JP2004357876A - Somascope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a somascope with which the influence of artifacts can be eliminated to perform in vivo observation. <P>SOLUTION: An ultrasonic wave is transmitted by an ultrasonic probe 11, reflected in a body and received by the ultrasonic probe 11. A blood flow detecting section 14 detects a position of the blood flow by the frequency of the reflected ultrasonic wave using the fact that the frequency of the ultrasonic wave is changed by Doppler effect when it is reflected by the intravascular blood flow. An analysis exclusion area deciding section 17 excludes the data acquired from the detected position of the blood flow from the subject for analysis. An analysis section 18 measures the thickness of a complex of the intima and the media or the like from the data of the ultrasonic measurement acquired from outside of the excluded area. The measurement error caused by the artifacts can be prevented by excluding the position of the blood flow from the subject for analysis, since the artifacts occur frequently at the position of the blood flow. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to an ultrasonic diagnostic apparatus for measuring the thickness of an intima-media complex of a blood vessel.
[0002]
[Prior art]
Since arteriosclerosis causes heart diseases such as angina pectoris and myocardial infarction, cerebral infarction and the like, it is desirable to conduct periodic examinations. The arteriosclerosis is a thickening and hardening of the intima and the media in the blood vessel wall of the artery having three layers of the adventitia, the media and the intima. Usually, the diagnosis of arteriosclerosis is performed by measuring the thickness of the intima-media complex of the carotid artery (Intima-Media Thickness, hereinafter referred to as "IMT"). Here, the carotid artery is measured because the IMT value of the carotid artery increases from the initial stage of arteriosclerosis compared to other sites, so that arteriosclerosis can be easily found. This is because the measurement is easy due to the shallow depth from the skin of 2 to 3 cm.
[0003]
Conventionally, the measurement of the IMT value has been performed by photographing the carotid artery with an ultrasonic diagnostic apparatus and analyzing the obtained ultrasonic image. Specifically, a doctor or a technician who is a measurer applies a caliper or the like to a screen of a display device or a printed image to obtain an IMT value. However, such a method not only requires a long time for measurement, but also has a problem that the measurement accuracy depends on the skill of the measurer. In order to determine arteriosclerosis, the measurement of the IMT value requires an accuracy of 0.1 mm, but it is difficult to perform measurement with this accuracy if the skill of the measurer is unskilled.
[0004]
In order to solve such a problem, some of the inventors of the present application have proposed in Patent Document 1 an ultrasonic diagnostic method and apparatus for measuring an IMT value from a luminance value of image data. As a result, the measurement time can be reduced, and the required measurement accuracy can be obtained without depending on the skill of the measurer.
[0005]
[Patent Document 1]
Japanese Patent No. 2888968 ([0033] to [0037], FIG. 6)
[0006]
In the ultrasonic diagnostic apparatus described in Patent Literature 1, specifically, an IMT value is obtained by the following operation. First, the measurer applies an ultrasonic probe to a predetermined position on the neck of the subject. On the ultrasonic probe, several tens of ultrasonic elements are arranged in a line, and when the measurement is started, ultrasonic waves are sequentially transmitted from each ultrasonic element. The transmitted ultrasonic wave is reflected inside the body, and the reflected ultrasonic wave is received by the ultrasonic element. An ultrasonic image around the carotid artery is obtained based on the time difference between the transmitted wave and the received wave. This ultrasonic image is updated every predetermined period and is displayed as a moving image.
[0007]
This ultrasonic image is fixed (frozen) to the image at the moment when the measurer performs a predetermined operation. When the region including the blood vessel wall in the frozen image is designated by the measurer, the ultrasonic diagnostic apparatus uses the image data (brightness value) stored in the memory for displaying the image to determine the endocardium in the region. And the inner wall position of the epicardium are detected, and the interval between them is calculated as the IMT value.
[0008]
[Problems to be solved by the invention]
The ultrasound image around the blood vessel acquired for the IMT value measurement includes signals (artifacts) other than the original reflected ultrasound due to multiple echoes, side lobes caused by ultrasound emitted in directions other than the main direction, and the like. May be mixed. This artifact is particularly pronounced in the bloodstream. This is because ultrasonic waves are repeatedly reflected between the blood vessel wall on the side close to the ultrasonic probe and the blood vessel wall on the far side of one blood vessel, and multiple echoes occur in the blood vessel, This is because the influence of side lobes that are negligible in the reflection at the position cannot be ignored near the blood vessel wall having a high luminance value. In this case, a position other than the original inner wall may be erroneously detected as an inner wall due to an artifact, and a correct IMT value may not be obtained.
[0009]
Conventionally, in order to prevent such an error, before calculating the IMT value, the measurer looks at the displayed ultrasonic image, removes noise due to artifacts from the image, and determines the position of the detected inner wall on the ultrasonic image. Had to be traced to see if the correct detection was made.
[0010]
The present invention has been made in order to solve such a problem, and an object of the present invention is to automatically eliminate the influence of artifacts without bothering a measurer and to improve the IMT with high accuracy. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of performing in-vivo observation such as calculating a value.
[0011]
[Means for Solving the Problems]
An ultrasonic diagnostic apparatus according to the present invention made in order to solve the above-described problem is an ultrasonic diagnostic apparatus that performs in-vivo observation based on reflected ultrasonic waves acquired from the inside of a subject by an ultrasonic probe,
a) a blood flow region detecting means for detecting a region of the blood flow by a Doppler effect in which the frequency is changed by reflection of the ultrasonic wave on the blood flow;
b) observation exclusion area determining means for determining an observation exclusion area based on the blood flow area;
c) in-vivo observation means for performing in-vivo observation on an area other than the observation exclusion area;
It is characterized by having.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the ultrasonic diagnostic apparatus of the present invention, predetermined in-vivo observations such as obtaining an ultrasonic image of the inside of the body based on reflected ultrasonic waves acquired from the inside of the subject by an ultrasonic probe and calculating an IMT value are performed. Is
[0013]
The blood flow region detecting means detects the blood flow in the blood vessel from the reflected ultrasonic waves by a method using the Doppler effect described below.
When the ultrasonic wave that has entered the body of the subject is reflected by slow moving objects such as blood vessels and muscles, the frequency of the reflected ultrasonic wave hardly changes from the frequency of the incident ultrasonic wave. On the other hand, when reflected by blood flowing in the blood vessel, the frequency of the reflected ultrasonic wave changes from the frequency of the incident ultrasonic wave according to the speed of the blood flow due to the Doppler effect. By detecting this frequency change, a blood flow region can be detected. If the angle of incidence of the ultrasonic wave into the body and the direction of the blood flow are orthogonal, the Doppler effect on the reflected ultrasonic wave does not occur. Set.
[0014]
The observation exclusion area determination means determines, from the blood flow area, an area to be excluded from an in-vivo observation target such as an IMT value measurement. Here, the observation exclusion area may be usually the same area as the blood flow area. However, if there is a possibility that an object to be observed exists near the boundary between the blood flow region and another region, the region near the boundary is excluded from the blood flow region by a predetermined range and the observation exclusion region is removed. Is determined, and a predetermined range of the edge portion of the blood flow region is included in the observation target. The region to be excluded from the observation exclusion region is specified by, for example, a predetermined length or a predetermined ratio of the blood flow region. Conversely, the observation exclusion area may be expanded to be larger than the blood flow area in order to more reliably eliminate the influence of the artifact near the boundary.
[0015]
The in-vivo observation means performs a predetermined in-vivo observation such as an IMT value measurement on an area other than the observation exclusion area. Since the observation exclusion area set as described above is not an observation target, even if an artifact exists in the observation exclusion area, it is not affected.
[0016]
【The invention's effect】
According to the present invention, at least a part of the blood flow region in the blood vessel can be excluded from the observation target. Observations can be made. In particular, this can be suitably used when detecting the inner wall of the intima and epicardium in the IMT value measurement.
[0017]
【Example】
FIG. 1 shows a block diagram of an embodiment of the ultrasonic diagnostic apparatus according to the present invention. The ultrasonic probe 11 transmits a desired transmitted ultrasonic wave of the frequency of 5 to 15 MHz into the body of the subject, receives the ultrasonic wave reflected in the body of the subject, and converts the ultrasonic wave into an electric signal. Things. The ultrasonic transmitting and receiving unit 12 controls transmission and reception of ultrasonic waves by the ultrasonic probe. The ultrasonic signal processing unit 13 converts the electric signal of the reflected ultrasonic wave output from the ultrasonic probe 11 into image data, and performs a predetermined process on the image data as described later. The blood flow detecting unit 14 detects a blood flow region in an image, as described later, based on the electric signal of the reflected ultrasonic wave. The display processing unit 15 performs a process for displaying an ultrasonic image to which information on a blood flow region is added on the monitor 16 based on the outputs of the ultrasonic signal processing unit 13 and the blood flow detection unit 14. The display processing unit 15 has a memory for storing data for displaying an image.
[0018]
The analysis exclusion area determination unit 17 and the analysis unit 18 perform predetermined operations according to the observation purpose such as IMT value measurement, and the control unit 19 controls the operations of these units. The input unit 20 includes a pointing device such as a mouse and a trackball, a keyboard, and the like, and is used by a measurer to input various conditions and the like when setting measurement / analysis conditions and analysis exclusion areas.
[0019]
An operation of displaying an ultrasonic image to which information on a blood flow region is added on the monitor 16 in the ultrasonic diagnostic apparatus of the present embodiment will be described. The electric signal of the reflected ultrasonic wave output from the ultrasonic probe 11 is output to the ultrasonic signal processing unit 13 and the blood flow detecting unit 14. The ultrasonic signal processing unit 13 performs first signal processing for image display, and the blood flow detection unit 14 performs second signal processing for blood flow detection as follows.
[0020]
In the first signal processing, the ultrasonic signal processing unit 13 first converts the electric signal into image data. The ultrasonic signal processing unit 13 further performs data processing suitable for image display, such as phasing addition, gain adjustment, and logarithmic compression, on the image data. The processed data is output from the ultrasonic signal processing unit 13 to the display processing unit 15.
[0021]
In the second signal processing, the blood flow detecting unit 14 compares the frequency of the reflected ultrasonic wave with the frequency of the transmitted ultrasonic wave based on the electric signal. When the frequency of the reflected ultrasonic wave has changed from the frequency of the transmitted ultrasonic wave by a predetermined value or more, the blood flow detecting unit 14 detects the area where the reflected ultrasonic wave is reflected as the blood flow area. The data of the detected blood flow region is output to the display processing unit 15.
[0022]
The display processing unit 15 converts the data input from the ultrasonic signal processing unit 13 into a signal for displaying on the monitor 16, and based on the data input from the blood flow detection unit 14, The signal is converted so as to be filled with a color. Thus, the measurer can recognize the blood flow region at a glance from the ultrasonic image displayed on the monitor 16. The ultrasonic image is updated every cycle of the moving image and forms a moving image. At the same time, the display processing unit 15 adds the blood flow region data to the image display signal and stores the data in the memory of the display processing unit 15.
[0023]
Hereinafter, data analysis used when performing in-vivo observation using the ultrasonic diagnostic apparatus according to the present embodiment will be described with an example in which IMT value measurement is performed.
First, the measurer freezes the ultrasonic image displayed as a moving image on the screen of the monitor 16 by performing a predetermined operation from the input unit 20.
[0024]
Next, the measurer sets a range including the intima-media as an analysis target from the displayed ultrasonic image. In this setting, the display processing unit 15 draws the analysis range designation frame 21 at the initial position in the image in accordance with an instruction from the control unit 19, and as shown in FIG. The measurement is performed by moving, enlarging, or the like by the measurer so that is included. In FIG. 2, reference numeral 22 indicates the adventitia of the carotid artery, reference numeral 25 indicates the blood flow region, and reference numeral 27 indicates a portion other than the carotid artery.
[0025]
The analysis exclusion area determination unit 17 acquires the image data of the area within the analysis range specification frame 21 from the memory of the display processing unit 15, and determines the analysis exclusion area based on the blood flow area data added to the image data. decide. The display processing unit 15 paints the analysis exclusion area with a predetermined color. The analysis exclusion area may be the entire blood flow area, or may be the remaining part of the blood flow area except for a predetermined range. The setting of the analysis exclusion area can be performed by the measurer inputting parameters such as the distance from the edge of the blood flow area and the ratio to the entire blood flow area from the input unit 20 in advance or after freezing. FIG. 3 shows an example in which the remaining portion excluding a region within a predetermined distance from the edge of the blood flow region is set as the analysis excluded region 26. Here, reference numeral 28 denotes a region that is excluded from the analysis exclusion region, that is, a region that is within the blood flow region 25 but is to be analyzed.
[0026]
The analysis unit 18 obtains image data corresponding to the frozen image from the memory of the display processing unit 15, and obtains a luminance value of each pixel in an area excluding the analysis exclusion area 26. From this luminance value, the position of the inner wall of the endocardium and the position of the inner wall of the epicardium are detected, and the interval between these two inner walls is calculated as the IMT value. For the detection of the inner wall position and the calculation of the IMT value, a conventionally used method is used.
[0027]
The analysis unit 18 outputs to the display processing unit 15 information on the IMT value and the position where the inner wall is detected. The display processing unit 15 displays the IMT value on the monitor 16 and displays the obtained positions of the two inner walls on the ultrasonic image as a high-luminance line (trace display).
[0028]
FIG. 4 shows an example of an ultrasonic image displayed after the IMT value measurement in the ultrasonic diagnostic apparatus of the present embodiment. For comparison, FIG. 5 shows an example of an ultrasonic image displayed when a position other than the actual inner wall is detected as an inner wall due to an artifact in a conventional ultrasonic diagnostic apparatus. FIG. 5 shows an example in which a blood flow region 25 in which an artifact exists is included in the analysis target region, so that the artifact is erroneously detected as an inner wall, and an erroneous trace (reference numeral 30) is performed. On the other hand, in the apparatus according to the present embodiment, as shown in FIG. 4, the inside of the blood flow region where the artifact is likely to appear is set as the analysis exclusion region 26 and is excluded from the analysis target. The position is correctly traced (reference numeral 29).
[0029]
The above embodiment is an example of the present invention, and can be appropriately changed, modified, and added within the scope of the present invention. For example, in the above-described embodiment, the measurer sets the analysis target area using the analysis range specification frame 21. However, the inner wall position is set to an area of several mm in actual size (not the distance on the screen) from the edge of the blood flow area 25. For this reason, in the case of the IMT value measurement, a region of a predetermined size around the edge may be automatically set as the analysis target region. In the above embodiment, the analysis exclusion area 26 is filled and displayed on the screen of the monitor 16. However, when it is desired to observe the state in the analysis exclusion area 26 simultaneously with the measurement of the IMT value, the analysis instead of the filling is performed. Colored luminance display may be performed so that the state in the exclusion area 26 can be seen. Alternatively, the analysis exclusion area may be set only in the analysis without filling or coloring, and may be used in the data processing.
[Brief description of the drawings]
FIG. 1 is a block diagram showing one embodiment of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 is a diagram showing a display on a screen when an analysis target range is set.
FIG. 3 is a diagram showing an example of an analysis exclusion area.
FIG. 4 is a diagram showing an example of displaying an analysis result on a screen.
FIG. 5 is a diagram showing an example in which analysis is not correctly performed in a conventional ultrasonic diagnostic apparatus.
[Explanation of symbols]
11 ... Ultrasonic probe 12 ... Ultrasonic transmission / reception unit 13 ... Ultrasonic signal processing unit 14 ... Blood flow detection unit 15 ... Display processing unit 16 ... Monitor 17 ... Analysis exclusion area determination unit 18 ... Analysis unit 19 ... Control unit 20 ... Input Part 21: Analysis range designation frame 22 Outer membrane 23 ... Media 24 ... Intima 25 ... Blood flow area 26 ... Analysis exclusion area 29 ... Correct trace 30 ... Wrong trace

Claims (1)

In an ultrasonic diagnostic apparatus that performs in-vivo observation based on reflected ultrasonic waves acquired from the inside of the subject by an ultrasonic probe,
a) a blood flow region detecting means for detecting a region of the blood flow by a Doppler effect in which the frequency is changed by reflection of the ultrasonic wave on the blood flow;
b) observation exclusion area determining means for determining an observation exclusion area based on the blood flow area;
c) in-vivo observation means for performing in-vivo observation on an area other than the observation exclusion area;
An ultrasonic diagnostic apparatus comprising:

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