JP2004357892A - Ultrasonic diagnostic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic device capable of easily setting a blood vessel wall which is the measured object of an intima-media thickness (IMT) value and performing more accurate measurement. <P>SOLUTION: A measurement region setting frame 21 is set so as to include both of the blood vessel wall 231 on the side closer to the skin and the blood vessel wall 232 on the side farther from the skin out of one carotid artery 22. For both of the blood vessel walls 231 and 232, the positions of the inner wall of an adventitia 24 and the inner wall of an intima 26 are detected respectively independently from the luminance value of image data, and the IMT value is calculated from their distances. Thus, a measuring person is not required to select the one vessel wall to be the measuring object from two or more blood vessel walls. Also, since the measuring person can select one vessel wall for which the most appropriate detection is performed from measurement results respectively indicated for the two or more blood vessel walls, more accurate measurement is made possible. <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 measurement of the carotid artery is performed because the IMT value of the carotid artery is increased from the initial stage of arteriosclerosis and the arteriosclerosis can be easily found, and the carotid artery skin This is because the measurement is easy due to the shallow depth 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 (the luminance value of each pixel) stored in the memory for displaying the image, and The inner wall position of the intima 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]
In the ultrasonic image, when a cross section parallel to the blood vessel is observed, two blood vessel walls on the side closer to the ultrasonic probe (body surface of the subject) and the side farther from the ultrasonic probe are obtained for one blood vessel. Is drawn. Usually, the image of the blood vessel wall on the side close to the ultrasonic probe tends to be unclear due to the influence of multiple reflections of the ultrasonic wave. Therefore, the image of the blood vessel wall on the side far from the ultrasonic probe is compared with the IMT value or the like. It is often measured. However, depending on the measurement conditions, it may be better to target the blood vessel wall on the side close to the ultrasonic probe. Therefore, the measurer looks at the ultrasonic image and determines which of the two blood vessel walls is the measurement target. You have to choose. The time required for this selection operation is not so long in each measurement, but when performing diagnosis on a large number of subjects as in a regular medical checkup, the cause of extending the total diagnosis time is It was.
[0009]
Further, if there is plaque or noise that cannot be clearly seen in the image near the blood vessel wall selected by the measurer as an IMT value measurement target as described above, an erroneous IMT value may be measured. In such a case, if the IMT value is measured for another blood vessel wall different from the selected blood vessel wall, a measurement error can be noticed due to a difference between the two values. However, this requires time and effort because the measurer must perform the measurement operation individually for both blood vessel walls.
[0010]
The present invention has been made to solve such a problem, and an object of the present invention is to make it possible to easily set an object to be measured, thereby shortening the time required for measurement and improving accuracy. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of performing an accurate IMT value measurement.
[0011]
[Means for Solving the Problems]
An ultrasonic diagnostic apparatus according to the present invention made in order to solve the above problems,
In an ultrasonic diagnostic apparatus that displays an image of the body based on reflected ultrasonic waves obtained from the body of the subject by an ultrasonic probe and measures the thickness of the intima-media complex of a blood vessel,
a) measurement area setting means for setting an area to be measured in the displayed image;
b) a blood vessel wall detecting means for detecting a blood vessel wall present at one or a plurality of places in the measurement area;
c) IMT measurement means for measuring the intima-media complex thickness for each detected blood vessel wall;
It is characterized by having.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the ultrasonic diagnostic apparatus of the present invention, ultrasonic waves are transmitted from the ultrasonic probe to the body of the subject, and the ultrasonic waves reflected inside the body are received by the ultrasonic probe. Based on the received reflected ultrasonic waves, an ultrasonic image of the body is obtained and displayed on a screen, and all IMT values within the range specified by the measurer are measured on the screen. Hereinafter, the operation will be described in detail.
[0013]
The measurement area setting means is for setting an area (measurement area) for measuring the IMT value on the ultrasonic image displayed on the screen. For example, the measurement area setting means superimposes and draws an initial frame on the ultrasonic image, and a measurer determines a desired area by moving or enlarging the frame using a mouse or the like, and then determining an area in the frame. Set as a measurement area. Conventionally, the measurer had to set such that the blood vessel wall was included only in one place in the area. However, in the apparatus of the present invention, the setting was performed such that the blood vessel wall was included in two or more places in the area. be able to.
[0014]
The blood vessel wall detecting means detects a blood vessel wall present in the measurement area. In the conventional ultrasonic diagnostic apparatus, it was assumed that there was only one blood vessel wall in the measurement area. However, in the ultrasonic diagnostic apparatus according to the present invention, two or more blood vessel walls were formed in the measurement area. Since the inclusion is permitted, all the blood vessel walls in the measurement area are detected.
[0015]
The detection of the blood vessel wall basically uses a conventionally used method. For example, the luminance value of each pixel is detected in the direction crossing the blood vessel, and a point where the luminance value suddenly changes beyond a predetermined reference value is detected. In the case of the carotid artery, the luminance value changes rapidly at the inner wall position of the intima of the blood vessel (that is, the boundary between the blood flow portion and the intima) and the inner wall position of the adventitia (that is, the boundary between the media and the adventitia). , Can be detected by detecting a sudden change in the luminance value that is equal to or greater than a predetermined reference. In the conventional ultrasonic diagnostic apparatus, because of the above premise, the distance between the suddenly changing luminance values detected in the measurement region was measured, and the measured distance was used as the intima-media composite film thickness (IMT value). In contrast, the ultrasonic diagnostic apparatus according to the present invention cannot use such a simple method because there is a possibility that a plurality of blood vessel walls exist in the measurement region.
[0016]
In one blood vessel wall, since a sudden change in the luminance value is detected at two places, the inner wall position of the intima and the inner wall position of the epicardium, when two or more blood vessel walls exist in the measurement region, This sudden change is detected in four or more places. However, when the boundary of the measurement region exists inside the intima or media, only one sudden change may be detected, and the number of sudden changes in the measurement region may be an odd number. In any case, when three or more suddenly changing brightness values are detected in the measurement area, the blood vessel wall detecting means determines the position of the blood vessel wall based on the distance between adjacent suddenly changing brightness values. That is, in a relatively large artery such as the carotid artery to be measured by the ultrasonic diagnostic apparatus, the thickness of the blood vessel wall is smaller than the inner diameter of the blood vessel. Therefore, for example, a specific reference value (for example, 3 mm in the case of the carotid artery) is provided for each measurement target, and depending on whether the reference value is greater than or less than the reference value, a plurality of suddenly changing brightness values are located on the same blood vessel wall. It belongs to the wall or belongs to another blood vessel wall. This reference value may be appropriately changed according to the symptom of the observation target site or the affected part.
[0017]
Alternatively, the distance between one set of adjacent places is compared with the distance between the next adjacent places, and the set of suddenly changed brightness values having the shorter distance is determined to belong to the same blood vessel wall. In most cases, the blood vessel wall is correctly detected by the above method.However, when the blood vessel wall is abnormally thickened, the blood vessel wall becomes larger than the inner diameter of the blood vessel and an erroneous determination occurs. There is also. In such a case, a measurer may manually provide a correction means.
[0018]
Further, the position of the blood vessel lumen may be designated by a method such as clicking with a mouse when the measurer designates the measurement region. The blood vessel wall detecting means can separate the tube walls on both sides from the click position.
[0019]
The IMT measuring means measures an IMT value for each blood vessel wall. With the method as described above, the position of the intima / media, etc. can be detected for each blood vessel wall. Therefore, even when a plurality of blood vessel walls are included in the measurement area, all the blood vessel walls are detected. Can be measured. When a sudden change in luminance value (above a predetermined reference value) is detected by the above method, the distance between the suddenly changing luminance values belonging to the same blood vessel wall is determined as the IMT value.
[0020]
【The invention's effect】
According to the present invention, measurement of two or more blood vessel walls included in an ultrasonic image can be performed simultaneously by a single operation, so that the measurer can check a plurality of blood vessel walls appearing in the displayed ultrasonic image. It is not necessary to perform the operation of selecting one blood vessel wall to be measured from. Therefore, the measurement target can be easily set, and the time required for the measurement can be reduced.
[0021]
In addition, since measurement is performed on a plurality of blood vessel walls, even if an erroneous measurement result affected by plaque, noise, or the like is obtained from one of the plurality of blood vessel walls, another blood vessel wall is not measured. From the measurement result for, the measurer can notice the error. Thereby, more accurate measurement can be performed.
[0022]
【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. . 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 further performs data processing on the image data suitable for image display. The display processing unit 14 performs a process for displaying an ultrasonic image on the monitor 15 on the data after the process. Further, the display processing unit 14 has a memory for storing data for image display.
[0023]
The measurement area determination unit 16 allows the measurer to arbitrarily set the area on the ultrasonic image, and determines the set area as the measurement area. The blood vessel wall detector 17 detects all blood vessel walls in the measurement area. The measurement unit 18 measures the IMT value for all the detected blood vessel walls.
[0024]
The control unit 19 is composed of a CPU and the like, and controls the above-mentioned units. The input unit 20 is used by a measurer to input settings and the like, and includes a pointing device such as a mouse or a trackball, a keyboard, and the like.
[0025]
Next, the operation of each unit until the ultrasonic image is displayed on the monitor 15 will be described in detail. The electric signal of the reflected ultrasonic wave output from the ultrasonic probe 11 is output to the ultrasonic signal processing unit 13. The ultrasonic signal processing unit 13 converts the electric signal into image data, and further performs data processing suitable for image display, such as phasing addition, gain adjustment, logarithmic compression, and the like. The processed data is output from the ultrasonic signal processing unit 13 to the display processing unit 14. The display processing unit 14 generates an electric signal to be displayed on the monitor 15 from the image data, and outputs the electric signal to the monitor 15. The operation up to this point is repeated at a predetermined cycle, and the ultrasonic image is displayed on the monitor 15 as a moving image. Note that the display processing unit 14 stores the image data in the memory in order to use the image data for the IMT value measurement.
[0026]
Hereinafter, detection of the blood vessel wall and measurement of the IMT value for the blood vessel wall will be described in detail. First, the measurer freezes an image displayed as a moving image on the screen of the monitor 15 by performing a predetermined operation on the input unit 20. FIG. 2 shows an ultrasound image around the frozen carotid artery 22. The upper blood vessel wall 231 is a blood vessel wall closer to the skin of the carotid artery 22, and the lower blood vessel wall 232 is a blood vessel wall farther from the skin. The blood vessel walls 231 and 232 are respectively composed of an adventitia 24, a media 25 and an intima 26. Reference numeral 27 indicates blood, and reference numeral 28 indicates a portion other than the carotid artery, such as a muscle.
[0027]
Next, the measurement region determination unit 16 transmits an initial frame setting signal to the display processing unit 14 according to the operation of the measurer. Upon receiving this signal, the display processing unit 14 superimposes and displays an initial frame of the measurement area setting frame 21 having a predetermined size at a predetermined position on the frozen ultrasonic image. The measurer operates the input unit 20 while looking at the screen, and moves the measurement region setting frame 21 so that the intima and the media of the blood vessel to be measured are included in the measurement region setting frame 21. Change In the present invention, it is possible to set so that both the intima / media of the blood vessel walls 231 and 232 on both sides are included in the measurement region setting frame 21. FIG. 2 shows an example in which the measurement area setting frame 21 is set as described above. The measurement area is determined by a predetermined operation of the measurer.
[0028]
First, the blood vessel wall detection unit 17 acquires, from the memory of the display processing unit 14, the luminance values of the pixels at one of the left and right ends of the measurement region for one column in the vertical direction. Thereby, data as shown in FIG. 3 is obtained. From this data, all locations where the luminance value changes abruptly on a predetermined basis are detected. In the example of FIG. 3, four suddenly changing brightness values 31 to 34 are detected.
[0029]
Next, the blood vessel wall detection unit 17 calculates the distance between all the brightness value suddenly changing places. Further, the calculated distance is compared between the distance between one set of suddenly changing luminance values and the distance between the next suddenly changing luminance values, and the shorter set of suddenly changing luminance values is identified by the same blood vessel. It is detected as belonging to the wall. In the example of FIG. 3, a distance 35 between the suddenly changing luminance values 31 and 32, a distance 36 between the suddenly changing luminance values 32 and 33, and a distance 37 between the suddenly changing luminance values 33 and 34 are calculated. 35 and 36 and distances 36 and 37 are compared. In this example, since the distances 35 and 37 are smaller than the distance 36, it is assumed that the suddenly changing luminance values 31 and 32 related to the distance 35 and the suddenly changing luminance values 33 and 34 related to the distance 37 belong to the same blood vessel wall. Is detected.
[0030]
The blood vessel wall detection unit 17 sequentially performs the processing from the acquisition of the luminance value to the detection of the blood vessel wall in the left-right direction of the measurement area, and detects all the blood vessel walls in the measurement area.
[0031]
The measurement unit 18 calculates the distance between two luminance value sudden change points as an IMT value for one of the detected blood vessel walls (for example, the blood vessel wall closest to the skin). The IMT value is similarly calculated for other blood vessel walls.
[0032]
As shown in FIG. 4, the display processing unit 14 displays an enlarged view of the ultrasonic image in which the position of the detected inner wall is displayed as a high-luminance line (trace display, reference numeral 29) for each of the detected blood vessel walls. , And IMT values on the screen of the monitor 15. The measurer can check whether the inner wall is correctly detected by looking at the trace display. In addition, when a plurality of blood vessel walls exist in the measurement region, a plurality of trace displays and a plurality of measurement results of the IMT value are displayed. Therefore, the measurer appropriately performs measurement from the plurality of measurement results. You can choose one.
[0033]
In the above description, an example in which the IMT value is measured for all the detected blood vessel walls has been described. First, the inner wall is trace-displayed on the monitor 15 for the detected blood vessel wall, and the measurer can check the plurality of trace results. And an IMT value may be calculated only for the selected blood vessel wall.
[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 a measurement area is set.
FIG. 3 is a graph showing an example of luminance value data when detecting a blood vessel wall.
FIG. 4 is a diagram showing an example of displaying a measurement result on a screen.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Ultrasonic probe 12 ... Ultrasonic transmission / reception part 13 ... Ultrasonic signal processing part 14 ... Display processing part 15 ... Monitor 16 ... Measurement area determination part 17 ... Measurement part 18 ... Control part 19 ... Input part 21 ... Measurement area setting frame 22 carotid artery 231 vascular wall 232 near skin vascular wall 24 far from skin outer membrane 25 media 26 intima 27 blood

Claims (2)

In an ultrasound diagnostic apparatus that displays an image of the body based on reflected ultrasound obtained from the body of the subject by an ultrasound probe and measures the thickness of the intima-media complex of a blood vessel,
a) measurement area setting means for setting an area to be measured in the displayed image;
b) a blood vessel wall detecting means for detecting a blood vessel wall present at one or a plurality of locations in the measurement area;
c) IMT measuring means for measuring the intima-media complex thickness for each detected blood vessel wall;
An ultrasonic diagnostic apparatus comprising: The blood vessel wall detecting means determines a position of a blood vessel wall based on a distance between adjacent luminance value suddenly changing places after detecting a place where a luminance value of each pixel of the image changes suddenly. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the thickness of the intima-media complex for each blood vessel wall is determined based on the distance between adjacent luminance value sudden change points belonging to the blood vessel wall.

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