JP2008148794A - Image generation method and ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate and display images in a new form relating to an ultrasonic diagnostic apparatus. <P>SOLUTION: The image generation method includes: a first operation step of obtaining blood flow velocity components in a direction connecting respective points on an observation surface and an ultrasonic transmission/reception point at the respective points on the basis of reception signals; a second operation step of obtaining a blood flow velocity composed of the combination of the blood flow velocity components obtained in the first operation step and the blood flow velocity components in a direction orthogonal to the blood flow velocity components within the observation surface at the respective points on the observation surface on the basis of the blood flow velocity components obtained in the first operation step; a ridge extraction step of extracting the set of the points on a ridge when the blood flow velocity at the respective points is liken to the geographic altitude on the basis of a blood flow velocity distribution including the set of the respective points on the observation surface, of the blood flow velocity between the blood flow velocity and the blood flow direction constituting the blood flow velocity obtained in the second operation step; and a display step of displaying the image indicating the set of the points on the ridge extracted in the ridge extraction step. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention repeats the transmission of ultrasonic pulses into the subject and the reception of reflected ultrasonic waves reflected back within the subject, and generates an image based on the received signal obtained by receiving the reflected ultrasonic waves. In particular, the present invention relates to an ultrasonic diagnostic apparatus that displays an image and a method for generating an image in the ultrasonic diagnostic apparatus.

  Conventionally, transmission of ultrasonic pulses into the subject and reception of reflected ultrasonic waves reflected back within the subject are repeated, and an image based on the received signal obtained by reception of the reflected ultrasonic waves is displayed. Ultrasonic diagnostic apparatuses that generate and display are used in the medical field.

  As one of the methods for generating and displaying diagnostic images on the display screen of an ultrasonic diagnostic apparatus, the blood flow velocity at each point on the observation surface in the living body using the ultrasonic Doppler method using the Doppler effect There is known a display method in which a component in the ultrasonic traveling direction is measured and this blood flow velocity distribution is superimposed and displayed on a monochrome tomographic image obtained by a pulse reflection method.

  The principle of blood flow velocity component measurement by this ultrasonic Doppler method is that an ultrasonic beam is radiated into a living body at a constant cycle by a transducer array, a reflected wave from a reflector inside the subject is received, and the received signal is By detecting the included frequency change component due to the Doppler effect, the motion velocity component of the reflector in the bloodstream in the direction of ultrasonic travel is measured, and the position is determined from the time until the reflected wave returns. This is displayed in color as two-dimensional blood flow information in real time.

  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 k-th output signal of the MTI filters 8a and 8b at a specific depth is set to x (k) and y (k), this calculation is performed for each of the real part and the imaginary part using the expressions (1a) and (1b). Indicated by

  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 a blood flow velocity component 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 component in the direction of the ultrasonic beam, Techniques for obtaining blood flow velocity and blood flow in all directions within an observation surface including blood flow velocity components 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).
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

  As described above, the technology of the ultrasonic diagnostic apparatus has been developed more and more. However, the problem here is that in addition to the various display modes in the current ultrasonic diagnostic apparatus, what kind of display is possible. It is a point that it is useful for diagnosis when it is done.

  In view of the above circumstances, an object of the present invention is to provide a method for generating an image of a new aspect and an ultrasonic diagnostic apparatus capable of generating an image of a new aspect in the ultrasonic diagnostic apparatus.

The image generation method of the present invention that achieves the above object repeats transmission of an ultrasonic pulse into a subject and reception of a reflected ultrasonic wave reflected back within the subject, and reception of the reflected ultrasonic wave. In the image generation method in the ultrasonic diagnostic apparatus for generating and displaying an image based on the received signal obtained by
A first calculation step for obtaining a blood flow velocity component in a direction connecting each point and the ultrasonic transmission / reception point at each point on the observation surface based on the received signal;
Based on the blood flow velocity component obtained in the first calculation step, the blood flow velocity component obtained in the first calculation step in the observation surface at each point on the observation surface, A second calculation step for obtaining a blood flow velocity comprising a composition of a blood flow velocity component in a direction perpendicular to the blood flow velocity component;
A 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 obtained in the second calculation step. A ridge extraction step for extracting a set of points on the ridge when mimicking the blood flow velocity of each point to the geographical elevation,
And a display step for displaying an image representing a set of points on the ridge extracted in the ridge extraction step.

  For example, in observing blood flow in the heart, it is important to know how blood is flowing. From this point of view, the ridge line when the blood flow velocity is simulated as the geographical altitude indicates a strong flow of blood flow, which gives extremely useful information.

  The image generation method of the present invention further develops a technique for obtaining a two-dimensional omnidirectional blood flow velocity, and the blood flow among the blood flow velocity and the blood flow direction constituting the two-dimensional blood flow velocity. Since a set of points on the ridge line is extracted based on the speed information and displayed, information extremely useful for grasping the entire blood flow can be given.

  Here, in the image generation method of the present invention, the ridge extraction step performs a spatial smoothing process on the blood flow velocity distribution, and based on the blood flow velocity distribution after the smoothing process is performed. Preferably, this is a step of extracting a set of points on the ridge.

  By performing the smoothing process, the risk that a noise component appearing on the blood flow velocity distribution is erroneously extracted as a point on the ridge is reduced.

  In the image generation method of the present invention, the ridge extraction step sequentially selects each point on the observation surface as a point of interest, and the blood flow velocity of the selected point of interest is In the case where there are two points that satisfy the condition that the blood flow velocity of two points adjacent to the point of interest is greater than that, it is preferable that the step of extracting the point of interest as a point on the ridge.

  When this calculation method is employed, a complicated mathematical process is not required, and points on the ridge are extracted with sufficient accuracy for practical use.

  In the image generation method of the present invention, it is preferable that each point on the ridge extracted in the ridge extraction step is displayed in a display mode according to the blood flow velocity at each point.

  When each point on the ridge extracted in the above ridge extraction step is displayed in a display mode corresponding to the blood flow rate at each point, the magnitude of the blood flow rate can be easily grasped, and the entire blood flow can be grasped. Is even easier.

In addition, the ultrasonic diagnostic apparatus of the present invention that achieves the above object repeats transmission of an ultrasonic pulse into a subject and reception of a reflected ultrasonic wave reflected back within the subject, In an ultrasonic diagnostic apparatus that generates and displays an image based on a received signal obtained by receiving a sound wave,
A first calculation unit for obtaining a blood flow velocity component in a direction connecting each point and the ultrasonic transmission / reception point at each point on the observation surface based on the received signal;
Based on the blood flow velocity component obtained by the first calculation unit, the blood flow velocity component obtained by the first calculation unit and the blood flow in the observation surface at each point on the observation surface. A second calculation unit for obtaining a blood flow velocity composed of a blood flow velocity component in a direction perpendicular to the velocity component;
Based on the blood flow velocity distribution composed of a set of points on the observation plane, the blood flow velocity of the blood flow velocity and the blood flow direction constituting the blood flow velocity obtained by the second calculation unit. A ridge extractor for extracting a set of points on the ridge when the blood flow velocity at each point is simulated as a geographical elevation;
And a display unit for displaying an image representing a set of points on the ridge extracted by the ridge extraction unit.

  According to the ultrasonic diagnostic apparatus of the present invention, a ridge line display representing a set of points on the ridge extracted by the ridge extraction unit based on the blood flow velocity distribution obtained by the second calculation unit. By generating an image and displaying the image on the display unit, it is possible to easily overview the blood flow distribution.

  In the ultrasonic diagnostic apparatus of the present invention, the ridge extraction unit performs a spatial smoothing process on the blood flow velocity distribution, and based on the blood flow velocity distribution after the smoothing process is performed. It is preferable to extract a set of points on the ridge.

  The ridge extraction unit performs spatial smoothing on the blood flow velocity distribution, thereby reducing the possibility that noise components appearing on the blood flow velocity distribution are erroneously extracted as points on the ridge. Accuracy extraction is performed.

  In the ultrasonic diagnostic apparatus of the present invention, the ridge extraction unit sequentially selects each point on the observation surface as a point of interest, and the blood flow velocity of the selected point of interest is sandwiched between the points of interest. When there are two points that satisfy the condition that the blood flow velocity of two points adjacent to the point of interest is larger than the point of interest, the point of interest is preferably extracted as a point on the ridge.

  By adopting this arithmetic algorithm, the ridge extraction unit does not require complicated mathematical processing, and points on the ridge are extracted with sufficient practical accuracy.

  In the ultrasonic diagnostic apparatus of the present invention, the display unit displays each point on the ridge extracted by the ridge extraction unit in a display mode according to the blood flow velocity at each point. It is preferable.

  According to this preferable display mode, the display unit provides an image that makes it easy to visually grasp the magnitude of the blood flow velocity, so that the whole blood can be grasped more accurately.

  As described above, according to the present invention, a new and useful image that has never existed is generated.

  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, 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 diagnostic apparatus shown in FIG. Only components that are different from the ultrasonic diagnostic apparatus will be described.

  A ridge line calculation circuit 30 is added to the ultrasonic diagnostic apparatus 100B of FIG. 3 as compared to the ultrasonic diagnostic apparatus 100A of FIG.

  The blood flow distribution image data representing the blood flow velocity component in the ultrasonic beam direction at each point on the observation surface obtained by the velocity detection circuit 10 is used for display as it is, and the ridge line calculation circuit 30 is bypassed for image processing. It is sent to the circuit 12. The subsequent processing in the image processing circuit 12 is as described with reference to FIG.

  On the other hand, in the mode for obtaining and displaying the ridge line, the blood flow distribution image data obtained by the speed detection circuit 10 is input to the ridge line calculation circuit 30, and ridge line image data representing the ridge line is generated to perform image processing. It is sent to the circuit 12. In the image processing circuit 12, image data representing an image in which a blood flow ridge line is drawn on a monochrome luminance image of a tomographic image is obtained, and an image based on the image data is displayed on the TV monitor 13.

  FIG. 4 is a configuration diagram of the ridge line calculation circuit shown by one block in FIG.

  The ridge line calculation circuit 30 includes a blood flow velocity calculation unit 301 and a ridge search unit 302.

  The blood flow velocity calculation unit 301 is based on the blood flow velocity component in the ultrasonic beam direction at each point on the observation surface obtained by the velocity detection circuit 10, and the blood flow velocity in the direction perpendicular to the blood flow velocity component. The component is calculated, and the blood flow velocity obtained by combining the blood flow velocity components of both of them is obtained.

  The ridge search unit 302 is a blood composed of a set of points on the observation surface of the blood flow rate of the blood flow direction and the blood flow rate constituting the blood flow velocity obtained by the blood flow velocity calculation unit 301. A flow velocity distribution is obtained, and based on the blood flow velocity distribution, a point on the ridge when the blood flow velocity at each point on the observation surface is imitated by geographical elevation is searched, and A set of points is extracted. Details will be described later.

  Note that the velocity detection circuit 10 shown in FIG. 3 corresponds to an example of the first calculation unit according to the present invention, and the blood flow velocity calculation unit 301 and the ridge search unit 302 constituting the ridge line calculation circuit 30 refer to the present invention. These correspond to examples of the second calculation unit and the ridge extraction unit, respectively.

  FIG. 5 is a flowchart for explaining an image forming method as an embodiment of the present invention.

  This flowchart shows processing after the speed detection circuit 10 in the mode for obtaining and displaying the ridge line.

  The contents of each step will be described below.

  First, in the velocity detection circuit 10, the blood flow velocity component in the direction connecting each point and the ultrasonic transmission / reception point (ultrasonic beam direction) at each point on the observation surface is determined based on the reception signal of the reflected ultrasonic wave. It is obtained (step S101).

  Next, in the blood flow velocity calculation unit 301, based on the blood flow velocity component obtained in step S101, the blood flow velocity component obtained in step S101 and the blood flow velocity component at each point on the observation surface The blood flow velocity obtained by combining the blood flow velocity components in the direction perpendicular to each other is obtained (step S102).

  Specifically, the blood flow velocity calculation unit 301 obtains the blood flow velocity 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 the contents are publicly known, only an 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 blood flow velocity component in the direction orthogonal to the direction of the ultrasonic beam is obtained by the calculation outlined below, and the blood flow velocity in the direction of the ultrasonic beam is obtained. The two-dimensional blood flow velocity at each point on the observation surface is obtained by combining the component and the blood flow velocity component in the direction orthogonal to it, and the blood flow direction and blood constituting the two-dimensional blood flow velocity are obtained. A blood flow velocity distribution that is a distribution on the observation surface of the blood flow velocity of the flow velocity is obtained.

  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, the blood flow velocity of the eddy current component in the direction perpendicular to the direction of the ultrasonic beam at each point when calculated under this constraint condition The components can be obtained, and a two-dimensional velocity vector relating to the vortex component at each point is obtained together with the blood flow velocity component for the vortex component 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.

  6 is integrated along the line L from the left and right ends of FIG. 6 (here, the right side of FIG. 7) to the left and right ends (left side of FIG. 6). 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, and the blood flow velocity component in the direction of the ultrasonic beam at each point (the blood flow velocity component of the component excluding the vortex component; 7) is obtained by subtracting the blood flow velocity component in the ultrasonic beam direction of the eddy current component from the original blood flow velocity component by the ultrasonic Doppler method, and by knowing the direction of blood flow at each point, The blood flow velocity component of each point in the direction perpendicular to the ultrasonic beam and excluding the eddy current component is obtained, and eventually the blood flow velocity vector indicating both the direction and the magnitude 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.

  The blood flow velocity information including the component in the direction perpendicular to the ultrasonic beam shown in FIG. 10 includes both the blood flow direction information and the blood flow velocity information. A ridge line is obtained based on the blood flow velocity distribution, which is the distribution of speed on the observation surface. Details will be described later.

  Returning to FIG. 5 again, the description will be continued. After the blood flow velocity is obtained, the ridge search unit 302 shown in FIG. 4 performs ridge search processing (step S103).

  FIG. 11 is a flowchart showing details of the ridge search processing shown in one step in FIG.

  The processing shown in FIG. 11 is performed by the ridge line search unit 302 shown in FIG.

  Here, the interval between the ultrasonic scanning lines is coarser than the pixel pitch of the display screen. Here, first, the blood flow velocity data at each point on the scanning line is converted into the pixel pitch of the display screen by interpolation processing. Blood flow velocity data mapped two-dimensionally at the corresponding pitch is obtained (step S201).

  Next, a smoothing process is performed on the blood flow velocity distribution at intervals corresponding to the pixel pitch on the display screen obtained in step S201 (step S202).

  FIG. 12 is a flowchart showing the smoothing process, and FIG. 13 is an explanatory diagram of the smoothing process.

  FIG. 13A and FIG. 13B show a large number of pixels constituting an image.

  In the smoothing process, a pixel of a point of interest on the image is selected, and an average value is obtained by the following calculation including eight pixels around the point of interest. The average value is a value representing the blood flow velocity of the new interest point. When there are no eight pixels in the surrounding area, the calculation is performed except for pixels that are present in the surrounding area.

  In this smoothing process, each point on the image memory storing blood flow velocity data is sequentially selected as a point of interest (step S301).

  Here, as an example, in FIG. 13A, for example, a coordinate point of (X, Y) = (5, 4) is selected as a point of interest. The pixel value of this interest point is P5.

  Next, as points adjacent to the point of interest having the pixel value of P5, the values P1 to P9 of the 3 × 3 square points surrounded by a thick frame are extracted (step S302).

  In FIG. 13A, pixel values actually exist in blank cells on the image, but are blank here for convenience of explanation.

  Next, a smoothing calculation is executed using the extracted point values (step S303).

In the smoothing calculation, the values of the points of the 3 × 3 squares are added and the average value is obtained. in this case,
P5 ′ = (1/9) × (P1 + P2 + P3 + P4 + P5 + P6 + P7 + P8 + P9)
And

  Next, the smoothed interest point value P5 'is set to the pixel value of the same coordinate point (X, Y) = (5, 4) as the coordinate point of P5 before smoothing (step S304).

  Next, it is determined whether or not all points on the image have been selected (step S305).

  If the determination result indicates that not all have been selected, the process returns to the next point of interest selection in step 301. For the next point of interest, the next point of interest and the surrounding eight points (3 × 3 square points) are selected and executed in the same manner as the smoothing calculation described above.

  On the other hand, in the case of a determination result indicating that all points on the image have been selected, the smoothing process has been completed for the entire image, and the blood flow velocity distribution after smoothing has been obtained. To do.

  Subsequently, extraction processing of points on the ridge shown in FIG. 11 is performed (step S204).

  FIG. 14 is a flowchart showing details of the point extraction process on one ridge shown in FIG. 11, and FIG. 15 is an explanatory diagram of the point extraction process on the ridge.

  Also here, first, one point on the observation surface is selected as a point of interest (step S401), and then a combination of two points adjacent to each other with the selected point of interest in between is extracted (step S402).

  Here, the process of extracting points on the ridge when the coordinate having the value P5 'shown in FIG. 13B is selected as the point of interest is as follows. The combination of two points adjacent to each other with the interest point in between is the combination shown in FIGS. 15 (a) to 15 (d).

  Next, the blood flow rates are compared as shown below (step S403).

  In FIG. 15A, it is determined whether P5 'is larger than both P2' and P8 '. In FIG. 15B, it is determined whether P5 'is larger than both P4' and P6 '. In FIG. 15C, it is determined whether P5 'is larger than both P1' and P9 '. In FIG. 15D, it is determined whether P5 'is larger than both P3' and P7 '.

  In this way, in any of FIGS. 15A to 15D, when P5 ′ is a value larger than both sides sandwiching the point of interest of P5 ′, the point of interest is on the ridge. Are extracted as points (step S403).

  Subsequently, it is determined whether or not all points on the observation surface have been selected as points of interest (step S406).

  On the other hand, if there is no combination in which the blood flow velocity at the point of interest is greater than both of its neighbors in step S404, the point of interest is not extracted as a point on the ridge, and the process directly proceeds to step S406. Advancing, it is determined whether all points on the observation surface have been selected as points of interest. If it is determined in step S406 that there is an observation point that has not been selected, the process returns to step S401, the next interest point is selected, and the above-described ridge extraction process is performed for the selected next interest point. Is performed (steps S402 to S405).

  On the other hand, if it is determined in step S406 that selection of all points of interest has been completed, the extraction process of points on the ridge shown in FIG. 14 is terminated, and the ridge line display step (FIG. 5) Proceed to step S104).

  In the image processing circuit 12 shown in FIG. 3, the data of the points on the ridge are read together with the monochrome luminance data obtained by the tomographic image processing unit 11, mapped onto the image memory, and the tomographic image and A ridge line image synthesized with an image representing the ridge line 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.

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. It is a block diagram of the ridge line calculation circuit shown by one block in FIG. 3 is a flowchart for explaining an image forming method as an embodiment of the present invention. It is a figure which shows an example of a blood flow distribution image. FIG. 7 is a diagram showing a blood flow velocity distribution on a single line L that is equidistant from the center point C, typically shown in FIG. 6. It is a figure showing the blood flow of the eddy current component of each point. 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 blood flow when the eddy current component and the other component of each point on an observation surface are added together. It is a flowchart which shows the detail of a ridge search process. It is a flowchart which shows the detail of a smoothing process. It is explanatory drawing of a smoothing process. It is a flowchart which shows the detail of the extraction process of the point on a ridge. 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 30 Ridge line calculation circuit 100A, 100B Ultrasonic diagnostic apparatus 301 Blood flow velocity calculation unit 302 Ridge search unit

Claims (8)

Ultrasound diagnosis that repeats the transmission of ultrasonic pulses into the subject and the reception of reflected ultrasonic waves reflected back within the subject, and generates and displays an image based on the received signal obtained by the reception In an image generation method in an apparatus,
A first calculation step for obtaining a blood flow velocity component in a direction connecting each point and the ultrasonic transmission / reception point at each point on the observation surface based on the received signal;
Based on the blood flow velocity component determined in the first calculation step, the blood flow velocity component determined in the first calculation step in the observation surface at each point on the observation surface; A second calculation step for obtaining a blood flow velocity comprising a composition of a blood flow velocity component in a direction perpendicular to the blood flow velocity component;
A 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 obtained in the second calculation step. A ridge extraction step for extracting a set of points on the ridge when the blood flow velocity of each point is simulated at a geographical elevation;
A display step of displaying an image representing a set of points on the ridge extracted in the ridge extraction step.   In the ridge extraction step, a spatial smoothing process is performed on the blood flow velocity distribution, and a set of points on the ridge is extracted based on the blood flow velocity distribution after the smoothing process is performed. The image generation method according to claim 1, wherein:   The ridge extraction step sequentially selects each point on the observation surface as a point of interest, and the blood flow velocity of the selected point of interest is the blood of two points adjacent to the point of interest with the point of interest in between. 2. The image generation method according to claim 1, wherein when there are two points satisfying a condition that the velocity is larger than the flow velocity, the point of interest is extracted as a point on the ridge.   The image generation according to claim 1, wherein the display step is a step of displaying each point on the ridge extracted in the ridge extraction step in a display mode according to the blood flow velocity of each point. Method. Ultrasound diagnosis that repeats the transmission of ultrasonic pulses into the subject and the reception of reflected ultrasonic waves reflected back within the subject, and generates and displays an image based on the received signal obtained by the reception In the device
A first calculation unit that obtains a blood flow velocity component in a direction connecting each point and an ultrasonic transmission / reception point at each point on the observation surface based on the received signal;
Based on the blood flow velocity component obtained by the first operation unit, the blood flow velocity component obtained by the first operation unit in the observation surface at each point on the observation surface, and the blood flow A second calculation unit for obtaining a blood flow velocity composed of a blood flow velocity component in a direction perpendicular to the velocity component;
Based on a 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 determined by the second calculation unit. A ridge extractor for extracting a set of points on the ridge when the blood flow velocity at each point is simulated as a geographical elevation;
An ultrasonic diagnostic apparatus comprising: a display unit that displays an image representing a set of points on the ridge extracted by the ridge extraction unit.   The ridge extraction unit performs a spatial smoothing process on the blood flow velocity distribution, and extracts a set of points on the ridge based on the blood flow velocity distribution after the smoothing process is performed. The ultrasonic diagnostic apparatus according to claim 5, wherein:   The ridge extraction unit sequentially selects each point on the observation surface as a point of interest, and the blood flow velocity of the selected point of interest is the blood of two points adjacent to the point of interest with the point of interest in between. 6. The ultrasonic diagnostic apparatus according to claim 5, wherein when there are two points satisfying a condition that the velocity is larger than the flow velocity, the point of interest is extracted as a point on the ridge.   6. The super display according to claim 5, wherein the display unit displays each point on the ridge extracted by the ridge extraction unit in a display mode corresponding to the blood flow velocity of each point. Ultrasonic diagnostic equipment.

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