JP3299002B2 - Ultrasound diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus having a function of detecting and displaying properties of a living tissue such as a strain and a strain rate in a subject.

[0002]

2. Description of the Related Art Ultrasonic waves are transmitted into a subject, particularly a human body, and received ultrasonic waves reflected in the subject are received to obtain a received signal, and a tomographic image or the like based on the received signal is displayed to display the internal organs of the human body. Ultrasound diagnostic apparatuses that are useful for diagnosing diseases such as the above have been used. Today, when diagnosing ischemic heart disease such as angina or myocardial infarction, the ischemic site is specified by observing the movement of the myocardium on an ultrasonic image. However, such a diagnosis is only a subjective diagnosis, and it is required to obtain objective data for more reliable diagnosis.

For this purpose, it is desirable to detect and display the properties of living tissue. Among the properties of living tissues that have been studied at present, minute displacement information is expected to be promising. It is known that in a normal heart, the thickness of the heart wall (hereinafter, referred to as wall thickness) differs between diastole and systole, and the change in wall thickness becomes smaller when ischemia occurs. Therefore, it is expected that the so-called “heart muscle life” can be seen by displaying the wall thickness change rate. For this purpose, it is necessary to accurately detect and display the degree of movement of the myocardium, which is the reason why the minute displacement information is considered useful.

FIG. 9 is a block diagram showing an example of the configuration of an ultrasonic diagnostic apparatus designed to detect and display the properties of a living tissue. Since the general configuration of the ultrasonic diagnostic apparatus is already widely known, the following description is limited to the parts necessary for comparison with the present invention. The transmission / reception circuit 11 sends a transmission pulse to an ultrasonic probe (not shown) to transmit the ultrasonic wave into the subject, receives the ultrasonic wave reflected in the subject, and obtains a reception signal. The received signal is supplied to a logarithmic amplification detection circuit 12 and a tissue property information detecting means 1.
3 is input.

The logarithmic amplification detection circuit 12 is composed of a logarithmic amplifier, a detection circuit, and the like, thereby generating an RF signal representing the amplitude of the reflected ultrasonic wave, and finally generating a tomographic image (B-mode image) of the subject. An image signal representing the image is generated, and the display means 1
5 is displayed. Further, the tissue property information detecting means 13
There may be various configurations depending on the tissue properties to be detected.However, when detecting the strain velocity, the velocity is detected by the quadrature detector and the autocorrelator, and the average velocity is differentiated in the depth direction by the differentiator. , Thereby detecting the strain rate.

[0006] The RF signal generated by the logarithmic amplification detection circuit 12 and the tissue property information detected by the tissue property information detecting means 13, for example, the strain rate, are input to a display control means 14. The display control means 14 displays a B-mode image on the display means 15 according to the amplitude of the RF signal, for example, a blood vessel or a diaphragm having a large amplitude (brightness in the case of display) in a liver or the like. For an area with a small value, for example, the distortion speed is displayed in color. Alternatively, for example, in the heart or the like, the B-mode display is performed as it is for a clutter component having a small amplitude, and the strain velocity is displayed in color for a myocardium having a large amplitude.

[0007]

However, when the tissue property information is displayed in a region having a large amplitude or a region having a small amplitude based on the amplitude of the RF signal as described above, inconvenience may occur. For example, in observing the heart,
Despite the fact that it is the region of the myocardium for which the strain rate is desired to be observed, not only the myocardium to be observed, but also the chest wall and the bottom of the heart have high brightness, and in some cases the brightness in the heart chamber is high due to multiple reflections etc. Therefore, various regions other than the myocardium to be observed are displayed in color, resulting in an image that is very difficult to make a diagnosis. In addition, since these unnecessary parts are almost stationary, as a result of differentiating the average velocity in the depth direction, an apparent large strain velocity occurs at the boundary with the moving myocardium, which leads to misdiagnosis. There is also a problem.

The present invention has been made in view of the above circumstances, and has as its object to provide an ultrasonic diagnostic apparatus capable of displaying tissue property information such as the above-mentioned minute displacement information only in a desired area.

[0009]

FIG. 1 is a diagram illustrating the principle of an ultrasonic diagnostic apparatus according to the present invention. It should be noted that components of the general ultrasonic diagnostic apparatus other than the features of the present invention are omitted. The same components as those of the ultrasonic diagnostic apparatus shown in FIG. 9 described above are denoted by the same reference numerals as those in FIG.

The received signal obtained by the transmitting / receiving circuit 11 is input to the tissue property information detecting means 13 and the speed information detecting means 16. The tissue property information detecting means 13 detects information on the tissue property of the tissue inside the subject. Here, the “tissue property information” includes a displacement, a strain, a strain rate, and a nonlinear parameter of the tissue inside the subject, and an amount calculated from at least one of the displacement, the strain, the strain rate, and the nonlinear parameter. included.

Here, the terms “displacement”, “strain”, and “strain rate” are terms with well-established concepts. Non-linear parameters are widely known terms, and are described as follows. That is, the non-linear parameter means that when measuring displacement or velocity in the subject, for example, a 3 MHz ultrasonic wave is transmitted / received in a state where the subject is vibrated by a pump wave of about 300 kHz and in a state where the vibration is not vibrated. Displacement or velocity, and refers to the spatial change in the subject of the displacement or velocity in these two states.

The speed information detecting means 16 detects speed information of the tissue inside the subject. The speed information detecting means 16 is composed of, for example, a quadrature detector, an autocorrelator and the like. Depending on what is selected as the tissue property information, the speed information detecting means 16 and the tissue property information detecting means 13 are selected.
May be partly shared. The display means 15 displays the tissue property information based on the control by the display control means 14. The display means 15 may display a B-mode image or the like together with the tissue property information or by switching to the tissue property information. Preferably, the display means 15 has a persistence function.

The display control means 14 comprises the speed information detecting means 1
The determination of whether or not to display the tissue property information is made based on the speed information detected by the control unit 6, and the display means 15 is controlled so that the tissue property information is displayed only in the display enabled area. The display control means 14 may control the display means 15 so that the tissue property information is displayed only in an area which is further reduced from an area which can be displayed based on the speed information. The display control means 14 may determine whether or not to display the tissue property information based on the speed information and the amplitude value of the received signal.

[0014]

In the case of observing the heart, for example, the moving speed is extremely low in a high-luminance part where no display is desired. Therefore, display or non-display may be determined according to the average speed. When the myocardium is moving in a direction perpendicular to the ultrasonic beam direction, the average speed is close to 0 and non-display is selected. However, since the speed variance becomes a certain level or more, the determination based on the speed variance Should be added. In some cases, it is also possible to make a determination based only on the speed dispersion.

In order to perform the differential operation, the number of data of about 2 to 3 mm is necessary in the depth direction, and 1 to 1.5 corresponding to half the number of data required for differentiation from the boundary of the myocardium.
By hiding about mm, incorrect analysis results can be excluded from the display. However, judging only by the above average speed and speed variance, the brightness is extremely low, but only the average speed is high.The apparent large distortion speed due to the high clutter component is extremely low even if the average speed and the speed variance are extremely low. Can be excluded from the display by making a determination in consideration of the conventional determination based on the luminance level that no display is made.

Also, a valve moving at a very high speed, such as a valve, can be excluded from the display by determining that only the one having a speed lower than a certain level is displayed. As described above, according to the present invention, the display or non-display of the tissue property information is determined based on the speed information or based on the luminance (amplitude) information in addition to the speed information, so that an easy-to-view image with less misdiagnosis is generated. Is done.

[0017]

Embodiments of the present invention will be described below. FIG. 2 is a block diagram showing a configuration of a characteristic portion of one embodiment of the ultrasonic diagnostic apparatus of the present invention. Doppler autocorrelator 16
From 1, velocity information of each tissue in the subject is output. Among the speed information, the average speed v and / or the speed fraction σ ² are input to the ROM table 162, and the average speed v is input to the differential filter 163. The ROM table 162 stores a table for converting speed information (horizontal axis) into “display enabled” or “display disabled” as shown in FIG. , Display enable / disable information indicating “display disable” is output and input to the digital scan converter 164.

The differential filter 163 differentiates the input average velocity v in the direction of the ultrasonic beam to obtain a distortion velocity. This distortion speed is also input to the digital scan converter 164. In the digital scan converter 164, of the input distortion speed, only the area of the display permission / inhibition information input from the ROM table 162, which is set to "display enabled", is converted into an image signal and sent to the display for display. At that time, it may be displayed together with the B-mode image.

FIG. 4 is a block diagram showing a configuration of a characteristic portion of another embodiment of the ultrasonic diagnostic apparatus according to the present invention. FIG.
2 are denoted by the same reference numerals as those shown in FIG. 2, and only differences will be described. In the embodiment shown in FIG. 4, an area reduction filter 165 is provided. Differential filter 16
The derivative of the average velocity v by 3 results in a large apparent strain velocity at the boundary with the myocardium. The region reduction filter 165 reduces the display region of the distortion speed so that the distortion speed of the region where the apparent large distortion speed occurs is not displayed.

FIG. 5 is a diagram showing an example of the area reduction filter 165. The display availability information from the ROM table 162 (see FIG. 4) is stored in the plurality of unit delay circuits 165-1 and 15-1.
65-1,..., 165-1. Also, the unit delay circuits 165-1, 165-1, ..., 165
Each output of -1 is input to an AND circuit 165-2, where a logical product is calculated.

That is, when the display enable / disable information sequentially input from the ROM table 165 shifts from "display disable" to "display enable", the "display enable" information is input to the last unit delay circuit 165-1. Until the information is displayed, the information of "display not" is output. When the display is changed from "display possible" to "display not", the information of "display not" is output when the information of "display not" is first input. Will be done. Thus, the number of unit delay circuits 165-1, 165-1,...
The “displayable” area is reduced.

FIG. 6 is a diagram showing another example of the area reduction filter. The area reduction filter 165 'shown in FIG.
Is different from the area reduction filter 165 shown in FIG. 5 in that an addition circuit 165-3 is provided instead of the AND circuit 165-2, and a comparator 165-4 for comparing the addition result with a threshold value M is provided. Have been.

In the area reduction filter 165 shown in FIG.
A plurality of unit delay circuits 165-1, 165-1, ..., 16
While “display not” is stored in any one of 5-1, “display not” is output. However, the area reduction filter 165 ′ shown in FIG. , If "displayable" is dominant, "displayable" is output,
If “display not” is dominant, “display not” is output.

FIG. 7 shows another example of the ultrasonic diagnostic apparatus of the present invention.
It is a block diagram showing the structure of the characteristic part of one Example. This embodiment is different from the embodiment shown in FIG. 2 in that a logarithmic amplification detection circuit 12 is provided. Since the logarithmic amplification detection circuit 12 has been described in the description of FIG. 9, the duplicate description will be omitted here.

The ROM table 162 receives the amplitude (luminance) information output from the logarithmic amplification detection circuit 12 in addition to the speed information output from the Doppler autocorrelator 161. The ROM table 162 stores “display enabled” and “display disabled” information for combinations of speed information and amplitude (luminance) information. As described above, by determining “display possible” and “display non-display” based on both the speed information and the amplitude (luminance) information, as described above, an apparently large distortion speed due to the clutter component is excluded from the display. It becomes possible.

FIG. 8 is a diagram showing one mode of display.
As shown in FIG. 8, it is effective to assign a color whose hue gradually changes from blue to green to red, for example, to the distortion speed and display in color, which is an effective display method for finding an ischemic site. It is. If displayed in this way, where the change in wall thickness is large, the area where the wall thickness increases becomes red, the area where the wall thickness decreases becomes blue, and in the ischemic area there is no change in green color. , Can quickly find the ischemic site.

In each of the above embodiments, color display is performed only at the moment when the myocardium moves. However, by adding a so-called persistence circuit, the color at the moment when the myocardium moves is changed to the color at the next moment when the myocardium moves. Can be maintained until the image is displayed. Although the above description has been limited to the display of minute displacement information, it is actually similarly effective in displaying information on other tissue properties such as a nonlinear parameter and a damping coefficient.

In each of the above embodiments, the average velocity v and the velocity variance σ ² are detected by the Doppler method. However, two-dimensional spatial differentiation is performed to obtain the distortion velocity by using the two-dimensional cross-correlation method. You may do so.

[0029]

As described above, according to the present invention,
The tissue property information can be displayed only for a desired area. In particular, in the heart, information on myocardial tissue, particularly information on changes in the thickness of the myocardium, can be accurately displayed. Therefore, the present invention greatly contributes to the development of an ultrasonic diagnostic apparatus for performing accurate diagnosis.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a characteristic portion of an embodiment of the ultrasonic diagnostic apparatus according to the present invention.

FIG. 3 is a diagram showing the contents of a ROM table.

FIG. 4 is a block diagram showing a configuration of a characteristic portion of another embodiment of the ultrasonic diagnostic apparatus of the present invention.

FIG. 5 is a diagram showing an example of a region minute filter.

FIG. 6 is a diagram showing another example of the area reduction filter.

FIG. 7 is a block diagram showing a configuration of a characteristic portion of another embodiment of the ultrasonic diagnostic apparatus of the present invention.

FIG. 8 is a diagram showing one mode of display.

FIG. 9 is a block diagram showing an example of a configuration of an ultrasonic diagnostic apparatus designed to detect and display a biological tissue property.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 transmission / reception circuit 12 logarithmic amplification detection circuit 13 tissue property information detection means 14 display control means 15 display means 16 speed information detection means 161 Doppler autocorrelator 162 ROM table 163 differential filter 164 digital scan converter 165, 165 'area reduction filter

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 8/00-8/15

Claims (5)

(57) [Claims] An ultrasonic diagnostic apparatus that transmits an ultrasonic wave into a subject, receives an ultrasonic wave reflected inside the subject, obtains a received signal, and displays information inside the subject based on the received signal. A tissue property information detecting means for detecting tissue property information of the internal tissue of the subject; a speed information detecting means for detecting speed information of the internal tissue of the subject; a display means for displaying the tissue property information; A display control means for controlling the display means so as to determine whether or not the tissue property information can be displayed and to display the tissue property information only in an area where the display is enabled. Diagnostic device. 2. The tissue property information includes a displacement, a strain, a strain rate, and a non-linear parameter of a tissue inside the subject, and an amount calculated from at least one of the displacement, the strain, the strain rate, and the non-linear parameter. 2. The method according to claim 1, wherein said at least one member is selected from a group.
An ultrasonic diagnostic apparatus as described in the above. 3. The display control means controls the display means so that the tissue property information is displayed only in an area reduced further than an area which can be displayed based on the speed information. 3. The ultrasonic diagnostic apparatus according to claim 1, wherein: 4. The apparatus according to claim 1, wherein the display control means determines whether or not to display the tissue property information based on the speed information and an amplitude value of the received signal. 4. The ultrasonic diagnostic apparatus according to 3. 5. The ultrasonic diagnostic apparatus according to claim 1, wherein said display means has a persistence function.