft. It is a figure which shows the region of interest set on a scanning surface. It is a figure for demonstrating the separate setting of the depth of the transmission focus point for every area. It is a figure for demonstrating the separate setting of the transmission focus point in a region of interest.

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

  FIG. 1 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus according to the present invention. This ultrasonic diagnostic apparatus is used in the medical field, and forms an ultrasonic image by transmitting / receiving ultrasonic waves to / from a living body. Examples of the ultrasound image include a B-mode tomographic image (monochrome tomographic image) and a two-dimensional blood flow image (blood flow velocity image, blood flow power image). Of course, the present invention can also be applied to an ultrasonic diagnostic apparatus that processes three-dimensional information.

  In the present embodiment, the probe 10 has a 1D array transducer. The 1D array vibrator is formed by arranging a plurality of vibration elements in a linear shape or an arc shape. An ultrasonic beam is formed by the 1D array transducer, and the ultrasonic beam is electronically scanned. As electronic scanning methods, electronic sector scanning, electronic linear scanning, and the like are known.

  In FIG. 1, a plurality of ultrasonic beams B are conceptually shown. They constitute the scanning plane S as a whole. The scanning plane S is a two-dimensional data capture area. A 2D array transducer may be provided for the probe 10 so that an ultrasonic beam is two-dimensionally scanned to form a three-dimensional echo data capturing area.

  The transmission unit 12 is a transmission beam former. That is, the transmission unit 12 supplies a plurality of transmission signals having a predetermined delay relationship to the 1D array transducer during transmission. As a result, a transmission beam is formed. At the time of reception, the reflected wave from the living body is received by the 1D array transducer, and a plurality of reception signals are output from the 1D array transducer to the receiving unit 14. The reception unit 14 is a reception beam former, and performs phasing addition processing on a plurality of reception signals. As a result, a reception beam is electronically formed, and a reception signal corresponding to the reception beam is beam data. The received signal after the phasing addition, that is, the beam data is output to the luminance signal processing unit 16 and the Doppler signal processing unit 22.

  The luminance signal processing unit 16 includes a signal processing circuit for B-mode image formation such as a detector and a logarithmic compression circuit. The received signal after the signal processing is output to a digital scan converter (DSC) 18. The DSC 18 has a coordinate conversion function, an interpolation function, etc., forms a B-mode tomographic image based on a plurality of beam data, and outputs the image information to the display processing unit 20. The DSCs 28 and 30 described later basically have the same function.

  In this embodiment, the Doppler signal processing unit 22 has a configuration such as a quadrature detection circuit, a wall filter, and an autocorrelation circuit. That is, the Doppler signal processing unit 22 is a circuit that extracts Doppler information included in the received signal. A complex signal is output from the Doppler signal processing unit 22 to the speed calculation unit 24 and the power calculation unit 26. The speed calculation unit 24 has a known circuit configuration and calculates a speed based on the autocorrelation result. This velocity is velocity information of each coordinate on the scanning plane of the beam. Similarly, the power calculation unit 26 calculates power for each coordinate. Further, distributed information or the like may be calculated. The DSC 28 generates a two-dimensional blood flow velocity image based on velocity information corresponding to each input coordinate, and outputs the image data to the display processing unit 20. Further, the DSC 30 generates a two-dimensional power image based on the input power information of each coordinate, and outputs the image data to the display processing unit 20.

  The display processing unit 20 has an image composition function and the like, and a color Doppler image and a color power image are generated in the display processing unit 20. That is, a color Doppler image or a color power image is synthesized on a two-dimensional luminance image as a background, and data of the synthesized image is output to the display unit 32. The above signal processing is well known.

  The ultrasonic diagnostic apparatus according to the present embodiment has a characteristic configuration described below. That is, the control unit 34 includes a determination unit 36, a frequency distribution generation unit 38, an analysis unit 40, a transmission / reception control unit 42, and the like. Incidentally, the control unit 34 is constituted by a CPU and an operation program, and the control unit 34 performs operation control of each component shown in FIG. Each configuration from the determination unit 36 to the transmission / reception control unit 42 can basically be realized as a software function. However, it may be realized by a hardware module. The input unit 44 includes an operation panel, and the operation panel includes a keyboard, a trackball, and the like.

  The discriminating unit 36 discriminates whether the Doppler information of each coordinate is blood flow or non-blood flow based on the combination information of speed and power calculated for each coordinate on the scanning plane. If it is a clutter, the speed is low and the power increases. Therefore, if such a combination condition is satisfied, it is determined to be clutter, and otherwise it is determined to be blood flow. . Of course, various determination conditions can be adopted, and it is desirable to determine whether or not the blood flow is based on at least a plurality of pieces of information. For example, luminance information may be further used to improve the discrimination accuracy. In any case, the determination unit 36 determines whether or not there is blood flow for each coordinate on the scanning plane.

  As will be described later with reference to FIG. 2, the frequency distribution generation unit 38 is determined to have blood flow for each coordinate on a measurement space (two-dimensional data processing space) having the same number of dimensions as the scanning plane. The frequency distribution is generated by obtaining the number of times. In the present embodiment, for example, the frequency distribution is generated based on a plurality of pieces of frame information corresponding to three heartbeats. Here, one frame information corresponds to one scanning plane. Of course, the measurement period for generating the frequency distribution can be arbitrarily determined. In general, it is desirable to create a frequency distribution based on information for at least one heartbeat, and according to such a configuration, the blood flow part is spatially stochastic in consideration of all changes in blood flow on the time axis. It becomes possible to specify.

  The analysis unit 34 analyzes the generated frequency distribution. Specifically, as will be described later, the first integrated projection distribution is generated by integrating and projecting a two-dimensional frequency distribution in the first direction, and the frequency distribution is integrated and projected in the second direction. Thus, the second integrated projection distribution is generated. According to such integrated projection processing, it is possible to capture the overall trend or spatial trend of the frequency distribution in a certain direction, and it is possible to obtain reference information useful in transmission / reception control. That is, the transmission / reception control unit 42 performs transmission / reception control based on the analysis result by the analysis unit 40, specifically, based on one or a plurality of integrated projection distributions. In the example described later, the region of interest (new Doppler beam scanning region) is set based on the analysis result, and the focus point depth of the transmission beam is set. According to the method of the present embodiment, such transmission / reception conditions can be set automatically and adaptively.

  Incidentally, in the above description, transmission / reception control is executed based on the frequency distribution, but other operation conditions in the ultrasonic diagnostic apparatus may be set appropriately based on the frequency distribution. Examples of such operation conditions include image processing conditions. That is, it is possible to apply special image processing to the region where the blood flow portion exists, or to reduce the brightness of the B-mode image of the blood flow portion. The update timing of the transmission / reception conditions, that is, the timing of generating the frequency distribution may be determined based on an explicit instruction from the user, or the timing may be automatically determined by determining whether a certain condition is satisfied. The above processing may be automatically executed at the time of switching to the Doppler mode.

  FIG. 2 conceptually shows the frequency distribution 46. In FIG. 2, three axes are shown. The first axis shows the beam address, the second axis shows the depth address, and the third axis shows the frequency. Here, addresses from 1 to a are illustrated as beam addresses, and addresses from 1 to b are illustrated as depth addresses. The frequency that is determined as the Doppler blood flow information is analyzed by analyzing the received signal, that is, Doppler information acquired at each coordinate specified by the beam address and the depth address, that is, for each intersection in FIG. Managed. The frequency corresponds to the number of frames that have blood flow information. For example, when a plurality of frames over 3 heartbeats are processed, the probability of blood flow at each coordinate is expressed as a frequency.

  In FIG. 3, a process for generating a frequency distribution is shown as a conceptual diagram. As shown in S101, for example, when the velocity data v of the coordinates specified by (a, b) is given, or when the absolute value of the velocity data is given, the velocity data (or the absolute value) is obtained. It is determined whether or not it is equal to or less than a predetermined threshold value α. On the other hand, as shown in S102, the power P of the coordinates (a, b) is given, and it is determined whether or not the power is greater than or equal to a predetermined threshold value β. If the speed data is less than or equal to α and the power data is greater than or equal to β, it is determined that it is clutter and is excluded from the frequency calculation (S105). On the other hand, when it is determined that it is not clutter, that is, when it is determined that it is blood flow (S103), the count value of the address (a, b) in the measurement space is incremented by one in S104. If such processing is executed at each coordinate in the frame and is executed for each frame, the frequency distribution shown in FIG. 2 can be generated. Incidentally, in FIG. 3, reference numeral 48 indicates that other information may be referred to in blood flow determination. For example, the luminance of the echo that synthesizes the B-mode image may be referred to and included in the determination condition. The contents of the process shown in FIG. 3 can basically be easily expanded to three dimensions. That is, according to such three-dimensional processing, a three-dimensional frequency distribution can be generated.

  Although it is possible to perform transmission / reception control using the two-dimensional frequency distribution generated as described above as it is, it is impossible to grasp the overall trend or the spatial trend with the frequency distribution as it is. In the embodiment, as described above, the cumulative projection process is executed. This will be described with reference to FIGS.

  FIG. 4 shows the first integrated projection distribution 50. That is, the integrated projection distribution 50 is generated by performing integrated projection of the frequency distribution shown in FIG. 2 on the beam address axis. When attention is paid to a certain beam address, frequency values existing at all depths on the beam address are integrated, and the integrated value is mapped to a position corresponding to the beam address. Based on the integrated projection distribution 50, for example, by comparing it with a predetermined threshold value k1, the width W in the beam scanning direction of the region of interest described later is defined as a section including a section having a frequency equal to or higher than a certain value. Is possible.

  FIG. 5 shows a second integrated projection distribution 52. This is generated by integrating and projecting the frequency distribution shown in FIG. 2 on the depth address axis. When attention is paid to each depth position, a plurality of frequency values existing at the depth position are integrated and mapped to a point corresponding to the depth address. By comparing such an integrated projection distribution 52 with a predetermined threshold value k2, an effective range can be specified as a range exceeding the threshold value k2, and the depth direction of the region of interest as a section including the effective range Width D can be defined. Further, by calculating the centroid of the integrated projection distribution 52 or the centroid of the integrated projection distribution within the range D, the centroid can be determined as the depth of the transmission beam focus point.

  FIG. 6 shows the control contents when transmission / reception control is performed based on the processing results as described above. Here, a scanning plane generated by electronic sector scanning is shown. In this scanning plane, the region of interest 54 is automatically set as a range from θ1 to θ2 and a range from r1 to r2. This region of interest 54 is a partial region for acquiring Doppler information, and transmission / reception of Doppler ultrasonic waves is executed only within this region. That is, it is possible to improve the frame rate for acquiring Doppler information by setting the region of interest 54 as described above. Incidentally, the entire scanning surface corresponds to a transmission / reception area for forming a B-mode image. According to the processing described above, in addition to the automatic setting of the region of interest 54, it is possible to automatically determine the depth F of the transmission focus point for the region of interest 54 or the entire scanning plane. The user's burden is greatly reduced when setting the region of interest and the depth of the transmission focus point, and such conditions can be set automatically and appropriately according to the presence of the blood flow part. The advantage is that it can be optimized. A modification is demonstrated using FIG.7 and FIG.8. These examples are based on electronic linear scanning.

  In FIG. 7, a two-dimensional space corresponding to the beam address scanning plane is divided into a plurality of sections 56 to 64 in the beam address direction. In the example shown in FIG. 7, the integrated projection distribution on the depth address axis is generated for each of the sections 56 to 64, and the depths F1 to F5 of the transmission focus point are obtained by obtaining the center of gravity of the distribution. Yes. If a plurality of sections are set in this way, there is an advantage that the depth of the transmission focus point can be set finely and appropriately over the entire scanning plane. Incidentally, if there is a problem due to discontinuity of the depth of the transmission focus point between sections, the depth position of the transmission focus point may be changed smoothly by connecting the entire depth position by spline interpolation calculation or the like. .

  In the example shown in FIG. 8, the range 68 in the beam address direction in the region of interest 66 is divided into a plurality of sections 70 to 74, and an integrated projection distribution on the depth address axis is generated for each section. Based on the above, the depths F6 to F8 of the transmission focus points are set for each section. In this way, it is possible to set a plurality of sections within the region of interest instead of the entire scanning plane. In any case, according to the configuration of the present embodiment, the temporal change of the blood flow part existing in the two-dimensional or three-dimensional real space can be captured and used as a basis for transmission / reception control. Since the probability can be taken into consideration, the transmission / reception condition or the image processing condition can be automatically optimized. In other words, it can be said that the burden on the user can be greatly reduced.

  10 probe, 24 speed calculation unit, 26 power calculation unit, 34 control unit, 36 discrimination unit, 38 luminance distribution generation unit, 40 analysis unit, 42 transmission / reception control unit.

Claims (8)

A transmission / reception unit that repeatedly forms a two-dimensional or three-dimensional beam scanning space, and acquires a plurality of Doppler information that is temporally different for each coordinate in the beam scanning space;
Determining means for determining whether the Doppler information is blood flow information based on each Doppler information;
Counting means for generating a two-dimensional or three-dimensional frequency distribution by individually counting the frequency at which blood flow information is determined for each coordinate in the measurement space corresponding to the beam scanning space;
Condition setting means for setting ultrasonic transmission / reception conditions or image processing conditions based on the frequency distribution;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
Analysis means for generating an integrated projection distribution representing a spatial tendency of the frequency distribution by an integrated projection process for the frequency distribution generated by the counting means;
The ultrasonic diagnostic apparatus characterized in that the condition setting means sets conditions based on an integrated projection distribution representing a spatial tendency of the frequency distribution. The apparatus of claim 2.
The beam scanning space is a two-dimensional scanning plane;
The frequency distribution represents the frequency at which blood flow information is determined at each coordinate on the scanning plane,
The analyzing unit generates the integrated projection distribution by performing an integrated projection process on at least one of a depth direction and a beam scanning direction with respect to the frequency distribution;
An ultrasonic diagnostic apparatus. The apparatus of claim 3.
The analysis means includes
First analysis means for generating a first integrated projection distribution along a depth direction by performing a first integrated projection process on the frequency distribution in a beam scanning direction;
Second analysis means for generating a second integrated projection distribution along the beam scanning direction by applying a second integrated projection process in the depth direction to the frequency distribution;
Including
The ultrasonic diagnostic apparatus characterized in that the condition setting means sets conditions based on the first integrated projection distribution and the second integrated projection distribution. The apparatus of claim 4.
The condition setting means sets a region of interest based on the first integrated projection distribution and the second integrated projection distribution, and sets a new beam scanning space based on the region of interest. Ultrasonic diagnostic equipment. The apparatus of claim 3.
The analysis means generates the integrated projection distribution along the depth direction by performing an integrated projection process in the beam scanning direction on the frequency distribution,
The ultrasonic diagnostic apparatus, wherein the condition setting means determines a depth of a transmission focus point based on the integrated projection distribution. The apparatus of claim 6.
The analysis means sets a plurality of sections in the beam scanning direction with respect to the frequency distribution, generates the integrated projection distribution for each section,
The ultrasonic diagnostic apparatus characterized in that the condition setting means determines the depth of a transmission focus point for each section based on an integrated projection distribution corresponding to the section for each section. The device according to any one of claims 1 to 7,
Each Doppler information includes speed information and power information,
The discrimination means discriminates that the velocity information is non-blood flow information when the velocity information is smaller than a velocity threshold and the power information is larger than a power threshold. .

Images