JP5710341B2 - Ultrasonic image display device and control program thereof - Google Patents

Description

  The present invention relates to an ultrasonic image display apparatus that performs multifractal analysis on an echo signal and a control program thereof.

  The ultrasonic image display apparatus can observe an ultrasonic image created based on an ultrasonic echo signal transmitted to a target in real time. For example, in an ultrasonic image display device that displays an ultrasonic image created based on an echo signal obtained by transmitting an ultrasonic wave to a human body, various diagnoses are made by observing the ultrasonic image. It is. Specifically, Patent Document 1 describes that a fatty liver is diagnosed based on an ultrasonic image.

JP 2010-233859 A (page 3, paragraph [0004])

  By the way, in the case of fatty liver, it is generally considered that a reflecting surface having different acoustic impedance is formed by a large number of fat droplets into hepatocytes, thereby increasing the brightness of the B-mode image. In addition, due to the scattering of ultrasonic waves by fat deposited on hepatocytes, the brightness may decrease due to attenuation of the ultrasonic waves as the depth increases. Therefore, the diagnosis of fatty liver is performed by observing an ultrasonic image for such a tendency, but it may be difficult to determine whether or not the liver is fatty liver only by the ultrasonic image. Therefore, there is a demand for an ultrasonic image display device capable of providing information useful for determination when making some determination such as diagnosis of fatty liver.

  The invention made to solve the above-described problems includes a multifractal analysis unit that performs multifractal analysis on an ultrasonic echo signal transmitted to a target, and a specificity spectrum obtained by the multifractal analysis. Display control for displaying at least one of an index value obtained based on a full width at half maximum, a maximum fractal dimension in the specificity spectrum and a specificity index in the maximum fractal dimension, a half width of the specificity spectrum, and the specificity spectrum And an ultrasonic image display device.

  According to the above aspect of the invention, multifractal analysis is performed on ultrasonic echo signals. Here, for example, a liver with a large amount of accumulated fat is included in the echo signal due to the influence of fat droplets contained in the hepatocytes even if the amplitude information (luminance information) of the echo signal is not significantly different from the normal liver. Signal pattern is different from normal liver. Therefore, the index value obtained based on the half-value width of the specificity spectrum obtained by performing multifractal analysis on the echo signal, the maximum fractal dimension in the specificity spectrum, and the specificity index in the maximum fractal dimension, By providing at least one of the half-value width of the specificity spectrum and the specificity spectrum, it is possible to provide information useful for determining information that is difficult to distinguish if it is an echo signal, such as diagnosis of fatty liver. Can do.

It is a block diagram which shows an example of schematic structure of embodiment of the ultrasonic image display apparatus which concerns on this invention. It is a block diagram which shows the structure of the control part in the ultrasonic image display apparatus shown in FIG. It is a figure which shows the display part in which the region of interest used as the object which performs multifractal analysis was set. It is a figure which shows an example of the specificity spectrum obtained by the multifractal analysis. It is a figure which shows the display part on which the value of FWHM and the value of index In were displayed. It is a figure which shows the display part on which the specificity spectrum was displayed. It is a figure which shows the display part in which the ultrasonic image which has a color image was displayed in the 1st modification of 1st embodiment. It is a figure which shows the display part in which the ultrasonic image which has a line was displayed in the 1st modification of 1st embodiment. It is a block diagram which shows the structure of the control part in the 2nd modification of 1st embodiment. It is a block diagram which shows the structure of the control part in 2nd embodiment. It is a figure explaining the coupling | bonding of the echo signal of the several sound ray in 2nd embodiment. It is a figure explaining the coupling | bonding of an echo signal in detail. It is a figure explaining the coupling | bonding of the echo signal of multiple sound rays in the modification of 2nd embodiment. It is a conceptual diagram which shows the signal used as the object of multifractal analysis in the modification of 2nd embodiment. It is a figure for demonstrating the area | region used as the object of the multifractal analysis in 3rd embodiment. It is a figure which shows the display part by which the color image was displayed on the division area in an ultrasonic image. It is a figure which shows the display part by which the cursor which designates the object which performs multifractal analysis was displayed on the ultrasonic image. It is a block diagram which shows the other structure of a control part. It is a figure explaining averaging of an echo signal. It is a conceptual diagram which shows the signal used as the object of multifractal analysis.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, a first embodiment will be described with reference to FIGS. An ultrasonic image display apparatus 1 illustrated in FIG. 1 includes an ultrasonic probe 2, a transmission / reception unit 3, an echo data processing unit 4, a display control unit 5, a display unit 6, an operation unit 7, and a control unit 8.

  The ultrasonic probe 2 transmits ultrasonic waves to a target from a plurality of ultrasonic transducers (not shown). The ultrasonic probe 2 transmits ultrasonic waves by scanning ultrasonic waves in order of sound rays. The ultrasonic probe 2 receives an ultrasonic echo signal.

  The transmission / reception unit 3 supplies an electrical signal for transmitting an ultrasonic wave from the ultrasonic probe 2 under a predetermined scanning condition to the ultrasonic probe 2 based on a control signal from the control unit 8. The transmitter / receiver 3 performs signal processing such as A / D conversion and phasing addition processing on the echo signal received by the ultrasonic probe 2.

  The echo data processing unit 4 performs processing for creating an ultrasound image on the data of the echo signal output from the transmission / reception unit 3. For example, the echo data processing unit 4 performs B-mode processing such as logarithmic compression processing and envelope detection processing, and Doppler processing such as orthogonal detection processing and filter processing.

  Incidentally, Doppler processing includes color Doppler processing for creating color Doppler images, power Doppler processing for creating power Doppler images, pulse Doppler processing for creating images using the pulse Doppler method, and images using the continuous wave Doppler method. Includes continuous wave Doppler processing to create.

  The display control unit 5 scans and converts the data obtained by the echo data processing unit 4 using a scan converter to create ultrasonic image data. Further, the display control unit 5 causes the display unit 6 to display an ultrasonic image based on the ultrasonic image data. The ultrasonic image is a B-mode image or an image based on data obtained by Doppler processing.

  In addition to the ultrasonic image, the display control unit 5 has a half-value width (to be described later) of a specificity spectrum (spectrum) Sp that is obtained by multi-fractal analysis by a multi-fractal analysis unit 82 to be described later. FWHM), an index value (index In, which will be described later) obtained based on the maximum fractal dimension Dmax in the specificity spectrum Sp and the specificity index hmax in the maximum fractal dimension Dmax, the half-value width of the specificity spectrum Sp, and the specificity At least one of the spectra Sp is displayed (display control function). The display control unit 5 is an example of an embodiment of a display control unit in the present invention, and the display control function is an example of an embodiment of a display control function in the present invention.

  The full width at half maximum of the specificity spectrum Sp, the maximum fractal dimension Dmax, the specificity index hmax in the maximum fractal dimension Dmax, the index value (index In), and the specificity spectrum Sp will be described later.

  The display unit 6 includes, for example, an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube). The operation unit 7 includes a keyboard and a pointing device (not shown) for an operator to input instructions and information.

  The control unit 8 includes a CPU (Central Processing Unit) (not shown). The control unit 8 reads a control program stored in a storage unit (not shown), and executes functions in each unit of the ultrasonic image display device 1.

  A detailed configuration of the control unit 8 will be described. As shown in FIG. 2, the control unit 8 includes a region-of-interest setting unit 81, a multifractal analysis unit 82, and a calculation unit 83. The functions of these units are also executed by the control program stored in the storage unit. The description of these functions will be described later. The region-of-interest setting unit 81 is an example of an embodiment of a range setting unit in the present invention. The multifractal analysis unit 82 is an example of an embodiment of a multifractal analysis unit in the present invention, and executes an example of an embodiment of a multifractal analysis function in the present invention. Furthermore, the calculation unit 83 is an example of an embodiment of a calculation unit in the present invention.

  Now, the operation of the ultrasonic image display apparatus 1 of this example will be described. When ultrasonic waves are transmitted / received to / from an object such as a human body, the obtained echo signals are processed by the transmission / reception unit 3 and the echo data processing unit 4. Based on the output signal from the echo data processing unit 4, the display control unit 5 creates ultrasonic image data. Then, the display control unit 5 causes the display unit 6 to display an ultrasonic image UG based on the ultrasonic image data.

  The multifractal analysis unit 82 performs multifractal analysis on the echo signal. Before performing the multifractal analysis, as shown in FIG. 3, the region of interest R to be subjected to the multifractal analysis is set in the ultrasonic image UG displayed on the display unit 6. Specifically, when the operator operates the pointing device or the like of the operation unit 7 to specify a region for multifractal analysis in the ultrasonic image UG, the region-of-interest setting unit 81 selects the specified region. The region of interest R is set.

  The echo signal to be subjected to multifractal analysis may be the output signal of the transmission / reception unit 3 or the output signal of the echo data processing unit 4. The output signal of the echo data processing unit 4 may be a signal obtained by B-mode processing, or an I signal or Q signal after orthogonal detection processing. Further, multifractal analysis may be performed on a signal obtained by combining these I signal and Q signal.

  The echo signal to be subjected to multifractal analysis is an echo signal for all or part of sound rays in the region of interest R. The multifractal analysis unit 82 performs multifractal analysis on the echo signal of each sound ray.

  The multifractal analysis unit 82 performs multifractal analysis using a WTMM (Wavelet Transform Modulus Maxima) method. This multifractal analysis using the WTMM method performs processing including Wavelet transformation, extraction of Modulus maxima line, processing by a distribution function, and Legendre transformation.

  By the multifractal analysis, a specificity spectrum Sp is obtained as shown in FIG. In this specificity spectrum Sp, the horizontal axis h is the specificity index (Lippsitz-Herder index), and the vertical axis D is the fractal dimension (fractal dimension). Dmax is the maximum value in the specificity spectrum Sp, that is, the maximum value (maximum fractal dimension) of the fractal dimension D, and hmax is the value of the specificity index h in Dmax in the specificity spectrum Sp. Further, FWHM (full width at half maximum) is a width (half-value width) of the specificity index h of the specificity spectrum Sp in Dhalf which is a half of Dmax.

  Incidentally, the specificity index h is an index indicating the degree of complexity of the waveform of the echo signal to be analyzed, and FWHM is a value related to the amount of different signal patterns included in the echo signal. For example, the more similar signal patterns are included in the echo signal, the smaller the value of FWHM.

When the specificity spectrum Sp is obtained, the calculation unit 83 calculates the Dmax, the FWHM, and the hmax in the specificity spectrum Sp. The calculation unit 83 may calculate a predetermined index (index) In obtained by the following (Equation 1).
In = FWHM × (hmax / Dmax) (Formula 1)
This index In is an example of an embodiment of an index value in the present invention.

  As shown in FIG. 5, the display control unit 5 displays the value of the FWHM and the value of the index In on the display unit 6 along with the ultrasound image UG. However, the display control unit 5 may display only one of the FWHM value and the index In value. Although not particularly shown, the display control unit 5 may display the Dmax value and the hmax value on the display unit 6 together with the FWHM value and the index In value. Furthermore, the display control unit 5 may display the specificity spectrum Sp on the display unit 6 along with the ultrasonic image UG as shown in FIG. The specificity spectrum Sp may be displayed together with the value of the FWHM and the value of the index In.

  When multifractal analysis is performed on echo signals of a plurality of sound rays, the value of FWHM and the value of index In for each sound ray may be displayed (that is, the value of a plurality of FWHM and the value of a plurality of indexes In) ), The calculation unit 83 may calculate and display the FWHM value and the index In value averaged for each sound ray. Further, the specificity spectrum Sp for each sound ray may be displayed (that is, a plurality of specificity spectra Sp are displayed), and the calculation unit 83 calculates the specificity spectrum Sp averaged for each sound ray. You may ask for this and display it. By averaging, even when the length of the region of interest R in the sound ray direction (depth direction) is particularly short and the number of echo signal data in one sound ray is reduced, a more appropriate result can be displayed. it can.

  Here, the reason why the multifractal analysis is performed on the echo signal to display the FWHM value, the index In value, and the specificity spectrum will be described. For example, in the case of diffuse fatty liver, the brightness (amplitude information of the echo signal) of the entire B-mode image increases uniformly, so it is difficult to recognize the difference in brightness, and it may be necessary to rely on an evaluation method for liver-kidney contrast. . However, since the liver-kidney contrast evaluation method needs to obtain a B-mode image including the kidney, it cannot be used for a portion away from the kidney. On the other hand, a liver with a large amount of accumulated fat has a signal pattern included in an echo signal different from that of a normal liver due to the influence of fat droplets included in hepatocytes. Therefore, the specificity spectrum Sp obtained by performing the multifractal analysis on the echo signal is different between the liver having a large amount of accumulated fat and the normal liver. From the above, by displaying the value of FWHM, the value of the index In, and the specificity spectrum Sp on the display unit 6, the operator can determine whether he has a fatty liver, for example, from an image including the kidney. Can be diagnosed.

  Next, a modification of the first embodiment will be described. First, the first modification will be described. As shown in FIG. 7, the display control unit 5 displays in the region of interest R a color image CG having a hue corresponding to the value of the FWHM calculated for the region of interest R or the value of the index In. May be. Specifically, the display control unit 5 adds the ultrasonic image UG and the color image CG and displays an image in which the color image CG is synthesized in the region of interest R on the ultrasonic image UG on the display unit 6. Let The color image CG is displayed in a state where the background ultrasonic image UG is seen through.

  However, the image is not limited to the color image CG as long as the image corresponds to the value of the FWHM or the value of the index In.

  When the value of FWHM and the value of index In are calculated for a plurality of sound rays, the display control unit 5 displays a line L corresponding to the sound ray in the region of interest R as shown in FIG. The L color may be displayed in a color corresponding to the value of FWHM or the value of index In.

  Next, a second modification will be described. In the second modification, the control unit 8 includes a preprocessing unit 84 in addition to the region-of-interest setting unit 81, the multifractal analysis unit 82, and the calculation unit 83, as shown in FIG. The pre-processing unit 84 performs smoothing processing, high-pass filter processing, down-sampling processing, or up-sampling processing as signal processing for the echo signal before performing multifractal analysis. One of these processes or a plurality of these processes is performed.

  By performing the smoothing process, the downsampling process, and the upsampling process, the result of the multifractal analysis can be stabilized. Further, in the multifractal analysis in which the analysis on the similarity of the signal is performed, the signal amplitude information is not necessary, and therefore, only the signal component necessary for the multifractal analysis can be extracted by performing the high-pass filter process. The pre-processing unit 84 is an example of an embodiment of the pre-processing unit in the present invention.

(Second embodiment)
Next, a second embodiment will be described. However, the description of the same matters as the first embodiment is omitted.

  In this example, multifractal analysis is performed on a signal obtained by combining echo signals from a plurality of sound rays. As shown in FIG. 10, the control unit 8 includes a signal combining unit 85 in addition to the region-of-interest setting unit 81, the multifractal analysis unit 82, and the calculation unit 83. The signal combining unit 85 combines echo signals from a plurality of sound rays. Specifically, as shown in FIG. 11, the echo signals sa, sb, and sc of the plurality of sound rays in the region of interest R are combined in the sound ray direction to combine one echo signal s (the signal is simplified). (Shown as a straight line). The multifractal analysis unit 82 performs multifractal analysis on the combined echo signal s.

  Here, as shown in FIG. 12, the end portions of the echo signals sa, sb, sc on the shallow side (side closer to the ultrasonic probe 2) are an, bn, cn, and the deep side (distant from the ultrasonic probe 2). Side) is af, bf, cf. The signal coupling unit 85 couples end portions on the side where the depths of adjacent echoes are close to each other. That is, the signal combining unit 85 combines the end af of the echo signal sa and the end bf of the echo signal sb, and connects the end bn of the echo signal sb and the end cn of the echo signal sc. Join. However, the present invention is not limited to such a case.

  Here, as the length of the region of interest R in the sound ray direction (depth direction) becomes shorter, the number of echo signal data decreases, and there is a possibility that an appropriate multifractal analysis result cannot be obtained. However, according to this example, since multifractal analysis is performed on an echo signal obtained by combining echo signals of a plurality of sound rays, even if the length of the region of interest R in the sound ray direction is short, Appropriate multifractal analysis results can be obtained. Therefore, for example, when the region of interest R is set avoiding blood vessels, an appropriate specificity spectrum Sp can be obtained even if the length of the region of interest R in the sound ray direction is shortened.

  Next, a modification of the second embodiment will be described with reference to FIGS. In FIG. 13, sl-a, sl-b, and sl-c indicate sound rays in the region of interest R (not shown in FIG. 13). The echo signal data at the sound ray sl-a is a1, a2, a3,..., The echo signal data at the sound ray sl-b is b1, b2, b3,. Let the echo signal data be c1, c2, c3,.

  The signal combining unit 85 creates a signal composed of a data string obtained by combining echo signal data arranged in the order of the sound ray direction in each sound ray so as to be arranged in the order of the ultrasonic scanning direction over a plurality of sound rays. Specifically, as shown in FIG. 14, the signal combining unit 85 includes a signal s composed of a data string arranged in the order of data a1, b1, c1, c2, b2, a2, a3, b3, c3,. Create

  Incidentally, as in the second embodiment, multifractal analysis is performed on a signal obtained by combining echo signals of a plurality of sound rays, or multi-fractal analysis is performed on a single sound ray echo signal as in the first embodiment. Whether fractal analysis is to be performed or not may be selected by, for example, input from the operation unit 7.

(Third embodiment)
Next, a third embodiment will be described. However, the description of the same matters as the above embodiments will be omitted.

  As shown in FIG. 15, the multifractal analysis unit 82 of this example performs multifractal analysis on the divided regions r1, r2, and r3 obtained by dividing the region of interest R in the sound ray direction. In this case, the calculation unit 83 calculates the value of the FWHM and the value of the index In obtained by performing the multifractal analysis on each sound ray of each of the divided regions r1 to r3 and averaging the analysis results, You may display for every division area r1-r3. The signal combining unit 85 may combine the sound rays in the divided regions r1 to r3, and perform multifractal analysis on the combined echo signals. Also in this case, the value of the FWHM and the value of the index In are displayed for each of the divided areas r1 to r3.

  Further, color images CG1, CG2, and CG3 corresponding to the FWHM value and the index value obtained for each of the divided regions r1 to r3 are converted into the divided regions r1 to r1 in the ultrasonic image UG as shown in FIG. You may display on r3.

  As mentioned above, although this invention was demonstrated by each said embodiment, of course, this invention can be variously implemented in the range which does not change the main point. For example, in the above-described embodiment, the target of multifractal analysis is specified by setting the region of interest R. Instead of the region of interest, cursors C1 and C2 are used as shown in FIG. May be specified. In this case, the echo signal between the cursors C1 and C2 becomes the target of multifractal analysis.

  Further, the result of the multifractal analysis may be stabilized by adjusting a sampling rate when A / D conversion is performed in the transmission / reception unit 3.

  Further, as shown in FIG. 18, the control unit 8 may include a signal averaging unit 86 in addition to the region of interest setting unit 81, the multifractal analysis unit 82, and the calculation unit 83. The signal averaging unit 86 creates a signal s ′ obtained by averaging the echo signal for a plurality of sound rays. This will be specifically described with reference to FIGS. 19 and 20. As shown in FIG. 19, the echo signal data in the sound ray sl-a is a1, a2, a3,..., An, and the echo signal data in the sound ray sl-b is b1, b2, b3,. , Bn, and echo signal data on the sound ray sl-c are c1, c2, c3,. As shown in FIG. 20, the signal averaging unit 86 is data of echo signals in each sound ray, and data (a1, b1, c1), (a2, b2, c2), (a3, b3, c3) and (an, bn, cn) are generated in the sound ray direction, and a signal s' composed of a data string of data x1, x2, x3,. Specifically, x1 = (a1 + b1 + c1) / 3, x2 = (a2 + b2 + c2) / 3, x3 = (a3 + b3 + c3) / 3,..., Xn = (an + bn + cn) / 3.

  Then, the value of FWHM, the value of the index In, and the specificity spectrum Sp obtained by performing multifractal analysis on the signal s ′ and displayed by the display control unit 5 are the average of a plurality of sound rays.

DESCRIPTION OF SYMBOLS 1 Ultrasonic image display apparatus 5 Display control part 81 Area of interest setting part (range setting part)
82 Multifractal analysis unit 83 Calculation unit 84 Preprocessing unit

Claims (13)

A multifractal analysis unit that performs multifractal analysis on an ultrasonic echo signal transmitted to a target;
Index values obtained based on the half-value width of the specificity spectrum obtained by multifractal analysis, the maximum fractal dimension in the specificity spectrum and the specificity index in the maximum fractal dimension, the half-value width of the specificity spectrum and the anomaly A display control unit for displaying at least one of the sex spectrum,
The said display control part displays the image according to the said index value or the value of the half value width of the said specific spectrum on the ultrasonic image based on the said echo signal, The ultrasonic image display apparatus characterized by the above-mentioned.   The ultrasonic image display device according to claim 1, wherein the index value, the half-value width of the specificity spectrum, and the specificity spectrum displayed by the display control unit are an average of a plurality of sound rays.   The ultrasonic image display apparatus according to claim 1, wherein the multifractal analysis unit performs multifractal analysis on a signal obtained by combining echo signals in a plurality of sound rays. A multifractal analysis unit that performs multifractal analysis on an ultrasonic echo signal transmitted to a target;
Index values obtained based on the half-value width of the specificity spectrum obtained by multifractal analysis, the maximum fractal dimension in the specificity spectrum and the specificity index in the maximum fractal dimension, the half-value width of the specificity spectrum and the anomaly A display control unit for displaying at least one of the sex spectrum,
The ultrasonic image display device, wherein the index value, the half value width of the specificity spectrum, and the specificity spectrum displayed by the display control unit are an average of a plurality of sound rays. A multifractal analysis unit that performs multifractal analysis on an ultrasonic echo signal transmitted to a target;
Index values obtained based on the half-value width of the specificity spectrum obtained by multifractal analysis, the maximum fractal dimension in the specificity spectrum and the specificity index in the maximum fractal dimension, the half-value width of the specificity spectrum and the anomaly A display control unit for displaying at least one of the sex spectrum,
The ultrasonic image display apparatus, wherein the multifractal analysis unit performs multifractal analysis on a signal obtained by combining echo signals in a plurality of sound rays.   The ultrasonic image display apparatus according to claim 5, wherein the multifractal analysis unit performs multifractal analysis on a signal formed by combining ends of echo signals in a plurality of sound rays.   The multifractal analysis unit performs multifractal analysis on a signal obtained by combining echo signal data in each sound ray so as to be arranged in order in the scanning direction of ultrasonic waves over a plurality of sound rays. Item 6. The ultrasonic image display device according to Item 5. A multifractal analysis unit that performs multifractal analysis on an ultrasonic echo signal transmitted to a target;
A display control unit for displaying an index value obtained based on a full width at half maximum of the specificity spectrum obtained by multifractal analysis, a maximum fractal dimension in the specificity spectrum, and a specificity index in the maximum fractal dimension. A characteristic ultrasonic image display device.   The display control unit displays at least one of the index value, the full width at half maximum of the specificity spectrum, and the specificity spectrum for a plurality of sound rays. The ultrasonic image display device according to item.   The ultrasonic wave according to any one of claims 1 to 9, further comprising a calculation unit that calculates the half-value width, the maximum fractal dimension, and a specificity index in the maximum fractal dimension in the specificity spectrum. Image display device.   The ultrasonic image created based on the echo signal includes a range setting unit that sets a range to be subjected to the multifractal analysis. Ultrasonic image display device.   2. A preprocessing unit that performs a smoothing process, a high-pass filter process, a downsampling process, or an upsampling process on the echo signal before performing the multifractal analysis. The ultrasonic image display apparatus as described in any one of -11. On the computer,
A multifractal analysis function that performs multifractal analysis on ultrasonic echo signals transmitted to the target;
Index values obtained based on the half-value width of the specificity spectrum obtained by multifractal analysis, the maximum fractal dimension in the specificity spectrum and the specificity index in the maximum fractal dimension, the half-value width of the specificity spectrum and the anomaly A display control function for displaying at least one of the sex spectrum and displaying an image corresponding to the index value or the half-value width of the specificity spectrum on the ultrasound image based on the echo signal;
A control program for an ultrasonic image display device.

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