JP2004344370A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic equipment capable of measuring carotid intima media thickness (IMT) with high precision without a dispersion of measured values caused by heartbeat. <P>SOLUTION: An ultrasonic wave probe 11 transmits an ultrasonic wave into a subject's body and receives the ultrasonic wave reflected therein. An ultrasonic wave image is displayed on a monitor 15 in accordance with the reflected ultrasonic wave. A cardiac electric potential detecting sensor 16 detects a cardiac cycle of the subject and obtains data for the ultrasonic wave image from a display processing part 14 in the timing corresponding to a predetermined phase of diastole, systole, or the like period. On the basis of the data, IMT value can be measured under the predetermined condition of the cardiac cycle phase, which prevents its dispersion of measured values caused by heartbeat. <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 it is easy to find arteriosclerosis. This is because the measurement is easy because the depth from the skin is as small as 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 IMT value of the carotid artery changes according to the heartbeat. That is, the IMT value increases during diastole and decreases during systole. Therefore, the measured value of the IMT varies depending on the timing of freezing the ultrasonic image. As described above, the determination of arteriosclerosis requires an accuracy of 0.1 mm in the measured value of IMT, and therefore it is desirable to suppress this variation in order to perform a more accurate diagnosis.
[0009]
The present invention has been made in order to solve such a problem, and an object of the present invention is to perform the measurement with higher accuracy without causing a variation in the IMT measurement value due to the heartbeat. It is an object of the present invention to provide an ultrasonic diagnostic apparatus that can perform the operation.
[0010]
[Means for Solving the Problems]
An ultrasonic diagnostic apparatus according to the present invention made in order to solve the above-mentioned problem, the thickness of the intima-media complex membrane of the blood vessel based on the reflected ultrasound acquired from the body of the subject by the ultrasound probe In an ultrasonic diagnostic apparatus for measuring the
a) a cardiac cycle detecting means for detecting a cardiac cycle of the subject and transmitting a cardiac cycle signal synchronized with the cardiac cycle;
b) IMT value measurement means for receiving the cardiac cycle signal and measuring the thickness of the intima-media composite membrane at a timing corresponding to the reception;
It is characterized by having.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In the ultrasonic diagnostic apparatus according to the present invention, the cardiac cycle of the subject is detected, and the IMT value is measured at a timing corresponding to the cardiac cycle. Here, the cardiac cycle means a cycle formed by the beating of the heart, and one cycle of the cardiac cycle includes a diastolic period, a systolic period, and the like.
[0012]
The ultrasonic diagnostic apparatus of the present invention has a cardiac cycle detecting means for detecting a cardiac cycle of a subject. The cardiac cycle detecting means transmits a signal synchronized with the detected cardiac cycle to the measuring means. As the cardiac cycle detecting means, for example, the following can be used.
[0013]
The first is a means for detecting a cardiac cycle by measuring a subject's electrocardiogram. In the first cardiac cycle detecting means, an existing cardiac cycle detecting method in electrocardiogram measurement can be used.
[0014]
The second one uses ultrasound image data acquired from the body of a subject by an ultrasound probe to obtain a state of a blood vessel such as a diameter of a blood vessel or a thickness of a blood vessel wall which changes in synchronization with a cardiac cycle. This is a means for measuring time change. For example, the diameter of a blood vessel increases during systole and decreases during diastole. In addition, the thickness of the blood vessel wall decreases during systole and increases during diastole. Therefore, the cardiac cycle can be measured by measuring the change in the state of these blood vessels. For measuring the state of the blood vessel based on the ultrasonic image data, an image processing method performed in an existing ultrasonic diagnostic apparatus can be used.
[0015]
The IMT value measuring means receives the signal from the cardiac cycle detecting means and measures the IMT value as follows at a timing corresponding to the signal.
In measuring the IMT value, image data (luminance value) for displaying an ultrasonic image on a monitor of the ultrasonic diagnostic apparatus is usually used. The IMT value measuring means acquires image data from a memory for image display or the like at a timing corresponding to a signal from the cardiac cycle detecting means. The intima media is detected from the image data, and the IMT value is calculated from the position of the intima media. The IMT value thus calculated is medically meaningful data because it can be measured at a characteristic phase such as a diastole or a systole in addition to the variability due to the heartbeat.
[0016]
【The invention's effect】
According to the present invention, the IMT value can be measured at a timing corresponding to the cardiac cycle. This eliminates variations in the IMT value due to the beating of the heart, and can be performed with higher accuracy. Further, by performing measurement at a characteristic phase such as diastole or systole, medically meaningful data can be collected.
[0017]
In the present invention, as the means for detecting the cardiac cycle of the subject, an existing electrocardiogram detection means used for electrocardiogram measurement can be used. Further, a means for detecting a temporal change in the state of the blood vessel from the reflected ultrasound can be used as the cardiac cycle detecting means. In this case, the cardiac cycle can be detected using the function of the ultrasonic diagnostic apparatus as it is, and there is no need to use separate hardware, so that an increase in cost can be prevented.
[0018]
【Example】
A first embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described. In this embodiment, an example in which a cardiac cycle is detected by measuring a subject's electrocardiogram will be described. FIG. 1 shows a block diagram of this embodiment.
[0019]
The ultrasonic probe 11 transmits an ultrasonic wave having a frequency of 5 to 15 MHz into the body of the subject and receives the ultrasonic wave reflected in the body of the subject. The transmission and reception of the ultrasonic waves are controlled by the ultrasonic transmitting and receiving unit 12. The ultrasonic probe 11 converts the received ultrasonic wave into an electric signal. This electric signal is output to the ultrasonic signal processing unit 13 via the ultrasonic transmitting and receiving unit 12. The ultrasonic signal processing unit 13 performs signal processing such as phasing addition, gain adjustment, logarithmic compression, and detection on the signal input from the ultrasonic probe 11. The processed signal is output from the ultrasonic signal processing unit 13 to the display processing unit 14. The display processing unit 14 is a circuit for displaying an ultrasonic image on a monitor using a signal input from the ultrasonic signal processing unit 13, and has an image memory for storing image data. An ultrasonic image is displayed on the monitor 15 by an output signal from the display processing unit 14.
[0020]
The electrocardiogram detection sensor 16 detects an electrocardiogram of the subject, and is attached to a body surface near the heart of the subject. As the electrocardiogram detection sensor 16, an existing sensor for measuring an electrocardiogram can be used. An electrocardiogram detection signal output from the electrocardiogram detection sensor 16 is input to a cardiac cycle signal acquisition unit 17. The cardiac cycle signal acquisition unit 17 obtains a cardiac cycle from the input electrocardiogram detection signal, and transmits a signal (cardiac cycle signal) to the control unit 18. Here, the cardiac cycle signal may be, for example, a sine wave signal synchronized with an electrocardiogram, or a signal that transmits a pulse-like signal at a specific phase of the cardiac cycle.
[0021]
The input unit 19 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. The measurement unit 20 performs a predetermined operation for measuring the IMT value. Details of the measurement unit 20 will be described later.
[0022]
The operation of the ultrasonic diagnostic apparatus according to the first embodiment will be described.
First, the ultrasonic probe 11 transmits an ultrasonic wave at a moving image cycle under the control of the ultrasonic transmitting and receiving unit 12. The ultrasonic waves are reflected by various parts of the body and detected by the ultrasonic probe 11. As described above, the detected ultrasonic wave is converted into an electric signal in the ultrasonic probe 11, and the electric signal is input to the display processing unit 14 after signal processing in the ultrasonic signal processing unit 13. The display processing unit 14 receives the cardiac cycle signal transmitted by the cardiac cycle signal acquiring unit 17, updates the image at a timing corresponding to the cardiac cycle signal, and stores the image data in the image memory of the display processing unit 14. To memorize. As a result, the image data stored in the image memory becomes data at a fixed phase corresponding to the cardiac cycle signal.
[0023]
When the measurer performs a predetermined operation from the input unit 19, the measurement unit 20 transmits a signal for displaying a frame used for setting an area to be measured in the image to the display processing unit 14. As shown in FIG. 2, the measurer adjusts the position and size of the vascular wall so that the media 23 and the intima 24 fall within the measurement range designation frame 21 displayed on the screen of the monitor 15. It is set from the input unit 19. In FIG. 2, reference numeral 22 indicates an adventitia of a blood vessel wall, reference numeral 25 indicates blood, and reference numeral 26 indicates a portion other than the blood vessel.
[0024]
The measurement unit 20 acquires the image data corresponding to the image in the set measurement target range designation frame 21 from the image memory of the display processing unit 14. The measuring unit 20 detects the positions of the inner wall 27 of the intima and the inner wall 28 of the outer membrane shown in FIG. 3 from the acquired image data (luminance value), and detects the distance between the inner wall 27 of the inner membrane and the inner wall 28 of the outer membrane. 29 is calculated as the IMT value. Here, obtaining the IMT value from the image data can be performed using the method described in Patent Document 1.
[0025]
As described above, in this embodiment, since the IMT value is obtained from the image data in a certain phase, it is possible to prevent the IMT value from being varied due to the heartbeat. In addition, by performing measurement at a characteristic phase such as a diastole or a systole, medically meaningful data can be obtained. For example, if the measurement is performed at such a phase each time in the regular health checkup, the change of the IMT value can be seen by comparing with the past data without being affected by the variation.
[0026]
The phase of the cardiac cycle for measuring the IMT value will be described with reference to FIG. The electrocardiogram detected by the electrocardiogram detection sensor 16 includes a P-wave 31 corresponding to atrial contraction, a Q-wave 32, an R-wave 33, an S-wave 34, and a T-wave 35 corresponding to ventricular contraction. It is during the ventricular systole that blood is pumped from the heart to various parts of the body. At that time, that is, during the period from the beginning of the Q wave 32 to the end of the T wave 35, the IMT value becomes smaller than at other times. In particular, the ventricle contracts most rapidly in the phase of the R wave 33, and the IMT value decreases. Therefore, if the IMT value is measured when the electrocardiographic detection sensor 16 detects the R wave 33 (reference numeral 36), the measurement can always be performed under the condition that the IMT value is minimized.
[0027]
On the other hand, immediately before the ventricle contraction starts, that is, immediately before the Q wave 32 is detected, the IMT value becomes maximum. However, since this time is before a change occurs in the electrocardiogram data, it is difficult for the electrocardiogram detection sensor 16 to detect this time. In order to perform the measurement at a constant phase where the IMT value is close to the maximum value, for example, the end of the P wave 31 (symbol 37) which is a characteristic phase appearing immediately before the Q wave 32 is determined by the electrocardiographic detection sensor 16. The measurement may be performed when is detected.
[0028]
In the present embodiment, an example in which the cardiac cycle signal is input to the display processing unit 14 has been described. However, the cardiac cycle signal is input to the ultrasonic transmission / reception unit 12, and the ultrasonic probe 11 receives the cardiac cycle signal according to the cardiac cycle signal. Alternatively, the ultrasonic waves may be transmitted at a cycle corresponding to the cardiac cycle. The display processing unit 14 updates an image displayed on the monitor 15 at the timing when reflected ultrasonic data is input from the ultrasonic transmission / reception unit 12 via the ultrasonic signal processing unit 13, and updates the image data. Store in the image memory. As a result, transmission of ultrasonic waves into the body can be minimized. Using this image data, the measurement unit 20 measures the IMT value in the same manner as described above.
[0029]
Next, a second embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described. This embodiment shows an example in which a cardiac cycle is detected by measuring a temporal change in a state of a blood vessel such as a diameter of a blood vessel or a thickness of a blood vessel wall which changes in synchronization with the cardiac cycle. FIG. 5 shows a block diagram of this embodiment.
[0030]
The operations of the ultrasonic probe 11, the ultrasonic transmitting / receiving unit 12, the ultrasonic signal processing unit 13, and the display processing unit 14 are the same as those in the first embodiment. In the second embodiment, the ultrasonic probe 11 transmits and receives ultrasonic waves in the body of the subject at a moving image cycle.
[0031]
The signal output from the ultrasonic signal processing unit 13 is input to the display processing unit 14 and also to the blood vessel state analysis unit 41. The blood vessel state analysis unit 41 extracts data of a characteristic portion of a blood vessel that changes with the heartbeat, such as the thickness of the blood vessel wall and the diameter of the blood vessel, from the signal output from the ultrasonic signal processing unit 13. For the extraction of this data, image processing means used in conventional IMT value measurement can be used. FIG. 6A shows a temporal change in the thickness of the blood vessel wall as an example of the blood vessel state data taken here. In this method, the outer wall and the inner wall of a blood vessel are detected from image data, and the thickness is obtained. It is desirable that the thickness of the blood vessel wall determined here is not the IMT value but the thickness of the blood vessel wall including the adventitia that can be more easily detected. The cardiac cycle is detected from the time change of the blood vessel state data thus obtained. In the example of FIG. 6A, when the thickness of the blood vessel wall is maximum (reference numeral 51) or when it is minimum (reference numeral 52) is detected.
[0032]
The cardiac cycle signal transmitting section 42 transmits a cardiac cycle signal to the control section 18 based on the cardiac cycle obtained by the blood vessel state analyzing section 41. This cardiac cycle signal can be the same as in the case of the first embodiment. For example, at the time when the thickness of the blood vessel wall is maximum (reference numeral 51 in FIG. 6) or minimum (reference numeral 52), a sine wave cardiac cycle signal 53 whose value is maximum or minimum is transmitted (for example, FIG. )) Or a pulse-shaped cardiac cycle signal 54 is transmitted at these times (for example, FIG. 6C).
[0033]
The measurement of the IMT value can be performed in the same manner as in the first embodiment, except that the cardiac cycle signal is transmitted from the cardiac cycle signal transmitting section 42.
[0034]
In the second embodiment, since the cardiac cycle is detected based on the reflected ultrasonic waves received by the ultrasonic probe 11, there is no need to separately provide hardware for detecting the cardiac cycle.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an ultrasonic diagnostic apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing an example of an ultrasonic image of a blood vessel.
FIG. 3 is a diagram for explaining a method of calculating an IMT value from an ultrasonic image.
FIG. 4 is a diagram for explaining a phase of a cardiac cycle in which an IMT value is measured.
FIG. 5 is a block diagram showing an ultrasonic diagnostic apparatus according to a second embodiment of the present invention.
FIG. 6 is a graph showing an example of detecting a cardiac cycle from data on the thickness of a blood vessel wall and a cardiac cycle signal corresponding to the cardiac cycle.
[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 ... Electrocardiogram detection sensor 17 ... Cardiac cycle signal acquisition part 18 ... Control part 19 ... Input part 20 ... Measurement Unit 21 Measurement target range designation frame 22 Outer membrane 23 Middle membrane 24 Inner membrane 25 Blood 27 Inner membrane inner wall 28 Outer membrane inner wall 31 P wave 32 Q wave 33 R wave 34 S wave 35 ... T-wave 41 ... blood vessel condition analyzer 42 ... cardiac cycle signal transmitter

Claims (3)

In an ultrasonic diagnostic apparatus that measures the thickness of the intima-media complex membrane of a blood vessel based on reflected ultrasound obtained from the body of a subject by an ultrasound probe,
a) a cardiac cycle detecting means for detecting a cardiac cycle of the subject and transmitting a cardiac cycle signal synchronized with the cardiac cycle;
b) an IMT value measuring means for receiving the cardiac cycle signal and measuring the thickness of the intima-media composite membrane at a timing corresponding to the reception;
An ultrasonic diagnostic apparatus comprising: The ultrasonic diagnostic apparatus according to claim 1, wherein the cardiac cycle detecting means detects an electrocardiogram of a subject. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the cardiac cycle detecting means detects a contraction / dilation cycle of a blood vessel from the reflected ultrasound.

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