JP2008161674A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus which enables the understanding of a brief summary of the distribution of physical characteristic values such as the hardness of a living tissue. <P>SOLUTION: The ultrasonic diagnostic apparatus includes a region setting section 31 for setting a region to be measured inside a subject, a transmission section for driving an ultrasonic probe to transmit ultrasonic transmission waves at least to the region to be measured of the subject, a reception section for generating a received signal by amplifying an ultrasonic reflected wave which is obtained when the ultrasound transmission wave is reflected at the region to be measured and is received by the ultrasonic probe, a measurement section 32 which obtains physical characteristic values of the subject at a plurality of measuring positions set in the region to be measured from the received signal, a counting operation section 33 for extracting the physical characteristic value which satisfies conditions, determined by using at least one threshold value, out of the physical characteristic values at the plurality of measuring positions, and a display section 21 for displaying an image from the extracted result. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus for measuring the hardness of a living tissue, particularly a blood vessel wall tissue.

  In recent years, an increasing number of people suffer from cardiovascular diseases such as myocardial infarction and cerebral infarction, and it has become a major issue to prevent and treat such diseases.

  Arteriosclerosis is closely related to the onset of myocardial infarction and cerebral infarction. Specifically, when an atheroma is formed on the artery wall, or when new cells of the artery are not made due to various factors such as hypertension, the artery loses its elasticity and becomes hard and brittle. Then, the blood vessel is blocked in the part where the atheroma is formed, or the vascular tissue covering the atheroma is ruptured and the atheroma flows into the blood vessel, and the artery is blocked in another part or the artery is hardened. These diseases are caused by the rupture of parts. Therefore, early diagnosis of arteriosclerosis is important for the prevention and treatment of these diseases.

  Conventionally, arteriosclerotic lesions have been diagnosed by directly observing the inside of a blood vessel using a vascular catheter. However, this diagnosis has a problem that the load on the subject is large because it is necessary to insert a vascular catheter into the blood vessel. For this reason, observation with a vascular catheter is used to identify the location of a subject who is certain that an arteriosclerotic lesion is present. For example, this method can be used as a test for health care. It was never used.

  Measuring a cholesterol level that is a cause of arteriosclerosis or measuring a blood pressure level is a test that can be easily performed with less burden on the subject. However, these values do not directly indicate the degree of arteriosclerosis.

  Further, if arteriosclerosis is diagnosed at an early stage and a therapeutic drug for arteriosclerosis can be administered to a subject, it will be effective in treating arteriosclerosis. However, when arteriosclerosis progresses, it is said that it is difficult to completely recover the cured artery even though the therapeutic agent can suppress the progress of arteriosclerosis.

  For these reasons, there is a need for a diagnostic method or a diagnostic device that has less burden on the subject and diagnoses at an early stage before arteriosclerosis proceeds.

  Conventionally, as a non-invasive medical diagnostic apparatus with less burden on the subject, an ultrasonic diagnostic apparatus and an X-ray diagnostic apparatus are widely used. By irradiating ultrasonic waves and X-rays from outside the body, such a diagnostic apparatus can obtain in-body shape information or shape time change information without causing pain to the subject. When time change information (motion information) of the shape of the measurement object in the body is obtained, the property information of the measurement object can be obtained. That is, the elasticity characteristic of the blood vessel in the living body can be obtained, and the degree of arteriosclerosis can be directly known. In particular, ultrasonic diagnosis is superior to X-ray diagnosis in that it can be measured simply by applying an ultrasonic probe to the subject, and therefore there is no need to administer contrast medium to the subject and there is no risk of X-ray exposure. Yes.

In addition, recent advances in electronics technology have made it possible to dramatically improve the measurement accuracy of ultrasonic diagnostic equipment. Along with this, development of ultrasonic diagnostic apparatuses that measure minute movements of living tissues is progressing. For example, using the technique described in Patent Document 1,
It has been reported that it is possible to measure the thickness and deformation of the blood vessel wall with high accuracy on the order of several microns because it can measure the vibration component of the blood vessel motion with a few microns up to several hundred Hz with high accuracy. ing.

  By using such a highly accurate measurement method, it is possible to measure in detail the two-dimensional distribution of the elastic characteristics of the artery wall. For example, Non-Patent Document 1 shows an example in which the state of the two-dimensional distribution of the elastic modulus of the carotid artery wall is displayed superimposed on the B-mode tomographic image. The degree of stiffness of the arterial wall is not uniform and has a certain distribution, and in the diagnosis of arteriosclerosis, the local distribution of the elastic modulus, which is a characteristic amount indicating the degree of hardening of the artery, is accurately determined. This is because it is important to understand.

Further, by displaying the local elastic modulus distribution as a histogram, it becomes possible to make a more detailed diagnosis of arteriosclerosis. For example, in Non-Patent Document 1, after measuring the elastic properties of the iliac artery, the iliac artery is stained in vitro to identify and identify each tissue of the iliac artery wall, and the positional information of the tissue identified by staining Is used to determine which tissue each elastic property in the two-dimensional distribution obtained by measurement belongs to. Further, it is disclosed that the elastic characteristics of the determined tissue are analyzed by a histogram, and the type of the tissue is estimated from the two-dimensional distribution of the elastic characteristics of the arterial wall based on the analysis result. Since the hardness varies depending on the constituent tissue, displaying the histogram makes it easy to grasp the frequency of the hard tissue and the frequency of the soft tissue in the local region, and has an effect on the diagnosis of arteriosclerosis.
Japanese Patent Laid-Open No. 10-5226 Hiroshi Kanai et al, "Elasticity Imaging of Atheroma With Transcutaneous Ultrasound Preliminary Study," Circulation, Vol.107, p3018-3021, 2003.

  The elastic modulus is a characteristic value indicating the degree of hardness or softness, and is not an index directly indicating a difference in structure. For this reason, even if it sees the two-dimensional distribution image of an elasticity modulus, it is unclear which part corresponds to what tissue, and it is very difficult to identify the tissue. In Non-Patent Document 1, a histogram of elastic modulus is displayed for a part that is known to be a lipid part and a smooth muscle / fibrous part from pathological anatomical results, and tissue is identified from the elastic modulus. Do not mean.

  However, even if the tissue cannot be identified, for example, it can be greatly useful for the preliminary diagnosis of arteriosclerosis by knowing whether or not the elastic modulus has a specific part compared to the surrounding tissue. It is done. For this reason, for the operator of the ultrasonic diagnostic apparatus and the doctor who analyzes the results obtained by the ultrasonic diagnostic apparatus, if the hardness / softness distribution of the measurement target area can be easily grasped, it will be useful for diagnosis. It is done.

  An object of the present invention is to solve such a problem and to provide an ultrasonic diagnostic apparatus capable of more easily grasping an outline of a distribution of physical characteristic values such as hardness of a living tissue.

An ultrasonic diagnostic apparatus of the present invention drives an ultrasonic probe to transmit an ultrasonic wave to at least the measurement target region of the subject, a region setting unit that sets a measurement target region inside the subject. A receiving unit that amplifies an ultrasonic reflected wave received by the ultrasonic probe and generates a reception signal, and a reception signal obtained by reflecting the ultrasonic transmission wave in the measurement target region A measurement unit for obtaining physical property values of the subject at a plurality of measurement positions set in the measurement target region, and at least one threshold value among the physical property values at the plurality of measurement positions. A counting operation unit that extracts physical characteristic values that satisfy the conditions determined by using the display unit, and a display unit that displays an image based on the extraction result.

  In a preferred embodiment, the counting operation unit counts the number of the extracted physical characteristic values, and the display unit displays the number.

  In a preferred embodiment, the ultrasonic diagnostic apparatus further includes a tomographic image generation unit that generates a tomographic image of the measurement target region based on the received signal, and the counting calculation unit includes the extracted physical characteristic value. The measurement unit generates the measurement position information, and the display unit superimposes and displays the extracted measurement position of the physical characteristic value on the tomographic image.

  In a preferred embodiment, the measurement unit creates information on a distribution image of the physical characteristic value in the measurement target region based on the measurement position, and the counting operation unit is configured to extract the extracted physical Information on the measurement position of the characteristic value is generated, and the display unit superimposes and displays the extracted measurement position of the physical characteristic value on the distribution image of the physical characteristic value.

  In a preferred embodiment, the counting calculation unit obtains the number of all measurement positions in the measurement target region, calculates a ratio of the number of the extracted physical characteristic values to the number of all measurement positions, and displays the display. The part displays the ratio.

  In a preferred embodiment, the counting operation unit determines at least two continuous positions adjacent to each other among the measurement positions of the extracted physical characteristic values, and the display unit The location is displayed superimposed on the tomographic image.

  In a preferred embodiment, the counting operation unit generates information on the physical characteristic value histogram, which displays the region satisfying the condition on the histogram by visual information different from other regions. To do.

  In a preferred embodiment, in the ultrasonic diagnostic apparatus, the counting operation unit generates a plurality of types of information on different images based on the extraction result, and the display unit is configured to generate the plurality of types based on a command from an operator. Switch between images.

  In a preferred embodiment, the physical characteristic value is at least one of a maximum thickness change amount, a strain amount, an elastic modulus, a viscosity, an IBS signal, and B-mode luminance information of a tissue constituting the subject. One.

  In a preferred embodiment, the measurement unit obtains motion information of a plurality of measurement positions set in the measurement target region based on the received signal, obtains position information based on the motion information, and acquires the position information. Based on the above, at least one of the maximum thickness change amount, strain amount, elastic modulus and viscosity of the tissue is obtained.

  In a preferred embodiment, the measurement unit obtains a statistic of physical characteristic values at each measurement position in the measurement target region and measurement positions around the measurement position, and based on the statistic, the physical at each measurement position is calculated. The accuracy of the physical characteristic value is determined, and the counting operation unit extracts a physical characteristic value satisfying a condition determined using at least one threshold value from the physical characteristic value having high probability.

  In a preferred embodiment, the statistic is at least one of a mean value, a standard deviation, and a variance.

  According to the ultrasonic diagnostic apparatus of the present invention, a physical characteristic value satisfying a condition determined using at least one threshold is extracted from physical characteristic values at a plurality of measurement positions, and an image based on the extraction result is extracted. Is displayed. Therefore, the operator can quickly grasp desired information in the measurement result of the subject by viewing the display of the ultrasonic diagnostic apparatus.

  Hereinafter, embodiments of an ultrasonic diagnostic apparatus according to the present invention will be described.

  FIG. 1 is a block diagram showing a configuration for diagnosing a vascular wall tissue property using the ultrasonic diagnostic apparatus 11 of the present embodiment. The ultrasonic probe 13 connected to the ultrasonic diagnostic apparatus 11 is held in close contact with the body surface 2 of the subject, and ultrasonic waves are transmitted to the inside of the extravascular tissue 1. The transmitted ultrasonic wave is reflected and scattered by the blood vessel 3 and the blood 5, and a part thereof returns to the ultrasonic probe 13 and is received as an echo (ultrasonic reflected wave). The ultrasonic diagnostic apparatus 11 analyzes and calculates the received signal and obtains shape information and motion information of the blood vessel front wall 4. In addition, a blood pressure monitor 12 is connected to the ultrasonic diagnostic apparatus 11, and blood pressure data of the subject measured by the blood pressure monitor 12 is input to the ultrasonic diagnostic apparatus 11. The ultrasonic diagnostic apparatus 11 determines the instantaneous position of the object by the constrained least square method using both the amplitude and the phase of the detection signal, for example, according to the method disclosed in Patent Document 1. By performing phase tracking with high accuracy (positional change measurement accuracy is ± 0.2 micron), the thickness of the minute part on the blood vessel front wall 4 and the state of the time change of the thickness change amount are measured with sufficient accuracy. be able to. Furthermore, by using the blood pressure data obtained from the sphygmomanometer 12, the elastic modulus of the local minute part in the blood vessel front wall 4 can be obtained. An electrocardiograph 22 is connected to the ultrasonic diagnostic apparatus 11, and an electrocardiographic waveform measured by the electrocardiograph 22 is input to the ultrasonic diagnostic apparatus 11 to determine the timing of data acquisition and data reset. Used as a trigger signal. The electrocardiograph 22 can be replaced with other sound signal detectors such as a heart sound meter and a pulse wave meter, and an electrocardiographic waveform and a pulse wave waveform can be used as a trigger signal instead of the electrocardiographic waveform.

  Hereinafter, the configuration and operation of the ultrasonic diagnostic apparatus 11 will be described in detail. FIG. 2 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 11. The ultrasonic diagnostic apparatus 11 includes a transmission unit 14, a reception unit 15, a delay time control unit 16, a tomographic image generation unit 25, a phase detection unit 17, a filter unit 18, a calculation unit 19, a storage unit 20, and a display unit 21. Yes. In addition, a control unit 24 that controls each unit and a user interface 23 that includes a keyboard, a trackball, a switch, a button, and the like for giving an instruction to the control unit 24 by an operator are provided.

  The transmission unit 14 generates a predetermined drive pulse signal and outputs it to the ultrasonic probe 13. The ultrasonic transmission wave transmitted from the ultrasonic probe 13 by the drive pulse signal is reflected and scattered by a living tissue such as the blood vessel 3, and the generated ultrasonic reflected wave is received by the ultrasonic probe 13. The frequency of the drive pulse for generating the ultrasonic wave is determined in consideration of the depth of the measurement target and the ultrasonic velocity so that the adjacent ultrasonic pulses adjacent on the time axis do not overlap.

  The receiving unit 15 receives an ultrasonic reflected wave using the ultrasonic probe 13. The reception unit 15 includes an A / D conversion unit, amplifies the ultrasonic reflected wave, generates a reception signal, and further converts it into a digital signal. The transmission unit 14 and the reception unit 15 are configured using electronic components.

  The delay time control unit 16 is connected to the transmission unit 14 and the reception unit 15 and controls the delay time of the drive pulse signal given from the transmission unit 14 to the ultrasonic transducer group of the ultrasonic probe 13. Thereby, the direction of the acoustic line of the ultrasonic beam of the ultrasonic transmission wave transmitted from the ultrasonic probe 13 and the depth of focus are changed. Further, by controlling the delay time of the received signal received by the ultrasonic probe 13 and amplified by the receiving unit 15, the aperture diameter can be changed or the focal position can be changed. The output of the delay time control unit 16 is input to the phase detection unit 17 and the tomographic image generation unit 25.

  The tomographic image generation unit 25 includes a filter, a detector, a logarithmic amplifier, and the like, and mainly analyzes the amplitude of the received signal to generate tomographic image data obtained by imaging the internal structure of the subject. The obtained tomographic image data is output to the display unit 21. In addition, tomographic image data is stored in the storage unit 20 in order to analyze measurement results offline after measurement.

The phase detection unit 17 performs phase detection on the reception signal subjected to delay control by the delay time control unit 16 and separates it into a real part signal and an imaginary part signal. The separated real part signal and imaginary part signal are input to the filter unit 18. The filter unit 18 removes a high frequency component, a reflection component other than a measurement target, a noise component, and the like. The phase detection unit 17 and the filter unit 18 can be configured by software or hardware.

  The real part signal and the imaginary part signal of the reception signal subjected to phase detection are input to the calculation unit 19. FIG. 3 is a block diagram showing the configuration of the calculation unit 19 in detail. The calculation unit 19 includes a region setting unit 31, a measurement unit 32, and a count calculation unit 33. The calculation unit 19 can be configured by software or hardware. Further, when the arithmetic unit 19 is realized by software, a microcomputer constituting the control unit 24 may execute the software.

  The region setting unit 31 sets a measurement target region inside the subject. The measurement target region is set by referring to the tomographic image, the elastic modulus distribution image created by the measurement unit 32 described later, or the received signal information output by the filter unit 18 (not shown). ) May be determined manually by the operator, or the target may be automatically determined based on image information and received signal information. The set position information of the measurement target region is output to the measurement unit 32 and the count calculation unit 33. The area setting unit 31 creates a setting area image indicating the set area and outputs it to the display unit 21.

  The measurement unit 32 calculates physical characteristic values such as strain and elastic modulus of the biological tissue at a plurality of measurement positions set in at least the measurement target region. Based on the real part signal and the imaginary part signal of the received signal output by the filter unit 18, the movement speed of the living tissue at a plurality of measurement positions is obtained, and the movement speed is integrated to obtain the position displacement amount (time displacement amount of the position). ) A thickness change amount (expansion / contraction amount) of the living tissue between each measurement position is obtained from the obtained position displacement amount.

  In addition, information on one cardiac cycle is received from the electrocardiograph 22, and the maximum thickness variation, the maximum thickness, and the inner diameter of the blood vessel, which are the differences between the maximum value and the minimum thickness variation in one cardiac cycle, are obtained. . Then, the strain of the living tissue is obtained from data such as the maximum thickness variation, the maximum thickness value, and the blood vessel inner diameter. Furthermore, using the blood pressure data obtained from the sphygmomanometer 12, the elastic modulus of the living tissue between each measurement position is obtained. The physical characteristic value obtained by the measurement unit 32 is output to the count calculation unit 33. The measurement unit 32 may obtain the physical characteristic value even outside the measurement target region determined by the region setting unit 31. The measurement unit 32 preferably creates spatial distribution image data of physical characteristic values such as the obtained maximum thickness variation, strain, and elastic modulus, and outputs the data to the display unit 21.

  As will be described in detail below, the strain and elastic modulus of the living tissue are obtained for a minute region of the living tissue sandwiched between two measurement positions, but the calculated strain and elastic modulus positions are calculated at two measurement positions. It is specified by either one.

  The count calculation unit 33 extracts a physical characteristic value obtained by the measurement unit 32 that satisfies a condition determined using a threshold value of at least one. Specifically, the count calculation unit 33 counts the number of physical characteristic values obtained by the measurement unit 32 that satisfy a condition determined using at least one threshold value. Preferably, a measurement position where a physical characteristic value that satisfies the condition is obtained is extracted and output to the display unit 21.

  The threshold value used for the condition used by the count calculation unit 33 may be determined by the operator, or the operator may select from a plurality of threshold values set in advance in the ultrasonic diagnostic apparatus. Two or more threshold values may be set. For example, using the condition that the elastic modulus is larger than the threshold value A, the number of elastic moduli larger than the threshold value A is counted, and the measurement position where the value satisfying this condition is obtained is extracted. Alternatively, a condition that the elastic modulus is larger than the threshold B and a condition that the elastic modulus is smaller than the threshold C may be set. In this case, the number of elastic moduli larger than the threshold value B is counted, the measurement position where a value satisfying this condition is extracted, the number of elastic moduli smaller than the threshold value C is counted, and this condition is satisfied. The measurement position where the value was obtained is extracted.

  In addition, the count calculation unit 33 preferably counts the number of all measurement positions in the measurement target region, and calculates the ratio of the number of physical characteristic values that satisfy the condition to the number of measurement positions. Furthermore, the count calculation unit 33 outputs information on the number of physical characteristic values that satisfy the condition, the ratio, and information on the measurement position at which the physical characteristic value that satisfies the condition is obtained to the display unit. As a result, the number, ratio, and position of physical characteristic values that satisfy the conditions can be displayed.

  Preferably, the counting calculation unit 33 determines at least N (N is an integer of 2 or more) continuous positions that are adjacent to each other among measurement positions corresponding to physical property values that satisfy the condition, The position information of the determined continuous location is output to the display unit 21. The number N of continuous locations can be set by the operator using the user interface 23. As a result, it is possible to determine the position of the physical characteristic value that satisfies the condition, without detecting the influence of noise, without detecting the noise that occurred accidentally.

  Further, the count calculation unit 33 may obtain a frequency distribution of physical characteristic values, create histogram image data based on the frequency distribution, and output the histogram image data to the display unit 21. In this case, on the histogram, an area that satisfies the set condition may be displayed by visual information different from other areas. For example, a class larger than the threshold A may be displayed with an emphasis with a color tone different from other classes, a different texture, or a different luminance. Thereby, the operator or the person who analyzes the measurement result can easily recognize the frequency and the degree of dispersion of the physical characteristic values that meet the conditions. The calculation of the frequency distribution of the physical characteristic values and the creation of the histogram image may be performed by the measurement unit 32.

  The display unit 21 displays an image based on the extraction result extracted by the count calculation unit 33 under a predetermined condition. More specifically, data of distribution images of various physical characteristic values created by the measurement unit 32, image data of measurement positions created by the count calculation unit 33, image data of histograms, and physical characteristic values that satisfy the conditions Receives the number of items and the ratio, etc., and displays them. In addition, the tomographic image data output from the tomographic image generation unit 25 and an image indicating the setting region created by the region setting unit 31 are displayed.

  Hereinafter, the calculation in the measurement unit 32 will be described in more detail with reference to FIGS. 4 and 5. FIG. 4 schematically shows an ultrasonic beam 67 propagating through the subject 60. In the figure, a blood vessel wall 64 and a living tissue 62 other than a blood vessel are shown. The ultrasonic wave transmitted from the ultrasonic probe 13 disposed on the surface of the living body 60 travels through the living body 60. The ultrasonic transmission wave propagates through the living body 60 as an ultrasonic beam 67 having a certain finite width, and a part of the ultrasonic wave reflected or scattered by the living tissue 62 and the blood vessel wall 64 in the process is sent to the ultrasonic probe 13. Returned and received as an ultrasonic reflected wave. The reflected ultrasonic wave is detected as a time series signal r (t), and the reflected time series signal obtained from the tissue closer to the ultrasonic probe 13 is located closer to the origin on the time axis. The width (beam diameter) of the ultrasonic beam 67 can be controlled by changing the delay time.

  A plurality of measurement positions Pn (P1, P2,... Pk... Pn, n is a natural number of 3 or more) in the blood vessel wall 62 located on the acoustic line 66 that is the central axis of the ultrasonic beam is a certain constant. P 1, P 2,... Pk... Pn are arranged in order from the ultrasonic probe 13 at the interval L. When the coordinates in the depth direction with the surface of the living body 60 as the origin are Z1, Z2,... Zk... Zn, reflection from the measurement position Pk is located at tk = 2Zk / c on the time axis. become. Here, c indicates the sound speed of the ultrasonic wave in the living body. The reflected wave signal r (t) is phase-detected by the phase detection unit 17, and the detected signal is separated into a real part signal and an imaginary part signal and passed through the filter unit 18. In the measurement unit 32 of the calculation unit 19, the amplitude does not change in the reflected wave signal r (t) and the reflected wave signal r (t + Δt) after a minute time Δt, and only the phase and the reflection position are changed. The phase difference is obtained by the least square method so that the waveform matching error between the reflected wave signals r (t) and r (t + Δt) is minimized. From this phase difference, the motion speed Vn (t) at the measurement position Pn is obtained, and by integrating this, the position displacement amount dn (t) can be obtained.

  FIG. 5 shows the relationship between the measurement position Pn and the target tissue Tn for elastic modulus calculation. The target tissue Tk is located with a thickness L in a range between adjacent measurement positions Pk and Pk + 1. From the n measurement positions P1... Pn, (n-1) target tissues T1.

  The thickness change amount Hk (t), which is the amount of expansion / contraction of the target tissue Tk, is calculated from Hk (t) = hk + 1 (t) −hk from the positional displacement amounts hk (t) and hk + 1 (t) at the measurement positions Pk and Pk + 1. It is calculated as (t).

  The change in the thickness of the tissue Tk of the blood vessel wall 64 occurs according to the change in blood pressure due to the heartbeat, and is repeated approximately in synchronization with the cardiac cycle. Accordingly, it is preferable to obtain a numerical value for each heartbeat in synchronization with the cardiac cycle. The maximum value and the minimum value are extracted from the thickness change amount Hk (t) in one cardiac cycle, and the difference between the maximum value and the minimum value is set as the maximum thickness change amount Δhk. Further, the difference between the maximum value and the minimum value of the blood pressure is set as the pulse pressure Δp. When the maximum thickness of the target tissue is Hm, the strain Sk and the elastic modulus xk can be obtained from the following equations, respectively.

Sk = Δhk / Hm
xk = Δp / Sk = Δp · Hm / Δhk

  The number of measurement positions Pn and the interval between them can be arbitrarily set according to the purpose of measurement and the characteristics of the biological tissue that is the measurement object. Moreover, although the example which calculates | requires the thickness variation | change_quantity and elastic modulus between adjacent measurement positions is shown in the above-mentioned description, thickness variation | change_quantity and elastic modulus are between two points | pieces which pinch | interpose one or more measurement positions. A value may be obtained. In this case, the position displacement amount between the two points is preferably an average value of the position displacement amounts between the two points and the measurement position therebetween.

  The range for obtaining the thickness change amount and the elastic modulus may be one place sandwiched between two arbitrary points, but the ultrasonic probe 13 used in the present embodiment has a plurality of superstructures arranged in an array. It has a sound wave vibrator, and it is possible to obtain the elastic modulus at all points in an arbitrary region within the tomographic plane.

  Through the above-described method, the measurement unit 32 calculates image characteristics by calculating physical characteristic values such as the maximum thickness change amount, strain, or elastic modulus of the living tissue, and the image is displayed on the display unit 21. Is done. Further, data and images such as the maximum thickness variation, strain, and elastic modulus calculated by the measurement unit 32 are stored in the storage unit 20 within the range allowed by the storage capacity, and can be read at any time. If an element such as a ring memory is used for the storage unit 20, for example, the latest data can always be updated and stored. Therefore, various data stored in the storage unit 20 can be displayed on the display unit 21 as needed. Alternatively, a plurality of frames stored in the storage unit 20 may be averaged in the time direction to form a single distribution image.

  Next, the operation of the count calculation unit 33 of the ultrasonic diagnostic apparatus will be described in more detail. FIG. 6 is a flowchart for explaining the operation from the measurement of the physical characteristic value to the display of the image. First, the region setting unit 31 determines a measurement target region (step S11). The measurement unit 32 measures and calculates the physical characteristic value in the measurement target region (step S12), and creates data of a spatial distribution image of the physical characteristic value (step S41). This spatial distribution image is displayed on the display unit 21 (step S42).

The physical characteristic value obtained by the measurement unit 32 is output to the count calculation unit 33. Here, first, the number of all measurement points in the measurement target area is counted (step S31). Then, condition processing using a predetermined threshold is performed on the physical characteristic value (step S13). Then, the number of physical characteristic values satisfying the conditions is counted (step S14), image information indicating the result is generated, and the image is displayed on the display unit 21 (step S16). Further, the ratio is obtained by dividing the total number of measurement points obtained in step S31 by the number satisfying the value condition obtained in step S14 (step S32), generating image information indicating the result, and displaying the image on the display unit 21 (step S33).

  In addition, the count calculation unit 33 extracts the position of the physical characteristic value that satisfies the condition obtained in step S13 (step S15), creates image information of the position (step S17), and in the display unit 21 It is displayed (step S18). Here, the count calculation unit 33 further determines N or more consecutively adjacent portions among the measurement positions of the physical characteristic values that satisfy the condition extracted in step S15 (step S19), and the position Image information can be created (step S20) and displayed on the display unit 21 (step S21).

  The count calculator 33 further calculates the frequency distribution of the physical characteristic values and creates histogram data (step S51). Information of a histogram image in which a class satisfying the conditions in the histogram is highlighted with a color tone, texture, brightness, etc. different from other classes may be created (step S52) and displayed on the display unit 21 (step S53).

  Display examples of the image information thus created will be described with reference to FIGS.

  FIG. 7 schematically shows an example in which the display unit 21 displays the result of measuring the elastic modulus distribution at an arbitrary position on the long-axis section of the arterial blood vessel wall using the ultrasonic diagnostic apparatus 11. A tomographic image display area 102, an elastic modulus color bar 111, and a histogram 112 are displayed on the monitor 101 constituting the display unit 21. A tomographic image is displayed in the tomographic image display area 102. FIG. 7 shows an example in which the setting area image 103 created by the area setting unit 31 and the elastic modulus distribution image 104 created by the measurement unit 32 are superimposed on the tomographic image. The tomographic image includes a blood vessel lumen region 105, a blood vessel wall intima region 106, and a blood vessel wall outer membrane region 107. The setting area image 103 indicates that a part of the intima area 106 is set as a measurement target area.

  In the setting area defined by the setting area image 103, the elastic modulus distribution image 104 created by the counting calculation unit 33 is shown. In FIG. 7, the spatial distribution of the elastic modulus at a total of 78 locations where 6 measurement microregions are arranged in the radial direction and 13 in the axial direction is shown. Each minute region is colored according to the relationship between the elastic modulus and the color scheme indicated by the color bar 11. The color bar 111 has a color scheme indicating that the elastic modulus is higher toward the upper side, that is, it is harder. Further, the total number of measurement points is displayed at the lower right in the monitor 101.

  In the upper right of the monitor 101, a histogram 112 created by the count calculation unit 33 is shown. The histogram 112 is divided into five classes in the present embodiment, and matches the number of classes of the color bar 111. Since the distribution of the minute region shown in the elastic modulus distribution image 104 matches the histogram 111 by matching the color bar 111, that is, the frequency distribution class of the elastic modulus distribution image 104 and the class of the histogram, the elastic modulus distribution image The hardness distribution at 104 can be easily recognized by the histogram 111. However, the class of the histogram 112 and the class of the color bar 111 may be different.

  In FIG. 8, the count calculation unit 33 performs a threshold condition process of “extracting an elastic modulus having a value equal to or greater than an arbitrary threshold s” on the measurement result shown in FIG. An example of displaying images and numerical values on the display unit 21 is schematically shown.

  In the setting area defined by the setting area image 103, the measurement position image 121 corresponding to the elastic modulus value that satisfies the condition created by the counting calculation unit 33 is superimposed on the elastic modulus distribution image 104, and the minute area that satisfies the condition Are highlighted with a border. A marker 122 indicating the value of the threshold s is displayed on the right side of the color bar 111. In the histogram 112, a region that satisfies the condition is displayed with an emphasis in a different color from other regions. Furthermore, in the lower right in the monitor 101, the number of measurement points (10 places) having an elastic modulus value equal to or greater than the threshold value s and the ratio (10/78 = 0.13) are displayed.

  Thus, by displaying an image based on the extraction result of physical property values that satisfy the threshold conditions, such as the number of elastic moduli that satisfy the threshold conditions, ratio, position, variance, etc., the operator can It becomes possible to grasp the information immediately.

  Further, in FIG. 9, the count calculation unit 33 performs a threshold condition process of “extracting an elastic modulus having a value equal to or greater than an arbitrary threshold s” on the measurement result illustrated in FIG. An example in which adjacent portions are extracted and various images and numerical values obtained from the calculation results are displayed on the display unit 21 is schematically shown.

  Within the setting area defined by the setting area image 103, the position image 123 of the continuous adjacent portion created by the counting calculation unit 33 is superimposed on the elastic modulus distribution image 104, and two or more of the minute areas satisfying the threshold condition The outlines of the adjacent parts are highlighted. In addition, the number of measurement points and the ratio having an elastic modulus value equal to or higher than the threshold value s displayed in the lower right in the monitor 101 are updated and displayed as numerical values of consecutive adjacent portions.

  It is considered that an isolated minute region having less than 2 continuous regions has a high elastic modulus value accidentally due to noise. By removing this, it is possible to provide an image that is easy for the operator to see. It becomes.

  Note that the operator can switch the images related to the physical characteristic values based on the extraction results shown in FIGS. 7 to 9 by the user interface 23 of the ultrasonic diagnostic apparatus 11. For example, by switching between the image 121 at the measurement position in FIG. 8 and the image at the position of the continuous adjacent portion in FIG. 9, the operator can grasp how much the influence of noise is seen.

  As described above, according to the present embodiment, by displaying the number, ratio, position, frequency, variance, and the like of the elastic modulus satisfying the threshold condition on the display unit 21, the operator can select a desired measurement result from the test subject. This makes it possible to accurately and instantly grasp the information, and to perform more accurate diagnosis.

  In the present embodiment, as shown in FIG. 9, by displaying a position image 123 of a portion where a minute region that meets the threshold condition is continuous, a minute region that shows a high elastic modulus value accidentally due to noise. Is not displayed. However, the influence of noise can be reduced by determining the probability of the elastic modulus value of each minute region based on the statistic and displaying the image using the result. Hereinafter, the operation of the calculation unit 19 according to this method will be described.

  FIG. 9 is a flowchart for explaining the operation of the ultrasonic diagnostic apparatus when the probability of the elastic modulus value of each minute region is determined after the physical characteristic value is measured and then the image is displayed. As described with reference to FIG. 6, first, the region setting unit 31 determines a measurement target region (step S11). The measurement unit 32 measures and calculates a physical characteristic value in the measurement target region, for example, an elastic modulus value (step S12).

  Next, the measurement unit 32 determines the certainty of the physical characteristic value in each obtained micro area based on the statistic, and the measurement position where the elastic modulus value that is considered to contain noise is obtained. The minute area is excluded from the image display (step S61). Specifically, as shown in FIG. 11, when each minute region is arranged in m rows and n columns, as shown by a broken line, the minute region in the i-th row and j-th column is the center, A sub-area including a surrounding minute region is determined. The sub area is smaller than the measurement target area.

  The size of the sub-area may be set by the operator, or an area of 3 rows and 3 columns (composed of 9 minute regions) and an area of 5 rows and 5 columns (composed of 25 minute regions) may be set in advance. The operator may select it. Alternatively, the control unit 24 may automatically determine what is frequently used by the operator by the learning function and set the determined value.

  The measurement unit 32 calculates the standard deviation, variance, or variation count of the elastic modulus value of the minute area in the sub-area, and if these values are larger than the predetermined standard deviation, variance, or variation count, It is determined that there is a high possibility that the elastic modulus value of the minute area in the sub-area includes noise. This calculation and determination are repeated by sequentially shifting the minute area that is the center of the sub-area and centering all the minute areas of the measurement target area.

  If the subarea is set so that all the microregions are centered, and the above calculation and determination are performed, the determination of the number of microregions constituting the subarea is made for the microregions other than the end portion of the measurement target region. Results are obtained. For example, when a subarea is configured with 3 rows and 3 columns, the above calculation and determination are performed nine times. Therefore, the threshold u is set, and a micro region whose number of times determined that the possibility of including noise is high is u or more is excluded from the image display on the assumption that the physical characteristic value includes noise. Note that, in the end portion of the measurement target region, the sub area cannot be set so that the sub area reaches the outside of the measurement target region and the minute region is the center. In this case, the above-described calculation is performed using only a minute region in the measurement target region.

  Alternatively, if the elastic modulus value Xi, j in the small area at the center of the subarea is not within the range of the average elastic modulus value within the subarea ± standard deviation, the elastic modulus value at the center of the subarea is incidental due to noise. An extreme value is shown, and it may be removed because the probability is low. This calculation and determination are performed for all the minute regions in the measurement target region so that each minute region is centered.

  By such processing, a physical characteristic value in each minute region of the measurement target region excluding the minute region determined to contain noise, that is, a highly reliable physical property value is obtained.

  As shown in FIG. 10, hereinafter, the same processing as described with reference to FIG. 6 is performed using the physical characteristic value with high probability, and a screen for displaying the measurement result is created. However, in the measurement target region, since a minute region where a physical characteristic value considered to contain noise is excluded, a threshold condition is used to exclude the influence of noise in the above-described embodiment. It is not necessary to perform a process (steps S19 to S21 in FIG. 6) for extracting a portion where measurement positions that match are consecutive.

  By such processing, it is possible to eliminate the influence of noise and obtain an image that is easy for the operator to see.

  8 and 9, the elastic modulus distribution image 104 is superimposed on the tomographic image, and the measurement position image 121 and the continuous adjacent portion position image 123 that satisfy the threshold condition are superimposed. However, only the B-mode image is superimposed. Alternatively, the measurement position image 121 and the continuous adjacent portion position image 123 may be superimposed on each other, or the measurement position image 121 and the continuous adjacent portion position image 123 may be superimposed only on the elastic modulus distribution image 104. 7 to 9, the number of physical characteristic values satisfying the threshold condition is displayed. However, the number may not be displayed. For example, the image 121 of the measurement position that satisfies the threshold condition is displayed as the elastic modulus. The distribution image 104 may be simply superimposed and displayed.

Further, in the present embodiment, the case of obtaining the two-dimensional distribution of the elastic modulus of the blood vessel wall is illustrated, but if the maximum thickness change amount and strain are measured when stress is applied from the body surface, the present invention The ultrasonic diagnostic apparatus can also suitably measure body tissues such as the liver and breast. If the stress is measured separately, the elastic modulus can be obtained.

  In this embodiment, an ultrasonic diagnostic apparatus that measures and displays a two-dimensional distribution of elastic modulus has been described. However, a three-dimensional diagnosis is performed by measuring a three-dimensional distribution of elastic modulus using a 3D mechanical probe or the like. It is also possible to do this.

  Further, in the present embodiment, the diagnosis is performed by obtaining the elastic modulus, but other physical characteristic values that can be measured from the composition may be measured. For example, the viscosity, the luminance information in the B-mode image, the IBS An (integrated backscatter) signal or the like may be obtained as a physical characteristic value.

  The ultrasonic diagnostic apparatus of the present invention is suitably used for measuring characteristic values of living tissue, and is preferably used for measuring property characteristic values such as the hardness of tissues such as blood vessel walls, livers, and breasts.

It is a block diagram which shows the structure for diagnosing the vascular wall tissue property using the ultrasonic diagnosing device by this invention. It is a block diagram which shows the structure of embodiment of the ultrasonic diagnosing device by this invention. It is a block diagram which shows in detail the structure of the calculating part of the ultrasonic diagnosing device shown in FIG. It is a figure which shows typically the ultrasonic beam which propagates the blood vessel wall, and a measurement position. It is a figure which shows the relationship between a measurement position and the object structure | tissue which calculates | requires an elastic characteristic. In this embodiment, it is a flowchart explaining the operation | movement from the measurement of a physical characteristic value to the display of an image or a numerical value. An example of the screen of the display part which shows the result of having measured the elastic modulus distribution of the blood vessel wall section using the ultrasonic diagnostic equipment of this embodiment is shown typically. 7 shows an example of a screen created based on the extraction result by setting a threshold condition for the measurement result shown in FIG. 7 shows another example of a screen created based on the extraction result by setting a threshold condition for the measurement result shown in FIG. It is a flowchart explaining the operation | movement of an ultrasonic diagnosing device when determining the probability of the elasticity modulus value of each micro area | region after measuring a physical characteristic value, and displaying an image after that. It is a schematic diagram explaining the subarea set in a measurement area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extravascular tissue 2 Body surface 3 Blood vessel 4 Blood vessel front wall 5 Blood 11 Ultrasound diagnostic apparatus 12 Sphygmomanometer 13 Ultrasonic probe 14 Transmission part 15 Reception part 16 Delay time control part 17 Phase detection part 18 Filter part 19 Calculation part 20 Memory | storage Unit 21 display unit 22 electrocardiograph 23 user interface 24 control unit 25 tomographic image generation unit 31 region setting unit 32 measurement unit 33 count calculation unit 60 living body 62 biological tissue other than blood vessel 64 blood vessel wall 66 acoustic line 67 ultrasonic beam 101 monitor 102 Tomographic image display area 103 Setting area image 104 Elasticity distribution image 105 Vascular lumen area 106 Inner and inner membrane area 107 Outer membrane area 111 Color bar 112 Histogram 121 Image of measurement position 122 Marker 123 Image of position of continuous adjacent portion

Claims (12)

An area setting unit for setting a measurement target area inside the subject;
A transmitter that drives an ultrasonic probe to transmit an ultrasonic transmission wave to at least the measurement target region of the subject; and
A reception unit that amplifies the ultrasonic reflected wave received by the ultrasonic probe and generates a reception signal, obtained by reflecting the ultrasonic transmission wave in the measurement target region;
A measurement unit for obtaining physical characteristic values of the subject at a plurality of measurement positions set in the measurement target region based on the received signal;
Among the physical characteristic values at the plurality of measurement positions, a counting operation unit that extracts physical characteristic values that satisfy a condition determined using at least one threshold;
A display unit for displaying an image based on the extraction result;
An ultrasonic diagnostic apparatus comprising: The counting operation unit counts the number of the extracted physical characteristic values,
The ultrasonic diagnostic apparatus according to claim 1, wherein the display unit displays the number. Further comprising a tomographic image generator for generating a tomographic image of the measurement target region based on the received signal;
The counting calculation unit generates information on a measurement position of the extracted physical characteristic value,
The ultrasonic diagnostic apparatus according to claim 1, wherein the display unit superimposes and displays the extracted measurement position of the physical characteristic value on the tomographic image. The measurement unit creates information on a distribution image of the physical characteristic value in the measurement target region based on the measurement position,
The counting calculation unit generates information on a measurement position of the extracted physical characteristic value,
The ultrasonic diagnostic apparatus according to claim 1, wherein the display unit superimposes and displays the extracted measurement position of the physical characteristic value on the physical characteristic value distribution image. The counting calculation unit obtains the number of all measurement positions in the measurement target region, calculates a ratio of the number of the extracted physical characteristic values to the number of all measurement positions,
The ultrasonic diagnostic apparatus according to claim 1, wherein the display unit displays the ratio. The counting calculation unit determines at least two consecutive locations that are adjacent to each other among the measurement positions of the extracted physical characteristic values,
The ultrasonic diagnostic apparatus according to claim 3, wherein the display unit displays the continuous portion so as to be superimposed on the tomographic image.   4. The count calculation unit generates information that is information of a histogram of the physical characteristic value and that displays an area that satisfies the condition on the histogram with visual information different from other areas. 5. The ultrasonic diagnostic apparatus in any one of. The counting operation unit generates a plurality of types of information of different images based on the extraction result,
The ultrasonic diagnostic apparatus according to claim 1, wherein the display unit switches and displays the plurality of types of images based on a command from an operator.   The physical property value is at least one of a maximum thickness change amount, a strain amount, an elastic modulus, a viscosity, an IBS signal, and B-mode luminance information of a tissue constituting the subject. The ultrasonic diagnostic apparatus in any one of 7 to 7.   The measurement unit obtains movement information of a plurality of measurement positions set in the measurement target region based on the received signal, obtains position information based on the movement information, and determines the maximum of the tissue based on the position information. The ultrasonic diagnostic apparatus according to claim 9, wherein at least one of thickness variation, strain, elastic modulus, and viscosity is obtained. The measurement unit obtains a statistic of the physical characteristic value at each measurement position in the measurement target region and the measurement positions around the measurement position, and based on the statistic, the probability of the physical characteristic value at each measurement position is determined. Decide
The ultrasonic diagnostic apparatus according to claim 1, wherein the counting operation unit extracts a physical characteristic value that satisfies a condition determined using at least one threshold value from the highly reliable physical characteristic value.   The ultrasonic diagnostic apparatus according to claim 11, wherein the statistic is at least one of an average value, a standard deviation, and a variance.

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