JP4939199B2 - Image interpolation method, image interpolation apparatus, and ultrasonic diagnostic apparatus - Google Patents

Description

  The present invention provides an intermediate image of a plurality of second-type images (for example, images representing bloodstream streamlines) derived from a plurality of first-type images (for example, color Doppler images by ultrasound). An image interpolation method, an image interpolation device, and a blood flow distribution in a subject by repeatedly transmitting an ultrasonic pulse into the subject and receiving a reflected ultrasonic wave reflected and returned in the subject. The present invention relates to an ultrasonic diagnostic apparatus that generates a blood flow distribution image.

  An ultrasonic diagnostic device that measures the blood flow velocity distribution in the living body using the ultrasonic Doppler method, and displays this blood flow velocity distribution on the monochrome tomographic image obtained by the pulse reflection method. It has been known. The measurement principle of this blood flow velocity distribution is based on the Doppler effect included in the received signal, in which an ultrasonic beam is pulsed into the living body by a transducer array at a fixed period, and the reflected wave from the reflector inside the living body is received. By detecting the frequency change component, the movement speed of the reflector in the bloodstream in the direction of ultrasonic travel is measured, and the position is obtained from the time until the reflected wave returns, and this is calculated in two dimensions in real time. Color display as blood flow information.

  FIG. 1 is a configuration diagram of a conventional ultrasonic diagnostic apparatus.

  The ultrasonic diagnostic apparatus 100A shown in FIG. 1 includes a probe 1, and transducers such as piezoelectric ceramics are arranged at the tip of the probe 1. A transmitter circuit 2 and a receiver circuit 4 are connected to the probe 1. The pulse generation circuit 3 generates a timing signal S11 (rate pulse) that gives a transmission repetition period (for example, 4 kHz) and supplies it to the transmission circuit 2. The transmission circuit 2 is composed of, for example, a 64-channel pulse driver and a delay circuit. The pulse driver generates a drive pulse having a period equal to the transmission frequency (for example, 2.5 MHz) at the timing of the rate pulse and applies it to the transducer of the probe 1. The delay circuit converges the ultrasonic beam and gives a predetermined delay to the pulse generation timing for each channel in order to give directivity. As a result, the ultrasonic beam is radiated in a direction corresponding to directivity. In this way, transmission / reception in the same direction (for example, the a direction in FIG. 1) is repeated, for example, six times toward the inside of a living body (not shown) at a rate pulse period, and further for tomographic image acquisition. One transmission / reception is performed, and one cycle (line cycle) is completed by a total of seven transmissions / receptions, and the same processing is performed for, for example, 64 scanning lines while sequentially switching the scanning directions b, c, d Complete the scan for the frame.

  On the other hand, the reflected ultrasonic wave (echo) on the discontinuous surface of the acoustic impedance in the living body is received for each channel by the receiving circuit 4 via the probe 1. The receiving circuit 4 includes a preamplifier, a delay circuit, and an adder circuit. The received signal is amplified by a preamplifier, given a predetermined delay for each channel by a delay circuit, and added by an adder circuit. Thereby, an echo from a direction corresponding to the directivity is received.

  The reception signal output from the reception circuit 4 is input to the mixer circuit 5. The mixer circuit 5 performs quadrature detection by mixing the received signal with a pair of reference signals generated by an oscillator (not shown) and having the same period as the transmission frequency and having a phase difference of 90 °, and the Doppler signal An in-phase signal S12a and a quadrature signal S12b are output. The two low-pass filters 6a and 6b respectively remove harmonic components of the in-phase signal S12a and the quadrature signal S12b of the Doppler signal generated as a result of mixing.

  The output signals of the low-pass filters 6a and 6b are converted into digital values by, for example, sampling 256 points at a constant sampling period in the depth direction by the A / D converters 7a and 7b. The MTI filters 8a and 8b are for removing only low-frequency components due to organ wall motion and the like contained in the Doppler signal and extracting only blood flow components, and are composed of, for example, a primary echo canceller shown in FIG.

  The autocorrelation circuit 9 receives the output signals of the MTI filters 8a and 8b. In the autocorrelation circuit 9, the in-phase signal of the Doppler signal obtained at repeated intervals is a real part and the quadrature signal is an imaginary part. Autocorrelation (R (1)) is calculated for data with 6 repetition periods. When the output signals of the MTI filters 8a and 8b at a specific depth are x (k) and y (k), this calculation is expressed by equations (1a) and (1b) for each real part and imaginary part.

  The calculation result is sequentially extracted for each depth in synchronization with the timing of the fifth rate pulse of each scanning line for each real part and imaginary part.

  The speed detection circuit 10 receives the autocorrelation value (R (1)), which is the calculation result of the autocorrelation circuit 9, and receives the declination value (arctan {Im [R (1)] / Re [R (1)]}. ). This declination value gives an amount proportional to the Doppler shift frequency. This declination value outputs the blood flow velocity in the direction of the ultrasonic beam at that point. Blood flow distribution image data representing a blood flow distribution composed of a set of blood flow velocity components in the direction of the ultrasonic beam at each point on the observation surface thus obtained is sent to the image processing circuit 12.

  On the other hand, the output signal of the receiving circuit 4 is also sent to the tomographic image processing unit 11. The tomographic image processing unit 11 detects the envelope of the received signal, performs A / D conversion, outputs it as monochrome luminance data, and the monochrome luminance data is also sent to the image processing circuit 12.

  The image processing circuit 12 applies a predetermined color scheme to the average velocity data sequentially input based on the direction (direction approaching or moving away from the probe 1) and the absolute value thereof, along with the monochrome luminance data of the tomographic image, Two-dimensional mapping is performed according to the scanning direction and depth, and this is stored as image data in an image memory (not shown). Further, the image data is read from the image memory at a constant cycle, and a diagnostic image in which a monochrome image indicating a tomographic image and a color image indicating a blood flow distribution are combined is displayed on the TV monitor 13. The above is the basic configuration of the ultrasonic diagnostic apparatus.

  In recent years, in the ultrasonic diagnostic apparatus having the above basic configuration, the blood flow velocity is directly required only for the direction component of the ultrasonic beam, but from the blood flow velocity distribution in the direction of this ultrasonic beam, Techniques for obtaining blood flow velocity and blood flow in all directions within the observation plane including blood flow velocity in a direction perpendicular to the ultrasonic beam have been proposed (see Non-Patent Document 1, Patent Documents 1 and 2).

  In addition, based on the above technique, a technique for obtaining a streamline distribution in consideration of springing and suction has been proposed (see Patent Document 3).

For example, display of streamline distribution in the heart may greatly contribute to diagnosis of heart disease.
Journal of Visualization Vol9 No. 1 2006, Ohmsha, Lid. , IOS Press Japanese Patent Laid-Open No. 11-83564 JP 2005-110939 A JP-A-11-108947

  However, in order to obtain an image representing the blood flow distribution in the observation plane using the ultrasonic diagnostic apparatus, there is a problem that it takes a considerably long time per image and the frame rate is low. For this reason, even if an image representing a streamline (hereinafter, simply referred to as a streamline image) is obtained by obtaining a streamline distribution of blood flow, it becomes a streamline image of a time interval of a considerably open time, It is difficult to understand the change of streamlines during the flight time. In order to solve this, it is conceivable to interpolate the streamline images of two frames and obtain and display a streamline image at the intermediate time between the two frames. It is an image that includes nonlinear components such as springs and sucks, and since the images of the two frames are quite different, the corresponding points cannot be determined, so interpolation by morphism cannot be applied and direct interpolation is impossible. There is a problem.

  Such a problem is not limited to an image representing a streamline distribution of blood flow, and even when a direct interpolation operation cannot be applied, such as a case where a nonlinear component is included, an interpolation that is still located at an intermediate time between the two images. This is a problem that similarly occurs when an image is required.

  In view of the above circumstances, the present invention provides an image interpolation method and an image interpolation apparatus capable of obtaining an image with high accuracy by indirect interpolation, and an ultrasonic diagnosis having a function for obtaining an image in the middle of a frame with high accuracy. An object is to provide an apparatus.

A first image interpolation method of the image interpolation methods of the present invention that achieves the above object is an intermediate between a plurality of streamline images representing a bloodstream streamline derived from each of a plurality of color Doppler images obtained by ultrasound. An image interpolation method for obtaining a typical image,
Using color Doppler image above Kifuku number, by interpolation, the interpolation determining an interpolated image of the color Doppler,
And a derivation step for deriving the intermediate image from the interpolated image obtained in the interpolation step.
The second image interpolation method of the image interpolation method of the present invention that achieves the above object mimics the blood flow velocity derived from each of a plurality of color Doppler images obtained by ultrasound to the geographical elevation. An image interpolation method for obtaining an intermediate image of a plurality of ridge line images representing a ridge line composed of a set of points on a ridge when
An interpolation step for obtaining an interpolated image of the color Doppler by interpolation using the plurality of color Doppler images,
And a derivation step for deriving the intermediate image from the interpolated image obtained in the interpolation step.

Here, in both the first and second image interpolation method of the present invention, a color Doppler image above Kifuku number of observation target time varying, at each time consisting of discrete time intervals status a plurality of color Doppler images representing said interpolation step, a color Doppler image above Kifuku number, by interpolation, even determining the interpolated image corresponding to the time at which the color Doppler image are not present Good.

The first and second image interpolation method of the present invention obtains an interpolated image of color Doppler by interpolating at the stage of basic and such Luke Radopura picture image to determine the streamlines image and ridges ray image, the interpolation of the color Doppler Since the streamline image and the ridgeline image are derived from the image, an interpolation image of the streamline image and the ridgeline image can be obtained with high accuracy.

The first image interpolating apparatus of the image interpolating apparatus of the present invention that achieves the above object is a plurality of streamline images representing a bloodstream streamline derived from each of a plurality of color Doppler images by ultrasonic waves. An image interpolation device for obtaining an intermediate image of
Using color Doppler image above Kifuku number, by interpolation, the interpolation operation unit for obtaining an interpolated image of the color Doppler,
And a derivation unit that derives the first intermediate image from the interpolation image obtained by the interpolation calculation unit.
The second image interpolating apparatus of the image interpolating apparatus according to the present invention that achieves the above object mimics the blood flow velocity derived from each of a plurality of color Doppler images obtained by ultrasound to the geographical altitude. An image interpolation device for obtaining an intermediate image of a plurality of ridge line images representing a ridge line composed of a set of points on a ridge at the time,
An interpolation calculation unit that obtains an interpolation image of the color Doppler by interpolation calculation using the plurality of color Doppler images,
And a derivation unit that derives the first intermediate image from the interpolation image obtained by the interpolation calculation unit.

The first and second image interpolation apparatuses of the present invention are apparatuses for performing the first and second image interpolation methods, respectively, and obtain an interpolation image of a streamline image and a ridge line image with high accuracy. Can do.

Further, the first ultrasonic diagnostic apparatus of the ultrasonic diagnostic apparatus of the present invention that achieves the above object is the transmission of an ultrasonic pulse into the subject and the reflected ultrasound reflected back within the subject. In an ultrasonic diagnostic apparatus that repeats reception of sound waves and generates a blood flow distribution image representing a blood flow distribution in a subject,
A streamline calculation unit for calculating a streamline image representing a streamline of blood flow from the blood flow distribution image;
An interpolation calculator that interpolates a plurality of images to obtain an interpolated image;
When obtaining a streamline image at a time when no blood flow distribution image exists, the blood flow distribution image exists by interpolating a plurality of blood flow distribution images representing blood flow distributions at different times in the subject to the interpolation calculation unit. It is characterized in that an interpolation image representing a blood flow distribution at a time not to be obtained is calculated, and a streamline calculation unit is provided with an arithmetic control unit for calculating a streamline image at that time from the interpolation image.

  According to a first ultrasonic diagnostic apparatus of the present invention, the interpolation calculation method of the present invention is incorporated into an ultrasonic diagnostic apparatus in a mode for obtaining a streamline image representing a streamline of blood flow. A highly accurate streamline image can be obtained.

Further, the second ultrasonic diagnostic apparatus of the ultrasonic diagnostic apparatus of the present invention that achieves the above object transmits an ultrasonic pulse into the subject and the reflection reflected back within the subject. In an ultrasonic diagnostic apparatus that repeats reception of ultrasonic waves and generates a blood flow distribution image representing a blood flow distribution in a subject,
A ridge line calculation unit that calculates a ridge line image composed of a set of points on the ridge when the blood flow velocity is simulated from the blood flow distribution image to a geographical elevation;
An interpolation calculator that interpolates a plurality of images to obtain an interpolated image;
When obtaining a ridge line image at a time when no blood flow distribution image exists, the blood flow distribution image exists by interpolating a plurality of blood flow distribution images representing blood flow distributions at different times in the subject to the interpolation calculation unit. And an arithmetic control unit that causes the ridge line calculation unit to calculate the ridge line image at the time from the interpolation image.

  The second ultrasonic diagnostic apparatus according to the present invention is a supersonic mode in which the interpolation calculation method according to the present invention is used to obtain a ridge line image composed of a set of points on the ridge when the blood flow velocity is simulated as a geographical elevation. It is incorporated in the ultrasonic diagnostic apparatus, and a highly accurate ridge line image between frames can be obtained.

  Note that the present invention is not only applied to streamline images and ridgeline images, and even when a direct interpolation operation cannot be applied, such as when a nonlinear component is included, it is still at an intermediate time between the two images. The present invention can be similarly applied to a case where a positioned interpolated image is required.

  As described above, according to the present invention, highly accurate interpolation is realized.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 3 is a configuration diagram of an ultrasonic diagnostic apparatus as an embodiment of the present invention.

  Here, the ultrasonic diagnostic apparatus as an embodiment of the present invention represented by FIG. 3 will be described, which also serves as an explanation of each embodiment of the image interpolation method of the present invention and the image interpolation apparatus of the present invention. Shall.

  In the description of the ultrasonic diagnostic apparatus of FIG. 3, the description of the same components as those of the conventional ultrasonic diagnostic apparatus described with reference to FIG. 1 is omitted, and the conventional ultrasonic wave shown in FIG. Only components that are different from the diagnostic apparatus will be described.

  The ultrasonic diagnostic apparatus shown in FIG. 3 has a mode for obtaining and displaying a streamline image representing a streamline distribution and a mode for obtaining and displaying a ridgeline image representing a ridgeline distribution.

  Compared to the ultrasonic diagnostic apparatus 100A of FIG. 1, an image data generation circuit 20 is added to the ultrasonic diagnostic apparatus 100B of FIG.

  When the blood flow distribution image data representing the blood flow velocity in the direction of the ultrasonic beam at each point on the observation surface obtained by the velocity detection circuit 10 is used for display as it is, the image data generation circuit 20 is bypassed and the image processing circuit is bypassed. 12 is sent. The subsequent processing in the image processing circuit 12 is as described with reference to FIG.

  In a mode in which a streamline image representing a streamline distribution is obtained and displayed, the blood flow distribution image data obtained by the velocity detection circuit 10 is input to the image data generation circuit 20 and streamline image data representing the bloodstream streamline. Is generated and sent to the image processing circuit 12. The image processing circuit 12 generates image data representing an image in which a streamline of blood flow is drawn on a monochrome luminance image of a tomogram, and an image based on the image data is displayed on a TV monitor.

  On the other hand, in the mode for obtaining and displaying the ridge line image representing the ridge line distribution, the blood flow distribution image data obtained by the speed detection circuit 10 is generated as in the case of the mode for obtaining and displaying the stream line image. The image data generation circuit 20 generates ridge line image data representing a ridge line made up of a set of points on the ridge when the blood flow velocity is simulated as a geographical elevation. It is sent to the image processing circuit 12. In the image processing circuit 12, image data representing an image in which a ridge line is drawn on a monochrome luminance image of a tomographic image is generated, and an image based on the image data is displayed on a TV monitor.

  FIG. 4 is a configuration diagram of the image data generation circuit 20 shown by one block in FIG.

  The image data generation circuit 20 corresponds to an example of an image interpolation device according to the present invention.

  The image data generation circuit 20 includes two frame memories 21 a and 21 b, an interpolation calculation unit 22, an image data calculation unit 23, and a calculation control unit 24.

  The image data calculation unit 23 corresponds to an example of a derivation unit according to the present invention. The image data calculation unit 23 also serves as a streamline calculation unit and a ridge line calculation unit according to the present invention.

  The two frame memories 21 a and 21 b are memories that temporarily store blood flow distribution image data sequentially input at a predetermined frame rate under the control of the arithmetic control unit 24.

  In addition, the interpolation calculation unit 22 plays a role of obtaining an interpolated image (image on data) by interpolating a plurality of images (here, two images on data temporarily stored in the two frame memories 21a and 21b). I'm in charge.

  Further, the image data calculation unit 23 plays a role of calculating a streamline image (image on data) and a ridge line image (image on data) from a blood flow distribution image (image on data).

  Furthermore, when calculating a streamline image or a ridgeline image at a time when no blood flow distribution image exists, the calculation control unit 24 causes the interpolation calculation unit 22 to provide a plurality of blood flows representing blood flow distributions at different times in the subject. The distribution image (here, the image on the two data temporarily stored in the two frame memories 21a and 21b) is input, and the interpolation calculation unit 22 interpolates the plurality of blood flow distribution images to obtain the blood flow distribution image. It controls the calculation of obtaining an interpolated image representing a blood flow distribution at a non-existing time and causing the image data calculating unit 23 to calculate a streamline image and a ridge line image at that time from the interpolated image.

  The blood flow distribution images of the subsequent two frames temporarily stored in the two frame memories 21a and 21b are input to the interpolation calculation unit 22, and the timing is adjusted by the calculation control unit 24 to the image data calculation unit 23. Are also entered directly.

  The order of input to the image data calculation unit 23 is that the blood flow distribution image stored first in time among the two blood flow distribution images stored in the two frame memories 21a and 21b is first calculated as image data. The interpolation image obtained by the interpolation calculation unit 22 from the two blood flow distribution images stored in the two frame memories 21a and 21b is then input to the image data calculation unit 23. Of the two blood flow distribution images stored in the two frame memories 21 a and 21 b, the blood flow distribution image stored later in time is input to the image data calculation unit 23. By repeating this, the blood flow distribution image stored in one of the two frame memories 21a and 21b and bypassing the interpolation calculation unit 22 and the interpolation image obtained by the interpolation calculation unit 22 are stored in the image data calculation unit 23. It will be input alternately.

  Here, first, the flow of streamline calculation will be described.

  FIG. 5 is a schematic diagram showing the flow of streamline calculation performed by the image data generation circuit 20 shown in FIG.

Figure 5 (A) is a certain time (referred to as time t ₁₎ 1 frame of blood flow distribution image generated in FIG. 5 (B), from the time t ₁ at a predetermined frame interval following it is a time (referred to as time t ₂₎ 1 frame of blood flow distribution image generated.

Figure 5 (A), the from time t ₁ of the blood flow distribution image, the time t _1, when obtaining the streamline image representing flow line distribution (FIG. 5 (D)), the operation control shown in FIG. 4 under the control of the parts 24, is input blood flow distribution image at time t ₁ shown in FIG. 5 (a) bypassing the interpolation operation unit 22 shown in FIG. 4 to the image data calculating section 23, the blood at time t ₁ from the flow distribution image (FIG. 5 (a)), the flow line image time _{t 1} (FIG. 5 (D)) is obtained.

Similarly to this, when obtaining the Figure 5 that time t ₂ of the flow line images from the bloodstream distribution image time t ₂ shown in (B) (FIG. 5 (E) under the control of the arithmetic control unit 24 in FIG. 5 blood flow distribution image at the time t ₂ shown in (B) is input to the image data calculating section 23 bypassing the interpolation operation unit 22 shown in FIG. 4, the blood flow distribution image at time t ₂ (FIG. 5 (B)) time _{t 2} of the flow line image from (FIG. 5 (E)) is obtained.

Here, since the frame rate of the blood flow distribution image is considerably low and is an image having a considerably wide time interval, a streamline image at time t ₁₂ between time t ₁ and time t ₂ (FIG. 5 ( F)) is also required. In obtaining the streamline image at the intermediate time t _2, the streamline image at the time t ₁ (FIG. 5D) and the streamline image at the time t ₂ (FIG. 5E) are directly interpolated. also only very inaccurate streamline image is determined, wherein adopts the following arithmetic processing to determine the precision of the flow line images corresponding to the time t _12.

That is, the blood flow distribution images of the subsequent two frames stored in the two frame memories 21a and 21b shown in FIG. 4 are input to the interpolation calculation unit 22 to interpolate the two blood flow distribution images (FIG. 5C )) Is required. In obtaining this interpolated image (FIG. 5C), as an example, each pixel (i, j) (i, j of the first blood flow distribution image of the two blood flow distribution images is on the image. Is represented by P1 _{i, j} , and the pixel value of each pixel (i, j) of another second blood flow distribution image is P2 _{i, j} . In this embodiment,
P12 _ij = (P1 _{i, j} + P2 _{i, j} ) / 2
The pixel value P12 _{i, j} of each pixel of the interpolated image is obtained by the following equation.

In FIG. 5, although described as an interpolation image corresponding to the center of the time t ₁₂ at time t ₁ and time t _2, 3 obtained by equally dividing between the example time t ₁ and time t ₂ The interpolation image at two times t ₁₂₁ and t _{122 at} the time may be obtained. In this case, the pixel value P121 _{i, j} of each pixel of the interpolation image corresponding to the time t ₁₂₁ is
P121 _{i, j} = (2 · P1 _{i, j} + P2 _{i, j} ) / 3
The pixel value P122 _{i, j} of each pixel of the interpolated image corresponding to time t ₁₂₂ is
P122 _{i, j} = (P1 _{i, j} + 2 · P21 _{i, j} ) / 3
It is calculated by the following equation. Further, in this case, the order of input to the image data calculation unit 23 shown in FIG. 4 is that the blood flow distribution image at time t ₁ input by bypassing the interpolation calculation unit 22 and the time t ₁₂₁ obtained by the interpolation calculation unit 22. , The interpolation image corresponding to the time t ₁₂₂ obtained by the interpolation calculation unit 22, and the blood flow distribution image at the time t ₂ input by bypassing the interpolation calculation unit 22. If an interpolation image for each time when the more finely divided between the times t ₁ and time t ₂ is the same.

  Note that the image interpolation method described above is an example, and in addition to the image interpolation method described above, it is more preferable to obtain an interpolated image that takes into account changes with time of each observation point in the blood flow distribution image before obtaining the interpolated image. .

  Although the linear interpolation using two images has been described here, higher order interpolation processing may be performed using a larger number of images.

  The interpolated image of the blood flow distribution image obtained by the interpolation calculating unit 22 is input to the image data calculating unit 23 shown in FIG. 4, and the image data calculating unit 23 now selects a streamline image (see FIG. 5 (F)) is calculated.

  The image data calculation unit 23 obtains streamlines as described below as an example. Here, it is assumed that the methods described in Non-Patent Document 1 and Patent Document 3 described above are adopted, and since they are known contents, only the outline thereof will be described below.

  FIG. 6 is a diagram illustrating an example of a blood flow distribution image.

  This blood flow distribution image is an image also called a color Doppler image because it is usually displayed in color. Each point on the image is associated with blood flow velocity data in the direction toward the center point C where the probe is placed or in the direction away from the center point C, and the blood flow in the direction toward the center point C. Is red, blood flow away from the center point C is displayed in blue, and the blood flow velocity is displayed in red or blue luminance. Here, based on the blood flow velocity data at each point, the streamline is obtained by the calculation outlined below.

  FIG. 7 is a diagram showing a blood flow velocity distribution on one line L that is equidistant from the center point C, which is representatively shown in FIG.

  In the region (A) along the line L, blood flow in the direction toward the central point C (herein referred to as “positive blood flow”) is observed, and in the region (B), blood flow away from the central point C (here) Is referred to as “negative blood flow”), and positive blood flow toward the center point C is observed in the region (C).

  Here, the eddy current component in which the positive blood flow rate and the negative blood flow rate are the same is divided into two components.

  In the example shown in FIG. 7, since the positive component is large and the negative component is small as a whole, the same area as the region (B) of the two regions (A) and (C) in which positive blood flow is observed. Only the minute is the first component. The first component is a vortex component that circulates across the line L and does not enter or exit the line L as a whole. On the other hand, the second component excluding the eddy current component is a component that flows across the line L as a whole. Although one line L is shown in FIG. 6, each line connecting equidistant from the center point C is divided into the vortex component and the other components as described above.

  Since the eddy current component is a component that circulates in the observation plane as a whole, if it is calculated under this constraint condition, the blood flow velocity for the eddy current component in the direction perpendicular to the ultrasonic beam at each point is obtained. A two-dimensional velocity vector related to the eddy current component at each point is obtained together with the blood flow velocity in the direction of the ultrasonic beam shown in FIG.

  FIG. 8 is a diagram showing the blood flow of the vortex component at each point obtained in this way.

  For the components excluding the vortex component, the velocity vector is obtained as follows.

  7 is integrated along line L from the left and right ends of FIG. 7 (here, the right side of FIG. 7) to the left and right ends (the left side of FIG. 7). The value obtained by integrating to the end of the line L is defined as 100%, and points on the line L where the integrated value is, for example, 10%, 20%,.

  This calculation is performed for each line connecting points equidistant from the center point C shown in FIG. 6, and a line connecting 10% points, 20% points,..., 100% points is obtained.

  FIG. 9 is a diagram showing a line obtained by connecting the same points with the integral% of the components excluding the vortex component on each line obtained in this way.

  The tangent of each point on each line in FIG. 9 indicates the direction of blood flow. The blood flow velocity in the direction of the ultrasonic beam at each point (the blood flow velocity of the component excluding the vortex component; see FIG. 7) ) Is obtained by subtracting the blood flow velocity in the ultrasonic beam direction of the eddy current component from the original blood flow velocity by the ultrasonic Doppler method, so by knowing the direction of blood flow at each point, A blood flow velocity in a direction perpendicular to the ultrasonic beam is obtained, and eventually a blood flow velocity vector indicating both the direction and the size of each point is obtained. As described above, this blood flow velocity vector is a blood flow velocity vector of a component excluding the vortex flow component. By combining this blood flow velocity vector and the blood flow velocity vector of the vortex flow shown in FIG. The blood flow velocity vector as a whole when the eddy current component and the other components at each point on the surface are added is obtained.

  In addition, although the calculation method which calculates | requires and synthesize | combines each of the two-dimensional blood flow velocity about a vortex flow and the two-dimensional blood flow velocity about the blood flow component except a vortex flow was employ | adopted here, When both the blood flow velocity component in the direction orthogonal to the acoustic beam and the blood flow velocity component in the direction orthogonal to the ultrasonic beam for the blood flow component excluding the vortex are first obtained, and the two are added together Based on the blood flow velocity component in the direction orthogonal to the ultrasonic beam and the blood flow velocity component in the direction of the ultrasonic beam (the sum of the vortex component and the component excluding the vortex component shown in FIG. 7) A proper blood flow velocity may be obtained.

  FIG. 10 is a diagram showing the blood flow when the eddy current component and the other components are added together at each point on the observation surface.

  As shown in FIG. 10, streamlines are obtained from a blood flow velocity distribution including a component perpendicular to the ultrasonic beam.

  In obtaining the streamline, for example, a single line connecting points that are equidistant from the center point C in the vicinity of the center point C shown in FIG. 6 is considered so that the flow rate on the line has the same value. Define multiple points. That is, a plurality of points are determined so that the flow rates between two adjacent points are the same.

  Next, the blood flow velocity vector is traced from each point, and a streamline starting from each point is obtained. If there is no flow or suction of blood flow on the observation surface of interest, the line connected by tracing the blood flow velocity vector as described above is the flow on the observation surface as it is. However, in general, there is a blood flow outflow and suction on the observation surface, and the streamline is not completed as it is. Therefore, a streamline that considers the flow of blood on the observation surface and suction is obtained in the manner described below.

  FIG. 11 is a diagram for explaining how to obtain streamlines in consideration of the flow and suction of blood flow on the observation surface.

  First, we will explain how to find streamlines that take into account the flow of blood to the observation surface.

  First, in accordance with the above-described method, a streamline obtained by tracing the blood flow velocity vector is obtained.

  In FIG. 11A, a first stream line 1 and a second stream line 2 connected by tracing a blood flow velocity vector are drawn.

  Here, the blood flow in the band-like region sandwiched between the adjacent first stream line 1 and second stream line 2 is obtained in the longitudinal direction of the band in order, and the flow rate in the band is doubled. Then, it is assumed that there is a source of blood flow there, and a streamline starting from the center point of the streamline on both sides of the belt is added.

  For example, as shown in FIG. 11 (A), the blood flow is obtained in order from the point AB in the longitudinal direction of the band (arrow X direction), and when the flow rate doubles between the points CD, It is considered that there is a point in the bloodstream. Then, as shown in FIG. 11B, a third stream line starting from the center point E of the stream lines (here, the first stream line 1 and the second stream line 2) on both sides of the band. Add 3

  Next, a method for obtaining streamlines in consideration of blood flow suction on the observation surface will be described.

  When obtaining a streamline in consideration of blood flow suction, two adjacent streamlines sandwiching one streamline are used.

  FIG. 11C illustrates a first streamline 4, a second streamline 5, and a third streamline 6 that are connected by tracing the blood flow velocity vector.

  Here, the blood flow volume of the band-like region sandwiched between the first stream line 4 and the third stream line 6 is obtained in order in the longitudinal direction of the band. It is assumed that there is a blood flow suction point, and a process for terminating one streamline at that point is performed.

  For example, as shown in FIG. 11 (C), blood flow is obtained in the longitudinal direction of the band (in the direction of the arrow X) from the region connected at the point FGH, and the flow rate is connected at the point IJK. When it becomes ½, it is considered that there is a blood suction point there. Then, as shown in FIG. 11D, it is assumed that there is a blood flow suction point at the point J, and processing for terminating the streamline 5 at the point J is performed.

  FIG. 12 is a schematic diagram showing a streamline image obtained by the method for obtaining streamlines described in FIG.

  In this streamline image, in addition to continuous streamlines, streamlines that start and end in the middle appear. That is, it can be seen that blood flow is spilled out or sucked in.

  By the calculation for obtaining the streamline, the image data calculation unit 23 shown in FIG. 4 obtains a streamline image.

  Streamline images (FIGS. 5D, 5F, and 5E) sequentially obtained in this way are sequentially input to the image processing circuit 12 shown in FIG. An image in which a streamline image is superimposed (an image on the data) is created, the image data is sent to the TV monitor 13, and an image in which the streamline image is superimposed on the tomographic line on the TV monitor 13 based on the image data. Is displayed. Here, an image in which a fluid image is superimposed on a tomographic image is displayed as a moving image, but it can be fixed to any one of the images at one time point and displayed as a still image, or can be frame-advanced. .

  Next, the flow of ridge line calculation will be described.

  Note that the description of the processing similar to the flow line calculation flow is simplified.

  FIG. 13 is a schematic diagram showing a flow of ridge line calculation performed by the image data generation circuit 20 shown in FIG.

Figure 13 (A) is a one frame blood flow distribution image generated at a certain time t _1, FIG. 5 (B), from time t ₁ to the next time t ₂ in which at a predetermined frame interval It is the produced | generated blood flow distribution image for 1 frame.

Figure 13 (A), the from time _{t 1} of the blood flow distribution image, the time _{t 1,} ridge line image representing a ridge line distribution (FIG. 13 (D)) is obtained.

Also, Similarly, from time _{t 2} the blood flow distribution image shown in FIG. 13 (B), ridge line image of the time _{t 2} (FIG. 13 (E)) is obtained.

Further, in order to obtain a high accuracy ridgeline image corresponding to the time t _12, described above, the same processing and operation processing for obtaining the streamline image is performed, the time t ₁ and time t ₂ intermediate time A ridge line image at t ₁₂ (FIG. 13F) is also obtained.

  Here, in the image data calculation unit 23 shown in FIG. 4, the ridge line is obtained as described below as an example.

  In the image data calculation unit 23, based on the blood flow distribution image, blood composed of a blood flow velocity component in the ultrasonic beam direction and a blood flow velocity component perpendicular to the ultrasonic beam at each point on the observation surface. Flow velocity is required.

  The method of obtaining the two-dimensional blood flow velocity is the same as the method of obtaining the blood flow velocity obtained in the middle stage of obtaining the blood flow stream (FIGS. 6 to 10 and explanations of these drawings). Here, redundant description is omitted.

  Next, the image data calculation unit 23 is based on the blood flow velocity distribution composed of a set of points on the observation surface of the blood flow velocity of the blood flow velocity and the blood flow direction constituting the blood flow velocity. As described below, points on the ridge are extracted when the blood flow velocity at each point is simulated as the geographical altitude.

  FIG. 14 is a schematic diagram showing each pixel on the image representing the blood flow velocity distribution on the observation surface.

  In obtaining the ridge line, each pixel of the blood flow velocity distribution image is selected as a point of interest one by one, and the pixel of the point of interest is calculated by the following calculation including the eight pixels around the point of interest. Is a pixel on the ridge line.

  Here, as an example, it is assumed that the coordinate point (X, Y) = (5, 4) in FIG. 14 is selected as the point of interest. The pixel value of this interest point is P5.

  Next, 3 × 3 square pixels (pixel values P1 to P4 and P6 to P9) surrounded by a thick frame are extracted as pixels adjacent to the point of interest (pixel value P5).

  In FIG. 14, pixel values also exist in blank pixels, but are blank because they are not necessary for the description here.

  FIG. 15 is an explanatory diagram of a process for extracting points on the ridge.

  Here, the blood flow rates are compared as follows.

  FIG. 15A shows that P5 is compared with both P2 and P8 to determine whether P5 is larger than both P2 and P8. FIG. 15B shows that it is determined whether P5 is larger than both P4 and P6, as in FIG. FIG. 15C shows that it is determined whether P5 is larger than both P1 and P9. Further, FIG. 15D shows that it is determined whether P5 is larger than both P3 and P7.

  Thus, as shown in FIGS. 15 (a) to 15 (d), when P5 is a value larger than both sides sandwiching the interest point of P5 (P5> P2, P8, or P5). > P4, P6, or P5> P1, P9, or P5> P3, P7), the point of interest is extracted as a point on the ridge.

  In the image data calculation unit 23, a set of points on the ridge is extracted as described above.

  The ridge lines (FIGS. 13 (D), (F), and (E)) sequentially obtained in this manner are sequentially input to the image processing circuit 12 shown in FIG. Then, a ridge line image (an image on the data) in which a ridge line is superimposed on a tomographic image is created, and the image data is sent to the TV monitor 13 on the TV monitor 13 based on the image data. A ridge line image in which lines are superimposed is displayed.

  FIG. 16 is a schematic diagram illustrating a ridge line image in which a ridge line is superimposed on a tomographic image.

  A region a 'surrounded by a line shown in the figure indicates a region in the heart.

  A black dot (b 'in the figure) represents a point on the ridge.

  FIG. 17 is a schematic diagram showing a ridge line image in which each point on the ridge line is displayed in a display mode corresponding to the blood flow velocity.

  The size of the white circle (b 'in the figure) corresponds to the blood flow rate.

  This ridge line image shows a state in which the blood flow branches. In addition, the situation where the blood flow changes from a strong place to a weak place is also shown.

  Since this ridge line image displays the ridge line inside the heart, it may greatly contribute to the diagnosis of heart disease.

  In the above-described embodiment, in the ultrasonic diagnostic apparatus, the interpolation calculation when obtaining the streamline image representing the streamline distribution and the ridgeline image representing the ridgeline distribution from the color Doppler image representing the blood flow velocity distribution has been described. However, the present invention is not limited to this, and can be widely employed when obtaining an intermediate image of a plurality of second type images obtained from each of a plurality of first type images.

It is a block diagram of the conventional ultrasonic diagnostic apparatus. It is a circuit block diagram of a primary echo canceller used as an MTI filter. 1 is a configuration diagram of an ultrasonic diagnostic apparatus as an embodiment of the present invention. FIG. 4 is a configuration diagram of an image data generation circuit shown by one block in FIG. 3. FIG. 5 is a schematic diagram illustrating a flow of streamline calculation performed by the image data generation circuit illustrated in FIG. 4. It is a figure which shows an example of a blood flow distribution image. It is the figure which showed the blood flow velocity distribution of each point on the line L which is equidistant from the center point. It is a figure showing the flow of the blood flow of an eddy current component. It is the figure which showed the line which% of the integral of the component except the eddy current component on each line connected the same point. It is a figure which shows the flow of the blood flow when adding the eddy current component and the other component of each point on an observation surface. It is explanatory drawing of the method of calculating | requiring the streamline which considered the spring of the blood flow on the observation surface, and suction | inhalation. It is a schematic diagram which shows the streamline image obtained by the method of calculating | requiring the streamline demonstrated in FIG. FIG. 5 is a schematic diagram illustrating a flow of ridge line calculation performed by the image data generation circuit illustrated in FIG. 4. It is a schematic diagram which shows each pixel on the image showing the blood flow velocity distribution on an observation surface. It is explanatory drawing of the extraction process of the point on a ridge. It is a schematic diagram which shows the ridge line image on which the ridge line was superimposed on the tomographic image. It is a schematic diagram which shows the ridge line image which displayed each point on a ridge line in the display mode according to the blood flow rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Probe 2 Transmission circuit 3 Pulse generation circuit 4 Reception circuit 5 Mixer circuit 6a, 6b Low pass filter 7a, 7b Converter 8a, 8b MTI filter 9 Autocorrelation circuit 10 Speed detection circuit 11 Tomographic image processing part 12 Image processing circuit 13 TV monitor 20 Image data generation circuit 21a, 21b Frame memory 22 Interpolation calculation unit 23 Image data calculation unit 24 Calculation control unit 100A, 100B Ultrasonic diagnostic apparatus

Claims (8)

An image interpolation method for obtaining an intermediate image of a plurality of streamline images representing a streamline of blood flow, derived from each of a plurality of color Doppler images by ultrasound ,
Using color Doppler image before Kifuku number, by interpolation, the interpolation determining an interpolated image of the color Doppler,
And a deriving step of deriving the intermediate image from the interpolated image obtained in the interpolating step.   An intermediate image of multiple ridge line images representing a ridge line consisting of a set of points on the ridge derived from each of a plurality of color Doppler images obtained by ultrasound, simulating blood flow velocity at geographical elevation An image interpolation method for obtaining
  An interpolation step for obtaining an interpolated image of the color Doppler by an interpolation operation using the plurality of color Doppler images;
  And a deriving step of deriving the intermediate image from the interpolated image obtained in the interpolating step.   The plurality of color Doppler images are a plurality of color Doppler images representing a state at each time consisting of discrete time intervals of an observation object that changes with time,
  3. The image interpolation method according to claim 1, wherein the interpolation step is a step of obtaining an interpolation image corresponding to a time when the color Doppler image does not exist from the plurality of color Doppler images by interpolation calculation. .   An image interpolation device for obtaining an intermediate image of a plurality of streamline images representing a streamline of blood flow, derived from each of a plurality of color Doppler images by ultrasound,
  An interpolation calculation unit for obtaining an interpolated image of the color Doppler by an interpolation calculation using the plurality of color Doppler images;
  An image interpolation apparatus comprising: a derivation unit that derives the intermediate image from the interpolation image obtained by the interpolation calculation unit.   An intermediate image of multiple ridge line images representing a ridge line consisting of a set of points on the ridge derived from each of a plurality of color Doppler images obtained by ultrasound, simulating blood flow velocity at geographical elevation An image interpolation device for obtaining
  An interpolation calculation unit for obtaining an interpolated image of the color Doppler by an interpolation calculation using the plurality of color Doppler images;
  An image interpolation apparatus comprising: a derivation unit that derives the intermediate image from the interpolation image obtained by the interpolation calculation unit.   The plurality of color Doppler images are a plurality of color Doppler images representing a state at each time consisting of discrete time intervals of an observation object that changes with time,
  The image interpolation according to claim 4 or 5, wherein the interpolation calculation unit obtains an interpolation image corresponding to a time when the color Doppler image does not exist from the plurality of color Doppler images by interpolation calculation. apparatus. An ultrasound that generates a blood flow distribution image representing the blood flow distribution in the subject by repeating the transmission of the ultrasonic pulse into the subject and the reception of the reflected ultrasonic wave reflected and returned in the subject. In the ultrasonic diagnostic equipment,
A streamline calculation unit for calculating a streamline image representing a streamline of blood flow from the blood flow distribution image;
An interpolation calculator that interpolates a plurality of images to obtain an interpolated image;
When obtaining a streamline image at a time when no blood flow distribution image exists, the interpolation calculation unit interpolates a plurality of blood flow distribution images representing blood flow distributions at different times in the subject, and the blood flow distribution image exists. An ultrasonic diagnostic apparatus, comprising: an arithmetic control unit that obtains an interpolated image representing a blood flow distribution at a non-performing time and causes the streamline calculating unit to calculate a streamline image at the time from the interpolated image . An ultrasound that generates a blood flow distribution image representing the blood flow distribution in the subject by repeating the transmission of the ultrasonic pulse into the subject and the reception of the reflected ultrasonic wave reflected and returned in the subject. In the ultrasonic diagnostic equipment,
A ridge line calculation unit for calculating a ridge line image consisting of a set of points on the ridge when mimicking the blood flow velocity from the blood flow distribution image to a geographical elevation;
An interpolation calculator that interpolates a plurality of images to obtain an interpolated image;
When obtaining a ridge line image at a time when there is no blood flow distribution image, the interpolation calculation unit interpolates a plurality of blood flow distribution images representing blood flow distributions at different times in the subject, and the blood flow distribution image exists. An ultrasonic diagnostic apparatus, comprising: an arithmetic control unit that obtains an interpolated image representing a blood flow distribution at a time not to be calculated and causes the ridge line calculation unit to calculate a ridge line image at the time from the interpolated image .

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