JP2006000421A - Ultrasonic blood-flow imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic blood-flow imaging apparatus which can generate a wide range of BMI (Blood Motion Imaging) image data excellent in dynamic display. <P>SOLUTION: When the BMI image data are generated by sequentially transmitting and receiving ultrasonic waves at predetermined intervals Tr in a plurality of directions of a subject, reception signals from the predetermined direction are collected M-times at intervals Tx (Tx=M×Tr) by so-called M-stage constant-interval alternate scanning wherein the transmission and reception of the ultrasonic wave in a plurality of other directions (M-1) are sequentially performed during the time from the first transmission and reception of the ultrasonic wave in the predetermined direction to the next transmission and reception of the ultrasonic wave. FIR filtering for extracting a reflected wave component from a blood cell is performed for the reception signals with a prescribed depth, which are acquired at the intervals Tx in each of a plurality of scanning directions, and the plurality of BMI image data in a plurality of time phases are generated according to data of a data string which is sequentially outputted by the FIR filtering. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic blood flow imaging apparatus that visualizes blood flow based on an ultrasonic reception signal obtained from a subject.

  The ultrasonic diagnostic method radiates an ultrasonic wave generated from a piezoelectric vibrator built in an ultrasonic probe into a subject and receives a reflected wave caused by a difference in acoustic impedance of the subject tissue by the piezoelectric vibrator. It is displayed on the monitor. This diagnosis method is widely used for organ function diagnosis and morphological diagnosis because real-time two-dimensional image data can be easily obtained by a simple operation by simply bringing an ultrasonic probe into contact with the body surface.

  Ultrasound diagnostic methods for obtaining biological information from reflected waves from the tissue or blood cells of a subject have made rapid progress with the development of two major technologies, the ultrasonic pulse reflection method and the ultrasonic Doppler method, and are obtained using the above technology. The B-mode image and the color Doppler image that are obtained are indispensable in today's ultrasound diagnosis.

  In a conventional ultrasonic blood flow imaging apparatus capable of observing a color Doppler image, ultrasonic transmission / reception is performed N times in the same direction, and the number of N data obtained at this time (hereinafter referred to as a packet). The average velocity and dispersion of blood flow in the ultrasonic wave transmission / reception direction and the calculation and display of power values have been performed.

  In addition to the conventional color Doppler method that displays the average velocity, dispersion, and power of blood flow, speckle data resulting from interference of reflected waves from red blood cells has recently been collected and obtained at high speed. A method has been proposed in which the speckle data is displayed in slow motion at a normal speed to visualize the blood flow (see, for example, Patent Document 1). According to this method, subtle temporal and spatial changes in speckle can be continuously captured, so that blood flow information is visualized as if it is actually flowing compared to the color Doppler method described above. It becomes possible.

  FIG. 14 is a diagram showing a scanning method and a data processing method in the method described in Patent Document 1 described above. In FIG. 14A, the horizontal axis corresponds to time, and the vertical axis corresponds to the scanning direction. The dots correspond to ultrasonic transmission / reception. For example, when ultrasonic scanning of a predetermined section is performed by sector scanning, ultrasonic transmission / reception in the direction Rp (p = 1 to P) is repeated at a time interval (hereinafter referred to as a rate period) Tr, and a plurality of scans SP1, SP2. , SP3,...

  For example, blood flow information is detected using six reception signals in a predetermined transmission / reception direction RPp obtained at time intervals Tx (Tx = Tr · P) by ultrasonic transmission / reception in the scans RP1 to RP6 as packets. However, in the conventional color Doppler method, all data in the packet is filtered to calculate the average velocity, variance, and power of blood flow at a predetermined position in the transmission / reception direction Rp. For example, FIR (Finite Impulse Response) filter processing is performed on the basis of three reception data continuously obtained at the time interval Tx in the transmission / reception direction Rp, and the power is calculated. In the conventional method, one piece of power data averaged in one packet is output, whereas in this method, a plurality (four in FIG. 14) of power data is output in one packet.

  FIG. 14B shows image data (hereinafter referred to as BMI image data) Fd1, Fd2,..., And tissue image data (so-called so-called so-called “BMI image data”) generated in parallel with the BMI image data. B mode image data) Fb1, Fb2,... Are schematically shown, with the horizontal axis corresponding to the image collection order and the vertical axis corresponding to the scanning direction. Then, data in the transmission / reception direction Rp constituting the BMI image data Fd1 (hereinafter referred to as BMI data) is obtained by performing FIR filter processing on the reception signals obtained by the scans SP1 to SP3. The BMI image data Fd1 is generated by performing such processing for all the transmission / reception directions R1 to RP.

  Similarly, the BMI image data Fd2 to Fd4 are also generated by FIR filter processing on the received signals of the scans SP2 to SP4, SP3 to SP5, and SP4 to SP6. That is, four BMI image data Fd1 to Fd4 can be obtained by performing FIR filter processing using three consecutive received signals in a packet composed of six received signals.

  By such processing, the inter-frame time interval between the BMI image data adjacent in the time direction (for example, BMI image data Fd1 and Fd2) becomes Tx, and the inter-frame time interval is N · Tx (N = 6). BMI image data can be generated at a higher frame rate than in the case of image data.

Next, by converting the BMI image data generated at a high speed by the above-described method to a normal display speed, speckle data that changes in a short time can be continuously visualized. Based on this, it is possible to visualize the blood flow.
US Pat. No. 6,277,075 (pages 5-9, 2-6)

  However, it is actually difficult to continuously image speckle data resulting from a reflected wave from a blood cell over a wide range by the method of Patent Document 1 described above.

  This is because, in order to observe the above speckle data continuously spatially and temporally, (1) there is a strong correlation between the speckle data of adjacent BMI data (for example, RRp and RRp + 1) constituting the BMI image data. The ultrasonic transmission / reception interval d is sufficiently close to a certain extent, and (2) ultrasonic transmission / reception in a predetermined direction Rp is performed at a repetition frequency fx (fx = 1 / Tx) that is high enough to prevent folding. (3) By filtering with a small number of data (Nx = 3 <N), it is possible to separate reflected waves from living tissue and reflected waves from blood cells and extract only blood flow information with high sensitivity (4 This is because it is necessary to satisfy the conditions such that the repetition frequency fx is low enough to separate the reflected wave from the living tissue and the reflected wave from the blood cell.

  For example, in carotid blood flow measurement using ultrasonic waves having a center frequency of 8 MHz, when the maximum blood flow velocity component in the direction of transmission and reception is 10 cm / sec, the minimum repetition frequency fx at which the above folding does not occur is 2.1 KHz. Become. Here, if the ultrasonic wave transmission repetition frequency (rate frequency) fr (fr = 1 / Tr) is 16.8 KHz, the number of ultrasonic wave transmissions possible in each two-dimensional scan is 8, for example, parallel to four directions. Even when simultaneous reception is applied, one piece of BMI image data is generated based on the received signals in 32 directions.

  That is, the BMI image data generated by the method of Patent Document 1 must be composed of 32 BMI data arranged at sufficiently close intervals, so that a sufficient field width (scanning width) can be obtained. Can not. In addition, in order to widen the visual field width, a method of performing the above-described two-dimensional scanning with two or more blocks and combining a plurality of obtained BMI image data is conceivable. Since the data is synthesized by the discontinuous BMI image data of the time phase, an unacceptable discontinuity occurs at the boundary, and the diagnostic ability is remarkably lowered.

  On the other hand, the method of further increasing the number of reception directions by the parallel simultaneous reception has a limit because the transmission / reception sensitivity in a predetermined direction deteriorates as the transmission ultrasonic beam spreads and the reception circuit becomes complicated.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an ultrasonic blood flow imaging apparatus that can generate a wide range of BMI image data excellent in dynamic display.

  In order to solve the above problem, an ultrasonic blood flow imaging apparatus according to the present invention according to claim 1 is an ultrasonic probe including an ultrasonic transducer, and a predetermined scanning direction of a subject using the ultrasonic transducer. Ultrasonic transmission / reception means for performing ultrasonic transmission / reception to and from the ultrasonic wave transmission / reception means, and ultrasonic transmission / reception means sequentially for a plurality of directions in a predetermined region including the reference direction with the predetermined direction as a reference direction. After performing the ultrasonic scanning, the ultrasonic scanning is sequentially performed a plurality of times in a plurality of directions in a predetermined region including the new reference direction, with a direction separated by a predetermined interval from the reference direction as a new reference direction. Repeating scanning control means and the scanning control means perform filtering on each received signal obtained from a plurality of directions of the predetermined region, and receive the blood cells due to the blood flow of the subject. Filtering means for detecting a signal component, image data generating means for generating image data displaying a change in speckle based on each data of a data sequence sequentially output by the filtering means, and the generated image data A display means for displaying is provided.

  According to a second aspect of the present invention, there is provided an ultrasonic blood flow imaging apparatus according to the present invention, wherein an ultrasonic probe provided with an ultrasonic transducer and ultrasonic transmission / reception with respect to a predetermined scanning direction of a subject using the ultrasonic transducer. An ultrasonic wave transmitting / receiving unit that performs a wave, and the ultrasonic wave transmitting / receiving unit sequentially performs ultrasonic wave transmission / reception with respect to a plurality of directions in a predetermined region including the reference direction with a predetermined direction as a reference direction. Scanning control means for repeating ultrasonic scanning for sequentially performing ultrasonic transmission / reception for a plurality of directions in a predetermined region including the new reference direction with a direction separated by a predetermined interval from the direction as a new reference direction; This scanning control means performs a filtering process on each received signal obtained from a plurality of directions of the predetermined area, and detects a received signal component caused by the blood cell flow of the subject. Filtering means, image data generating means for generating image data displaying changes in a plurality of speckles having different time phases based on each data of the data string sequentially output by the filtering means, and the image data generating means The flow data generating means for generating blood flow data by the inter-image processing of the plurality of image data generated by the above and the display means for displaying the generated blood flow data are provided.

  According to the present invention, it is possible to generate a wide range of BMI image data excellent in dynamic display.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the embodiments of the present invention described below, when the BMI image data is generated by sequentially performing ultrasonic transmission / reception at a predetermined interval Tr in a plurality of directions of the subject, the first ultrasonic transmission / reception from the first direction to the next is performed. In the so-called M-stage constant interval alternating scanning, the received signals from the predetermined direction are separated by an interval Tx (Tx = M) by sequentially performing ultrasonic transmission / reception in other directions (M-1) while performing ultrasonic transmission / reception. -Collect M times at Tr).

  Then, FIR filter processing for extracting the reflected wave component from the blood cell is performed on the reception signal obtained at the interval Tx in each of the plurality of scanning directions, and the data string data sequentially output in the FIR filter processing is performed. Based on this, a plurality of BMI image data in a plurality of time phases are generated.

(Device configuration)
Hereinafter, the configuration of the ultrasonic blood flow imaging apparatus and the operation of each unit in the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of the ultrasonic blood flow imaging apparatus according to the present embodiment. FIGS. 2 and 4 show the transmission / reception unit and the data generation unit that constitute the ultrasonic blood flow imaging apparatus. It is a block diagram which shows a detailed structure.

  An ultrasonic blood flow imaging apparatus 100 shown in FIG. 1 includes an ultrasonic probe 10 that includes a plurality of one-dimensionally arranged piezoelectric vibrators and transmits / receives ultrasonic waves to / from a subject, and these piezoelectric vibrators. And a transmission / reception unit 20 for performing phasing addition on the reception signal obtained by the piezoelectric vibrator (adding the reception signal obtained from a predetermined direction in phase), A data generation unit 30 for generating BMI data based on speckle information resulting from a reflected wave from a blood cell with respect to a reception signal obtained from the transmission / reception unit 20 and B-mode data, color Doppler data, and this data The data generated in the generation unit 30 is stored to generate two-dimensional B-mode image data, color Doppler image data, and BMI image data. A data storage and calculation unit 50 for generating a flow vector data and streamline data of a blood flow by using the MI image data, and a display unit 9 for displaying these image data generated.

  Furthermore, the ultrasonic blood flow imaging apparatus 100 includes a reference signal generation unit 1 that generates a continuous wave or a rectangular wave having a frequency substantially equal to the center frequency of the transmission ultrasonic wave to the transmission / reception unit 20, and subject information and An input unit 11 for inputting apparatus setting conditions and various command signals, a scanning control unit 12 for controlling the scanning direction of ultrasonic waves, and a system control unit 13 for comprehensively controlling each unit described above are provided. ing.

  The ultrasonic probe 10 is for transmitting and receiving ultrasonic waves by bringing its front surface into contact with the surface of a subject. For example, the ultrasonic probe 10 has M0 piezoelectric vibrators arranged one-dimensionally at its tip. Yes. This piezoelectric vibrator is an electroacoustic transducer, and functions to convert electrical pulses to transmitted ultrasound during transmission, and to convert ultrasonic reflected waves (received ultrasound) into electrical signals (received signals) during reception. have.

  Next, the transmission / reception unit 20 shown in FIG. 2 performs phasing addition on the transmission unit 2 that supplies a drive signal to the M0 channel piezoelectric vibrator and the reception signal obtained by the piezoelectric vibrator. A receiving unit 3 is provided.

  The transmission unit 2 includes a rate pulse generator 21, a transmission delay circuit 22, and a drive circuit 23. The rate pulse generator 21 divides the continuous wave supplied from the reference signal generation unit 1 by dividing the continuous wave. A rate pulse that determines the repetition period (rate period) of the sound wave is generated. Further, the transmission delay circuit 22 determines a delay time for converging the transmission ultrasonic wave to a predetermined depth and a delay time for radiating the transmission ultrasonic wave in a predetermined direction in order to obtain a narrow beam width in the transmission. Give to the pulse. The drive circuit 23 generates a drive signal for driving the M0 channel piezoelectric vibrator in the ultrasonic probe 10 based on the timing of the rate pulse.

  On the other hand, the receiving unit 3 includes a preamplifier 24, an A / D converter 25, and a beam former 26. The preamplifier 24 is for amplifying the received signal of the M0 channel supplied from the ultrasonic probe 10 to ensure a sufficient S / N, and a high voltage supplied from the drive circuit 23 is provided at the first stage. A limiter circuit (not shown) is provided for protection from the drive signal. The reception signal amplified to a predetermined size by the preamplifier 24 is converted into a digital signal by the A / D converter 25 and sent to the beam former 26.

  The beam former 26 has a delay circuit and an adder circuit (not shown), and converges an ultrasonic reflected wave from a predetermined depth with respect to the M0 channel reception signal converted into a digital signal by the A / D converter 25. The delay time for convergence and the reception directivity of the ultrasonic reflected wave are sequentially changed to give a deflection delay time for scanning the subject, and then these received signals are added and synthesized (phased addition). . The beam former 26 has a so-called parallel simultaneous reception function for separately receiving each of the received ultrasonic waves obtained simultaneously from a plurality of directions of the subject.

  There are various methods of beam forming by the beam former 26. For example, phasing addition is performed on a complex signal (I signal and Q signal) obtained by quadrature detection using a quadrature detection circuit (not shown). It is.

  Next, the scanning control unit 12 controls the transmission delay time of the transmission delay circuit 22 and the reception delay time of the beam former 26 in order to perform two-dimensional ultrasonic scanning on the subject. In particular, when color Doppler image data or BMI image data is generated, I / Q signals are collected by a constant interval alternating scanning method. Incidentally, the constant interval alternating scanning is described in Japanese Patent No. 2770209.

  FIG. 3 shows a constant-interval alternate scanning method used in the generation of BMI image data in this embodiment, where the horizontal axis corresponds to the scanning directions θ1 to θP, the vertical axis corresponds to time, and the ultrasonic wave transmission / reception direction. Corresponds to the direction perpendicular to the page. In the present embodiment, the case where eight steps of regular interval alternate scanning are used will be described, but the present invention is not limited to this.

  That is, according to the scanning control signal supplied from the scanning control unit 12, the transmission / reception unit 20 first performs the first scanning SP1 by ultrasonic transmission / reception with a rate period Tr with respect to θ1 to θ8, and then with respect to θ2 to θ9. The second scan SP2 is performed by ultrasonic transmission / reception of rate cycle Tr.

  Similarly, by repeating the third and subsequent scans SP3, SP4,... While shifting the scan direction one by one, for example, in the scan direction θ8, the received signals a1 to a8 are collected by the scans SP1 to SP8. In the scanning direction θ9, the reception signals b1 to b8 are collected by the scanning SP2 to the scanning SP9, and in the scanning direction θ10, the reception signals c1 to c8 are collected by the scanning SP3 to the scanning SP10. Similarly, the received signals d1 to d8, e1 to e8,...

  Next, the data generation unit 30 shown in FIG. 4 performs color processing on the B-mode data generation unit 4 and the color Doppler data by processing the reception signal output from the beam former 26 of the reception unit 3 to generate B-mode data. A color Doppler data generation unit 5 for generating the BMI data and a BMI data generation unit 6 for generating the BMI data.

  The B mode data generation unit 4 includes an envelope detector 31 and a logarithmic converter 32. The envelope detector 31 performs envelope detection by calculating the absolute value of the received signal (complex signal) output from the beamformer 26 of the receiver 3, and the logarithmic converter 32 performs the envelope detection after the envelope detection. B-mode data in the scanning direction is generated by relatively emphasizing a small signal amplitude by logarithmic conversion processing on the received signal.

  The color Doppler data generation unit 5 includes an I / Q signal storage circuit 34, an MTI filter 35, an autocorrelation calculator 36, and a speed / dispersion / power calculation circuit 37.

  The complex signal supplied from the beamformer 26 of the receiving unit 3 is temporarily stored in the I / Q signal storage circuit 34, and then the MTI filter 35, which is a high-pass digital filter, performs a constant interval alternating scan. The M complex signals in the predetermined scanning direction sequentially stored in the I / Q signal storage circuit 34 are read out, and the received signal component from the fixed reflector such as an organ or the respiratory movement or beat of the organ is obtained by filtering the complex signal. A received signal component caused by dynamic movement or the like is removed, and a Doppler signal component caused by blood flow is extracted.

  Next, the autocorrelation calculator 36 calculates an autocorrelation value for the Doppler signal extracted by the MTI filter 35, and the velocity / dispersion / power calculation circuit 37 calculates an average of blood flow based on the autocorrelation value. Color Doppler data for each scanning direction is generated by calculating a flow velocity value, a dispersion value, and a power value.

  On the other hand, the BMI data generation unit 6 includes an I / Q signal storage circuit 38, an FIR filter 39, and a data shift circuit 40. The I / Q signal storage circuit 38 is alternately arranged at regular intervals as already described with reference to FIG. The received signal (complex signal) collected by scanning is temporarily stored.

  FIG. 5 schematically shows the I signal and the Q signal stored in the I / Q signal storage circuit 38. In the storage area corresponding to the scanning direction θ8, the I signals obtained by the scans SP1 to SP8 are displayed. The signals a1 (I) to a8 (I) and the Q signals a1 (Q) to a8 (Q) are stored, and the I signal b1 (I obtained by the scans SP2 to SP9 is stored in the storage area corresponding to the scan direction θ9. ) To b8 (I) and Q signals b1 (Q) to b8 (Q) are stored. Further, eight I signals and Q signals are similarly stored in each of the storage areas corresponding to the scanning direction θ10 and thereafter.

  Next, the FIR filter 39 reads the I / Q signal in each scanning direction once stored in the I / Q signal storage circuit 38 and performs FIR filter processing.

FIG. 6 shows the principle of FIR filter processing. For example, filter constants (h1, h2, h3) = (0.5, − for the I / Q signals a1 to a7 collected at the interval Tx. The power value data strings A1 to A5 are calculated by the FIR filter processing of the following expression (1) using the 1.0, 0.5) FIR filter 39.

  Note that the reception signals a8, b8, c8,... Collected in the regular interval alternating scan of FIG. 4 are collected by the first ultrasonic transmission / reception wave of the M-stage alternating scan, so that the reflected wave from the deep part of the living body. The effect of (reverberation echo) is different from other received signals. For this reason, the reverberation echo may be emphasized and detected in the above-described filter processing. Therefore, it is desirable to perform the FIR filter processing without using the received signals a8, b8, c8,.

  Next, the data shift circuit 40 performs a predetermined data shift on the power value data string in each scanning direction obtained by the FIR filter 39 to generate BMI data for each scanning direction.

  FIG. 7 is a diagram for explaining the data shift of the power value data string performed by the data shift circuit 40. The horizontal axis of FIG. 7A represents the power value data strings A1 to A5, B1 to B5, and C1 to C5. The vertical directions of the scanning directions θ8, θ9, θ10,... In which... Are obtained correspond to the scans SP1, SP2,.

  On the other hand, FIG. 7B shows BMI data generated by the data shift of the power value data string by the data shift circuit 40, and the data shift circuit 40 uses the power in each scanning direction obtained by the FIR filter 39. .., (Q = 1 to 5) are shifted so that the head data A1, B1, C1,... Match, and BMI data is generated. Then, the generated BMI data in the scanning direction unit is stored in the data storage unit 7 in the data storage / calculation unit 50 described later.

  Returning to FIG. 1, the data storage / calculation unit 50 includes a data storage unit 7 and a flow data generation unit 8.

  The data storage unit 7 sequentially stores the B mode data, color Doppler data, and BMI data generated in the scanning direction unit by the data generation unit 30 to generate B mode image data, color Doppler image data, and BMI image data.

  FIG. 8 schematically shows BMI image data generated in the data storage unit 7, and is generated using the BMI data shown in FIG. 7B. For example, the BMI image data Fd1 is composed of a power value A1 in the scanning direction θ8, a power value B1 in the scanning direction θ9, a power value C1 in the scanning direction θ10, and the BMI image data Fd2 is similarly scanned. The power value A2 of θ8, the power value B2 of the scanning direction θ9, the power value C2 of the scanning direction θ10, and so on.

  On the other hand, the flow data generation unit 8 uses the plurality of BMI image data Fd1, Fd2, Fd3,... Generated in the data storage unit 7 to move blood cells (that is, speckle patterns). A direction and a moving amount (or moving speed) are estimated, and flow vector data and streamline data are generated based on these results.

  That is, the above-described flow data generation unit 8 includes an arithmetic circuit (not shown). For example, the movement of the speckle pattern in these image data by the cross-correlation calculation between images using two pieces of BMI image data adjacent in the time direction. The amount and direction of movement are estimated, and blood flow vector data or stream line data is generated based on these estimation results.

  Hereinafter, the flow vector estimation method will be described with reference to FIG. The flow data generation unit 8 divides the two-dimensional BMI image data generated in the data storage unit 7 into a plurality of blocks as shown in FIG. 9 with respect to the scanning direction and the transmission / reception direction. The cross-correlation coefficient between the block B (0, 0) of the BMI image data Fdn and each block of the (n + 1) th BMI image data Fdn + 1 is calculated. The BMI image data shown in FIG. 9A is divided into 5 × 5 blocks, and each block is composed of 3 × 3 pixels. However, the number of blocks and the number of pixels are as described above. It is not limited to the value.

  That is, the flow data generation unit 8 uses the pixels at the same coordinates in the block B (0, 0) of the BMI image data Fdn and the blocks B (−2, −2) to B (2, 2) of the BMI image data Fdn + 1. The cross correlation coefficient of each block of the BMI image data Fdn + 1 with respect to the block B (0, 0) of the BMI image data Fdn by adding or averaging the multiplication results obtained with 3 × 3 pixels Is calculated.

  Next, the block B (α, β) of the BMI image data Fdn + 1 having the largest cross-correlation coefficient with respect to the block B (0, 0) of the BMI image data Fdn is detected, and the block B (0, 0) is used as a reference. And the magnitude (length) and direction of the flow vector are set based on the distance and direction to the block B (α, β). At this time, the thickness of the flow vector may be set based on the average value or integrated value of the pixel values (power values) in the block B (0, 0) of the BMI image data Fdn. Then, the calculation of the cross-correlation coefficient and the setting of the flow vector described above are performed for other blocks of the BMI image data Fdn, and also for other BMI image data.

  Furthermore, the flow data generation unit 8 includes a display determination unit (not shown) that determines display / non-display of the flow vector based on the above-described distance and power values that determine the length and thickness of the flow vector. If the average value or integrated value of power values is smaller than a preset threshold value, it is determined as noise and the flow vector is set to non-display. Similarly, if the distance is greater than a predetermined threshold, it is determined that the cross-correlation coefficient has not been calculated correctly for reasons such as aliasing, and the flow vector is set to non-display.

  Next, the display unit 9 includes a display data generation circuit, a conversion circuit, and a monitor (not shown). For the B-mode image data, color Doppler image data, and BMI image data generated in the data storage / processing unit 70, The display data generation circuit performs scan conversion processing corresponding to a predetermined display form to generate display image data.

  The conversion circuit performs D / A conversion and television format conversion on the display image data to generate a video signal, and displays the video signal on the monitor. That is, the two-dimensional BMI image data generated in the data storage unit 7 of the data storage / calculation unit 50 is converted into the sector display type BMI image shown in the schematic diagram of FIG. 8 by the scan conversion processing by the display data generation circuit. Data Fd1, Fd2, Fd3... Are converted and displayed on the monitor.

  Note that this display data generation circuit is usually used for B-mode image data, color Doppler image data, BMI image data, and flow vector data and streamline data in accordance with an image display mode set in advance in input described later. Then, desired data is synthesized and display image data is generated. For example, BMI image data, flow vector data, and streamline data are combined with B-mode image data and color Doppler image data and displayed on the monitor of the display unit 9.

  FIG. 10 shows a specific example of the flow vector display. As described above, the speckle in the BMI image data is started from the center of each block set in the BMI image data by the flow data generation unit 8. The flow vector reflecting the moving direction, moving amount, and pixel value (speckle power value) is displayed. When the number of vectors in the flow vector display is too large and observation is difficult, the above vector may be thinned and displayed in order to display a flow vector with an appropriate density.

  On the other hand, FIG. 11 shows a specific example of streamline display, and the method of setting the direction and thickness of the streamline in this streamline display is the same as in the case of the flow vector described above. For example, when the block B (0, 0) of the BMI image data Fdn is used as a reference, the flow data generation unit 8 uses the block B (α, B) in the BMI image data Fdn + 1 having the highest correlation with the block B (0, 0). The position of β) and the power value of the pixel in the block B (0, 0) are detected. The display unit 9 then displays a line of thickness or luminance corresponding to the power value of the block B (0, 0) at the center of the detected block B (0, 0) and block B (α, β). Connected by minutes to form streamlines.

  Such a calculation is performed for other blocks in the BMI image data Fdn, and is also performed for other BMI image data. Note that this streamline display can display a two-dimensional distribution of flow that is higher in density and superior in continuity than the flow vector display, but in this case too many streamlines are observed. If this is difficult, it may be displayed with appropriate thinning.

  Further, the display unit 9 has a so-called slow motion display function that converts a plurality of BMI image data collected at high speed by the transmission / reception unit 20 and the data generation unit 30 to a normal display speed.

  For example, in the present embodiment, the rate frequency fr is 10 KHz, the number of received data collected at the interval Tx in the same transmission / reception direction is 8, the number of stages of alternating scanning at regular intervals is 8, and the number of image rasters constituting one BMI image data Is 128, the image collection interval Tx of the BMI image data Fd1, Fd2, Fd3,... Shown in FIG. 8 is Tx = 8/10 KHz = 0.8 msec. For example, the image collection interval Tf of the BMI image data generated by the reception signals in the transmission / reception directions θ1 to θP is (128 × 8) / 10 KHz = 102 msec.

  In this embodiment, when displaying BMI image data collected at a high speed with an image collection interval Tx = 800 μsec (that is, a repetition frequency of 1.25 KHz), the BMI image data is displayed on the display unit 9 at the same frame rate. Since it is impossible to display on the monitor, the display speed is converted and the slow motion display is performed.

  FIG. 12 is an explanatory diagram of slow motion display, and FIG. 12A shows the generation timing of the BMI image data Fd1 to Fd5 in the scanning directions θ8 to θ15 generated in the data storage unit 7 of the data storage / calculation unit 50. FIG. 12B shows the display timing in the slow motion display of the BMI image data Fd1 to Fd5.

  As shown in FIG. 12 (a), the BMI image data Fd1 to Fd5 in the scanning directions θ8 to θ15 have the repetition period of each image data (that is, the image collection interval of the BMI image data in the entire region in the scanning directions θ1 to θP). ) It is generated in a period of 3.2 msec in Tf = 102 msec.

  When displaying the five pieces of BMI image data Fd1 to Fd5 thus obtained at high speed, the display unit 9 reads out these BMI image data Fd1 to Fd5 at intervals of, for example, 20.4 msec and displays them on the monitor. By doing so, continuous slow motion display becomes possible.

  Next, returning to FIG. 1, the input unit 11 includes an input device such as a display panel, a keyboard, a trackball, a mouse, a selection button, and an input button on the operation panel, and inputs patient information, an image data collection mode, Setting of display mode, selection of alternate scanning at regular intervals, setting of the number of alternate stages, input of various command signals, etc. are performed.

  The system control unit 13 includes a CPU and a storage circuit (not shown), and the above-described various information input or set by the operator from the input unit 11 is stored in the storage circuit. In addition, the memory circuit has previously set values such as a threshold for determining whether or not to display or hide a flow vector or a flow line in flow vector display or stream line display, or a block size or the like when calculating a cross-correlation coefficient. It is stored.

  Based on these pieces of information, the CPU controls the scanning control unit 12, the transmission / reception unit 20, the data generation unit 30, the data storage / calculation unit 50, the display unit 9, and the entire system.

(Image data generation procedure)
Next, a procedure for generating BMI image data and the like in the present embodiment will be described with reference to FIGS.

  First, the operator of the ultrasonic blood flow imaging apparatus 100 inputs patient information, selects an image data collection mode and a display mode, and sets the number of alternating stages in the constant interval alternate scanning, etc. in the input unit 11. The selection information and the setting information are stored in a storage circuit (not shown) of the system control unit 13. In the following, the case where the acquisition mode and the display mode for B-mode image data and BMI image data are selected and the number of alternating stages is set to 8 will be described, but the present invention is not limited to this.

  Next, the system control unit 13 that has received the image data collection mode selection information and the alternating stage number information from the input unit 11 generates these image data for each unit of the ultrasonic blood flow imaging apparatus 100. Each unit that supplies a control signal and receives the control signal generates B-mode image data and BMI image data by eight-stage constant interval alternate scanning in the scanning directions θ1 to θP.

  When generating the BMI image data, the system control unit 13 in FIG. 1 sets the transmission delay time and the reception delay time of the transmission / reception unit 20 in order to perform ultrasonic transmission / reception in the scanning direction θ1 of the scanning SP1 shown in FIG. Control. Next, the rate pulse generator 21 in the transmission unit 2 in FIG. 2 divides the reference signal supplied from the reference signal generation unit 1 to determine the rate period Tr of the transmission ultrasonic wave (ultrasonic pulse). A pulse is generated, and this rate pulse is supplied to the transmission delay circuit 22 of the M0 channel.

  The transmission delay circuit 22 uses a delay time for converging the ultrasonic wave to a predetermined depth and a deflection for radiating the ultrasonic wave in the scanning direction θ1 in accordance with the delay time control signal supplied from the system control unit 13. A delay time is given to the rate pulse, and this rate pulse is supplied to the driving circuit 23 of the M0 channel. Then, the drive circuit 23 supplies the impulse generated by the rate pulse drive or the drive signal having a predetermined waveform to the M0 channel piezoelectric vibrator of the ultrasonic probe 10 via the M0 channel cable (not shown), and the scanning direction. A transmission ultrasonic wave is radiated with respect to θ1.

  A part of the transmitted ultrasonic wave radiated to the subject is reflected at an interface or tissue between organs having different acoustic impedances. Further, when this ultrasonic wave is reflected by a moving reflector such as a heart wall or blood cell, the ultrasonic frequency is subjected to Doppler shift.

  Received ultrasonic waves (ultrasound reflected waves) reflected by the tissue or blood cells of the subject are received by the piezoelectric vibrator of the ultrasonic probe 10 and converted into electric signals (received signals), and further, the M0 channel After being supplied to the preamplifier 24 of the receiving unit 3 through the cable and amplified to a predetermined size, it is converted into a digital signal by the A / D converter 25.

  The M0 channel received signal converted into a digital signal is supplied to the beam former 26, and phasing addition is performed on each of the I signal and the Q signal obtained by quadrature detection. Then, the phase-added I signal and Q signal are temporarily stored in the I / Q signal storage circuit 38 in the BMI data generation unit 6 of FIG.

  Similarly, the system control unit 13 stores an I / Q signal obtained by performing ultrasonic transmission / reception in the scanning directions θ2 to θ8 of the scanning SP1 in the I / Q signal storage circuit 38 of the BMI data generation unit 6. Further, I / Q signals obtained by ultrasonic transmission / reception in the scanning directions θ2 to θ9 of the scanning SP2 and the scanning directions θ3 to θ10 of the scanning SP3 are also stored in the I / Q signal storage circuit 38.

  On the other hand, the FIR filter 39 selects, for example, a time interval with respect to the scanning direction θ8 from the I and Q signals in each scanning direction (see FIG. 5) stored in the I / Q signal storage circuit 38 by the above procedure. The I signals a1 (I) to a8 (I) and Q signals a1 (Q) to a8 (Q) of the scans SP1 to SP8 obtained at Tx are read, and the power is obtained by FIR filter processing based on the equation (1) already shown. Value data strings A1 to A5 are calculated (see FIG. 6). These obtained power value data strings are temporarily stored in a buffer circuit (not shown) of the data shift circuit 40.

  Similarly, the I signals b1 (I) to b8 (I) and Q signals b1 (Q) to b8 (Q) of the scans SP2 to SP9 obtained with respect to the scanning direction θ9 and the scan direction θ10 are obtained. .., Read out the I signals c1 (I) to c8 (I) and the Q signals c1 (Q) to c8 (Q)... Of the scans SP3 to SP10, and the power value data strings B1 to B5 obtained by the FIR filter processing. , C1 to C5 are stored in the buffer circuit of the data shift circuit 40 (see FIG. 7A).

  Then, the data shift circuit 40 performs data shift so that the head data A1, B1, C1,... Match the power value data string in the scanning directions θ8 to θP stored in the buffer circuit. BMI data is generated, and the BMI data is stored in the data storage unit 7 of the data storage / calculation unit 50.

  Next, the data storage unit 7 of the data storage / calculation unit 50 sequentially stores the BMI data in the scanning direction supplied from the data shift circuit 40 of the BMI data generation unit 6 to generate two-dimensional BMI image data.

  When the generation of the BMI image data is completed, ultrasonic transmission / reception for generating B-mode image data is performed. That is, the system control unit 13 controls the transmission delay time and the reception delay time of the transmission / reception unit 20 in order to obtain B-mode data in the scanning directions θ1 to θP. Next, the transmitting / receiving unit 20 and the ultrasonic probe 10 first perform ultrasonic transmission / reception with respect to the scanning direction θ1, and the B-mode data generation unit outputs the I signal and the Q signal phased and added in the beam former 26 of the receiving unit 3 4 is supplied.

  The envelope detector 31 of the B-mode data generation unit 4 performs envelope detection by calculating the absolute value of the I / Q signal output from the beamformer 26, and the logarithmic converter 32 performs post-envelope detection. Logarithmic conversion is performed on the received signal to generate B-mode data. The generated B mode data is stored in the data storage unit 7 of the data storage / calculation unit 50.

  Similarly, ultrasonic transmission / reception is performed in the scanning directions θ2 to θP, and the obtained B-mode data is stored in the data storage unit 7. That is, the B mode data generated by the B mode data generation unit 4 in units of the scanning direction is sequentially stored in the data storage unit 7, and two-dimensional B mode image data is generated.

  On the other hand, the flow data generation unit 8 performs cross-correlation calculation between images using two pieces of BMI image data adjacent in the time direction from among a plurality of pieces of BMI image data having different time phases stored in the data storage unit 7. Then, the movement amount and movement direction of the speckle pattern in the BMI image data are estimated. Then, based on these estimation results, blood flow vector data or stream line data is generated, and the obtained flow vector data or stream line data is stored in the data storage unit 7.

  Next, a display data generation circuit (not shown) of the display unit 9 in FIG. 1 reads out the B-mode image data and BMI image data generated in the data storage / processing unit 70 and corresponds to a predetermined display form (sector display). The image data for display is generated by synthesizing after performing the scan conversion processing. At this time, a slow motion display conversion process for displaying a plurality of BMI image data collected at high speed on a normal monitor is performed.

  The conversion circuit performs D / A conversion and television format conversion on the display image data to generate a video signal, and displays the video signal on the monitor.

  In addition, when the flow vector data or streamline data is combined with the B-mode image data and displayed, the slow-motion display conversion process is performed on the flow vector data or streamline data, and then the B-mode image data and Synthesis is performed.

  According to the embodiment of the present invention described above, since the BMI image data is generated by applying the constant interval alternate scanning method, the BMI image data can be obtained at an extremely high frame rate, and therefore the blood cell flow is reduced. It becomes possible to observe continuously in time. In addition, it is possible to observe a wide range of BMI image data that is spatially continuous by the regular interval alternate scanning.

  In addition, a plurality of BMI image data generated at a high frame rate can be continuously observed on a normal monitor by the display speed conversion means of this embodiment. Furthermore, the blood flow state can be accurately and quantitatively diagnosed by displaying flow vector data or stream line data generated based on the BMI image data.

  That is, the display of BMI image data, flow vector data, and streamline data obtained by the present embodiment enables the operator to observe blood flow information over a wide range as if it is actually flowing. Therefore, the diagnostic ability is greatly improved and the burden on the operator is reduced.

  As mentioned above, although the Example of this invention has been described, this invention is not limited to said Example, It can change and implement. For example, although the ultrasonic wave receiving direction in the constant interval alternating scanning of the above-described embodiment is set to one direction, so-called parallel processing is used in which received ultrasonic waves are simultaneously received from a plurality of directions centering on the ultrasonic wave transmitting direction. Simultaneous reception may be applied. FIG. 13 shows a case where two-stage parallel simultaneous reception is applied to the constant interval alternating scanning of FIG. 3, and a plurality of received signals are collected for each of the scanning directions θ1 to θP. By combining such parallel simultaneous reception methods, the frame rate of BMI image data can be further improved.

  In the above-described embodiment, the movement information of the speckle pattern is detected by the cross-correlation process between the BMI image data, but the present invention is not limited to the cross-correlation process. For example, the pixel value (power) of the corresponding pixel is detected. The movement information may be estimated by an SAD (Sum Absolute Difference) method in which an absolute value of a difference between the two values is obtained and the absolute values are integrated within the block.

  In the above display method, the BMI image data, the flow vector data, and the stream line data have been described as being combined with the B-mode image data, but may be displayed independently. A composite display may be used. Furthermore, flow vector data or stream line data and BMI image data may be combined and displayed.

  Further, the order of ultrasonic transmission / reception for obtaining the B-mode image data is not limited to the method of the above-described embodiment. For example, a part of a reception signal obtained by ultrasonic transmission / reception for BMI is used. You may generate using.

  Although the piezoelectric transducers of the ultrasonic probe of the above-described embodiment have been described as being arranged one-dimensionally, two-dimensionally arranged piezoelectric transducers may be used. It is also possible to simultaneously generate BMI image data in the cross section. Further, the scanning method may be a linear scanning method, a convex scanning method, a radial scanning method, or the like in addition to the sector scanning method described above.

1 is a block diagram showing the overall configuration of an ultrasonic blood flow imaging apparatus according to an embodiment of the present invention. The block diagram which shows the structure of the transmission / reception part in the Example. The figure which shows the fixed interval alternating scan used in the production | generation of the BMI image data of the Example. The block diagram which shows the structure of the data generation part in the Example. The figure which shows typically the I signal and Q signal which were preserve | saved at the I / Q signal memory | storage circuit of the BMI data generation part in the Example. The figure which shows the principle of the FIR filter process in the Example. The figure for demonstrating the data shift of the power value data sequence in the Example. The figure which shows typically the BMI image data produced | generated by the Example. The figure which shows the estimation method of the flow vector in the Example. The figure which shows the specific example of the flow vector display in the Example. The figure which shows the specific example of the streamline display in the Example. The figure for demonstrating the slow motion display in the Example. The figure which shows the fixed interval alternating scan which applied the parallel simultaneous reception in the modification of the Example. The figure which shows the scanning method and data processing method in the conventional BMI method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reference signal generation part 2 ... Transmission part 3 ... Reception part 4 ... B-mode data generation part 5 ... Color Doppler data generation part 6 ... BMI data generation part 7 ... Data storage part 8 ... Flow data generation part 9 ... Display part 10 ... ultrasonic probe 11 ... input unit 12 ... scanning control unit 13 ... system control unit 20 ... transmission / reception unit 30 ... data generation unit 38 ... I / Q signal storage circuit 39 ... FIR filter 40 ... data shift circuit 50 ... data storage / calculation Unit 100 ... Ultrasonic blood flow imaging apparatus

Claims (10)

An ultrasonic probe with an ultrasonic transducer;
Ultrasonic transmission / reception means for performing ultrasonic transmission / reception with respect to a predetermined scanning direction of the subject using the ultrasonic transducer;
The ultrasonic wave transmitting / receiving unit sequentially performs ultrasonic wave transmission / reception with respect to a plurality of directions in a predetermined region including the reference direction with a predetermined direction as a reference direction, and then is separated by a predetermined interval from the reference direction. Scanning control means for repeating ultrasonic scanning for sequentially performing ultrasonic transmission / reception with respect to a plurality of directions in a predetermined region including the new reference direction as a new reference direction;
Filtering means for performing a filtering process on each received signal obtained from a plurality of directions of the predetermined region by the scanning control means to detect a received signal component caused by a blood cell flow of the subject;
Image data generating means for generating image data displaying a change in speckle based on each data of the data sequence sequentially output by the filtering means;
An ultrasonic blood flow imaging apparatus comprising display means for displaying the generated image data. An ultrasonic probe with an ultrasonic transducer;
Ultrasonic transmission / reception means for performing ultrasonic transmission / reception with respect to a predetermined scanning direction of the subject using the ultrasonic transducer;
The ultrasonic wave transmitting / receiving unit sequentially performs ultrasonic wave transmission / reception with respect to a plurality of directions in a predetermined region including the reference direction with a predetermined direction as a reference direction, and then is separated by a predetermined interval from the reference direction. Scanning control means for repeating ultrasonic scanning for sequentially performing ultrasonic transmission / reception with respect to a plurality of directions in a predetermined region including the new reference direction as a new reference direction;
Filtering means for performing a filtering process on each received signal obtained from a plurality of directions of the predetermined region by the scanning control means to detect a received signal component caused by a blood cell flow of the subject;
Image data generating means for generating image data displaying changes in a plurality of speckles having different time phases based on each data in the data sequence sequentially output by the filtering means;
Flow data generating means for generating blood flow data by inter-image processing of a plurality of the image data generated by the image data generating means;
An ultrasonic blood flow imaging apparatus comprising display means for displaying generated blood flow data.   The ultrasonic blood flow imaging apparatus according to claim 1 or 2, wherein the filtering means detects a received signal component caused by the blood cell flow by an FIR type high-pass filter.   The image data generation means generates a plurality of pieces of image data having different time phases by shifting and synthesizing respective data strings obtained by ultrasonic transmission / reception in the plurality of scanning directions. The ultrasonic blood flow imaging apparatus according to claim 1 or 2.   At least one of B-mode image data generation means and color Doppler image data generation means, and the display means is generated by the B-mode image data generated by the B-mode image data generation means or the color Doppler image data generation means The ultrasonic blood flow imaging apparatus according to claim 1, wherein color Doppler image data and the image data are combined and displayed.   The flow data generation unit generates at least one of flow vector data or stream line data based on information on a blood flow velocity and a blood flow direction obtained by the inter-image processing. Ultrasound blood flow imaging device.   3. The ultrasonic blood flow imaging apparatus according to claim 2, wherein the flow data generation means generates the blood flow data by cross-correlation calculation or SAD calculation for the plurality of pieces of image data having different time phases. .   At least one of a B-mode image data generation unit and a color Doppler image data generation unit, and the display unit generates the B-mode image data generated by the B-mode image data generation unit and the color Doppler image data generation unit The ultrasonic blood flow imaging apparatus according to claim 6, wherein at least one of color Doppler image data and the image data is combined with the flow vector data or stream line data and displayed.   The ultrasonic transmission / reception unit separates reception ultrasonic waves from a plurality of directions around each of the ultrasonic transmission / reception directions and receives them substantially simultaneously. Ultrasound blood flow imaging device.   The scanning control unit sequentially performs ultrasonic transmission / reception in a plurality of scanning directions sequentially set at predetermined intervals with a predetermined scanning direction as a reference scanning direction, and then scans separated by the predetermined interval with respect to the reference scanning direction. The ultrasonic blood flow imaging apparatus according to claim 1 or 2, wherein ultrasonic transmission / reception is sequentially performed in a plurality of scanning directions that are sequentially set at the predetermined interval with a direction as a new reference scanning direction.

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