JP2987109B2 - Ultrasound Doppler diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic Doppler diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that clearly displays the velocity dispersion of a motion in a measurement area on an image.

[0002]

2. Description of the Related Art An ultrasonic Doppler diagnostic apparatus can be used for non-destructively measuring the motion state inside an inspection object. For example, an ultrasonic Doppler diagnostic apparatus has been conventionally used to measure a state of movement in a living body such as a blood flow or a body fluid flow in an organ such as a heart or a circulatory organ and a blood vessel. The conventional device described in Japanese Patent Publication No. 2-16139 transmits an ultrasonic pulse beam, detects a moving speed by a frequency shift of a reflected echo from a moving body in a living body, and detects a moving speed between ultrasonic pulses. The variance of the movement speed is detected from the autocorrelation. The velocity dispersion indicates, for example, the degree of irregular fluctuation of the blood flow. That is, when the velocity dispersion is small, it is determined that the blood flow is laminar, and when it is large, it is determined that the blood flow is turbulent, which is very useful information for medical diagnosis.

In the conventional apparatus, the direction, velocity, and velocity dispersion of blood flow are displayed in color on a normal gray scale B-mode tomographic image (color flow mapping). FIG. 8 is a schematic chromaticity diagram illustrating the principle of color flow mapping. In the color flow mapping, a flow approaching the probe is usually distinguished by a red hue, and a flow approaching the probe is distinguished by a blue hue. The magnitude of the velocity | V |
The green chromaticity is given to the speed variance T. That is, a y-axis from blue to red and an x-axis according to the degree of green are defined on the chromaticity diagram, and speed-dispersion display is performed using this coordinate system.
One point on the chromaticity diagram corresponds to a set of a certain speed value V and a certain speed variance value T, and the chromaticity designated at that point is defined as a pixel value to form an image. For example, for the same T, as V increases in the positive direction, the color becomes reddish, and as V increases in the negative direction, the color becomes bluish.
On the other hand, for the same V, the green component becomes stronger as T increases, that is, when the variance increases, for example, a positive speed represented by red becomes yellowish, and a negative speed represented by blue becomes blue. It turns green. The distribution image of the velocity represented by the color and the variance thereof is referred to as a color Doppler tomographic image. In addition, the echo intensity is represented by brightness of darkness, and, for example, a reflected echo from a stationary biological tissue is displayed in white.

[0004] According to such a display, the tissue structure in the living body, the direction, the velocity, and the velocity dispersion of the blood flow are simultaneously displayed on the image, so that extremely high-density diagnostic information can be provided. For example, when blood regurgitation is caused by a lesion such as insufficiency of the mitral or pulmonary valve of the heart, velocity dispersion is increased. As a result, the color tone of the color Doppler image at that location changes with time, and such an abnormality is visually detected.

[0005]

However, for example, in the case of the above-described abnormal blood flow due to abnormalities of the heart valve, the temporal change of the flow velocity of the cardiac blood flow due to the contraction and expansion of the heart is rapid, so that the color tone of the color Doppler image changes. May be instantaneous. As described above, when a disease causes a turbulence phenomenon that lasts only for a short time or a turbulence phenomenon that occurs in a small area, the conventional apparatus has a problem that it is easy to overlook them and a lesion cannot be detected sharply.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an instant or minute turbulence phenomenon can be easily detected on an image, so that a more accurate diagnosis can be performed. It is an object to provide an ultrasonic Doppler diagnostic device.

[0007]

An ultrasonic Doppler diagnostic apparatus according to the present invention comprises: measuring means for measuring a velocity V and a velocity dispersion T at each point in a measurement area by transmitting and receiving ultrasonic waves; A first dispersion emphasizing means for performing a variance conversion for transitioning the speed variance T according to the magnitude of T to obtain a post-transition velocity variance _Tm, and a speed conversion for transitioning the velocity V according to the magnitude of the velocity variance T comprising a second dispersion emphasis means for determining the velocity V _m after the transition, an image forming unit for forming an ultrasound image to determine the pixel value based on the post-transition velocity V _m and the post-transition velocity dispersion T _m, the It is characterized by the following.

According to the present invention, the transition of the speed variance T and the speed V by the variance conversion and the speed conversion are performed according to the magnitude of the speed variance T. Here, the transition is not a uniform movement from one start state to another one end state, but one end state is selected from a plurality of states based on a certain rule, and the selected end state is selected from the start state. Meaning transition to state. Therefore, for example, even if two pixels have the same T, the amount of transition of T (T _m −T) or the amount of transition of V (V _m −V) for these two pixels may be different. A certain rule at the time of performing a transition refers to, for example, following a stochastic distribution, following a transition direction defined for a partial area unit on an ultrasonic image, and the like. In the case of following the former stochastic distribution, the width of the stochastic distribution or the magnitude of the variance of the distribution is determined according to the magnitude of the velocity variance T.
In this case, stochastic processing may be performed in pixel units,
Stochastic processing may be performed for each partial area including a plurality of pixels. When the direction of the latter transition is defined, the magnitude of the absolute value of the transition amount is determined according to the magnitude of the velocity variance T, and the transition amount is moved by the absolute value in the defined direction. in this case,
Although the same transition direction is defined in the partial region, a pixel can be used as the partial region. The first and second variance emphasizing means perform the above-described variance conversion and velocity conversion, for example, in an area where T is larger on the ultrasound image, the spatial fluctuation width of the post-transition velocity variance T _m and the post-transition velocity V _m. Becomes larger. That is, the variation in the values of T _m and V _m increases, and the variation in the pixel value based on them also increases.
On the ultrasonic image, the magnitude of T is emphasized and displayed as the magnitude of the spatial variation of the pixel value, which makes it easier to visually recognize.

[0009] In a preferred embodiment of the present invention, the image forming means, wherein the post-transition velocity V _m and on the basis of the combination of the post-transition velocity dispersion T _m, to determine the chromaticity as the pixel value And According to this embodiment, defined by coordinates a transition after speed V _m of the one-way on the chromaticity diagram, defined by the post-transition velocity dispersion the other direction of the coordinate T _m, these V _m,
The chromaticity at the point specified by _{Tm is} defined as a pixel value. As a result, the velocity information and the velocity dispersion information are simultaneously displayed on the ultrasonic image. According to the present invention, the velocity dispersion information included in the multiplexed information image can be easily recognized.

In a preferred aspect of the present invention, the first variance emphasis means uses a random first transform coefficient R _T and a monotonically increasing function F (T) relating to the velocity variance T, The post-transition velocity variance T _m is obtained by the following equation: T _m = T + F (T) × _RT , and the second variance emphasis means uses a random second transform coefficient R _V and the monotone increasing function F (T ) and used, and obtains the following _{equation, V m = V + F (} T) × R V wherein after transition velocity V _m by.

According to this aspect, the respective transition amounts (T _m -T) and (V _m -V) of T and V are monotonically increasing functions F (T)
Therefore, the variation in T _m and V _m increases as T increases, and the magnitude of T is highlighted. The first and second random conversion coefficients R _T and R _V are, for example, average values 0
May be a random number that follows a Gaussian distribution, or a random number that is uniformly generated in a certain range. Further, the values of R _T and R _V may be continuous or discrete. further,
The values of R _T and R _V may be defined for each pixel, or may be defined for each group of a plurality of pixels.

Further, in a preferred aspect of the present invention, the first variance emphasis means is based on a random first conversion coefficient R _T defined for each small region constituting the ultrasonic image. The variance conversion is performed, and the second variance emphasis means performs the speed conversion based on a random second conversion coefficient R _V defined for each of the small areas. In another preferred aspect of the present invention, the first
The dispersion emphasizing means includes a first transform coefficient _RT that is a value for each pixel of a first irregular waveform function that varies irregularly along a scan line forming the ultrasonic image. Performing a variance conversion, wherein the second variance emphasis means is based on a second conversion coefficient R _V that is a value for each pixel of a second irregular waveform function that varies irregularly along the scanning line. And performing the speed conversion.

According to this aspect, the first and second dispersion emphasizing means are provided for the set of pixels included in the small area or the set of pixels corresponding to the waveform width of the irregular waveform function on the scanning line. Gives the same tendency and degree of T and V transition amounts, and gives another set of pixels adjacent to this pixel set a different tendency and degree of T and V transition amounts. This makes it possible to vary the pixel value of the ultrasonic image for each spatial unit larger than the pixel. In other words, a difference occurs in the average level of the pixel values in the small regions and the like included in the region where T is large, so that a smooth image quality is obtained in the region where T is small, while T is small. In a large area, for example, a mosaic pattern appears in units of the small area or the like, and the effect of appealing to the visual sense is further improved.

The ultrasonic Doppler diagnostic apparatus according to the present invention transits the velocity dispersion T according to the magnitude of the velocity dispersion T measured at each point in the measurement area by the transmission and reception of the ultrasonic wave, and performs the velocity dispersion after the transition. a dispersion emphasis means for determining the T _m, characterized in that it comprises an image forming means for forming an ultrasound image to determine the pixel values based on at least the post-transition velocity dispersion T _m. Further, the ultrasonic Doppler diagnostic apparatus according to the present invention transits the speed V according to the magnitude of the speed variance T measured at each point in the measurement area by the transmission and reception of the ultrasonic wave to change the post-transition speed _Vm . a dispersion enhancement means for determining, characterized in that it comprises an image forming unit for forming an ultrasound image to determine the pixel values based on at least the post-transition velocity V _m, a. ADVANTAGE OF THE INVENTION According to this invention, in the ultrasonic image which displays the arbitrary measured quantity in a measurement area | region, the information of a velocity dispersion | variation can be emphasized and superimposed and displayed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a main part of an ultrasonic color Doppler diagnostic apparatus embodying the present invention. Here, a living body is considered as a measurement target. The probe 2 has a transducer array. The vibrator array is supplied with a pulse-like transmission signal generated by the transmission / reception circuit 4 and is excited.
An ultrasonic pulse beam is transmitted into the body, which is a measurement area.
The reflected echo of the ultrasonic pulse beam from the inside of the body is converted into an electric reception signal by the probe 2 and taken into the reception system via the transmission / reception switch in the transmission / reception circuit 4.
The beam scan is performed by controlling the transmission direction of the ultrasonic pulse beam by controlling the phase difference of the transmission signal between the transducer arrays, and by processing the reflected echo obtained thereby, the living body is scanned. A tomographic image can be obtained. The present apparatus is configured to perform both normal B-mode display and color Doppler display as tomographic images. The reception signal is amplified by the transmission / reception circuit 4 and subjected to a process such as a wave phasing process for adjusting the phase difference of the reception signal between the transducer arrays, and then to a B mode display process via a distributor therein. Are output to both the receiving and shaping detection circuit 6 which is the system of the above and the quadrature phase detection circuit 8 which is the system of the color Doppler display processing.

In generating a B-mode tomographic image, a received signal is received by a reception shaping detection circuit 6, an analog / digital (A / A /
D) After being input to the image display generation circuit 12 using the digital scan converter (DSC) through the conversion circuit 10,
It is stored as mode tomographic image data.

In the generation of a color Doppler tomographic image,
The received signal is output from a quadrature detection circuit 8, an A / D conversion circuit 16,
Through the clutter suppression circuit 18 and the blood flow information calculation circuit 20,
The image data is input to the image display generation circuit 12 and stored as color Doppler tomographic image data. Here, the quadrature phase detection circuit 8 performs quadrature phase detection processing for detecting a received signal from a living body with reference waves having phases different from each other by 90 ° to generate a complex Doppler signal. This output also includes reflected signals from relatively slow-moving heart walls and valve movements. This low-frequency Doppler signal has a large amplitude, for example, several hundred times that of the reflected signal from the blood flow, and significantly interferes with the blood flow measurement (clutter). The clutter suppression circuit 18 removes this clutter by removing low frequency components in the Doppler signal.

The blood flow information calculation circuit 20 is a circuit for analyzing the Doppler signal, and calculates the average blood flow velocity at each point from the average Doppler frequency by the autocorrelation method or the like, and performs the distributed calculation to calculate the spread of the velocity. , Power calculation for obtaining the power of the Doppler signal. The speed V and the variance T obtained as a variable value representing the motion state by these calculations are stored in the buffer memory as a speed image and a speed dispersion image, respectively. The X and Y addresses of this memory correspond to the measurement coordinate system. That is, when measured in the rectangular coordinate system (X, Y), the X and Y addresses correspond to the X and Y addresses, respectively. Therefore, in the case of the rectangular coordinate system, the speed image and the speed dispersion image respectively stored in the memory directly correspond to the image of the actual measurement area, and thus these may be directly input to the image display generation circuit 12. When measured in the polar coordinate system (r, θ), the X coordinate and the Y coordinate correspond to the θ coordinate and the r coordinate, respectively. However, in the case of the polar coordinate system, when the speed image and the speed dispersion image respectively stored in the memory are directly displayed on the display 14, for example, the actual measurement area of the sector type is displayed in a different rectangle from the actual area. In this case, the image display generation circuit 12 performs a process of converting the image on the memory into the image of the actual area via the DSC. In this apparatus, color flow mapping is performed, and the chromaticity is determined based on the speed V and the variance T stored in the memory as described in the description of the related art, and is set as a pixel value. An image is generated.
The image display generation circuit 12 receives the color Doppler display data and the B-mode display data using the chromaticity as a pixel value, forms an image in which these are superimposed, and forms a display 14.
Display with.

FIG. 1 is a diagram focusing on the flow of a received signal, and shows a control system for adjusting the timing of the scanning operation by the probe 2 and the image display, for example. Is omitted.

Although the above-mentioned block configuration is the same as that of the conventional device, the feature of this device lies in the processing in the blood flow information calculation circuit 20 or the image display generation circuit 12. That is,
In the conventional apparatus, if the measured velocity V and the velocity variance T are the same, the chromaticity corresponding to the pixel value is uniquely determined, whereas in the present apparatus, the following equations (1) and (2) are used. As represented by the following equation, the speed variance T and the speed V obtained by the measuring means are transited based on random transform coefficients R _T and R _V to obtain the post-transition speed variance T _m and the post-transition speed V _m . After conversion, the chromaticity is determined using these T _m and V _m .

T _m = T + F (T) R _T (1) V _m = V + F (T) R _V (2) Here, for example, R _T and R _V are respectively −1 to 1 Is a random number taking the value of. The distribution is a Gaussian distribution having an average value of 0 in the present apparatus. In addition, R _T and R _V may be uniform random numbers in a certain range, or may be random numbers having discrete values, and various types can be used. R _T , R _V
What is essential for is that, in each case, different values can be taken, especially in adjacent areas of the image, and that a clear display of the speed variance on the image is possible. Therefore, as the dispersion emphasizing means of the present apparatus, a configuration using non-random numbers for R _T and R _V is also possible. For example, the values become 1, -1 alternately in a checkered pattern according to the position on the image. May be defined. F (T) is a monotonically increasing function of the velocity variance T, and is, for example, a function represented by the equation (3).

F (T) = K · sin ⁿ (π / 2 · T / T _M ) (3) where K is a constant and T _M is a constant defined as the maximum value of T. FIG. 2 shows an example of F (T) expressed by the equation (3), and shows a case where n = 1.5 and 2. In addition, F (T) may be any function as long as it is a monotonically increasing function. However, empirically, the function shown in equation (3) shows a good result for the purpose of clearly displaying the velocity dispersion T. Note that F (T) may be a different function in the equations (1) and (2), for example, a function having a different n in the equation (3). Further, instead of F (T), a function F (T, V) defined by two arguments of T and V can be used.

As described above, T _m and V _m are T and V, respectively.
Are randomly distributed around them. Since T _m and V _m vary randomly, even if there is a point where the pair of T and V is the same, the pair of T _m and V _m is not necessarily the same for them. Therefore, different chromaticities will be defined.
The degree of variation of each of T _m and V _m increases as the velocity variance T increases due to the monotone increasing function F (T). That is, dispersion enhancement is performed by the processing according to the equations (1) and (2). This device differs from the conventional device in that it has a dispersion enhancement means for a color Doppler image based on the conversion processing. By increasing the variation of the chromaticity according to the speed variance T, an image that gives a sense of roughness can be obtained visually where the speed variance T is large, and the difference in chromaticity, that is, the intensity of the green component of the chromaticity is obtained. Only by the speed dispersion T
This makes it easier to perceive the speed dispersion than in the conventional device that expresses the information.

The dispersion emphasizing means employed in this apparatus divides the image area into small areas (windows) in order to further enhance the visual appeal, and the pixels in each window have random numbers R _T , R _{T. V}
The same is used as a set of. The window is, for example, a 3 × 2 pixel area obtained by dividing an image into three pixels in the horizontal direction and two pixels in the vertical direction. By using the small area in this way, the image is represented in a mosaic shape. By making the spatial unit of dispersion emphasis not a pixel but an area of a certain size, it becomes more visually noticeable. However, if the size of the region is too large, it becomes difficult to specify a place where dispersion is large, for example, where the turbulence of the blood flow has occurred. And the accuracy required for detecting the position where the turbulence occurs. At this time, it goes without saying that the resolution of the image, that is, the maximum value of the X and Y addresses (corresponding to the number of horizontal pixels and the number of scanning lines of the image, respectively) is also involved. Note that since only random numbers are defined in common between pixels in the window, the original magnitude relationship between T and V between pixels is preserved. Therefore, the pixel values are generally not uniform in the window, and the resolution does not deteriorate. Hereinafter, the details will be described.

FIG. 3 is a schematic block diagram of a blood flow information converter that performs dispersion enhancement processing on the velocity image and velocity dispersion image stored in the memory. These image memories may be in the blood flow information calculation circuit 20 or before or after the DSC of the image display generation circuit 12. Further, it may be an orthogonal coordinate system or a polar coordinate system. For convenience, the description will be made using an orthogonal coordinate system (X, Y). The blood flow information converter 40 receives the velocity V from the velocity memory 42 storing the velocity image and the velocity dispersion T from the velocity dispersion memory 44 storing the velocity dispersion image. The input X and Y addresses of V and T in the memories 42 and 44 are specified by an image address generator 46. The X and Y addresses output from the image address generator 46 are also input to the blood flow information converter 40. The blood flow information converter 40 includes a random number generator 50 and three ROMs (Read Only Memory) 5.
2, 54, 56, and (1),
The conversion represented by equation (2) is performed to generate and output V _m and T _m .

The random number generator 50 is a table that assigns an index i associated with the random numbers R _V and R _T to each window of the image area. FIG. 4 shows a random number generator 50.
FIG. 4 is an image diagram of a table stored in the table. In the present apparatus, the window has a size of three horizontal pixels and two vertical pixels, and the entire image area, for example, an area of 512 × 512 pixels is divided into windows. X, Y
Index i for each pixel specified by the address
Is stored in the index i, and the same value is set for the pixels included in the same window. The index is, for example, an integer of i = 0 to 63, and is randomly and uniformly distributed between windows in the image area.

Each of the ROMs 52, 54, and 56 stores a two-dimensional conversion table that associates one value with two parameters. The value of _Tm corresponding to the set (T, i) of the velocity variance T and the index i is stored in the ROM 52 as (1)
It is calculated and stored in advance based on the formula. In this calculation, a random value R _T (i) associated with the index i is used as the conversion coefficient R _T. Also, processing after conversion is performed. For example, the velocity variance T _m is 0 ≦
The condition of T _m ≦ T _M is imposed, and the value of equation (1) is T _m <0.
Become (T, i) for the stores T _m = 0 to ROM 52, relative to the (1) the value of the equation is the _{T m> T M (T,} i), T m the ROM 52 = T _M is stored.

On the other hand, the dispersion emphasizing process for the speed V is RO
This is performed using the M54 and the ROM 56. In the ROM 54, the value of the second term on the right side of the equation (2) is calculated and stored in advance corresponding to the set (T, i). That is, [F (T) · R _V (i)] calculated using the random value R _V (i) associated with the index i is stored. ROM56
Is the speed V and [F (T) · R _V output from the ROM 54.
(i)] as two parameters, a value obtained by adding these two parameters to each other, that is, the value of the equation (2) is calculated and stored in advance. The contents of the ROM 56 also reflect the processing after the conversion based on the equation (2). That is, for example, the ROM 56
Stores the value (V _m −2 V _M or V _m +2 V _M ) subjected to the return processing when | V _m |> maximum flow velocity V _M by the calculation of equation (2).

By giving T and i to ROM 52 in this way, T _m corresponding thereto is determined, while RO is given.
By providing T, V, i to M54,56, V _m corresponding to these are determined, T from blood flow information converter 40
_m and _Vm are output. Conventionally, color flow mapping and display on the display 14 have been performed using T and V before conversion. In comparison with this, the present apparatus is different in that T _m and V _m obtained by randomly varying are used in place of T and V. Processing of color flow mapping and display 14
The display processing of the color Doppler image can be performed using the conventional circuit as it is. Note that the random numbers R _T (i) and R _V (i) used in the present apparatus are based on a Gaussian random number function generated, for example, in the range of −1 to 1 with an average value of 0. Other random number functions may be used.

FIG. 5 is a schematic diagram of a chromaticity diagram for explaining the principle of the color flow mapping in the present apparatus, and is a diagram for explaining the correspondence between the speed V, the speed variance T, and the points on the chromaticity diagram. . The setting of the coordinate axes is the same as in FIG. For example,
Three measuring points A (T ₁ , T ₁ ,
V ₁ ), B (T ₂ , V ₂ ), and C (T ₃ , V ₃ ). Dotted circles centered on the measurement points A, B, and C respectively represent the distribution ranges of points ( _Tm , _Vm ) corresponding to the measurement points. The blood flow information converter 40 has a function of associating each measurement point with one point randomly selected from the respective distribution ranges based on the random numbers R _T and R _V. The chromaticity specified on the chromaticity diagram by the selected one point ( _Tm , _Vm ) is determined as the pixel value of the color Doppler image.

Radius r ₁ , r ₂ , r of each distribution range
₃ is determined by equation (3). For example, r ₁ = F (T ₁ ), r
₂ = F (T ₂ ). If T ₁ <T ₂ , r ₁ <r ₂ , and the larger the measured value of the velocity dispersion T, the larger the variation in T _m and V _m . Therefore, when the blood flow becomes abnormal due to a disease or the like and the velocity dispersion T increases, the region becomes
One is that the change in chromaticity within the same window is emphasized,
The other is that the chromaticity gap between adjacent windows is large, and the mosaic-like pattern is clearly visible, so that it becomes visually conspicuous.

At the measurement point C, the velocity V ₃ is close to the maximum flow velocity V _M , so that the distribution range indicated by a circle partially protrudes from the domain of the chromaticity diagram. The blood flow information converter 40 accurately determines the point (T _m , V ′ _m ) in the protruding shaded area 80 as a point in the shaded area 82 on the opposite side on the velocity axis (y axis in the chromaticity diagram). Is R such that it corresponds to the point of (T _m , V ′ _m −2V _M ).
A conversion table of the OM 56 is defined. This is the return processing.

Speed memory 42, speed dispersion memory 44
In the case where the speed image and the speed dispersion image respectively stored in the image data correspond to, for example, a sector image represented by the polar coordinate system (r, θ), the conversion is performed by the same processing as described above. In this case, in order to display a sector image as an actual image on the display unit 14, the image display generation circuit 12 performs coordinate conversion by DSC. In addition, the velocity image and the velocity dispersion image in the polar coordinate system are
, The image may be once converted into an image in the rectangular coordinate system, and then the same processing as described above may be performed.

In the above-described configuration, the speed memory 42 and the speed image stored in the speed dispersion memory 44 are provided before the blood flow information converter 40, but the speed image and the speed dispersion image are stored here. It is not essential that the be stored. For example, the velocity V and velocity variance T of each point obtained by the measurement are sequentially converted into V _m and T _m by a blood flow information converter,
The converted data may be stored in the image display generation circuit 12 to form an image.

In this apparatus, the function of the blood flow information converter is
This is realized by conversion using a table stored in M or the like. In this table, various exceptional processes such as the return process can be defined in advance.
Therefore, even in the case where the arithmetic unit requires the condition determination processing and the processing time increases, the conversion using the table used in the present apparatus can be performed at a high speed with an inexpensive and simple configuration. Of course, it is also possible to realize the function of the blood flow information converter by using an arithmetic unit to implement the present invention.

When determining the contents of the ROMs 52 and 54, the random numbers R _T and R _{V as} the conversion coefficients are determined depending only on the index i. That is, the random numbers are R _T (i),
R _V (i). However, the contents of the ROMs 52 and 54 may be determined using random numbers of the form R _T (i, T) and R _V (i, T) that also depend on the speed variance T, for example. As the argument T at this time, for example, the average velocity dispersion in the window can be used. Further, even if the speed V and the speed variance T do not change, it is effective to make the variation itself change over time so as to appeal more visually, so that the lesion can be detected more sharply. One specific configuration example for realizing such a temporal change is to store a plurality of tables having different contents as tables corresponding to (T, i) in the ROMs 52 and 54, respectively. A different one is selected from the table for each frame of the image and used.

Although the present apparatus is an ultrasonic Doppler diagnostic apparatus using a living body as a subject, the present invention can also be applied to an ultrasonic Doppler diagnostic apparatus for measuring another subject.

Embodiment 2 Another embodiment of the present invention will be described with reference to the drawings. Since the configuration shown in FIG. 1 is the same in the present apparatus, the figure is used in the following description. The present apparatus is different from the apparatus according to the above embodiment in the blood flow information calculation circuit 20 or the blood flow information converter in the image display generation circuit 12. The block configuration of the blood flow information converter of the present apparatus is the same as that of FIG. 3 of the above embodiment, so that FIG. However, since each component has a difference from each other, in the following description, the reference numerals of the blood flow information converter and its components are distinguished by adding 100 to the reference numerals in FIG. Specifically, the blood flow information converter 1 of the present apparatus
The reference numeral 40 designates R _T and R _V , which are not the uncorrelated random numbers as in the first embodiment, but associates an irregular waveform with each scanning line, and performs the conversion shown in equations (1) and (2). FIG. 6 (a),
(B) is a graph showing an example of an irregular waveform function for R _T (i) and R _V (i), respectively. Since R _T and R _V are different from those in the first embodiment, the ROMs 152, 154,
The contents of the table 156 are stored in the ROMs 52, 5
4 and 56 are different. The random number generator 150 is also provided in FIG.
Is different from the random number generator 50 of the above embodiment in having the block configuration shown in FIG. Hereinafter, the details will be described. In addition,
The speed V and the speed variance T stored in the speed memory 42 and the speed dispersion memory 44 may be measured by the rectangular coordinate system (X, Y) or by the polar coordinate system (r, θ). Good.

As in the first embodiment, the blood flow information converter 140 stores the X and Y addresses output from the image address generator 46 and the X and Y addresses from the speed memory 42 and the speed dispersion memory 44. The corresponding read speed V,
The speed variance T is input. The reading of the speed V and the speed variance T is performed by sequential scanning with the X address direction as the scanning line direction.

The random number generator 150 is a circuit which receives an X and Y address and outputs an index i.
First, the counter 170 counts up by dividing the Y address signal pulse by two. That is, assuming that the output count value of the counter 170 is W, Y = 0, 1, 2, 3,.
W = 0, corresponding to the sequence of Y of 4, 5,.
0, 1, 1, 2, 2,... Are sequentially output. ROM172
Stores a positive random number a using W as an index, and outputs a random number a corresponding to the input W. a is 0
.Ltoreq.a.ltoreq.N, where N is the maximum value of the X addresses of the speed memory 42 and the speed distribution memory 44.

The counter 174 operates in synchronization with the X address signal pulse. The counter 174 loads the Y address and resets the random number a based on the lower bits. For example, here, a is changed every time the Y address increases by 2. Therefore, the counter 174 takes in a when the lower 1 bit of the Y address represented by a binary number becomes “0”. The counter 174 counts up for each X address signal pulse using a as an initial value, and outputs the count value as i. Specifically, i = a, a + 1,
a + 2,..., N, 0, 1, 2,.

As in the first embodiment, the ROM 152 stores a T _m corresponding to a set (T, i) of the velocity variance T and the index i.
Of the value is stored is previously calculated based on the equation (1), the index i in the R _T In this calculation
Is different from the above embodiment in that the irregular waveform function value R _T (i) associated with This ROM 152 is the first
A Distributed emphasizing means, and outputs a post-transition velocity dispersion T _m. In the value stored in the ROM 152, the range limits of the post-transition velocity dispersion _{T m (0 ≦ T m ≦} T M) that is considered the same as the above embodiment.

On the other hand, the ROM 154 and the ROM 156 are the second dispersion emphasizing means as in the first embodiment, and the post-transition velocity V
Output _m . The difference from the first embodiment is that the second right-hand side of the expression (2) stored in the ROM 154 corresponding to the pair (T, i)
In calculating the value of the term, irregular waveform function as R _V value R
_V (i) is used. In the value stored in the ROM 156, that the loopback of the post-transition velocity dispersion V _m is taken into account is the same as the above embodiment.

The irregular waveform functions R _T (i) and R _V (i) are, for example, irregular waveforms having a correlation between successive arguments i. This can be generated, for example, by moving-averaging the value of the uncorrelated random number sequence over a predetermined width L of the argument i. By selecting the width L, the average period of the irregular waveform and the degree of change are adjusted. Here, the average period is set to be, for example, about several pixels. In the irregular waveform function, the start position on the scanning line given by a is randomly changed every two scanning lines.

As a result, the pixel value is modulated at a spatially irregular period in the scanning line direction (that is, in the X address direction) in accordance with the variation of the irregular waveform function, while two pixels are modulated in the Y address direction. The modulation period is as large as Therefore, in the present apparatus, the speed variance T changes the pixel value for each pixel by a variation amount corresponding to the speed variance T,
Apart from being emphasized on the image, it is also emphasized on the image by a two-dimensionally distributed granular pattern. That is, the same visibility improving effect as the mosaic pattern obtained by defining the random numbers for each window described in the first embodiment is also realized in the present apparatus. When the window of the first embodiment is used,
The period of the spatial change of the pixel value is constant, for example, every three pixels. However, when an irregular waveform function is used, the period becomes irregular, which is different from the first embodiment.

It should be noted that the size of the grain of the pattern, that is, the size of the grain is determined in consideration of, for example, the ease of recognizing the presence / absence of turbulence and the accuracy required for detecting the position where turbulence occurs. Same as in the first embodiment. In the present apparatus, the particle size is adjusted in the scanning line direction by, for example, the moving average width L at the time of generating the irregular waveform function.
In the address direction, the frequency is adjusted by changing the division ratio of the counter 170 and changing the load timing of the counter a 174 in accordance with this.

In this apparatus, the function of the blood flow information converter is realized by conversion using a table such as a ROM for the reason described in the first embodiment, but this may be realized by using an arithmetic unit. Further, the random number generator 150 may be constituted by a ROM storing a table for outputting an argument i of an irregular waveform function corresponding to each pixel when X and Y coordinates are designated. In this case, since the conversion by the equations (1) and (2) can be performed irrespective of the order of the X and Y addresses, the speed memory 42 and the speed dispersion memory 44 can be omitted. Further, a plurality of tables corresponding to different irregular waveform functions are stored in, for example, the ROMs 152 and 154 so that the variations themselves change with time even if the speed V and the speed variance T do not change. A different table may be selected and used for each frame of the image from a plurality of tables.

[0048]

According to the ultrasonic Doppler diagnostic apparatus of the present invention, in an ultrasonic image in which pixel values are determined based on the velocity V and the velocity variance T, as the velocity variance T increases, the spatially post-transition velocity V _m increases. , post-transition velocity dispersion T _m of these V _m to vary with a large amplitude, T _m is defined, therefore, the magnitude of the velocity dispersion T is expressed is emphasized in the image as a variation in the pixel values. As a result, the effect that turbulence is generated and the velocity dispersion is increased can be easily detected even if the phenomenon is instantaneous or minute, and for example, a heart disease accompanying the above phenomenon can be obtained. It becomes possible to detect more accurately.

Further, according to the present invention, the pixel value of the ultrasonic image is varied according to the size of T for each spatial unit larger than the pixel, so that a smooth image quality can be obtained in a region where T is small. On the other hand, in a region where T is large, for example, a mosaic pattern appears in units of the small region or the like. Thereby, the effect of appealing to the visual sense of the magnitude of the speed variance T is further improved, and the effect of increasing the speed variance T can be more accurately detected.

Further, according to the present invention, in an ultrasonic image displaying an arbitrary measured amount in a measurement area, each pixel value is varied according to the magnitude of the velocity variance T corresponding to each pixel. Accordingly, the effect that the information of the velocity dispersion T can be superimposed and displayed on the ultrasonic image in an easily detectable manner can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of an ultrasonic color Doppler diagnostic apparatus embodying the present invention.

FIG. 2 shows a monotone increasing function F used for dispersion enhancement processing.
The graph which shows an example of (T).

FIG. 3 is a schematic block diagram of a blood flow information converter.

FIG. 4 is an image diagram of a table stored in a random number generator according to the first embodiment;

FIG. 5 is a schematic chromaticity diagram for explaining the effect of the dispersion emphasis processing of the present invention on color flow mapping.

FIG. 6 shows an irregular waveform function R _T (i) according to the second embodiment;
7 is a graph showing a waveform example of R _V (i).

FIG. 7 is a block diagram of a random number generator according to the second embodiment.

FIG. 8 is a schematic chromaticity diagram illustrating the principle of color flow mapping.

[Explanation of symbols]

2 probe, 4 transmission / reception circuit, 6 reception shaping detection circuit,
8 Quadrature phase detector, 10, 16 A / D converter,
12 image display generation circuit, 14 display, 18 clutter suppression circuit, 20 blood flow information calculation circuit, 40, 140 blood flow information converter, 42 speed memory, 44 speed dispersion memory, 46 image address generator, 50, 150 random number generator, 52, 54, 56, 152, 154, 1
56,172 ROM, 170,174 counter.

Claims (7)

(57) [Claims] 1. A measuring means for measuring a velocity V and a velocity variance T at each point in a measurement area by transmission and reception of ultrasonic waves, and a dispersion conversion for transiting the velocity variance T according to the magnitude of the velocity variance T. perform a first dispersion emphasis means for determining a post-transition velocity dispersion T _m, performs rate shifts the velocity V conversion according to the size of the velocity dispersion T, the second dispersion emphasis means for determining the velocity V _m after the transition When ultrasonic Doppler diagnostic apparatus characterized by comprising an image forming means for forming an ultrasound image to determine the pixel value based on the post-transition velocity V _m and the post-transition velocity dispersion T _m. 2. The image forming device according to claim 1, wherein the post-transition speed V
_m and based on a combination of the post-transition velocity dispersion T _m, the ultrasonic Doppler diagnostic apparatus according to claim 1, wherein the determining the chromaticity as the pixel value. 3. The first variance emphasis means uses a random first transform coefficient R _T and a monotonically increasing function F (T) related to the velocity variance T, using the following equation: T _m = T + F (T ) × _RT to obtain the post-transition velocity variance T _m , and the second variance emphasis means includes a random second transform coefficient R
Using the _V and the monotone increasing function F (T), the following _{equation, V m = V + F (} T) × ultrasonic Doppler according to claim 1, wherein R _V by determining the post-transition velocity V _m, and wherein Diagnostic device. 4. The method according to claim 1, wherein the first dispersion emphasizing means includes a first random number defined for each small area constituting the ultrasonic image.
Performs the variance conversion on the basis of the conversion coefficient R _T , and performs the speed conversion on the basis of a random second conversion coefficient R _V defined for each of the small areas. The ultrasonic Doppler diagnostic apparatus according to claim 1, wherein: 5. The method according to claim 1, wherein the first dispersion emphasizing unit is a first irregular waveform function that varies irregularly along a scanning line forming the ultrasonic image, the first irregular waveform function being a value for each pixel. Performing the variance conversion based on the conversion coefficient R _T , wherein the second variance emphasis means is a second irregular waveform function that varies irregularly along the scanning line, the second irregular waveform function being a value for each pixel. 2. The ultrasonic Doppler diagnostic apparatus according to claim 1, wherein the velocity conversion is performed based on a conversion coefficient R _{V of} 2. According magnitude of the measured velocity dispersion T at each point 6. within the measurement area by transmitting and receiving ultrasonic waves, a dispersion emphasis means for determining a post-transition velocity dispersion T _m by transitioning the velocity dispersion T, ultrasonic Doppler diagnostic apparatus which comprises image forming means for forming an ultrasound image to determine the pixel values based on at least the post-transition velocity dispersion T _m, a. 7. According to the magnitude of the velocity variance T measured at each point in the measurement area by the transmission and reception of ultrasonic waves, the velocity V
A dispersion emphasis means for determining the velocity V _m after the transition by transition, characterized in that it comprises an image forming unit for forming an ultrasound image to determine the pixel values based on at least the post-transition velocity V _m, a super Ultrasonic Doppler diagnostic device.