JP2006314807A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic equipment which raises the displaying ability of a low velocity sector obtained by tissue doppler imaging and facilitates distinction of normality/abnormality of an interested section. <P>SOLUTION: This ultrasonic diagnostic equipment comprises an extraction means to extract a doppler signal according to the motion of a tissue included in the section layer of a subject, a speed calculating means to determine the speed of the motion of the tissue based on the doppler signal, a manipulating signal receiving means to designate a scale which assigns in accordance with collar data measurable doppler frequency ranges restricted by a pulse repetition frequency, a scale setting means to establish the scale so that the desired low velocity regions among the doppler frequency ranges are assigned to the gradation data of the value of a predetermined region according to the manipulating signal and that the remaining speed regions of the doppler frequency ranges may be assigned to the gradation data of a constant value, a speed conversion means to convert the speed into the gradation data based on the scale, and a displaying means for displaying the converted gradation data by coloring up them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus applied to tissue Doppler imaging (TDI) using an ultrasonic pulse Doppler method.

  Conventionally, as an ultrasonic diagnostic apparatus for performing tissue Doppler imaging, for example, there is JP-A-6-114059 (title of the invention: ultrasonic color Doppler tomographic apparatus) that has been proposed by the present applicant. The ultrasonic diagnostic apparatus described in this publication detects the movement speed of the tissue of the myocardium and blood vessel wall using a pulse Doppler method and a low-pass filter, calculates various physical quantities related to movement from the movement speed, and appropriately calculates the calculation result. A mechanism for color display is provided. In detecting the movement speed of the tissue, the movement speed of the tissue is significantly lower than that of the blood flow. Therefore, the pulse repetition frequency (PRF) of the transmitted ultrasonic pulse (rate pulse) is lowered to reduce the tissue movement speed. It is possible to measure ultra-low speed.

  There are various modes of color display of the calculation results, and among the inventions according to the above-mentioned publication, two-dimensional color display is proposed. With regard to the gradation of this color display, a technique in blood flow imaging using a color Doppler device, which is based on a common basis with tissue Doppler imaging, can be applied.

In the blood flow imaging, the Doppler shift frequency fd is in the range of “−fr / 2 to fr / 2” (fr: pulse repetition frequency of the ultrasonic pulse signal: PRF). As shown in FIG. 27, the image is displayed with 32 gradations (fr / 32 per gradation). That is, a scale having a uniform gradation change with respect to speed (Doppler shift frequency) is assigned to the entire speed range of “−fr / 2 to fr / 2”, and red (yellow) -blue (light blue) is applied. The gradation of color display is set.
JP-A-6-114059

  As described above, tissue Doppler imaging is characterized by the fact that it is possible to measure the ultra-slow motion speed of the tissue by setting a low pulse repetition frequency (= low frame rate). Therefore, the range of the Doppler shift frequency particularly required for display in the tissue Doppler imaging is narrower than that in the case of blood flow imaging, and is, for example, about “−fr / 8 to fr / 8”.

  In spite of this, at present, color tone assignment in blood flow imaging must be applied to tissue Doppler imaging as it is. As a result, the number of gradations assigned to the low-speed area is very small, and the tissue site such as the myocardium to be observed is displayed in, for example, red of almost the same color or red of almost the same brightness, and the speed difference in the low-speed area is visually recognized. In addition, it is extremely difficult to evaluate accurately, and even if a speed difference of fr / 32 or less can be detected, the displayed hue or luminance does not change. There is an unsolved problem that the function of high detection accuracy cannot be fully exhibited.

  Furthermore, in diagnosis using tissue Doppler imaging, it is desirable to quickly identify whether the region of interest in the tissue such as the myocardium is normal or abnormal. On the other hand, according to the conventional display method, since the color gradation assignment is uniform from the low speed range to the high speed range, the display capability in the low speed range is low as described above, and the normal / abnormal of the diagnosis part is determined. Difficult to distinguish, requiring a long time for diagnosis, and requiring unexplained problems that require a high degree of skill from the examiner.

  The present invention has been made in view of the above-mentioned unsolved problems. The first is to improve the display capability of the low-speed region by utilizing the measurement function for the low-speed region motion obtained by tissue Doppler imaging. Objective.

  In addition, a second object of the present invention is to provide a TDI image that can easily distinguish between normal / abnormal regions of interest while achieving the first object.

  In order to achieve the above object, the invention according to any one of claims 1 to 8 is an ultrasonic diagnostic apparatus for displaying a color image of a tomographic plane related to a motion of a tissue included in a tomographic plane of a subject. A scanning unit that scans along the tomographic plane and obtains an echo signal having an electrical quantity corresponding to an ultrasonic reflection signal from the tomographic plane; an extracting unit that extracts a Doppler signal according to the movement of the tissue from the echo signal; Speed calculation means for obtaining data on the speed of movement of the tissue for each sample point of the tomographic plane based on the Doppler signal, and a measurable Doppler frequency range limited by a predetermined pulse repetition frequency of the ultrasonic pulse signal. An operation signal receiving unit that receives an operation signal that specifies a scale that associates the data relating to the speed with the gradation data of the color display assigned to the data. And a desired low speed region in the Doppler frequency range is assigned to a predetermined range of gradation data in accordance with the operation signal and the remaining speed region of the Doppler frequency range is a constant value. Scale setting means for setting the scale to be assigned to gradation data, speed conversion means for converting data relating to the speed to the gradation data based on the scale, and gradation converted by the speed conversion means And display means for displaying data in color.

  In the scale, for example, the change rate of the gradation data with respect to the data relating to the speed in the low speed range is set nonlinearly. For example, when the predetermined pulse repetition frequency of the ultrasonic pulse signal is fr and the Doppler shift frequency is fd, the low speed region is −fr / 8 ≦ fd ≦ fr / 8, −fr / 12 ≦ fd ≦. One of fr / 12 and -fr / 16≤fd≤fr / 16. Further, the gradation data includes color data having a gradation that has a continuous connection that changes in accordance with a change in the data relating to the speed, and at least the highest value of the gradation data is a gradation degree that is lower than the gradation degree. Discontinuous color data.

  Furthermore, the invention described in claims 9 to 21 is an ultrasonic diagnostic apparatus that displays a color image related to the motion of a tissue included in a tomographic plane superimposed on a tomographic image of a tomographic plane of a subject, and displays the ultrasonic pulse signal in the ultrasonic diagnostic apparatus. A scanning unit that scans along the tomographic plane and obtains an echo signal having an electrical quantity corresponding to an ultrasonic reflection signal from the tomographic plane; an extracting unit that extracts a Doppler signal according to the movement of the tissue from the echo signal; Speed calculation means for obtaining data on the speed of movement of the tissue for each sample point of the tomographic plane based on a Doppler signal; tomographic image forming means for forming data of the tomographic image from the echo signal; and the ultrasonic pulse Data on the speed in a measurable Doppler frequency range limited by a predetermined pulse repetition frequency of the signal, and color display gradation data assigned to the data; A scale corresponding to each other is assigned to gradation data having a predetermined range of values in a desired low speed range in the Doppler frequency range, and gradation data having a constant value in the remaining speed range in the Doppler frequency range. Scale setting means for setting to be assigned, speed conversion means for converting the speed-related data into the gradation data based on the scale, gradation data converted by the speed conversion means, and calculation by the speed calculation means Blank processing means for subjecting the sample points where the amount of any one of the data relating to the speed exceeding a specified threshold value to blank processing, and data relating to the speed that has undergone blank processing by the blank processing means as the tomography A display means for superimposing the data on the image and displaying the data relating to the speed in color. Characterized in that was.

  The scale setting means relates to the speed corresponding to the maximum value of the gradation data, wherein the ratio of the gradation data to the change of the Doppler frequency is higher than the ratio at the time of the kinetic fluid analysis of the subject. It is means for setting the scale to assign the highest value to data larger than the data. Furthermore, a threshold value specifying means for specifying the threshold value independently of the setting of the scale can be provided. Further, the scale setting means is means for automatically determining the threshold value in conjunction with the setting of the scale, for example.

[Action]
The ultrasonic diagnostic apparatus according to one embodiment of the present invention is applied to tissue Doppler imaging (TDI). In this imaging, a part such as the myocardium is scanned by an ultrasonic pulse Doppler method to obtain an echo signal, and the motion speed is calculated for each sample point on the scanning tomographic plane. This movement speed is attached to a two-dimensional color display. In this display, for example, a desired value within a speed range “−fr / 2 ≦ fd ≦ fr / 2” (fr: pulse repetition frequency of ultrasonic pulse, fd: Doppler shift frequency) that can be measured by the ultrasonic pulse Doppler method. In the low speed range of “−fr / 8 ≦ fd ≦ fr / 8”, the scale of “data relating to speed” vs. “tone data for color display” changes in a predetermined range when the data relating to speed changes. Is set as follows. On the other hand, the scale for the remaining speed range of the predetermined low speed range is set so that the gradation data remains constant even if the data regarding the speed changes. Accordingly, since the display resolution in such a low speed region is increased, a slight change in the slow motion of the myocardium is displayed with high sensitivity by the change in the luminance of the color or the multi-gradation of the hue. For this reason, even if the measurement function for low-speed motion is increased with a low pulse repetition frequency, the measurement function is not impaired by the color display. Further, for example, a pixel having the highest gradation speed is displayed with a discontinuous hue from a pixel having a lower gradation speed, so that the distinction is facilitated and the visibility is improved.

  In the ultrasonic diagnostic apparatus according to another aspect of the present invention, the tomographic image data is formed from the echo signal, while the velocity measurement with respect to the measurable Doppler frequency limited by the predetermined pulse repetition frequency of the ultrasonic pulse signal is performed. A scale that associates the speed data in the range and the gradation data of the color display assigned to the data with the speed change in the low speed range within the speed measurement range emphasized over the speed change in the remaining speed range is set. Is done. For example, in this scale, the gradation data of the color display changes as the speed changes in such a low speed range, but in the remaining speed range, the gradation data of the color display remains constant even if the speed changes. Set to be retained. Based on this scale, the data relating to the speed is converted into gradation data, and the sample point where the amount of either the gradation data or the data relating to the speed exceeds the specified threshold value is subjected to blank processing. The speed-related data that has undergone the blanking process is superimposed on the tomographic image data, and the speed-related data is displayed in color. That is, the TDI color image of the sample point whose tissue motion speed is higher than the threshold value is not displayed, and only the background B-mode tomographic image is displayed. For this reason, it is possible to eliminate or minimize the speed color image having no gradation by appropriately specifying the threshold value.

  According to the ultrasonic diagnostic apparatus of the present invention, the velocity of the scale for measuring the motion speed of the tissue in the subject based on the ultrasonic pulse Doppler method and displaying the two-dimensional color display can be measured by the pulse Doppler method. Among them, a desired low speed region is assigned to a predetermined range of gradation while the remaining speed region is assigned to a certain gradation, so that the speed display capability of the low speed region is enhanced. This makes it possible to detect different gradations (e.g., even with a slight difference in speed) without impairing the high-sensitivity detection for low-speed regions of tissues such as the myocardium, which depend on setting a low pulse repetition frequency, by color display. Therefore, it is possible to easily and accurately evaluate the speed difference in the low speed region through vision, and the display function in the tissue Doppler imaging can be enhanced. In addition, for example, a pixel having the highest gradation speed is displayed with a discontinuous hue from a pixel having a lower gradation speed, so that the distinction is easy and the visibility with respect to the outline is improved.

  Further, in the ultrasonic diagnostic apparatus of the present invention, since blank processing is additionally performed, a TDI color image of a sample point where the motion speed of a tissue such as a myocardium is higher than a threshold is displayed by this blank processing. Since only the background B-mode tomographic image is displayed, the maximum gradation (for example, the maximum luminance) that cannot provide diagnostically effective image information without gradation by specifying the threshold appropriately. ) Speed color image can be eliminated or minimized, and a B-mode tomographic image as a background image can be displayed instead, so that more useful image information can be obtained from the background image and normal region of interest can be obtained. / It is possible to provide a TDI image in which an abnormality can be easily identified.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. The ultrasonic diagnostic apparatus according to the first embodiment is a diagnostic apparatus for obtaining a TDI (tissue Doppler imaging) image of a myocardium (heart wall) as a tissue.

  FIG. 1 shows a block configuration of an ultrasonic diagnostic apparatus. As shown in the figure, this ultrasonic diagnostic apparatus 10 includes an ultrasonic probe 11 responsible for transmission / reception of an ultrasonic signal to / from a subject, and a reception signal of the ultrasonic probe 11 that drives the ultrasonic probe 11. An apparatus main body 12 that processes the information, an ECG (electrocardiograph) 13 that is connected to the apparatus main body 12 and detects electrocardiogram information, and is connected to the apparatus main body 12 and can output instruction information from the operator to the apparatus main body. And an operation panel 14.

  The apparatus main body 12 can be broadly classified into an ultrasonic probe system, an ECG system, and an operation panel system depending on the type of signal path to be handled. The ultrasonic probe system includes an ultrasonic transmission / reception unit 15 connected to the ultrasonic probe 11, and a B-mode DSC (digital scan converter) unit 16 disposed on the output side of the ultrasonic transmission / reception unit 15. A phase detector 20 for color mapping, a filter 21, a frequency analyzer 22, a code, which are connected to the ultrasonic probe 11, while having a frame memory (FM) 17, a memory synthesizer 18, and a display 19. , A TDI DSC unit 24, and a TDI frame memory 25 are provided. The ECG system includes an ECG amplifier 40 connected to the ECG 13, and includes a trigger signal generator 41 and a reference data memory 42 connected to the output side of the amplifier 40. Further, the operation panel system includes a CPU (central processing unit) 43 for inputting operation information from the operation panel 14 and a timing signal generator 44 placed under the control of the CPU 43. The CPU 43 can supply an ROI (region of interest) setting signal instructed by the operator via the operation panel 14 to each component necessary for ROI setting.

  In this embodiment, the ultrasonic probe 11 and the ultrasonic transmission / reception unit 15 form the scanning unit of the present invention, the phase detection unit 20 forms the extraction unit, and the filter unit 21 and the frequency analysis unit 22 of the present invention. The speed calculation means is formed. Further, the TDI DSC section 24, the TDI frame memory 25, the memory composition section 18 and the display 19 form the display means of the present invention. The encoding calculation unit 23 corresponds to scale setting means and speed conversion means.

  The ultrasonic probe 11 includes a phased array type transducer in which a plurality of strip-shaped piezoelectric vibrators are arranged. Each piezoelectric vibrator is excited by a drive signal from the ultrasonic transmission / reception unit 15. By controlling the delay time of each drive signal, the scanning direction can be changed to enable sector electronic scanning. The delay time pattern of the ultrasonic transmission / reception unit 15 is controlled by the CPU 43 using a reference signal sent from a timing signal generator 44 described later as a reference time. The ultrasonic transmission / reception unit 15 outputs a drive voltage signal, the delay time pattern of which is controlled corresponding to the scanning direction, to the ultrasonic probe 11. The ultrasonic probe 11 that has received the drive voltage signal converts the voltage signal into an ultrasonic signal in the transducer. The converted ultrasonic signal is transmitted toward the subject's heart. The transmitted ultrasonic signal is reflected by each tissue including the heart and returns to the ultrasonic probe 11 again. Therefore, the reflected ultrasonic signal is converted again into a voltage signal (echo signal) in the transducer in the probe 11, and the echo signal is output to the ultrasonic transmission / reception unit 15.

  Similarly to the transmission, the signal processing circuit of the ultrasonic transmission / reception unit 15 delays and adds the input echo signal, and generates an equivalent echo beam signal when the ultrasonic beam is narrowed in the scan direction. The phased and added echo beam signal is detected and then output to the B-mode DSC unit 16. The DSC unit 16 converts ultrasonic scan echo data into standard television scan data and outputs it to the memory synthesis unit 18. In parallel with this, the B-mode DSC unit 16 stores a plurality of pieces of image data in an arbitrary cardiac phase in the B-mode frame memory 17.

  On the other hand, the echo signal processed by the ultrasonic transmission / reception unit 15 is also output to the phase detection unit 20. The phase detector 20 includes a mixer and a low-pass filter. An echo signal reflected from a portion that moves like a myocardium is subjected to Doppler shift in frequency due to the Doppler effect. The phase detection unit 20 performs phase detection on the Doppler frequency and outputs only the Doppler signal to the filter unit 21.

  The filter unit 21 uses the fact that the magnitude of the motion speed is in the relationship of “myocardium <valve <blood flow” (see FIG. 2), and from the phase-detected Doppler signal, valve motion other than the heart wall, blood Unnecessary Doppler components such as flow are removed, and a myocardial Doppler signal in the direction of the ultrasonic beam is efficiently detected. In this case, the filter unit 21 functions as a low-pass filter.

  The filter section is also mounted on a color Doppler tomography apparatus for obtaining blood flow information that has already been put into practical use. In the case of a color Doppler tomography device that obtains this blood flow information, it functions as a high-pass filter for echo signals in which blood flow, heart wall, and valve motion are mixed, and removes Doppler signals other than blood flow. ing. For this reason, a filter part can improve versatility by enabling switching between a low-pass filter and a high-pass filter according to the purpose of the apparatus.

  The Doppler signal filtered by the filter unit 21 is output to the frequency analysis unit 22 at the next stage. The frequency analysis unit 22 applies an FFT method, an autocorrelation method, or the like, which is a frequency analysis method used in ultrasonic Doppler blood flow measurement, and observes at each sample point in the tomographic plane to be scanned. The average speed and maximum speed within the time (time window) are calculated as speed data. Specifically, for example, using the FFT method or the autocorrelation method, the average Doppler frequency (that is, the average velocity of the motion of the observation target at that point) and the dispersion value (the degree of disturbance of the Doppler spectrum) at each point of the sample, Furthermore, the maximum value of the Doppler frequency (that is, the maximum speed of movement of the observation target at that point) and the like are calculated almost in real time using the FFT method. The analysis result of the Doppler frequency is output to the encoding calculation unit 23 at the next stage as color Doppler information of the motion speed.

The encoding calculation unit 23 has a CPU function, and the Doppler shift frequency fd for each sample point on the tomographic plane sent from the frequency analysis unit 22 is converted into a predetermined number of bits using a specified speed conversion scale. The speed display data is encoded. In this ultrasonic pulse Doppler method, the pulse repetition frequency fr of the ultrasonic pulse signal corresponds to the sampling frequency. Therefore, from the sampling theorem, the maximum measurable Doppler shift frequency fdmax is
[Equation 1]
fdmax = fr / 2
It is.

An operable Doppler shift frequency fd that does not cause aliasing in the frequency analysis unit 22 is:
[Equation 2]
−fr / 2 ≦ fd ≦ fr / 2
However, out of this frequency (ie, speed) range,
[Equation 3]
−fr / 8 ≦ fd ≦ fr / 8
The frequency range is quantized with a quantization rate of “fr / 128” and encoded into a speed display code having a data length of, for example, 5 bits. In this case, the Doppler shift frequency fd is
[Equation 4]
−fr / 2 ≦ fd <−fr / 8
Is set to the same encoded data as in the case of “−fr / 8” corresponding to the highest gradation in one movement direction (for example, the direction away from the ultrasonic beam),
[Equation 5]
fr / 8 <fd ≦ fr / 2
Is set to the same encoded data as that of “fr / 8” corresponding to the highest gradation in the other motion direction (for example, the direction approaching the ultrasonic beam).

  As a result, the range of the Doppler shift frequency “−fr / 2 ≦ fd ≦ fr / 2” is taken on the horizontal axis, and the speed display code representing the hue change of the color display color from red (yellow) to blue (light blue) is plotted on the vertical axis. As shown in FIG. 3, the speed conversion scale when the value is taken is expressed in a form that saturates at a speed whose absolute value is larger than “fr / 8”. The encoded speed display data for each sample point having a data length of 5 bits is output to the TDI DSC unit 24 in the next stage. An outline of the above procedure is shown in steps S1 to S5 in FIG.

  The TDI DSC unit 24 includes a scanning system conversion DSC 24a and a color circuit 24b having a lookup table for colorizing the speed display data converted into codes. For this reason, the velocity data sent from the encoding calculation unit 23 is converted into a standard television scanning signal by the DSC 24a and also converted into data for color display by the color circuit 24b. The data is output to the memory synthesis unit 18.

  Here, the color display method of the myocardial velocity processed by the color circuit 24b will be described. The color display is roughly divided into (i) display of velocity magnitude (absolute value), (ii) display of motion direction and speed magnitude, and (iii) display of motion direction. As the display method of (i), there are a: changing the luminance according to the size in a single color, and b: changing the color according to the size. As for the display method of (ii), in addition to the method of indicating the direction by color and the size by luminance, there are the method of indicating the direction by hue and indicating the size by the change of the hue, etc. For, the applicable expression method is limited depending on the mode of speed information obtained. Here, the color is determined in the color circuit 24b of the TDI DSC section 24 as shown in FIG. In other words, the motion that approaches the conventionally known ultrasonic beam is shown in red, the motion away from the ultrasonic beam is shown in blue, the myocardial contraction motion is red (yellow), and the myocardial expansion motion is blue (light blue). ) And the gradation is changed to yellow or light blue as its absolute value increases. As a result, the speed display data of the desired low speed region “−fr / 8 ≦ fd ≦ fr / 8” is 32 gradations per movement direction with respect to a series of color display colors “light blue → blue → red → yellow”. Converted to color information.

  Further, the DSC 24 a of the TDI DSC unit 24 further stores a plurality of color Doppler images in an arbitrary cardiac phase in the TDI frame memory 25.

  On the other hand, the ECG 13 described above detects electrocardiogram information of each cardiac phase of the subject. This detection signal is output to the trigger signal generator 41 and the reference data memory 42 via the ECG amplifier 40. Among these, the reference data memory 42 stores electrocardiogram information in each cardiac time phase, and supplies necessary information to the memory synthesis unit 18 as necessary. The trigger signal generator 41 informs the timing signal generator 44 of timing information of each cardiac time phase. The timing signal generator 44 is normally under the control of the CPU 43 that controls the delay time pattern in the ultrasonic transmission / reception unit 15 in accordance with an instruction from the operation panel 14, but the timing of each cardiac phase from the trigger signal generator 41. Is transmitted, the reference signal for ultrasonic transmission / reception is oscillated to the ultrasonic transmission / reception unit 15.

  As described above, the memory synthesizing unit 18 includes the B-mode image signal output from the B-mode DSC unit 16, the TDI mode image signal output from the TDI DSC unit 24, and, if necessary, the reference data. The electrocardiogram information from the memory 42 is input. In the memory synthesis unit 18, the input signal data is superimposed and the superimposed data is output to the display 19. The display 19 here comprises a CRT.

  As a result, blood flow and valve Doppler signals have already been cut by the filter unit 21, and the display 19 displays the B-mode tomographic image (monochrome gradation) of the heart and the velocity conversion shown in FIG. According to the scale, a tomographic image obtained by superimposing the color image color-coded by the color bar shown in FIG. 5 is displayed almost in real time as shown in FIG. 6, for example (the hatched portion in FIG. 5 indicates the myocardium HM). That is, the color of the myocardium HM shown in FIG. 6 is red (yellow) during contraction movement and blue (light blue) during expansion movement, and the red and blue are repeated periodically and in real time. Moreover, the change in the movement speed during the contraction and expansion movements is expressed almost in real time by the change in the hue of red or yellow or blue or light blue. Therefore, the motion speed of the myocardium HM can be displayed in color almost in real time and with high accuracy, and a basic image for quantitatively and highly accurately evaluating deterioration in the function of the heart can be acquired.

  In particular, the ultra-low speed range of interest in tissue Doppler imaging “−fr / 8 ≦ fd ≦ fr / 8” corresponds to the full gradation range of the color bar. In this case, a fine Doppler shift frequency (that is, a motion speed) of “fr / 128” per gradation is substantially assigned here. This is because the ultra-low speed range “−fr / 8 ≦ fd ≦ fr / 8” is compared to the case of the conventional method in which 32 gradations are assigned to the full scale “−fr / 2 ≦ fd ≦ fr / 2” described above. This means that the gradation display ability is improved by a factor of four. As a result, the ultra-low-speed motion speed of the myocardium detected at a low pulse repetition frequency is displayed with a much larger gradation than before, so a slight speed difference in the ultra-low speed range becomes a display color of a different hue, The speed difference can be easily differentiated and evaluated visually.

  In the applicant's clinical evaluation, the maximum speed range of the low speed range is selected between 4 cm / s and 10 cm / s, and a speed larger than this maximum speed range is saturated and the maximum luminance (instead of the hue change) is selected. The luminance change of the designated color is encoded as the red or blue speed display data (adopted as gradation data for color display). However, the aliasing speed obtained from the sampling frequency was 4 or 8 times higher than its saturated maximum speed, between 30 cm / s and 40 cm / s. The velocity of the ventricular wall was measured under these conditions, and it was confirmed that aliasing did not occur.

  Therefore, even when scanning is performed with an ultrasonic pulse signal having the same pulse repetition frequency as in the prior art, it is not necessary to impair the measurement function for the ultra-low-speed motion speed of the tissue, and the function of the apparatus can be enhanced.

  Since the diagnostic apparatus in the above embodiment includes two types of frame memories 17 and 25 for B mode and TDI, cine loop reproduction such as slow motion reproduction and frame advance reproduction and moving image reproduction are performed as necessary. Or images having different cardiac phases can be displayed individually or in parallel for the B mode and the CFM.

  Further, the tomographic apparatus can be provided with a Doppler filter or an FFT (Fast Fourier Transform) frequency analyzer for Doppler display of the movement of the myocardium.

  Furthermore, in the above-described embodiment, the configuration in which the image on which the myocardial TDI image is superimposed is a B-mode tomogram and the diagnosis target is the heart has been described, but the present invention is not necessarily limited to such a configuration. . For example, an M mode image may be used instead of the B mode image (in this case, each component for obtaining the B mode image may be replaced with that of the M mode image), or instead of the myocardium. The blood vessel wall may be diagnosed (in this case, the cutoff frequency of the filter unit 21 is adjusted for the blood vessel wall). Further, only the TDI (color Doppler) image may be displayed independently without superimposing the B mode image and the M mode image.

  Furthermore, as can be seen in normal B-mode tomographic devices and blood flow color flow mapping, in order to clarify correspondence with biological signals such as electrocardiograms, simultaneous display of biological signal waveforms and time difference display from electrocardiogram R waves, etc. May be performed.

  Furthermore, an absolute velocity calculation unit is inserted between the frequency analysis unit 22 and the coding calculation unit 23 in the above embodiment, so that the absolute velocity of the movement of the tissue such as the myocardium (that is, the movement of the tissue at each sample point) The direction speed itself can be estimated and calculated as shown in, for example, Japanese Patent Laid-Open No. 6-114059, and the absolute speed can be displayed in a two-dimensional color.

  On the other hand, the low-speed area for gradation of the gradation display capability according to the present invention is not limited to “−fr / 8 ≦ fd ≦ fr / 8” in the above-described embodiment, and the program of the encoding operation unit 7 for example, the range of “−fr / 12 ≦ fd ≦ fr / 12” as shown by the one-dot chain speed conversion scale in FIG. 7 or the two-dot chain speed conversion scale as shown in FIG. , “−fr / 16 ≦ fd ≦ fr / 16” may be set. Further, these frequency ranges “−fr / 8 ≦ fd ≦ fr / 8”, “−fr / 12 ≦ fd ≦ fr / 12”, “−fr / 16 ≦ fd ≦ fr / 16” are manually operated by the operator. Switching may be performed according to the signal, and an appropriate range may be selected while viewing the display screen. For this purpose, in FIG. 1, the CPU 43 that has received a manual operation signal from the operation panel 14 may send a switching signal related to the operation to the encoding operation unit 23.

  Further, in the low speed region emphasis display according to the present invention, for example, as shown in FIG. 8, a speed conversion with a larger gradient is performed in a desired low speed region, for example, “−fr / 12 ≦ fd ≦ fr / 12”. A scale may be assigned, and a speed conversion scale having a gentler slope may be assigned to the medium speed region outside the scale, and the switching operation of the slopes of the multi-stage speed conversion scale shown in FIG. What should I do? As a result, a two-dimensional color image can be obtained in which the speed relationship between the low speed region and its peripheral part is slightly taken into consideration.

  Further, in the low speed region highlighting method according to the present invention, a speed conversion scale shown by a solid line in FIG. 9 can also be used (the one-dot chain line in FIG. 9 is a scale for conventional blood flow analysis). This speed conversion scale is stored in advance in the encoding calculation unit 23 in the form of a storage table, for example. For example, in a range of −fr / 8 <fd <+ fr / 8, which is defined as a low speed range, gradation of a hue that gradually changes (ie, continuously) from red to yellow and from blue to light blue in each tissue motion direction. A speed display code corresponding to the data is assigned. However, when the averaged Doppler shift frequency fd (that is, the average motion speed of the tissue) reaches fd ≧ ± fr / 8, the hue is changed to a previously changing hue from red to yellow or blue to light blue, Are uniformly assigned speed display codes of special display colors CL1 and CL2, which are not continuous at all. The special display colors CL1 and CL2 are colors generated by mixing a certain hue with, for example, red and blue hues. Of course, the speed threshold at this time is not limited to ± fr / 8, and can be changed. As a result, the movement speed of the tissue exceeding the predetermined low-speed range can be distinguished at a glance based on the discontinuous hue, so that the observation of the image for diagnosis is further facilitated in combination with the highlighting of the low-speed range. Pushed forward.

  Further, the gradation data of the speed display code according to the color display of the present invention changes the luminance of red (or blue) according to the speed as well as the hue changing according to the speed as described above. You may make it make it.

  Furthermore, the above-described embodiments and modifications thereof can be applied to an ultrasonic diagnostic apparatus that performs conventional blood flow Doppler imaging as necessary.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment described above, the purpose is to improve the display capability of the low-speed region. However, the ultrasonic diagnostic apparatus of the second embodiment performs normal / abnormality of the region of interest in addition to the improvement of the display capability. This makes it easy to distinguish diagnoses. In order to achieve this object, the ultrasonic diagnostic apparatus of the second embodiment is configured as shown in FIG.

  Specifically, this ultrasonic diagnostic apparatus drives the ultrasonic probe 100 and processes the received signal of the ultrasonic probe 100, which is responsible for transmission and reception of ultrasonic signals with the subject. The apparatus main body 101 is provided.

  Among them, the ultrasonic probe 100 is formed in a phased array shape as in the first embodiment. The apparatus main body 101 includes an ultrasonic transmission / reception unit 110 connected to the ultrasonic probe 100. A phase detector 111, an A / D converter 112, a filter 113, a motion speed analysis unit 114, a DSC 115, a color are provided on the output side. A processor 116, a D / A converter 117, and a color monitor 118 are sequentially connected.

  In addition, a blank controller 121 for blanking at least a part of a color image of tissue motion, which will be described later, is connected to the motion speed analysis unit 114. The blank controller 121 is connected via an input device 122. Necessary information is given by the examiner.

  The ultrasonic transmission / reception unit 110 drives the ultrasonic probe 100 at a given rate pulse period, and performs a phasing addition of echo signals from the ultrasonic probe 100, and the transmission / reception circuit 110a has a raster address and the like. An RPG (Rate Pulse Generator) 110b that provides necessary information and an envelope detector 110c that generates a B-mode image signal function in the same manner as in the first embodiment.

  The output side of the transmission / reception circuit 110a is sequentially connected to a phase detector 111, an A / D converter 112, and a filter 113, and these units are the phase detector 20 and the filter unit 21 (A / D conversion in the first embodiment). Function).

  The frequency analysis unit 114 includes a frequency analyzer 114a that performs Doppler frequency analysis of each sample point on the fault plane based on an autocorrelation method or the like, and based on the analysis result, an average Doppler frequency (average velocity) of each sample point. Is provided with a speed calculator 114b that calculates a dispersion value (spectrum disturbance degree) and a power calculator 114d that calculates intensity (power).

  In this embodiment, the speed calculator 114b includes a CPU 1140 and a memory 1141, as shown in FIG. A program for the process shown in FIG. 12 is previously stored in a predetermined storage area of the memory 1141, and the process is automatically executed when the speed calculator 114b is activated. The speed calculator 114b may be configured by combining analog and digital electronic circuits so as to function in the same manner as in FIG.

With blank controller 121 decrypts the signal supplied from the input unit 122, thereof corresponding to the decoded value, blanking threshold signal S _{[theta] th} and scaling thresholds theta _th polarization angle values theta required supplying a counting signal _{S K} of the coefficient K to the speed calculator 11b.

  The DSC 115 inputs the black and white B-mode tomographic image data output from the envelope detector 110c and the TDI image data output from the speed calculator 114b, dispersion calculator 114c, and power calculator 114d. Then, frame image data is formed by superimposing (combining) the TDI image on the B-mode image. This frame image data is sent to the color processor 116. The color processor 116 colors the TDI image pixels according to the speed display code, and sends the colorized frame image data to the color monitor 118 via the D / A converter 117.

  Here, the processing of the speed calculator 114b will be described with reference to FIG.

The CPU 1140 of the speed calculator 114b first reads the threshold signal S _θth supplied from the blank controller 121 in step 200. Then proceeds to store the threshold theta _th specified by the threshold signal S _{[theta] th} to step 201. As will be described later, the speed calculator 114b, for example, Re, Im among the autocorrelation coefficients Re, Im (complex number), Po (power) of the average Doppler frequency (average speed) that is the analysis result of the frequency analyzer 114a. , And the declination angle θ representing the point on the unit circle on the complex plane corresponding to the tissue motion speed V is obtained (see FIG. 13), and the threshold θ _th is the motion speed as shown in FIG. This corresponds to a threshold value _Vth of V (ie, Doppler frequency).

CPU1140 then proceeds to step 202, reads a coefficient signal _{S K} that specifies the scale conversion factor for display performance enhancement of TDI K (> 1) from a blank controller 121. And stores the scaled coefficients K corresponding to the coefficient signal S _K in step 203. When the coefficient K = 1, the blood flow velocity is being analyzed.

Next, in step 204, the CPU 1140 inputs, for example, autocorrelation coefficients Re and Im analyzed by the frequency analyzer 114a, and in step 205 calculates the deflection angle θ corresponding to the tissue motion velocity V described above. The deflection angle θ at this time is a scale conversion coefficient K = 1, that is, a value corresponding to blood flow velocity analysis, and moves on a straight line (velocity conversion scale) indicated by a one-dot chain line d in FIG. In the figure, a speed display code CD _V (e.g., 8-bit) representing a luminance gradation as gradation data of the movement speed V on the horizontal axis and the red (movement direction approaching the probe) and blue (movement direction away from the probe) on the vertical axis. Each of the logical value data). On the same figure, various straight lines according to the present invention, that is, a speed conversion scale can be drawn as will be described later, but the straight line d is a speed conversion scale corresponding to blood flow analysis. As is well known, the speed conversion scale d is uniformly assigned a speed display code CD _V that continuously changes to all the speeds V within the range of the folding speed ± fr / 2.

Furthermore, in step 206, the CPU 1140 determines whether or not the deviation angle θ calculated in step 205 is θ> θ _th (ie, V> V _th ) with respect to the threshold value θ _th set in step 201. . If the determination is YES (θ> θ _th ), the process proceeds to step 207, and blank processing is instructed for the pixel having the motion speed that satisfies θ> θ _th (V> V _th ). This blank processing is processing for forcibly setting the speed display code CD _V of the pixel to speed display code CD _V = “0, 0,..., 0” (blank code) when V = 0.

When this blank command ends or when NO (θ ≦ θ _th ) is determined in step 206, the process proceeds to step 208. In step 208, the scale conversion coefficient K (> 1) set in step 203 is multiplied by the declination value θ calculated in step 205.

By the multiplication “K · θ” of the coefficient, the declination value θ, that is, the motion speed V of the tissue is converted into a highlighted display mode in the low speed region of the TDI image. For example, the speed conversion scale that makes a predetermined value such that K = K ₁ (>1; for example, “4”) shifts from a straight line d corresponding to blood flow analysis to a in FIG. Even if the declination value θ (= 0) that has already been blanked is multiplied by the coefficient K, the value is zero, so that the speed conversion scale a showing an example for TDI is V = ± as shown in FIG. V a (for example, ± fr / 8) is represented by a straight line using speed display codes for all the set luminance gradations of the display colors “red” and “blue”, and is maximum in the range of Va ≧ | V | ≧ V _th It becomes saturated with the speed display code ± CDV (MAX) corresponding to the brightness, and falls to correspond to the horizontal axis passing through the origin at V = ± V _th , that is, the black display color.

As another example, the speed conversion scale when the coefficient K = K ₂ (> K ₁ : for example “8”), K = K ₃ (> K ₂ : for example “16”) is multiplied by the declination value θ is shown in FIG. 14 are characteristic lines b and c. The speed conversion scale b linearly increases / decreases between V = ± Vb (for example, ± fr / 12), saturates between Vb ≧ | V | ≧ V _th , and the speed display code with maximum brightness of red and blue ± CD _{V (MAX)} is set. In the case of the other speed conversion scale c, V = ± Vc (for example, ± fr / 16) is similarly linearly increased / decreased and saturated between Vc ≧ | V | ≧ V _th and the maximum luminance speed is obtained. Display code ± CD _{V (MAX)} is set. Both scales b and c fall by blanking in the range of | V | ≧ _Vth . Thus, the linear portion of the speed conversion scale becomes steep in proportion to the value of the coefficient K to be multiplied. For this reason, in proportion to the value of the scale conversion coefficient K, the display capability of the gradation portion in the low speed region is emphasized.

When the multiplication of the scale conversion coefficient K for the TDI display is thus completed, the CPU 1140 proceeds to step 209 in FIG. 12, and the K-folded deflection angle value θ (that is, the speed V) is converted to the speed display code CD _V. Perform conversion. This conversion is performed by referring to a storage table indicating the correspondence between the deflection angle value θ stored in advance in the memory 1141 and the speed display code CD _V (for example, 8-bit value). Next, at step 210, and outputs the converted rate display code CD _V to DSC115.

Again determines whether or not to change the threshold value θ _{th (V th)} or / and the coefficient K of the threshold signal S.theta _th and coefficient signal _S declination value in step 212 of _K theta in addition step 211, changes If so, the process returns to step 201 or 203. When the blank process is continued without changing the threshold value _θth and the coefficient K, the process returns to step 204 via step 213. Blank control is performed as described above.

  An echo signal obtained by transmitting an ultrasonic beam into the living body from the ultrasonic probe 100 is received by the probe 100 again. This echo signal is converted into a reception signal of an electric quantity by the probe 100, subjected to reception processing by the transmission / reception circuit 11a, and further subjected to quadrature detection by the phase detector 111. From the Doppler signal detected by the detection, the filter 113 extracts a component including a frequency component corresponding to the tissue motion, and sends the Doppler signal including the clutter component to the frequency analyzer 114a. The frequency analysis result is sent to the speed calculator 114b, the dispersion calculator 114c, and the power calculator 114d, and a target amount related to the tissue motion is calculated. The power calculator 114d performs the process “K · log10Po”.

As shown in FIG. 14, the velocity calculator 114 b is connected to the threshold value θ _th for the declination value θ (that is, the velocity threshold value V _th for the tissue motion V) via the input device 122 and the blank controller 121. , And a scale conversion coefficient K = K ₂ (straight line b) related to TDI display is commanded. In this case, the entire code conversion characteristic on FIG. 14 is represented by a one-dot chain line mb.

For this reason, when the average velocity (value of K · θ) calculated for TDI highlighting falls within the low velocity range of | V | <± Vb, the entire allowable velocity display code CD _V is used. When the speed V falls within the range of ± Vb ≦ | V | <± V _th , it is saturated at the maximum luminance code of ± CD _{V (MAX)} , and a blank code is assigned to the speed _satisfying ± V _th ≦ | V | .

The motion speed analysis result including the average speed data blanked in this way is sent to the DSC 115. The DSC 115 also receives B-mode image data from the envelope detector 110c, and motion speed information is superimposed on the B-mode image. The superimposed frame image data is colored by the color processor 116 and displayed on the color monitor 118. This display image is a black and white B-mode image on which background motion speed information such as a tissue motion color image is superimposed. A pixel having a speed value equal to or higher than the specified speed _Vth is shown in step 207 of FIG. Since the blank processing is performed, the color image of the pixel is not displayed. That is, the color information is not overwritten on the pixels in the high speed region where ± V _th ≦ | V |, and the B-mode image of the background image can be seen by the inspector.

For this reason, by setting a velocity threshold value V _th (specifically, a threshold value θ _th of the declination θ) designated for cutting the high velocity region to an appropriate value, the motion of the tissue such as the myocardium The maximum luminance portion having no gradation can be suppressed to a necessary minimum area (pixel). As a result, an easy-to-view screen can be obtained, and the situation where the highest luminance part unnecessary for analysis of tissue motion obstructs the diagnosis can be avoided, thereby contributing to an improvement in diagnosis efficiency (diagnosis time and diagnosis effort).

  In addition, since a background image (monochrome B-mode image) appears instead of such a high-intensity image, there is an advantage that information useful for diagnosis is increased.

  Naturally, since the speed conversion scales a, b, and c (see FIG. 14) that emphasize the low speed range are used, the slow motion speed of the necrotic tissue can be easily identified, and the normal / abnormal of the region of interest can be distinguished. Diagnostic ability is improved.

Further, in this embodiment, the threshold value _Vth of the motion speed V can be set independently of the speed conversion scale a (... C), and the maximum luminance of red and blue left on the monitor screen ± CD _{V (MAX)} . The portion can be adjusted as appropriate for the same speed conversion scale a (... C) (ie, the same low speed enhancement function). Therefore, as is the selection condition of the speed threshold V _th and scale conversion coefficient K shown by a dashed line m ₁ of FIG. 15, can either be left luminance region of highest grayscale on the monitor screen, the As indicated by the solid line m ₂ , it is possible to blank out only the TDI color image before reaching the maximum gradation brightness.

In this embodiment, a plurality of speed conversion scales a ... c are prepared in advance for tissue motion analysis, and they can be selected / switched as appropriate (see steps 202 and 211 in FIG. 12). For this reason, versatility is greatly improved. Note that virtual lines ma and mc on FIG. 14 show another example of the speed conversion characteristics when the speed threshold _Vth is constant.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS. In the ultrasonic diagnostic apparatus according to the third embodiment, the above-described blanking process in the high speed region of tissue motion is performed after the speed display code for emphasizing the low speed region is calculated. In the third and subsequent embodiments, the same reference numerals are used for the same or equivalent components as in the second embodiment, and the description thereof is omitted or simplified.

FIG. 16 shows a block configuration of the ultrasonic diagnostic apparatus of the third embodiment. A blank processor 125 is interposed between the motion speed analysis unit 114 and the DSC 115. From the blank controller 121 while only factor signal S _K described above is supplied to the speed calculator 114b described above, the code threshold signal S _CDth rate display code to a blank processor 125 is adapted to be supplied ing.

  The blank controller 121 has a computer function including a CPU 1210 and a memory 1211. The CPU 1210 performs a series of processes shown in FIG. In this embodiment, the CPU 1140 of the speed calculator 114b performs a series of processes shown in FIG. Further, the blank processor 125 also includes a CPU 1250 and a memory 1251, and the CPU 1250 performs a series of processes shown in FIG.

First, the operation of the blank controller 121 will be described with reference to FIG. The CPU 1210 calculates the scale conversion coefficient K from the operation signal read from the input device 122 in steps 250 and 251. And outputting a coefficient signal _{S K} which corresponds to the calculated coefficient K to the speed calculator 114b (step 252). Thereafter, in step 253, the speed ± V _(MAX) corresponding to the speed display code ± CD _{V (MAX)} with the highest luminance when the speed conversion scale corresponding to the blood flow analysis is multiplied by K is calculated (see FIG. 29 ₎ . ). The calculation of ± V _(MAX) may be performed by the speed calculation unit 114b, and the calculated value may be sent back.

Next, in step 254, the CPU reads an operation signal from the input device 122, and in step 255, calculates a desired speed threshold V _th desired by the examiner (see FIG. 20). The speed threshold here is not directly related to the deflection angle θ. This is because the speed threshold value V _th is intended to give a threshold value for the already converted speed display code CD _V output from the speed calculator 114b.

In the next step 256, it is determined whether or not | V _th | ≦ V _MAX using the speed threshold value V _th . When this determination is YES, that is, when −V _MAX ≦ V _th ≦ + V _MAX , the threshold value CD _th (see FIG. 20) of the speed display code corresponding to the threshold value V _th is calculated (step 257), Next, the code threshold value signal S _CDth corresponding to the threshold value CD _th is output to the blank processor 125 (step 258). On the other hand, if NO in step 256, that is, if | V _th |> V _MAX , in step 259, a display indicating that blank processing is not possible is displayed on the monitor 118 via the DSC 115 (FIG. 16). Signal _SUN ).

After the processing of step 259 and step 258, the operation signal from the input device 122 is tried again in step 260, and the examiner wants to change the scale conversion coefficient K or / and the speed threshold value _Vth in step 261. Determine whether or not. If the determination is YES (change), the process returns to step 251 or 255 and the above-described processing is repeated. Further, if NO in step 261 (does not change), it is determined in step 262 whether or not the process is finished. If the process is to be continued, the process waits while performing the processes in steps 260 to 262.

Next, the operation of the speed calculator 114b is shown in FIG. This operation is the same as or equivalent to the corresponding code portion in the series of processes shown in FIG. 12 described above, except for steps 200, 201, 206 and 207. Thus, in real-time in response to the scaling factor K, which is commanded from the blank controller 121, speed display code CD _V emphasizing the low-speed range is output to the blanking processor 125.

Further, the operation of the blank processor 125 will be described with reference to FIG. The CPU 1250 of the processor 125 first reads the code threshold value signal S _CDth supplied from the blank processor 121 in step 270 and sets the threshold value CD _th of the speed display code in step 271. Next, at step 272, the speed display code CD _V is read from the speed calculator 114b, and at step 273, it is determined whether or not | CD _V |> CD _th . When this determination is YES (the absolute value of the sent code CD _V exceeds the threshold value CD _th ), the _{routine proceeds} to step 274, where the speed display code CD _V is blanked. As a result, a blank code is forcibly assigned to the velocity V of the pixel where | CD _V |> CD _th .

When NO at step 273, that is, when | CD _V | ≦ CD _th, and when the blank processing is finished at step 274, the speed display code (code including the blank code) CDV * is output to the DSC 115 (step 275). ).

Next, the _{CPU 1250 tries} to read the code threshold value signal S _{CDth which} may be supplied from the blank processor 121 in step 276, and determines whether or not the threshold value CD _th is _{desired to} be changed in step 277. To do. If the threshold value CD _{th is} to be changed, the process returns to step 271; otherwise, it is determined in step 278 whether or not the process has ended. If not, the process returns to step 272 and the above-described processing is repeated.

The blank processor 125 is not particularly illustrated, but when observing the dispersion value and / or power value of the speed alone, these values are supplied directly to the DSC 115 and used together with the speed V. When observing, priority is given to the speed V (that is, the speed display code CD _V ), and the pixels satisfying | CDv> CD _th are blanked. These processes are performed based on a command signal S _con from a console (not shown).

Blank controller 121, the speed calculator 114b, since the blank processor 125 operates as described above, as shown in FIG. 20, the threshold V _th of the blank processing examiner instructs the low speed region of the tissue motion Only when the speed is within the speed ± V _th corresponding to the highest gradation when the is highlighted, pixels having a speed exceeding the speed threshold value ± V _th are automatically blanked. As a result, the same effects as those of the second embodiment can be obtained, and the blank process can be fixed even when the scale conversion coefficient K is changed.

However, in this embodiment, the speed display code CV _V after ± V _{MAX in} FIG. 20 has no gradation, so even if the inspector specifies a threshold value ± V _th exceeding ± V _MAX , the inspector However, blank processing is not performed. Thus, the examiner can freely command the value of ± V _th without paying special attention to where the ± V _MAX in the low speed region highlighting is, and the operation becomes easy.

The function of the blank processor 125 may be included in the DSC 130 as shown in FIG. In this case, the code threshold signal S _CDth and the other control signals Sun and S _con are supplied to the DSC 130. The DSC 130 performs blank processing on the speed display code CD _v with the code threshold value CD _th corresponding to the speed threshold value V _th as described above, and superimposes the tissue motion information image data and the B-mode image data. As a result, an appropriate speed threshold value V _th (CD _th ) can be set in the low speed range having the gradation of the speed calculation output CD _v , and the blank action and effect equivalent to the third embodiment can be obtained. It is done.

(Fourth embodiment)
In the second to third embodiments described above, the blank processing threshold value can be set regardless of the speed conversion scale for low-speed emphasis display, but in conjunction with the setting of the speed conversion scale. The threshold value (that is, the blank area) can be determined. The following examples illustrate such an ultrasonic diagnostic apparatus.

  A fourth embodiment of the present invention will be described with reference to FIGS.

The ultrasonic diagnostic apparatus shown in FIG. 22 includes the speed calculator 114b described above, and the CPU 1140 performs a series of processes shown in FIG. From the blank controller 121 so that the only factor signal S _K for the low speed range highlight is supplied.

23, the CPU 1140 of the speed calculator 114b performs the processing of Steps 300 and 301 (the same processing as Steps 202 and 203 of FIG. 12), and then the speed conversion scale (see the straight line a ... c in FIG. 24). The code threshold value ± _{CDV (MAX)} corresponding to the highest gradation level is calculated. Thereafter, the processing of Steps 303 and 304 (the same processing as Steps 204 and 205 in FIG. 12) is performed. In the process of FIG. 23, when the deflection angle θ is obtained in step 304, the process of steps 305 and 306 (the same process as steps 208 and 209 in FIG. 12) is immediately executed. Next, the CPU 1140 proceeds to step 307 and determines whether or not the speed display code CD _V is | CD _V | <CD _{V (MAX)} using the code threshold value ± CD _{V (MAX)} .

This determination is based on the intention to perform blanking for tissue movements at or above the speed corresponding to the maximum gradation. Therefore, the speed threshold _{Vth for} blanking is automatically set according to the maximum gradation of the scale after being multiplied by K. It will be decided. In other words, the speed threshold value is determined in conjunction with the speed conversion scale for low speed enhancement. For example, in the example of FIG. 24, in the case of the speed conversion scale a when the scale conversion coefficient K = K ₁ (> 1), the speed threshold value ± V _th−1 is set to K = K ₂ (> K ₁ ). In the case of the scale b, it is determined in conjunction with the speed threshold value ± V _th−2 , and in the case of the scale c when K = K ₃ (> K ₂ ), it is determined in conjunction with the speed threshold value ± V _th−3. .

When the determination in step 307 is YES (| CD _V | <CD _{V (MAX)} ), the process proceeds to step 309 and the speed display code CD _V having the code value as it is is output to the DSC 115. However, when NO (| CD _V | ≧ CD _{V (MAX)} ), that is, when the obtained speed display code CD _V has reached the maximum gradation of the red or blue luminance, the speed display code CD is determined in step 308. Force code value of _V = blank code. The code CD _V blanked in this way is also output to the DSC 115 in step 309. As a result, for example, when ± CD _{V (MAX)} = ± 128, blank processing is not performed until CD _V = ± 127, but blank processing is performed when CD _V = ± 128. As shown in FIG. 24, this is a characteristic in which the maximum gradation degree ± CD _{V (MAX)} falls to CD _V = 0.

  Next, the CPU 1140 performs the processing of steps 310 to 312 in the same manner as steps 211 to 213 of FIG.

With the above blanking process, the speed conversion scale a (... C) for highlighting the low speed region of tissue motion can be arbitrarily selected / switched, and the speed value V _th or more determined in conjunction with each scale a (... C) Pixels at the speed of are automatically blanked and a background image appears.

  Therefore, even in this embodiment, the advantages of the low speed region emphasis display and blank processing described above can be enjoyed well. In addition, there is an advantage that the inspector only needs to use the scale conversion coefficient K to command from the input device 122.

In the above embodiment, the blank processing threshold is set to the maximum gradation of ± CD _{V (MAX)} . However, if necessary, an appropriate code value lower than this can be set. In addition, the speed threshold value is automatically determined in conjunction with the code value, and only the color pixels having a higher speed are blanked in the same manner.

(5th Example)
Next, a fifth embodiment of the present invention will be described with reference to FIGS.

In this embodiment, as shown in FIG. 25, a separate blank processor 131 is inserted between the tissue motion analysis unit 114 and the DSC 115 as in FIG. 16, and processing including the steps shown in FIG. )). The blank controller 121 _{supplies a} threshold signal S _CDth blank processor 131 representing the code threshold value CD _th here.

As shown in FIG. 26, the blank processor 131 reads the code threshold value signal S _CDth and _sets the corresponding code threshold value CD _th (here, for example, ± CD _{V (MAX)} as in the above embodiment). (Steps 320 and 321). Next, the calculated speed display code CD _V is read, and it is determined whether or not | CD _V | <CD _th (steps 323 and 324). When | CD _V | = CD _th , blank processing is performed (step 325).

  Accordingly, when the speed range to be blanked is linked to the speed conversion scale, even after the display code of the average Doppler speed is calculated, it can be easily implemented by appropriately determining the code threshold value, and the same operation as FIG. An effect is obtained.

In this embodiment, the code threshold value S _CDth may be calculated by the speed calculator _{114 b and supplied} to the blank processor 131.

In addition, the function of the above-described blank processor 131 can be integrated and included in the DSC 115 as a display system (see FIG. 21; however, in this case, the control signal S _UN regarding whether or not the threshold value can be set) Supply is not required).

Although further wherein in the second to fifth embodiment and its modifications showing a speed display code CD _V as the gradation of red and blue luminance identifying the direction of tissue motion, speed display code CD _V, for example to other It may be expressed by hue gradation.

1 is a block diagram of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. The graph which shows the characteristic of the Doppler shift frequency (movement speed), such as a structure | tissue and a blood flow, and the characteristic of the low-pass filter used for a tissue Doppler imaging in the Example. The graph which shows an example of the speed conversion scale of the Example. The schematic flowchart of the process of the encoding calculating part in the Example. The figure which shows the relationship between the motion direction of the myocardium and a color bar in the Example. The figure which shows the example of a display of the myocardium in the Example. The figure which shows another example of a speed conversion scale. The figure which shows another example of a speed conversion scale. The figure which shows another example of a speed conversion scale. The block diagram of the ultrasonic diagnosing device which concerns on 2nd Example of this invention. The block diagram of the speed calculator in the Example. The flowchart which shows the process example of a speed calculator. The figure explaining the output data of a frequency analyzer. The figure which shows the example of a speed conversion scale. The figure explaining increase / decrease in the blank area corresponding to the change of a speed threshold value. The block diagram of the ultrasonic diagnosing device which concerns on 3rd Example of this invention. The flowchart which shows the process example of the blank controller in the Example. The flowchart which shows the process example of the speed calculator in the Example. The flowchart which shows the process example of the blank processing device in the Example. The figure which shows an example of the speed conversion scale in the Example. The block diagram of the ultrasound diagnosing device which concerns on the modification of this invention. The block diagram of the ultrasonic diagnosing device which concerns on 4th Example of this invention. The flowchart which shows the process example of the speed calculator in the Example. The figure which shows the example of the speed threshold value of the blank area linked with a speed conversion scale. The partial block diagram of the ultrasonic diagnosing device which concerns on 5th Example of this invention. The flowchart which shows the process example of the blank controller of the Example partially. The figure of the speed conversion scale at the time of the blood-flow velocity analysis which shows an example of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic diagnostic apparatus 11 Ultrasonic probe 14 Operation panel 15 Ultrasonic transmission / reception part 19 Display 20 Phase detection part 21 Filter part 22 Frequency analysis part 23 Coding calculating part 24 TSC DSC part 100 Ultrasonic probe 110 Ultrasonic transmission / reception part 111 Phase detector 112 A / D converter 113 Filter 114a Frequency analyzer 114b Speed calculator 115 DSC
116 Color processor 117 D / A converter 118 Color monitor 121 Blank controller 122 Input device 125 Blank processor 130 DSC
131 Blank processor

Claims (21)

In an ultrasonic diagnostic apparatus that displays a color image of a tomographic plane related to the motion of a tissue included in the tomographic plane of a subject
Scanning means for scanning an ultrasonic pulse signal along the tomographic plane to obtain an echo signal of an electric quantity corresponding to the ultrasonic reflection signal from the tomographic plane;
Extraction means for extracting a Doppler signal following the movement of the tissue from the echo signal;
Speed calculating means for obtaining data on the speed of movement of the tissue based on the Doppler signal for each sample point of the tomographic plane;
An operation signal for specifying a scale for associating the speed-related data in the measurable Doppler frequency range limited by a predetermined pulse repetition frequency of the ultrasonic pulse signal with the gradation data of the color display assigned to the data is received. An operation signal receiving means;
In accordance with the operation signal, a desired low speed range in the Doppler frequency range is assigned to gradation data having a predetermined range of values, and the remaining speed range of the Doppler frequency range is constant value gradation data. Scale setting means for setting the scale to be assigned to
Speed conversion means for converting the data relating to the speed into the gradation data based on the scale;
An ultrasonic diagnostic apparatus comprising: display means for displaying the gradation data converted by the speed conversion means in color. The ultrasonic diagnostic apparatus according to claim 1, wherein the scale is set such that a rate of change of the gradation data with respect to data relating to the speed in the low speed range is set nonlinearly. The low velocity region is defined as −fr / 8 ≦ fd ≦ fr / 8, −fr / 12 ≦ fd ≦ fr /, where fr is a predetermined pulse repetition frequency of the ultrasonic pulse signal and fd is a Doppler shift frequency. 12. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is one of 12 and −fr / 16 ≦ fd ≦ fr / 16. 4. The scale according to claim 1, wherein the scale is a scale in which the low speed range is assigned to all values of the gradation data and the remaining speed range is assigned to the maximum value of the gradation data. An ultrasonic diagnostic apparatus according to 1. The ultrasonic diagnostic apparatus according to claim 4, wherein the scale changes linearly with respect to the low speed range. The scale changes into a bent straight line having a first value and a second value lower than the first value with respect to the low speed range, and a change in a straight line portion having the first value. The ultrasonic diagnostic apparatus according to claim 4, which is located on a low speed side within the Doppler frequency range. The ultrasonic diagnostic apparatus according to any one of claims 1 to 6, wherein the gradation data includes a plurality of color data in which one of a luminance and a hue of a color representing the movement direction of the tissue is changed. . The gradation data includes color data of gradation that has a continuous connection that changes in accordance with changes in the data related to the speed, and at least the highest value of the gradation data is gradationally different from its low gradation side. The ultrasonic diagnostic apparatus according to claim 7, which is discontinuous color data. In an ultrasonic diagnostic apparatus that displays a color image related to the motion of a tissue included in a tomographic plane superimposed on a tomographic image of a tomographic plane of a subject,
Scanning means for scanning an ultrasonic pulse signal along the tomographic plane to obtain an echo signal of an electric quantity corresponding to the ultrasonic reflection signal from the tomographic plane;
Extraction means for extracting a Doppler signal following the movement of the tissue from the echo signal;
Speed calculating means for obtaining data on the speed of movement of the tissue based on the Doppler signal for each sample point of the tomographic plane;
Tomographic image forming means for forming data of the tomographic image from the echo signal;
A scale that correlates the data relating to the velocity in the measurable Doppler frequency range limited by a predetermined pulse repetition frequency of the ultrasonic pulse signal and the gradation data of the color display assigned to the data is defined in the Doppler frequency range. A scale setting means for setting so that a desired low speed region is assigned to gradation data of a predetermined range of values and the remaining speed region of the Doppler frequency range is assigned to gradation data of a constant value;
Speed conversion means for converting data relating to the speed into the gradation data based on the scale;
Blank processing means for subjecting the sample point where the amount of any one of the gradation data converted by the speed conversion means and the speed-related data calculated by the speed calculation means exceeds a specified threshold value to blank processing When,
An ultrasonic diagnostic apparatus comprising: display means for superimposing data relating to the speed, which has undergone blank processing by the blank processing means, on data of the tomographic image and displaying the data relating to the speed in color. The scale setting means relates to the speed corresponding to the maximum value of the gradation data, wherein the ratio of the gradation data to the change of the Doppler frequency is higher than the ratio at the time of the kinetic fluid analysis of the subject. The ultrasonic diagnostic apparatus according to claim 9, which is means for setting the scale for assigning the highest value to data larger than data. The ultrasonic diagnostic apparatus according to claim 10, wherein the gradation data includes gradation data of luminance of a designated color that represents the direction of movement of the tissue. The ultrasonic diagnostic apparatus according to claim 10, wherein the gradation data includes gradation data of a hue of a designated color that represents the direction of movement of the tissue. The ultrasonic diagnostic apparatus according to claim 10, further comprising threshold value specifying means for specifying the threshold value independently of the setting of the scale. The ultrasonic diagnostic apparatus according to claim 13, wherein the one amount is speed data calculated by the speed calculation unit. The speed calculation means includes frequency analysis means for analyzing a frequency component of the Doppler signal, and speed calculation means for calculating data relating to the speed at each sample point based on an analysis result after the frequency analysis, 15. The ultrasonic diagnostic apparatus according to claim 14, wherein the speed calculation means, the speed conversion means, and the blank processing means are provided in one calculation unit. The ultrasonic diagnostic apparatus according to claim 14, wherein the threshold value is a value of data relating to the speed corresponding to a maximum value of the gradation data determined by the scale. The one amount is gradation data converted by the speed conversion means, and the threshold value designation means designates a threshold value of gradation data in a range lower than the maximum value of the gradation data. The ultrasonic diagnostic apparatus according to claim 13, which is means for performing The ultrasonic diagnostic apparatus according to claim 17, wherein the blank processing unit is provided in a processor independent of at least the speed calculation unit and the display unit. The ultrasonic diagnostic apparatus according to claim 17, wherein the display unit includes a digital scan converter that superimposes the velocity data on the tomographic image data, and the digital scan converter includes the blank processing unit. The ultrasonic diagnostic apparatus according to claim 10, wherein the scale setting unit is a unit that automatically determines the threshold value in conjunction with the setting of the scale. 21. The ultrasonic diagnostic apparatus according to claim 20, wherein the one amount is gradation data converted by the speed conversion unit.

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