JP2004351062A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operator with operational information on pressurization to obtain proper elastic images. <P>SOLUTION: This ultrasonic diagnostic equipment, which measures displacement values in each part based on two tomograms measured at different times by applying an external force by a pressurizing means to a subject, calculates an elastic modulus in each tissue based on the measured displacement data in each part, and displays the produced elastic images on a display means, is provided with a pressure determination means which determines whether the pressurizing operation by the pressurizing means has been properly performed or not by analyzing the displacement data. As a result, the displaying of the determination result by the pressure determination means on the display and the outputting through voice enable the operator to quickly adjust the pressurizing means to obtain proper elastic images. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and specifically, obtains an elastic modulus of each part of a living tissue based on two tomographic image data that are different in time series and are measured while applying pressure to a subject. And a technique for creating and displaying an elastic image representing the hardness or softness of a living tissue.
[0002]
[Prior art]
An ultrasonic diagnostic apparatus applies an ultrasonic probe to the surface of a subject, transmits ultrasonic waves from the probe to the subject, receives a reflected wave from the inside of the subject, and based on the received signal. The state of each part of the subject is displayed as an image such as a tomographic image for diagnosis. In the field of such an ultrasonic diagnostic apparatus, an external force is applied to the living tissue from the body surface of a subject, and based on two tomographic image data different in time series, based on displacement and pressure of each part of the living tissue. It has been proposed that the elastic modulus of each part of a living tissue is obtained by using the method, and an elastic image showing the hardness or softness of the living tissue is created and displayed (Patent Document 1).
[0003]
According to this elasticity image, it is possible to easily observe the site and size of a tumor such as a cancer cell that is harder than the surrounding tissue. In addition, when treating a lesion by radiotherapy, high-intensity ultrasonic irradiation, laser irradiation, electromagnetic RF wave irradiation, electromagnetic microwave irradiation, etc., the therapeutic effect can be monitored non-invasively, and the effect of drug administration such as anticancer drugs There is a demand for non-invasive observation of such images, and it is considered that an elasticity image is effective for such a demand.
[0004]
[Patent Document 1]
JP-A-5-317313
[Problems to be solved by the invention]
However, in the related art, the appropriateness of the pressurizing (including depressurization; hereinafter, the same in the present specification) operation of applying an external force to the living tissue from the body surface of the subject is not considered, and therefore, it is not necessarily appropriate. In some cases, an elastic image cannot be obtained.
[0006]
That is, the elasticity image obtains the elastic modulus from the displacement (strain), the pressure, and the like of each part of the living tissue based on the frame data of two time-series different tomographic images obtained by applying an external force to the living tissue, This is a qualitative image of the mode of the distortion itself or a quantitative image of the elastic modulus. The distortion of each part of the living tissue changes depending on the pressing operation such as the size of the pressing, the pressing speed, the pressing time, and the pressing direction, and the difference in the distortion between two adjacent frames is some degree. Otherwise, an appropriate elasticity image cannot be created.
[0007]
In particular, external force may be applied by mechanical means, but for simplicity, it is often applied by pressing the ultrasonic probe against the body surface of the subject, and the pressurized state fluctuates greatly due to the operator's hand. Therefore, an appropriate elastic image may not always be obtained. Similarly, since there are individual differences among subjects, even if the subject is operated under a constant pressurized state, an appropriate elasticity image is not always obtained.
[0008]
In addition, lateral displacement may occur in the living tissue depending on the direction of pressing and the pressing method. Even in the case of such a pressing operation, disturbance (noise) due to the lateral displacement is included in the elastic image, and an appropriate elastic image is not obtained. May not be obtained.
[0009]
SUMMARY OF THE INVENTION It is an object of the present invention to provide pressure operation information for obtaining an appropriate elastic image to an operator.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject, an ultrasonic transmission unit that outputs an ultrasonic signal that drives the ultrasonic probe, Pressurizing means for applying an external force to the subject, and two temporally different tomographic image data obtained from reflected echo signals received by the ultrasonic probe, based on the two tomographic image data The displacement measuring means for measuring the displacement of each part, the elastic modulus calculating means for calculating the elastic modulus of the tissue of each part based on the displacement data of each part measured by the displacement measuring means, and the elastic modulus calculating means In an ultrasonic diagnostic apparatus comprising: an image generating unit that generates an elasticity image based on an elasticity modulus; and a display unit that displays the generated elasticity image, the displacement data is analyzed to apply a pressure by the pressing unit. Pressure operation A pressure determination means, characterized in that the determination result of the pressurizing determining means is provided and a determination output means for displaying on the display means.
[0011]
As described above, since the appropriateness of the pressurizing operation is immediately displayed on the display means, the operator adjusts the pressurizing operation by the pressurizing means (for example, a probe) according to the appropriateness of the displayed pressurized state. By doing so, an appropriate elastic image can be obtained. Further, since the displacement data is analyzed to determine whether or not the pressurizing operation is appropriate, it is possible to determine whether or not the pressurizing operation is appropriate including the individual difference of the subject. As a result, it is possible to realize an elastic image pickup which is excellent in convenience for the operator.
[0012]
Here, the pressurizing determination unit obtains a strain rate distribution in the tomographic image based on the displacement data, and determines whether pressurization by the pressurizing unit is appropriate based on whether the strain rate distribution is within an appropriate range. be able to. In addition to or instead of this, the pressurizing determination means obtains the degree of the lateral shift in the tomographic image based on the displacement data, and determines whether the pressurizing by the pressurizing means depends on whether the degree of the lateral shift is within an appropriate range. Compliance can be determined. Furthermore, the determination output means may output guidance and / or voice for correcting the pressurizing operation based on the determination result.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a block diagram of an ultrasonic diagnostic apparatus of the present invention, FIG. 2 shows a flowchart of a processing procedure of elastic image acquisition according to the ultrasonic diagnostic apparatus of the present embodiment, and FIG. It is a figure showing an example of a display image.
[0014]
As shown in FIG. 1, the ultrasonic diagnostic apparatus takes in a probe 1 for transmitting and receiving ultrasonic waves to and from a subject, and a reflected echo signal output from the probe 1 to reconstruct a tomographic image. It comprises a tomographic image constructing unit 2 to be configured and a display unit 3 for displaying a reconstructed tomographic image. The illustration of an ultrasonic transmission unit that outputs an ultrasonic signal for driving the probe 1 is omitted. The elasticity calculation unit 4 sequentially captures the frame data of the reflected echo signal input to the tomographic image construction unit 2 and measures the displacement of the tissue of each part of the tomographic image based on two time-series adjacent tomographic image data. And an elastic modulus calculating means for calculating the elastic modulus of the tissue of each part based on the displacement data of each part measured by the displacement measuring means. Further, the elasticity calculation unit 4 is configured to include a pressure determination unit that analyzes the displacement data and determines whether the pressure operation is appropriate.
[0015]
The elasticity image construction unit 5 creates an elasticity image based on the elasticity modulus obtained by the elasticity calculation unit 4, outputs the created elasticity image to the display unit 3, and stores it in the cine memory 12. The result of the pressing operation determined by the elasticity calculating unit 4 is stored in the pressurized state memory 6 in association with each elasticity image and output to the operation information output unit 7. The operation information output unit 7 outputs and displays the determination result of the pressing operation on the display unit 3 and can output the determination result of the pressing operation by voice via the voice output unit 8.
[0016]
On the other hand, various operation commands and setting information input from the operation input unit 9 are input to the central processing unit 10, and the central processing unit 10 controls the cine memory image reproducing unit 11 and the like according to the input instruction and the like. Has become.
[0017]
An operation of acquiring an elasticity image by the ultrasonic diagnostic apparatus configured as described above will be described with reference to a flowchart of FIG. 2 and a display image example of FIG. First, as shown in FIG. 3A, at the start of the measurement of the elasticity image, the tomographic image 21 is output and displayed on the display unit 3 from the tomographic image construction unit 2 and is added to the display unit 3 from the operation information output unit 7. A dialog 22 for displaying the pressure state is displayed (S1). The dialog 22 has a bar chart-like horizontally long display area, and two triangular marks 23a and 23b are displayed along the display area. The mark 23a is a lower limit value of an appropriate range of the pressing operation, and the mark 23b is Corresponds to the upper limit.
[0018]
Next, the operator presses the body surface of the subject with the probe 1 to press the living tissue (S2). In this pressurized state, the tomographic image construction unit 2 sequentially acquires the reflected echo signals and updates the tomographic image on the display unit 3 (S3). The elasticity calculation unit 4 sequentially acquires frame data of the tomographic image from the tomographic image construction unit 2, measures the displacement of the tissue of each part based on two frame data adjacent in time series, and measures the measured displacement data of each part. The elastic modulus of the tissue of each part is calculated on the basis of (S4), and the data of the calculated elastic modulus is output to the elastic image construction unit 5 (S5). In step S4, the elasticity calculation unit 4 analyzes the displacement data to determine whether or not the pressing operation is appropriate, and outputs the determined pressing state to the pressing state memory 6 (S7). For example, as shown in FIG. 4, the distribution 31 of the distortion rate ε in the tomographic image based on the displacement data, that is, the distortion rate of each pixel is set on the horizontal axis, and the number of pixels having the same distortion rate is set on the vertical axis, as shown in FIG. Then, the distribution of the strain rate ε is obtained. Appropriateness of the pressurizing operation by the pressurizing means is determined based on whether or not the average value εm of the strain rate distribution 31 is within the upper and lower limits (εH, εL) of the appropriate range. For example, the distortion rate distributions 32 and 33 indicated by broken lines in FIG. 4 are inappropriate examples because the average values are out of the upper and lower limits (εH, εL). Incidentally, the strain rate distribution 32 is an example when the pressing speed is too slow, and the strain rate distribution 33 is an example when the pressing speed is too fast. The pressurized state is determined at, for example, eight evaluation levels, stored in the pressurized state memory 6 and output to the operation information output unit 7.
[0019]
The elasticity image constructing unit 5 constructs an elasticity image by color mapping based on the elasticity modulus data output from the elasticity calculating unit 4, and superimposes the elasticity image on the tomographic image 21 of the display unit 3 as shown in FIG. The elasticity image 24 is displayed (S7). Further, the elastic image data is stored in the cine memory 12 (S8). Next, the operation information output unit 7 acquires the evaluation level of the pressurized state output from the elasticity calculation unit 4 (S9), determines the state display of the dialog 22 based on this, and outputs it to the display unit 3 ( S10) For example, as shown in FIG. 3C, the display unit 3 updates the display of the dialog 22. Note that the example in the figure shows a case where the evaluation level in the pressurized state is too fast, exceeding the appropriate range. The operator adjusts the pressurizing speed to a lower value while watching the display of the dialog 22, and based on the adjusted pressurizing speed in the next elastic image creating process executed by returning to step S2 in FIG. An appropriate elastic image as shown in FIG. 3D is obtained. Therefore, as shown in FIG. 3E, the state display of the dialog 22 is within the proper range of the marks 23a and 23b, and it can be understood that a proper elasticity image has been obtained. The marks 23a and 23b of the dialog 22 in FIG. 3 correspond to the upper and lower limits (εH, εL) of the appropriate range.
[0020]
As described above, according to the present embodiment, the suitability of the pressurizing operation is immediately displayed on the dialog 22, so that the operator can adjust the probe 1 according to the suitability of the pressurized state displayed on the dialog 22. By adjusting the operation, a pressing operation for obtaining an appropriate elastic image can be easily performed. Moreover, according to the present embodiment, it is possible to determine whether or not the pressurizing operation is appropriate including the individual difference of the subject, so that the operator can very easily perform the appropriate pressurizing operation.
(Embodiment 2)
In the first embodiment, an example is shown in which the appropriateness of the pressurizing operation is displayed on the display unit 3 by a dialog, but the present invention is not limited to this, and the appropriateness of the pressurizing operation may be output by voice. it can. FIG. 5 is a flowchart showing a case where the appropriateness of the pressing operation is output by voice, and FIG. 6 shows an example of a display image in this case. In FIG. 5, step S21 is the same as steps S2 to S8 in FIG. The operation information output unit 7 acquires the evaluation level of the pressurized state output from the elasticity calculation unit 4 (S22), and determines whether the evaluation level is appropriate (proper) (S23). If the evaluation level is appropriate, the process ends. If the evaluation level is not appropriate, it is determined whether the evaluation level exceeds the appropriate range and is "fast" or "slow", and the evaluation result is set to "fast" or "slow" sound, respectively (S25, S26). As a result, "fast" and "slow" voice output commands are issued from the operation information output unit 7 (S27), and the evaluation result, that is, the operation information is output by the voice specified by the voice output unit 8. FIGS. 6A to 6E show examples of display images at this time.
[0021]
As described above, according to the present embodiment, the operator can obtain the operation information by voice without looking at the display image, so that the pressing operation for obtaining the appropriate elastic image can be easily performed.
(Embodiment 3)
FIG. 7 shows a flowchart in the case where the elastic image stored in the cine memory 12 of FIG. 1 is reproduced and displayed. When the operation input unit 9 instructs the central processing unit 10 to reproduce cine memory (S31), the central processing unit 10 outputs a cine memory reproduction instruction to the cine memory image reproducing unit 11 (S32). Accordingly, the cine memory image reproducing unit 11 acquires the elasticity image from the cine memory 12 (S33), and acquires the evaluation result of the pressurized state synchronized with the elasticity image read out from the pressurized state memory 6 (S34). Next, it is determined whether the read-out pressurized state is appropriate (S35), and if not, the process ends. If appropriate, the central processing unit 10 outputs a command to display the elasticity image reproduced by the cine memory image reproduction unit 11 on the display unit 3 (S36). Thereby, the elasticity image stored in the cine memory 12 is displayed on the display unit 3 (S37). That is, only the appropriate elastic image stored in the cine memory 12 is reproduced and displayed.
(Embodiment 4)
Embodiments 1 to 3 are embodiments in which operation information is provided based on whether or not the speed of the pressurizing operation is appropriate. However, the present invention is not limited to this. The operation information can be provided in the case of a pressure that causes lateral displacement. In other words, even if the pressurizing speed is temporally constant in the process of the pressurizing operation, it is not always the time period (hereinafter, referred to as a time phase) in which the subject can be evenly pressurized in the vertical direction. Absent. For example, when there is a time phase in which the subject is pressed obliquely or non-uniformly, a time phase occurs in which the distribution of stress applied to the living tissue becomes discontinuous. In such a time phase, since a coordinate area that jumps discontinuously occurs in the time change, an area where the time jumps is included as a disturbance (noise) in the obtained elasticity image, and image diagnosis cannot be appropriately performed. There is a problem. In other words, there is a problem that image diagnosis cannot be performed properly when a lateral shift occurs in which the living tissue moves in the horizontal direction due to, for example, inability to apply pressure evenly in the vertical direction.
[0022]
In the present embodiment, the case where the living tissue is laterally displaced by such a pressing operation is detected, and operation information is provided. This embodiment can be realized by replacing the pressure determining means constituting the elasticity calculating unit 4 in the embodiment of FIG. That is, as shown in FIG. 8, the displacement data is taken in from the displacement measuring means 39 which takes in the frame data of the RF data from the tomographic image construction unit 2 and measures the displacement, and judges the degree of the lateral shift. Is stored in the pressurized state memory 6. 8, elastic modulus calculating means 40 calculates the elastic modulus of each part of the tissue based on the displacement data, and is a function included in the elasticity calculating unit 4 of FIG.
[0023]
FIG. 9 shows a flowchart focusing on the processing procedure in the lateral displacement determining means 38 according to the present embodiment. When the elasticity diagnosis mode is turned on from the operation input unit 9 to the central processing unit 10, as shown in FIG. 10, a region of interest (ROI) 36 for obtaining an elasticity image on the tomographic image 35 and the elasticity modulus are displayed on the display unit 3. The color map 37 is displayed (S41). Next, the displacement measuring unit 39 fetches a set of frame data adjacent in time series from the tomographic image construction unit 2 (S42), and performs displacement or movement vector (direction of displacement) of each pixel on the tomographic image by correlation processing or the like. And size), and detect a lateral shift (S43 to S45).
[0024]
For example, a well-known block matching method can be applied to the correlation processing in the displacement measuring unit 39. In the block matching method, an image is divided into blocks each including N × N pixels (N is a natural number), and a block in which the image is closest to the block of interest in the current frame is searched from the previous frame, and the block is referred to. This is a method of predictive encoding. As illustrated in FIG. 11, a block including N × N pixels is set as a correlation window 41, and an area including a plurality of blocks including N × N pixels is set as a search range 42. It is also assumed that the block referred to in the previous frame has the highest correlation with the block in the current frame. Here, in order to simplify the explanation, the size of the search range 42 is set to the size of nine correlation windows 41 as shown in FIG. That is, it is assumed that blocks having the same size as the correlation window 41 are arranged in the vertical, horizontal, and oblique directions around the correlation window 41. Needless to say, the correlation window 41 and the search range 42 can be set arbitrarily. Now, assuming that the stress applied from the probe is evenly applied in the vertical direction of the subject, the block in which the correlation between the current frame and the previous frame is the largest is the vertical direction with respect to the central correlation window 41 in FIG. Block-2,8. On the other hand, when the tissue of the subject has moved in the lateral direction due to the stress from the probe, the blocks having the largest correlation are blocks -4 and 6 located on the left and right of the correlation window 41 (however, the blocks are referred to as blocks 4 and 6). -1, 3, 7, 9). Then, in order to find the position of the block having the largest correlation within one search range 42, a correlation operation is performed on the nine blocks to find the block position having the largest correlation. In this correlation calculation, for example, when the correlation is the maximum in the horizontally located blocks -2 or 8, it is determined that there is a lateral displacement, and the lateral displacement counter is counted up. In this way, the correlation processing is performed on the target data in the ROI, and the displacement amount in the ROI and the count number C of the lateral displacement counter are calculated. Further, since the data in the ROI is divided by the search range 42, the number A of the divided search ranges 42 is also calculated. The amount of displacement in the ROI is sent to the elastic modulus calculating means 40, and the count number C of the horizontal shift counter and the number A of the divided search ranges 42 are sent to the horizontal shift determining means 38.
[0025]
The lateral deviation determining means 38 determines a lateral deviation based on the input A and C (S46). This determination depends on whether the following equation (1) holds. Here, X is a threshold value determined empirically.
[0026]
A / X <C (1)
When the magnitude relation of Expression (1) is established, it can be determined that a force is uniformly applied to the subject in the vertical direction. In this case, the lateral displacement occurrence flag is set to "0" and stored in the pressurized state memory 6 (S47). Conversely, when the relationship of Expression (1) does not hold, it can be determined that the biological tissue is laterally displaced in a state where the force is not uniformly applied to the subject in the vertical direction. In this case, the lateral displacement flag is set to "1" and stored in the pressurized state memory 6 (S52). The contents of the pressurized state memory 6 are warned by displaying "lateral deviation" on the lower side of the tomographic image 35, for example, as shown in FIG. 10 (S56).
[0027]
On the other hand, the elasticity modulus calculating means 40 calculates the strain data S based on the displacement amount B measured by the displacement measuring means 39 (S48, S53), and the elasticity image constructing section 5 of FIG. The elasticity image is constructed by performing the conversion process and displayed on the display unit 3.
[0028]
As described above, according to the present embodiment, the operator can check in real time how the force of the probe is being applied to the subject. Since it is possible to adjust the operation of the tentacle so that the lateral displacement does not easily occur, it is possible to quickly obtain an appropriate elastic image.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to provide the operator with operation information of pressurization for obtaining an appropriate elastic image, and thus it is possible to efficiently obtain an elastic image.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 shows a flowchart of a processing procedure for acquiring an elasticity image according to the ultrasonic diagnostic apparatus of the present embodiment.
FIG. 3 is a diagram illustrating an example of a display image according to the present embodiment.
FIG. 4 is a diagram showing an example of a distortion rate distribution used for determining whether or not a pressing operation is appropriate.
FIG. 5 shows a flowchart in the case of outputting the propriety of pressurization operation by voice.
6 shows an example of a display image according to the embodiment of FIG. 5; FIG. 7 shows a flowchart in a case where an elastic image stored in a cine memory is reproduced and displayed;
FIG. 8 is a diagram showing a configuration around a lateral shift judging means of a characteristic portion according to Embodiment 4 of the present invention.
FIG. 9 is a flowchart mainly showing a processing procedure in a lateral displacement determining unit.
FIG. 10 is a diagram illustrating a state of a display image according to the embodiment in FIG. 8;
FIG. 11 is a diagram illustrating a block matching method for detecting a lateral shift.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 probe 2 tomographic image construction unit 3 display unit 4 elasticity calculation unit 5 elasticity image construction unit 6 pressurized state memory 7 operation information output unit 8 audio output unit 9 operation input unit 10 central processing unit 11 cine memory image reproduction unit 12 cine memory

Claims (4)

An ultrasonic probe that transmits and receives ultrasonic waves to and from the subject, an ultrasonic transmitting unit that outputs an ultrasonic signal that drives the ultrasonic probe, and a pressurizing unit that applies an external force to the subject Displacement measurement means for acquiring two temporally different tomographic image data from the reflected echo signals received by the ultrasonic probe, and measuring the displacement of each part based on the two tomographic image data; Elastic modulus calculating means for calculating the elastic modulus of the tissue of each part based on the displacement data of each part measured by the displacement measuring means, and an image for creating an elastic image based on the elastic modulus obtained by the elastic modulus calculating means Generating means, an ultrasonic diagnostic apparatus including a display means for displaying the generated elasticity image,
A pressure determination unit that analyzes the displacement data to determine whether the pressure operation by the pressure unit is appropriate; and a determination output unit that displays a determination result of the pressure determination unit on the display unit. An ultrasonic diagnostic apparatus, comprising: The pressurizing determination unit obtains a strain rate distribution in the tomographic image based on the displacement data, and determines whether pressurization by the pressurizing unit is appropriate based on whether the strain rate distribution is within an appropriate range. The ultrasonic diagnostic apparatus according to claim 1, wherein The pressurizing determination unit obtains a degree of a lateral shift in the tomographic image based on the displacement data, and determines whether the pressurizing unit is appropriate for the pressurization based on whether the degree of the lateral shift is within an appropriate range. The ultrasonic diagnostic apparatus according to claim 1, wherein: 4. The ultrasonic diagnostic apparatus according to claim 2, wherein the determination output unit outputs guidance and / or voice for correcting a pressurizing operation based on the determination result. 5.

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