JP2015023913A - Elasticity measurement device, program of elasticity measurement device, and ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elasticity measurement device which allows setting of a measurement area where more precise measurement can be performed.SOLUTION: An elasticity measurement device comprises: an area setting unit 53 for setting a measurement area where the elasticity of a biological tissue is measured; an evaluation unit 54 for detecting a non measurement target which is not the measurement target of elasticity on the basis of data on the ultrasonic image and evaluating the measurement area; and a display unit for displaying an image based on the evaluation by the evaluation unit 54. The evaluation unit 54 detects the non measurement target which is not the measurement target of elasticity, on the basis of the signal intensity of data on the ultrasonic image.

Description

  The present invention relates to an elasticity measuring device capable of knowing the elasticity of a living tissue, a program for the elasticity measuring device, and an ultrasonic diagnostic apparatus.

  An elastic measurement method is known in which an ultrasonic pulse (push pulse) having a high sound pressure is transmitted to a living tissue to measure the elasticity of the living tissue (for example, see Patent Document 1). As an elastic measurement method using a push pulse, for example, there are the following two methods. One is a method of calculating a propagation speed of a shear wave generated by vibration of a living tissue by a push pulse and calculating an elastic value of the living tissue based on the propagation speed. The other is a method of calculating the position of the living tissue based on the ultrasonic echo signal and calculating the displacement of the living tissue caused by transmitting the push pulse based on the position information.

  Prior to performing such elasticity measurement, a region of interest that is a target for measuring elasticity is set in the ultrasound image.

JP2012-100997A

  By the way, for example, when performing elastic measurement to evaluate fibrosis of the liver, the target of measurement is the liver parenchyma (substrate portion), and other vessels, diaphragm, ascites, etc. are not the target of measurement. . Therefore, if elasticity measurement is performed on a region of interest including such a non-object, an accurate measurement result cannot be obtained. Therefore, it is desirable to be able to set a measurement area where more accurate measurement can be performed.

  One aspect of the invention made in order to solve the above-described problem is that, in an ultrasonic image of a biological tissue, a region setting unit that sets a measurement region for measuring elasticity of the biological tissue, and data of the ultrasonic image And an evaluation unit that detects a non-measurement target that is not an elastic measurement target and evaluates the measurement region, and a display unit that displays an image based on the evaluation of the evaluation unit. It is an elasticity measuring device.

  According to the above aspect of the invention, a non-measurement object that is not an elastic measurement object is detected, the measurement area is evaluated, and an image based on the evaluation is displayed. Therefore, a measurement area that can perform more accurate measurement Can be set.

1 is a block diagram illustrating a schematic configuration of an ultrasonic diagnostic apparatus that is an example of an embodiment of the present invention. It is a block diagram which shows the structure of a display control part. It is a block diagram which shows the structure of a control part. It is a flowchart which shows the processing flow in 1st embodiment. It is a figure which shows the B mode image displayed on the display part. It is a figure which shows the state by which the measurement area | region was set to the B mode image. It is a figure which shows the color elasticity image displayed on the display part. In the 1st modification of 1st embodiment, it is a figure which shows the state in which the 1st color image and the 2nd color image were displayed. It is a flowchart which shows the processing flow in 2nd embodiment. It is a figure which shows the state by which the pulse indicator which shows a push pulse was displayed. It is a block diagram which shows the structure of the display control part in 3rd embodiment. In 3rd embodiment, it is a conceptual diagram which shows the push pulse transmitted from an ultrasonic probe. It is a flowchart which shows the processing flow in 3rd embodiment. It is a figure which shows the numerical indicator displayed on the display part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. An example in which the elasticity measuring apparatus according to the present invention is implemented in an ultrasonic diagnostic apparatus will be described.
(First embodiment)
First, a first embodiment will be described with reference to FIGS. An ultrasonic diagnostic apparatus 1 illustrated in FIG. 1 includes an ultrasonic probe 2, a transmission / reception beam former 3, an echo data processing unit 4, a display control unit 5, a display unit 6, an operation unit 7, a control unit 8, and a storage unit 9.

  The ultrasonic probe 2 transmits ultrasonic waves to the living tissue of the subject. The ultrasonic probe 2 transmits an ultrasonic wave (push pulse) for generating a shear wave in the living tissue. The ultrasonic probe 2 transmits an ultrasonic wave for measuring the propagation speed of the shear wave and receives an echo signal thereof. The ultrasonic probe 2 transmits an ultrasonic wave for creating an ultrasonic image and receives an echo signal thereof. The ultrasonic probe 3 is, for example, a 1D array probe having a plurality of ultrasonic transducers arranged in one direction (azimuth direction, X direction).

  The transmission / reception beamformer 3 drives the ultrasonic probe 2 to transmit ultrasonic waves having a predetermined transmission parameter. The transmission / reception beamformer 3 performs signal processing such as phasing addition processing on the ultrasonic echo signal. As will be described later, the propagation speed of the shear wave is calculated based on the echo signal after the phasing addition processing.

  The echo data processing unit 4 performs signal processing for creating an ultrasonic image on the echo data output from the transmission / reception beamformer 3. For example, the echo data processing unit performs B-mode processing such as logarithmic compression processing and envelope detection processing to create B-mode data.

  As shown in FIG. 2, the display control unit 5 includes an ultrasonic image data creation unit 51, a display image control unit 52, a region setting unit 53, and an evaluation unit 54. The ultrasonic image data creation unit 51 scans and converts the data (raw data) input from the echo data processing unit 4 using a scan converter to create ultrasonic image data. The ultrasonic image data creation unit 51 creates B-mode image data based on, for example, B-mode data.

  The display image control unit 52 causes the display unit 6 to display an ultrasonic image based on the ultrasonic image data. The ultrasonic image is, for example, a B mode image. In addition, the display image control unit 52 displays an image based on the evaluation of the evaluation unit 54 on the display unit 6 (display image control function in the present invention) as described later. In addition, the display image control unit 52 displays various images on the display unit 6.

  The region setting unit 53 sets a measurement region R (see FIG. 6) in the B-mode image based on an input from the operation unit 7 by an operator (region setting function). The measurement region R is a region for measuring the elasticity of the living tissue. The area setting unit 53 is an example of an embodiment of the area setting unit in the present invention. The area setting function is an example of an embodiment of the area setting function in the present invention.

  The evaluation unit 54 evaluates the measurement area from the viewpoint of measurement accuracy (evaluation function). The evaluation unit 54 detects a non-measurement object that is not an elasticity measurement object based on the data of the B-mode image, and evaluates the measurement region. Details will be described later. The evaluation unit 54 is an example of an embodiment of an evaluation unit in the present invention. The evaluation function is an example of an embodiment of the evaluation function in the present invention.

  The display unit 6 is an LCD (Liquid Crystal Display), an organic EL (Electro-Luminescence) display, or the like. The display unit 6 is an example of an embodiment of a display unit in the present invention.

  Although not particularly illustrated, the operation unit 7 includes a keyboard for inputting instructions and information by an operator, a pointing device such as a trackball, and the like.

  The control unit 8 includes a CPU (Central Processing Unit) (not shown). The control unit 8 reads the control program stored in the storage unit 9 and executes functions in each unit of the ultrasonic diagnostic apparatus 1.

  Further, the control unit 8 executes a calculation function by the elasticity calculation unit 81 shown in FIG. This calculation function is a function for calculating the elastic modulus of the living tissue to which the push pulse is transmitted. The elastic modulus of the living tissue is calculated for the measurement region R. Details will be described later. The elasticity calculator 81 is an example of an embodiment of an elasticity calculator in the present invention.

  The storage unit 9 is an HDD (Hard Disk Drive), a semiconductor memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory).

  Next, a processing flow in the case of measuring the elasticity of a living tissue by the ultrasonic diagnostic apparatus 1 of this example will be described based on the flowchart of FIG. In this example, the measurement object of elasticity is liver parenchyma in the liver.

  First, in step S1, the operator transmits and receives ultrasonic waves using the ultrasonic probe 2, and displays a real-time B-mode image BI on the display unit 6 as shown in FIG.

  Next, in step S2, the operator specifies the cross section for measuring the elasticity of the living tissue by moving the ultrasonic probe 2 or performing a bending operation while viewing the B-mode image BI. When the operator specifies the measurement cross section, as shown in FIG. 6, the operator sets a measurement region R in a region where elasticity is to be measured in the B-mode image BI. The region setting unit 53 sets a measurement region R based on an input from the operation unit 7 by an operator.

  Next, in step S3, the evaluation unit 54 evaluates whether or not the measurement region R is a region in which measurement reliability can be ensured. The measurement region in which the reliability of measurement can be ensured means a region in which the non-elastic target is not included as much as possible and the measurement result is as accurate as possible for the liver parenchyma.

  Specifically, the evaluation unit 54 calculates the degree of dispersion of the signal intensity of the data of each pixel in the B-mode image BI in the measurement region R. Any one of dispersion, coefficient of variation, standard deviation, etc. is calculated as the degree of dispersion.

  Here, in the B-mode image, the blood vessels and ascites, which are non-measurement targets for elasticity, have lower luminance than the liver parenchyma, which is the measurement target for elasticity. Further, in the B-mode image, the diaphragm, which is an elastic non-measurement target, has a higher luminance than the liver parenchyma. Therefore, when a non-measurement target is included in the measurement region R, the degree of signal intensity distribution increases. Therefore, the evaluation unit 54 detects a non-measurement object based on the signal intensity dispersion degree and performs evaluation. Specifically, when the dispersion degree is equal to or greater than a predetermined threshold value TH, the evaluation unit 54 evaluates that the measurement area includes many non-measurement targets and has low reliability in terms of measurement accuracy. To do. On the other hand, when the spread degree is smaller than the predetermined threshold value TH, the evaluation unit 54 evaluates that the non-measurement target is not included so much that the measurement area is highly reliable in terms of measurement accuracy. .

  The predetermined threshold value TH may be set by an operator using the operation unit 7.

  Next, in step S4, the display image control unit 52 causes the display unit 6 to display an image corresponding to the evaluation result in step S3. Specifically, when it is evaluated in step S3 that the measurement area has low reliability, the display image control unit 52 displays a message prompting the change of the measurement area R as an image corresponding to the evaluation result. Display.

  On the other hand, when it is evaluated in step S3 that the measurement area is highly reliable, the display image control unit 52 displays a message asking whether to start measurement as an image corresponding to the evaluation result.

  Next, in step S5, it is determined whether or not the operator changes the measurement region R. When the operator determines that the measurement region R is to be changed (“YES” in step S5), the operator inputs an instruction to reset the measurement region R in the operation unit 7, and returns to step S2 to set the measurement region R. Set again. Thereby, the operator can reset the measurement area | region R to the part which can perform more exact measurement. On the other hand, when the operator determines that there is no need to change the measurement region R (“NO” in step S5), the operator performs an input for instructing measurement at the operation unit 7.

  When an input for instructing measurement is performed in step S5, elasticity measurement for the measurement region R is performed in step S6. Specifically, a push pulse is transmitted from the ultrasonic probe 2 to the living tissue. Next, an ultrasonic pulse for measurement for detecting the propagation speed of the shear wave generated in the living tissue by the push pulse is transmitted from the ultrasonic probe 2, and the echo signal is received. Based on the echo signal, the elastic calculation unit 81 calculates the propagation velocity of the shear wave, and calculates the elastic modulus based on the propagation velocity.

  The push pulse may be transmitted to a plurality of different locations in the measurement region R. In this case, an ultrasonic pulse for measurement is transmitted for each of the plurality of push pulses. The elasticity calculator 81 calculates the propagation velocity for each of a plurality of push pulses. Thereby, the propagation speed in each part in the measurement region R is calculated.

  As shown in FIG. 7, the display image control unit 52 may display a color elasticity image CE having a color corresponding to the elastic modulus calculated by the elasticity calculation unit 81 in the measurement region R.

  According to this example described above, the measurement region R can be set so as not to include non-measurement targets. Therefore, more accurate elasticity measurement can be performed.

  Next, a modification of the first embodiment will be described. In the step S3, the evaluation unit 54, in the measurement region R, the pixel whose signal intensity of the data of the B-mode image BI is not less than the first threshold value TH1 and the second threshold value TH2 (TH2 <TH1). The following pixels are detected as non-measurement targets. A pixel that is equal to or greater than the first threshold TH1 is an example of an embodiment of the first portion in the present invention. Further, the pixels having the second threshold value TH2 or less are an example of the second embodiment of the present invention.

  Next, in step S4, the display image control unit 52, as shown in FIG. 8, has a first color image Cl1 in which a color is applied to pixels that are equal to or higher than the first threshold TH1, and is equal to or lower than the second threshold. The second color image Cl2 in which the pixel is colored is displayed. The first color image Cl1 and the second color image Cl2 may have different colors.

  Said 1st threshold value TH1 and said 2nd threshold value TH2 may be set when an operator inputs in the said operation part 7. FIG. Further, the average value Av of the signal intensity of the data of the B-mode image BI in the measurement region R may be calculated and set based on this average value. The first threshold value TH1 is set so that a portion equal to or higher than the first threshold value TH1 becomes a non-measurement target having a signal intensity higher than that of the liver parenchyma, such as a diaphragm. The second threshold value TH2 is set so that the portion below the second threshold value TH2 becomes a non-measurement target whose signal intensity is smaller than that of the liver parenchyma, such as a vascular vessel or ascites.

  The portion above the first threshold TH1 and the portion below the second threshold TH2 are non-measurement targets and are portions with low reliability from the viewpoint of measurement accuracy. In this example, the measurement region R is evaluated by detecting a portion equal to or higher than the first threshold TH1 and a portion equal to or lower than the second threshold TH2.

  By displaying the first color image Cl1 and the second color image Cl2, for example, the operator can reset the measurement region R in a portion where they are not displayed, so that more accurate measurement can be performed. The measurement region R can be set in a portion.

(Second embodiment)
Next, a second embodiment will be described. The ultrasonic diagnostic apparatus of this example has the same configuration as the ultrasonic diagnostic apparatus 1 of the first embodiment, and the operation will be described below based on the flowchart of FIG.

  In FIG. 9, step S11 and step S12 are the same as step S1 and step S2 of the first embodiment, and a description thereof is omitted. In step S13, as shown in FIG. 10, the display image control unit 52 displays a pulse indicator PIn indicating a push pulse on the B-mode image BI. This pulse indicator PIn is a sound line of a push pulse indicated by a broken line, and is displayed at a position where the push pulse is transmitted.

  Next, in step S14, the operator determines whether or not to change the measurement region R with reference to the pulse indicator PIn. In step S14, a message asking the operator whether to change the measurement region R may be displayed on the display unit 6.

  Here, when there is a non-measurement target such as a vascular vessel, ascites, or a diaphragm on the path through which the push pulse is transmitted, accurate elasticity measurement cannot be performed. Therefore, when the operator can confirm that there is a non-measurement target on the pulse indicator PIn in the B-mode image BI, the operator determines to change the measurement region R (“YES” in step S14). When the operator determines to change the measurement region R, the operator inputs an instruction to reset the measurement region R in the operation unit 7, returns to the step S12, and sets the measurement region R again. Thereby, the measurement region R can be reset so that a non-measurement target does not exist in the portion where the push pulse is transmitted.

  On the other hand, when the operator determines that there is no need to change the measurement region R (“NO” in step S14), the operator performs an input instructing not to change the measurement region R on the operation unit 7.

  In step S14, when an instruction for not changing the measurement region R is made, the process proceeds to step S15. In step S15, as in step S3 of the first embodiment, the evaluation unit 54 evaluates whether or not the measurement region R is a region in which measurement reliability can be ensured.

  In addition, the processes of step S16, step S17, and step S18 are the same as those of step S4, step S5, and step S6 of the first embodiment, respectively, and the description thereof is omitted.

  According to the example described above, the measurement region R can be set so that the non-measurement target does not exist on the path through which the push pulse is transmitted while having the same effect as the first embodiment. Therefore, more accurate elasticity measurement can be performed.

(Third embodiment)
Next, a third embodiment will be described. The ultrasonic diagnostic apparatus of this example has basically the same configuration as the ultrasonic diagnostic apparatus 1 of the first and second embodiments, but as shown in FIG. In addition to the image data creation unit 51, the display image control unit 52, the region setting unit 53, and the evaluation unit 54, a movement detection unit 55 and a determination unit 56 are included.

  The operation of this example will be described. Also in this example, the measurement region R ′ is set and elasticity measurement is performed basically in the same manner as the processing of steps S1 to S5 of the first embodiment or steps S11 to S17 of the second embodiment. However, in this example, the elasticity measurement method is different. In the first and second embodiments, the elastic modulus in each part of the two-dimensional measurement region R is calculated and the color elastic image CE is displayed. In this example, as shown in FIG. A push pulse PP is transmitted on the line, and one elastic modulus is calculated for the measurement region R ′ at the focal point. However, as will be described later, the push pulse PP is transmitted a plurality of times on one sound ray, and the elastic modulus is calculated for each transmission.

  In this example, in steps S3 and S15, the signal strength of the data in the measurement region R ′ (or the average signal strength when the measurement region R ′ is a plurality of pixels) is the first threshold TH1. When it is above or when it is less than or equal to the second threshold TH2, the evaluation unit 54 may evaluate that the reliability of the measurement region R ′ is low.

  The measurement of the elasticity of the measurement region R ′ in steps S6 and S18 in this example will be described based on the flowchart of FIG. First, in step S <b> 21, the operator inputs the push pulse transmission number n in the operation unit 7.

  Next, in step S22, data of the B-mode image BI1 is stored in the storage unit 9. The B mode image BI1 is a B mode image in which the measurement region R ′ is set.

  Next, in step S23, elasticity is measured for the measurement region R '. That is, after the push pulse PP is transmitted to the living tissue, a measurement ultrasonic pulse (not shown) for detecting the propagation speed of the shear wave is transmitted. Then, based on the echo signal of the ultrasonic pulse for measurement, the elasticity calculator 81 calculates the propagation speed of the shear wave, and calculates the elastic modulus based on the propagation speed.

  Next, in step S24, ultrasonic waves for B-mode images are transmitted / received to / from the living tissue again, and a B-mode image BI2 is created. Then, the data of the B-mode image BI2 is stored in the storage unit 9.

  Next, in step S <b> 25, the movement detection unit 55 detects the movement of the biological tissue before and after measurement by the elasticity calculation unit 81. Specifically, the movement detection unit 55 detects an image movement amount between the B-mode image BI1 and the B-mode image BI2. A known method is used to detect the movement amount of the image. The movement detector 55 is an example of an embodiment of a movement detector in the present invention.

  Next, in step S26, the determination unit 56 determines whether or not the movement amount detected by the movement detection unit 55 is greater than or equal to a predetermined movement amount. The determination unit 56 is an example of an embodiment of a determination unit in the present invention.

  If it is determined in step S26 that the movement amount is equal to or greater than the predetermined movement amount ("YES" in step S26), the process proceeds to step S27. On the other hand, if it is determined in step S26 that the amount is less than the predetermined movement amount ("NO" in step S26), the process proceeds to step S28.

  In step S27, the display image control unit 52 causes the display unit 6 to display a message asking whether or not the re-measurement is performed because the movement amount is equal to or greater than a predetermined movement amount. When the operator intends to perform re-measurement (“YES” in step S27), the operator inputs an instruction to that effect on the operation unit 7. As a result, the process returns to step S22, and the processes after step S22 are performed again. On the other hand, when the operator does not perform remeasurement (“NO” in step S27), the operator inputs an instruction to that effect on the operation unit 7. Thereby, the process proceeds to step S28.

  Next, in step S28, the measurement data (elastic modulus) obtained in step S23 is stored in the storage unit 9. When the amount of movement is less than a predetermined amount of movement, a message to that effect may be displayed on the display unit 6. When the measurement data is stored in the storage unit 9, for example, as shown in FIG. 14, the numerical indicator FIn displayed on the display unit 6 and indicating the current number of measurements may be updated. This numerical indicator FIn means that the measurement has been performed up to m (m ≦ n) times among the n measurements. As a result of the update, the value of m increases by one.

  Next, in step S29, it is determined whether or not the elasticity measurement count m has reached the nth time. If the number of measurements m has not reached the nth time ("NO" in step S29), the process returns to step S22, and the processes after step S22 are performed again. On the other hand, when the number of times of measurement m has reached the nth time, the process proceeds to step S30.

  In step S30, the elasticity calculation unit 81 calculates the average value of the elastic modulus obtained by n measurements. This average value may be displayed on the display unit 6. However, in this step S30, instead of the average value, the median value of the elastic modulus obtained by n measurements may be specified, and this median value may be displayed on the display unit 6. Furthermore, the degree of elasticity distribution obtained by n measurements may be calculated and displayed on the display unit 6.

  According to this example, when the living tissue moves before and after the elasticity measurement, remeasurement can be performed. Therefore, when the same part is measured a plurality of times and the average value is calculated, different parts are measured due to the body movement and heartbeat of the subject, movement of the ultrasonic probe 2 and the like. Can be prevented. Thereby, an accurate average value and median value can be obtained.

  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, a plurality of push pulses for the same portion may be transmitted at the same timing in one cardiac cycle based on an ECG (Electrocardiogram) signal from the subject. As a result, even when the elasticity measurement is performed a plurality of times on the portion where the motion due to the heartbeat occurs, the measurement on the same portion can be performed.

  Further, the elasticity calculation unit 81 may calculate the displacement generated in the living tissue by the push pulse transmitted to the living tissue as the elasticity of the living tissue. In this case, the displacement is calculated based on an ultrasonic echo signal for measurement transmitted to the living tissue.

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus 6 Display part 53 Area | region setting part 54 Evaluation part 55 Movement detection part 56 Judgment part 81 Elasticity calculation part

Claims (12)

An area setting unit for setting a measurement area for measuring elasticity of the biological tissue in an ultrasonic image of the biological tissue;
Based on the ultrasonic image data, an evaluation unit that detects a non-measurement object that is not an elasticity measurement object and evaluates the measurement region;
A display unit for displaying an image based on the evaluation of the evaluation unit;
An elastic measuring device comprising:   The elasticity measuring apparatus according to claim 1, wherein the evaluation unit detects the non-measurement target based on a signal intensity of data of the ultrasonic image.   The elasticity measurement apparatus according to claim 1, wherein the evaluation unit detects the presence / absence of the non-measurement target based on a distribution degree of signal intensity of B-mode image data in the measurement region. The evaluation unit detects, as the non-measurement target, a first portion in which the signal intensity of the B-mode image data is equal to or higher than a predetermined strength and a second portion that is equal to or lower than a predetermined strength in the measurement region,
The elasticity measurement apparatus according to claim 1 or 2, wherein the display unit displays the first part and the second part in the B-mode image.   The elasticity measuring device according to any one of claims 1 to 4, further comprising an elasticity calculating unit that calculates an elasticity value of the living tissue to which the push pulse is transmitted.   The said elasticity calculation part calculates the elasticity value of a biological tissue based on the propagation velocity of the shear wave which arose in the said biological tissue by the push pulse transmitted with respect to the said biological tissue. The elasticity measuring device as described.   The elasticity calculation unit calculates a displacement generated in the living tissue by a push pulse transmitted to the living tissue based on an echo signal of a measurement ultrasonic wave transmitted to the living tissue. The elasticity measuring device according to claim 5. A movement detector for detecting movement of the biological tissue before and after measurement;
A determination unit for determining whether or not the movement amount detected by the movement detection unit is equal to or greater than a predetermined movement amount;
A display unit on which a determination result by the determination unit is displayed;
The elasticity measuring device according to any one of claims 5 to 7, comprising:   The elasticity measurement apparatus according to claim 8, wherein the movement detection unit detects movement of a living tissue by detecting movement of the ultrasonic image before and after measurement.   The indicator which shows the push pulse transmitted to the living tissue in order to measure the elasticity of the living tissue on the ultrasonic image is displayed. Elasticity measuring device. On the computer,
An area setting function for setting a measurement area for measuring elasticity of the biological tissue in an ultrasonic image of the biological tissue;
Based on the ultrasonic image data, an evaluation function that detects a non-measurement object that is not an elasticity measurement object and evaluates the measurement region;
A display image control function for displaying an image based on the evaluation of the evaluation function;
The program of the elasticity measuring device characterized by performing this.   An ultrasonic diagnostic apparatus comprising the elasticity measuring apparatus according to claim 1.