JP2007007347A - Ultrasonograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonograph which reduces influences caused by noises to measure the characteristics with a high precision. <P>SOLUTION: The ultrasonograph comprises a transmitting section 102 for generating a drive signal for driving a probe so as to transmit an ultrasonic wave to a subject periodically deformed by a stress, a receiving section 103 for receiving echoes, obtained by the ultrasonic wave reflected by the subject, by the probe and for generating a received-echo signal, a computing section 151 for computing a thickness variation waveform representing a variation of the distance between two given measurement portions in the subject from the received-echo signal, a reference waveform generating section 117 for generating a reference waveform, and a thickness variation estimating section 118 for computing the maximum variation of the thickness variation waveform from the entire thickness variation waveform by using the reference waveform. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that measures a property characteristic of a tissue constituting a subject, particularly an elastic modulus.

  The ultrasonic diagnostic apparatus irradiates a subject with ultrasonic waves and analyzes information included in the echo signal to inspect the subject non-invasively. 2. Description of the Related Art Conventionally, an ultrasonic diagnostic apparatus that has been widely used obtains the structure of a subject as a tomographic image by converting the intensity of an echo signal into the luminance of a corresponding pixel. Thereby, the internal structure of the subject can be known. In addition, an ultrasonic diagnostic apparatus that detects Doppler shift of an echo signal and displays an image of motion information of a subject, for example, blood flow information, has been used.

  On the other hand, in recent years, by analyzing mainly the phase of the echo signal, the movement of the tissue of the subject is accurately measured, and physical (property) characteristics such as tissue distortion, elastic modulus, and viscosity are obtained. Has been tried.

  Patent Document 1 uses the amplitude and phase of the detection output signal of the echo signal to determine the instantaneous position of the subject, thereby tracking the subject tissue with high accuracy and applying it to the beating heart tissue. A method for capturing the minute vibrations that occur is disclosed. According to this method, ultrasonic pulses are transmitted a plurality of times at intervals of ΔT in the same direction with respect to the subject, and the ultrasonic waves reflected by the subject are received. As shown in FIG. 17, it is assumed that the received echo signals are y (t), y (t + ΔT), and y (t + 2ΔT). The reception time t1 of the echo signal obtained from a certain depth x1 is t1 = x1 / (C / 2) where the pulse transmission time is t = 0. Where C is the speed of sound. At this time, if the phase shift between y (t1) and y (t1 + ΔT) is Δθ, and the center frequency of the ultrasonic wave near t1 is f, the movement amount Δx of x1 in this period ΔT is expressed by the following equation ( 1).

  Δx = −C · Δθ / 4πf (1)

  By adding the movement amount Δx to x1, the position x1 ′ of x1 after ΔT seconds can be obtained as shown in the following formula (2). By repeating this calculation, the same part x1 of the subject is obtained. Can be tracked. This method is called a phase difference tracking method.

  x1 '= x1 + Δx (2)

  Patent Document 2 discloses a method of further developing the method of Patent Document 1 and obtaining the elastic modulus of a subject tissue, particularly an arterial wall. According to this method, first, as shown in FIG. 18, an ultrasonic wave is transmitted from the probe 101 toward the blood vessel wall 16, and echo signals from the measurement points A and B set on the blood vessel wall 16 are patented. By analyzing according to the method of Document 1, the movement of the measurement sites A and B is tracked. FIG. 19 shows tracking waveforms TA and TB indicating the positions of the measurement points A and B. An electrocardiographic waveform ECG is also shown.

  As shown in FIG. 19, the tracking waveforms TA and TB have a periodicity that matches the electrocardiogram waveform ECG. This indicates that the artery expands and contracts in line with the heart cycle of the heart. Specifically, when a large peak called an R wave is seen in the electrocardiogram waveform ECG, the contraction of the heart starts, and blood is pushed out into the artery by the contraction of the heart. The blood vessel rapidly expands due to the blood pressure change at this time. Therefore, after the R wave appears in the electrocardiogram waveform ECG, the tracking waveforms TA and TB also rise rapidly, and the artery expands rapidly. Thereafter, as the heart expands slowly, the tracking waveforms TA and TB also gradually fall, and the arterial blood vessels slowly contract. The artery repeats this movement.

  The difference between the tracking waveforms TA and TB is a thickness change waveform W between the measurement points AB. The thickness change waveform W can also be regarded as a distortion waveform between AB. The maximum thickness change amount ΔW can be obtained from the difference between the maximum value Wmax and the minimum value Wmin of the thickness change waveform W.

  ΔW = Wmax−Wmin (3)

  If the reference thickness at the time of initialization between the measurement points AB is Ws, the maximum strain amount ε between the measurement points AB is as follows.

  ε = ΔW / Ws (4)

  Further, the maximum blood pressure Pmax and the minimum blood pressure Pmin of the subject at this time are measured using a blood pressure monitor or the like. The blood pressure difference ΔP is expressed by the following equation.

  ΔP = Pmax−Pmin (5)

  The maximum strain amount ε is considered to have occurred due to the blood pressure difference ΔP. Since the elastic modulus Er is defined as a value obtained by dividing the stress by the strain, the elastic modulus Er between the measurement points AB is expressed by the following equation.

  Er = ΔP / ε = ΔP · Ws / ΔW = ΔP · Ws / (Wmax−Wmin) (6)

  Non-Patent Document 1 discloses a method of calculating the elastic modulus of each part using the maximum strain amount ε and the blood pressure difference ΔP when the blood vessel is a tube having a non-uniform thickness.

By performing these calculations on a plurality of points on the tomographic image, a distribution image of the elastic modulus Er is obtained. As shown in FIG. 18, when the atheroma 11 occurs in the blood vessel wall 16, the elastic modulus is different between the atheroma and the surrounding vascular wall tissue. Therefore, if an elastic modulus distribution image is obtained, it is possible to diagnose the generation and position of atheroma.
Japanese Patent Laid-Open No. 10-5226 JP 2000-229078 A Hasegawa et al., “Measuring method of local wall elastic modulus of pipe with non-uniform wall thickness”, J Med Ultrasonics Vol.28 No.1 (2001)

  However, the elastic modulus measurement method according to the prior art has a problem that noise resistance is low because the elastic modulus is measured using the difference between the maximum value Wmax and the minimum value Wmin of the thickness change waveform W. For example, when the thickness change waveform W shown in FIG. 20 is obtained, the elastic modulus is obtained with the values at times t1 and t2 as the maximum value Wmax and the minimum value Wmin, respectively. However, as shown in the figure, the value of the thickness change waveform W at time t2 is not correct because noise is mixed therein.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus that solves such problems of the prior art, reduces the influence of noise, and can measure property characteristics with high accuracy.

  An ultrasonic diagnostic apparatus according to the present invention includes: a transmission unit that generates a drive signal for driving a probe to transmit ultrasonic waves to a subject that is periodically deformed by stress; and the ultrasonic waves in the subject. An echo obtained by reflection is received by the probe, and a change in the distance between any two measurement sites in the subject is shown based on the reception unit that generates a reception echo signal and the reception echo signal A thickness for calculating the maximum change amount of the thickness change waveform from the whole of the thickness change waveform by using a calculation unit for calculating the thickness change waveform, a reference waveform generation unit for generating a reference waveform, and the reference waveform. A change amount estimation unit.

  In a preferred embodiment, the thickness change amount estimation unit obtains a coefficient by which the thickness change waveform or the reference waveform is multiplied so that a matching error between the thickness change waveform and the reference waveform is minimized, The maximum change amount of the thickness change waveform is calculated from the coefficient and the amplitude of the reference waveform.

  In a preferred embodiment, the reference waveform generation unit includes a storage unit that stores data of the reference waveform.

  In a preferred embodiment, the reference waveform is an average of thickness change waveforms acquired from a plurality of subjects in advance.

  In a preferred embodiment, the ultrasound diagnostic apparatus further includes a period adjusting unit that adjusts a period of the reference waveform based on a deformation period of the subject, and the thickness change amount estimating unit adjusts the period. The maximum change amount of the thickness change waveform is calculated based on the reference waveform and the thickness change waveform.

  In a preferred embodiment, the ultrasonic diagnostic apparatus further includes a period adjustment unit that adjusts a period of the thickness change waveform based on a deformation period of the subject, and the thickness change amount estimation unit includes a period The maximum change amount of the thickness change waveform is calculated on the basis of the thickness change waveform adjusted in the above and the reference waveform.

  In a preferred embodiment, the ultrasonic diagnostic apparatus further includes an averaging unit that obtains an average of a plurality of cycles of the thickness change waveform whose cycle is adjusted, and is based on the averaged thickness change waveform and the reference waveform. The maximum change amount of the thickness change waveform is calculated.

  In a preferred embodiment, when the period of the thickness change waveform is not constant, the ultrasonic diagnostic apparatus extracts data of each period in accordance with the shortest period among the periods of the thickness change waveform, and the thickness The apparatus further includes a period adjusting unit that makes the period of the variation waveform constant.

  In a preferred embodiment, the arithmetic unit is based on the movement waveform calculation unit that calculates a movement waveform that indicates a change in position of a plurality of measurement sites in the subject based on the received echo signal, and the movement waveform. And a calculation unit for calculating a thickness change waveform between the two measurement parts.

  In a preferred embodiment, the reference waveform generation unit generates the reference waveform based on the movement waveform.

  In a preferred embodiment, the ultrasound diagnostic apparatus further includes a blood vessel diameter calculation unit that calculates a change waveform of a blood vessel diameter included in the subject based on the movement waveform, and the reference waveform generation unit includes the change waveform. Based on the above, the reference waveform is generated.

  In a preferred embodiment, the reference waveform generation unit generates the reference waveform based on a blood pressure change waveform of the subject.

  In a preferred embodiment, the ultrasonic diagnostic apparatus further includes an elastic modulus calculation unit that receives information on a stress difference of the stress generated in the deformation cycle of the subject and obtains an elastic modulus from the maximum change amount.

  The control method of the ultrasonic diagnostic apparatus of the present invention is a control method of the ultrasonic diagnostic apparatus by the control unit of the ultrasonic diagnostic apparatus, the step (A) of driving the probe and transmitting the ultrasonic wave, the stress A step (B) of receiving an echo obtained by the reflection of the ultrasonic wave in the subject periodically deformed by the probe by the probe, and any two of the subjects in the subject based on the received echo signal A step (C) for calculating a thickness change waveform indicating a change in distance between measurement sites, a step (D) for generating a reference waveform, and the thickness from the entire thickness change waveform using the reference waveform. And (E) calculating a maximum change amount of the change waveform.

  In a preferred embodiment, the step (E) obtains a coefficient by which the thickness change waveform or the reference waveform is multiplied so that a matching error between the thickness change waveform and the reference waveform is minimized. The maximum change amount of the thickness change waveform is calculated from the amplitude of the reference waveform.

  In a preferred embodiment, the reference waveform is an average of thickness change waveforms acquired from a plurality of subjects in advance.

  In a preferred embodiment, the method for controlling an ultrasonic diagnostic apparatus further includes a step of adjusting a cycle of the reference waveform based on a cycle of deformation of the subject, and the step (E) has a cycle adjusted. The maximum change amount of the thickness change waveform is calculated based on the reference waveform and the thickness change waveform.

  In a preferred embodiment, the method for controlling an ultrasonic diagnostic apparatus further includes a step of adjusting a cycle of the thickness change waveform based on a cycle of deformation of the subject, wherein the step (E) includes a cycle. The maximum change amount of the thickness change waveform is calculated on the basis of the thickness change waveform adjusted in the above and the reference waveform.

  In a preferred embodiment, the method of controlling an ultrasonic diagnostic apparatus further includes a step of obtaining an average of a plurality of cycles of the thickness change waveform having the adjusted period, and the averaged thickness change waveform and the reference waveform The maximum change amount of the thickness change waveform is calculated based on the above.

  In a preferred embodiment, the step (C) includes a step of calculating a movement waveform indicating a change in position of a plurality of measurement sites in the subject based on the received echo signal, and based on the movement waveform, Calculating a thickness change waveform between the two measurement sites.

  In a preferred embodiment, the step (D) generates the reference waveform based on the movement waveform.

  In a preferred embodiment, the control method of the ultrasonic diagnostic apparatus further includes a step of calculating a change waveform of a blood vessel diameter included in the subject based on the movement waveform, and the step (D) includes the change. The reference waveform is generated based on the waveform.

  In a preferred embodiment, the step (D) generates the reference waveform based on a blood pressure change waveform of the subject.

  In a preferred embodiment, the control method of the ultrasonic diagnostic apparatus further includes a step of receiving information on a stress difference of the stress generated in the deformation cycle of the subject and obtaining an elastic modulus from the maximum change amount.

  According to the present invention, the maximum thickness change amount is estimated from the entire thickness change waveform using the reference waveform. For this reason, even if sudden noise or the like is superimposed on the thickness change waveform, it is possible to obtain a more accurate maximum thickness change amount and elastic modulus.

(First embodiment)
Hereinafter, a first embodiment of an ultrasonic diagnostic apparatus according to the present invention will be described. FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus 201. The ultrasonic diagnostic apparatus 201 includes a transmission unit 102, a reception unit 103, a calculation unit 151, a reference waveform generation unit 117, and a thickness change amount estimation unit 118. In addition, the ultrasonic diagnostic apparatus 201 includes a control unit 100 in order to control each component of the ultrasonic diagnostic apparatus 201.

  The transmission unit 102 generates a drive signal for driving the probe 101 at a predetermined timing based on a command from the control unit 100. The probe 101 transmits an ultrasonic wave based on the drive signal. The transmitted ultrasonic wave reaches the subject that is periodically deformed by the stress and is reflected inside the subject. In the present embodiment, the subject includes a blood vessel wall of an arterial blood vessel, and the elastic modulus of the blood vessel wall is obtained. Since blood flows in the arterial blood vessel in a cycle that matches the cardiac cycle, the blood vessel wall is periodically deformed by the stress received from the blood.

  The receiving unit 103 receives an echo reflected from the subject by the probe 101, converts the echo into an electric signal, amplifies it, and generates a received echo signal. Also, the received echo signal is converted into a digital signal.

  The transmission unit 102 and the reception unit 103 preferably transmit an ultrasonic wave so as to scan the subject, and set a delay time of the drive signal and the reception echo signal so as to detect only the ultrasonic wave from a predetermined position and direction. It is preferable that a delay time control unit to be controlled is included. The probe 101 preferably includes an array transducer in which a plurality of ultrasonic transducers are arranged.

  The computing unit 151 tracks the movements of a plurality of measurement parts of the subject by analyzing the received echo signal. And the thickness change waveform which is the distance change between the arbitrary two measurement parts in a subject is produced | generated. For this purpose, the calculation unit 151 includes a movement waveform calculation unit 115 and a thickness change waveform calculation unit 116. The movement waveform calculation unit 115 receives the received echo signal, and calculates a movement waveform that is a change in position of the plurality of measurement sites xi set in the subject according to the equations (1) and (2). The thickness change waveform calculation unit 116 calculates a thickness change waveform indicating a change in distance between two selected from a plurality of measurement sites xi by obtaining a difference between movement waveforms of the two measurement sites.

  A plurality of measurement sites can be set on one ultrasonic beam according to the resolution determined by the frequency of ultrasonic waves to be transmitted. Therefore, by moving the ultrasonic beam, it is possible to acquire each movement waveform of the measurement sites arranged in two dimensions.

  The reference waveform generation unit 117 generates a reference waveform. As will be described in detail below, this reference waveform serves as a reference for the thickness change waveform calculated by the thickness change waveform calculation unit 116. In the present embodiment, the reference waveform is obtained in advance by measurement or the like, and the reference waveform data is stored in a storage unit such as a semiconductor memory provided in the reference waveform generation unit 117.

  As will be described in detail below, the thickness change amount estimation unit 118 determines the thickness based on the thickness change waveform obtained from the thickness change waveform calculation unit 116 and the reference waveform obtained from the reference waveform generation unit 117. The maximum change amount of the change waveform is calculated. More specifically, the maximum thickness change amount ΔW is calculated from the entire thickness change waveform using the reference waveform. This calculation is performed for each period of the thickness change waveform. In this respect, the conventional technique for obtaining the maximum change amount from the maximum value and the minimum value of the thickness change waveform is greatly different from the present invention.

  The ultrasonic diagnostic apparatus 201 preferably further includes an elastic modulus calculation unit 120 that calculates an elastic modulus from the obtained maximum change amount. The elastic modulus calculation unit 120 receives information related to stress applied to the subject such as the sphygmomanometer 119. For example, the blood pressure difference ΔP between the maximum blood pressure and the minimum blood pressure is received from the sphygmomanometer. Then, the elastic modulus Er is obtained from the blood pressure difference ΔP and the maximum thickness change amount ΔW according to the equation (6). Here, the reference thickness Ws is a distance (for example, 400 μm) between the two measurement parts for which the thickness change waveform is obtained, and is determined in advance according to the positions of the two measurement parts selected by the thickness change waveform calculation unit 116. Is set. In this way, the elastic modulus of the subject can be obtained.

  The obtained elastic modulus is preferably displayed together with the tomographic image of the subject. This is because the position of the measurement site can be easily shown. For this reason, it is preferable that the ultrasonic diagnostic apparatus 201 further includes a tomographic image generation unit 104, an image synthesis unit 105, and an image display unit 106. The tomographic image generation unit 104 includes a filter and an amplitude detector, mainly analyzes the amplitude of the received echo signal received from the reception unit 103, and generates an image signal of a tomographic image obtained by imaging the internal structure of the subject.

  The image constructing unit 105 receives the image signal and the elastic modulus data obtained from the elastic modulus calculating unit 120 and maps the image signal and the elastic modulus so that the obtained elastic modulus is mapped to an appropriate position on the tomographic image. Is combined with the data. The image display unit 106 displays the synthesized image.

  Next, the operations of the reference waveform generation unit 117 and the thickness variation estimation unit 118, which are the main parts of the present invention, will be described in more detail. FIG. 2 shows the reference waveform M (t) stored in the storage unit of the reference waveform generation unit 117. This waveform is obtained in advance by measuring a thickness change waveform for a plurality of subjects and obtaining an average for one cardiac cycle. The reference waveform M (t) is prepared in advance according to an object to be measured by the ultrasonic diagnostic apparatus 201. In this embodiment, in order to obtain the elastic modulus of the vascular wall of the arterial blood vessel, the reference waveform of the arterial blood vessel wall obtained from a plurality of subjects is also used as the reference waveform M (t).

  ΔW that is the amplitude of the reference waveform M (t) is normalized to be a reference value, for example, 1 μm. Since data obtained from a plurality of subjects is averaged, the influence of noise and the like is reduced even with actually measured data.

  FIG. 3 shows the thickness change waveform y (t) obtained from the thickness change waveform calculation unit 116. This thickness change waveform is one cardiac cycle of the waveform obtained by actually measuring the subject. t represents the sampling time. When the number of sampling points is N, t is an integer represented by t = 0, 1,... N−1.

  The thickness change amount estimation unit 118 receives the reference waveform M (t) and the thickness change waveform y (t), and when the amplitude of the thickness change waveform y (t) is multiplied by what, the reference waveform M (t) Whether they are similar is calculated by the method of least squares. When the coefficient to be multiplied by y (t) is k, and R is the square of the difference between M (t) and k · y (t), R is expressed by Expression (7).

  The equation (7) is partially differentiated by k using the coefficient k as a variable, and when the partially differentiated equation becomes 0, the square difference R is minimized.

  Solving equation (8) for k yields equation (9).

  When the measured thickness change waveform y (t) is multiplied by k, the square of the difference from the reference waveform M (t) having an amplitude of 1 μm is minimized. Means the best match. Therefore, the amplitude A of the measured thickness change waveform y (t) is obtained by the following equation (10).

  A = 1 / k (μm) (10)

  Similar to the above-described calculation, it may be calculated how many times the amplitude of the reference waveform M (t) is multiplied to approach the actual thickness change waveform y (t). In this case, if the coefficient to be multiplied by the reference waveform M (t) is a and the residual is R ′, the following equation (11) is obtained.

  When a value obtained by partial differentiation of R ′ with a is set to 0 (formula (12)), and the coefficient a is solved, formula (13) is obtained.

  In this case, the coefficient a means that when the reference waveform having an amplitude of 1 μm is multiplied by a, the square of the difference from the actually measured thickness change waveform y (t) is the smallest and the two waveforms are the best match. ing. Therefore, the amplitude A ′ of the thickness change waveform y (t) can be obtained by the equation (14).

  A ′ = a (μm) (14)

  As described above, the thickness change amount estimation unit 118 receives the reference waveform M (t) and the thickness change waveform y (t), and uses the equation (9) or the equation (13) to obtain the reference waveform M (t). And a coefficient k or a that minimizes the matching error between the thickness change waveform y (t) and the thickness change waveform y (t). From the calculated coefficient k or coefficient a, the maximum thickness change amount that is the amplitude of the thickness change waveform is further calculated.

FIG. 4 schematically shows one cardiac cycle of thickness change waveforms y ₀ (t) and y ₁ (t) obtained from blood vessel walls having different elastic moduli. As shown in FIG. 4, although the amplitude is different due to the difference in elastic modulus, the changes in the time axis direction of the two thickness change waveforms are the same. This means that a change in blood pressure, which is a stress change that the subject receives, or a state of vibration of the heart is ideally almost constant regardless of the hardness of the blood vessel.

  As shown in FIG. 4, according to the conventional method, when the maximum thickness change amount of the thickness change waveform is obtained, it is necessary to obtain the maximum value Wmax and the minimum value Wmin of the thickness change waveform. In contrast, in the present invention, the maximum thickness change amount is estimated by analyzing the overall consistency between the thickness change waveform and the reference waveform. As described above, when it is assumed that only the thickness change waveform amplitude is different due to the difference in elastic modulus, this means that the maximum thickness change amount is estimated from the entire thickness change waveform for one cardiac cycle.

As shown in the thickness change waveform y ₀ (t) in FIG. 4, the maximum value Wm of the thickness change waveform
The ax and the minimum value Wmin are determined at each point of the thickness change waveform y ₀ (t). However, the inclinations of the inclined portions a1, a2, and a3 between the maximum value Wmax and the minimum value Wmin of the thickness change waveform change according to the maximum value Wmax and the minimum value Wmin. That is, the inclinations of the inclined portions a1, a2, and a3 include information on the maximum value Wmax and the minimum value Wmin. For this reason, even if the maximum value Wmax and the minimum value Wmin cannot be obtained correctly by superimposing noise on the thickness change waveform, as long as the noise is not superposed so that the shape of the thickness change waveform is significantly deformed. The maximum thickness change amount can be estimated from the entire thickness change waveform including the inclined portions a1, a2 and a3.

  Therefore, according to the present invention, the maximum thickness change amount or the elastic modulus can be obtained with high accuracy without being easily influenced by noise such as spike noise that is suddenly mixed.

  As is clear from the above description, since information on the maximum value Wmax and the minimum value Wmin is included in the inclined portions a1, a2, and a3, respectively, even if a part of one heart cycle of the thickness change waveform is used. Thus, it is possible to estimate the maximum thickness change amount in which the influence of noise is reduced as compared with the conventional case. However, since the accuracy of the estimated maximum thickness change amount increases as the section to be selected increases, it is most preferable to obtain the maximum thickness change amount by comparing the reference waveform with the entire one-center cycle of the thickness change waveform. This can be explained as follows using equation (13). When the thickness change waveform y (t) is expressed by the sum of the thickness change s (t) and the noise n (t), the equation (13) can be expressed as follows.

  When the noise n (t) is spike noise or random noise, the second term of the numerator of the equation (13 ′) becomes smaller than the first term as the addition interval becomes longer. Therefore, the thickness change s (t) is similar to the reference waveform (s (t) = a ′ · M (t)), the addition interval is sufficiently long, and the second term of the equation (13 ′) can be ignored. In this case, the expression (13 ′) can be expressed as the following expression (13 ″).

  Therefore, the true coefficient a 'can be estimated. On the contrary, it can be understood from this that the thickness change amount in which the influence of noise is reduced can be estimated by comparing the reference waveform with the entire thickness change waveform.

  In the present invention, since the maximum thickness change amount and the elastic modulus are obtained using the reference waveform and the measured value, it is important to prepare an appropriate reference waveform. When the thickness change waveform varies in the time direction depending on the part of the subject to be measured, it is preferable to prepare a reference waveform corresponding to the part. Specifically, when measuring the elastic modulus of the blood vessel wall of an arterial blood vessel, reference waveform data may be prepared for the intima, media and outer membrane of the blood vessel wall. By storing a plurality of reference waveform data in the reference waveform generation unit 117 and switching the reference waveform data in accordance with the measurement site, it is possible to estimate the thickness change amount more precisely.

  Further, a plurality of reference waveform data is stored in the storage unit of the reference waveform generation unit 117 for each state of the subject, such as a reference waveform for a healthy person, a reference waveform for a diabetic patient, a reference waveform for an arteriosclerosis patient, It is also possible to select a reference waveform according to an operator's instruction. This makes it possible to estimate the thickness change amount more precisely.

(Second Embodiment)
Hereinafter, a second embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described. FIG. 5 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 202. The ultrasonic diagnostic apparatus 202 is different from the ultrasonic diagnostic apparatus 201 of the first embodiment in that it further includes a cycle adjustment unit 140. The transmission unit 102, the reception 103, the calculation unit 151, and the thickness change amount estimation unit 118 of the ultrasonic diagnostic apparatus 202 function in the same manner as the corresponding components of the ultrasonic diagnostic apparatus 201 of the first embodiment.

  The cycle adjustment unit 140 adjusts the cycle of the reference waveform so that the cycle of the reference waveform generated by the reference waveform generation unit 117 matches the cycle of the thickness change waveform calculated by the thickness change waveform calculation unit 116. For this purpose, the ultrasound diagnostic apparatus 202 receives information regarding the period of stress change of the subject from the external period detection unit 141. When the subject is a blood vessel wall of an arterial blood vessel, a blood pressure change, an electrocardiographic change, a heart sound change, or the like of the subject can be used. For example, an electrocardiograph that detects the heartbeat cycle of the heart can be suitably used as the cycle detection unit 141.

  6A, 6 </ b> B, and 6 </ b> C show an electrocardiogram waveform obtained from the period detection unit 141, a thickness change waveform y (t) obtained from the thickness change waveform calculation unit 116, and a reference waveform generation unit 117. The reference waveform M (t) obtained from FIG. As shown in FIG. 6A, an R wave is observed in the electrocardiographic waveform. As is clear from FIGS. 6A and 6B, the period of the electrocardiogram waveform and the period Ty of the thickness change waveform y (t) coincide with each other. This is because a change in the thickness of the arterial blood vessel wall is caused by a change in blood pressure caused by the heartbeat.

  On the other hand, as apparent from FIGS. 6B and 6C, the period Tm of the reference waveform M (t) does not coincide with the period Ty of the thickness change waveform y (t).

  The period adjustment unit 140 is based on the information on the period of stress change of the subject received from the period detection unit 141 in order to eliminate the discrepancy between the periods of the reference waveform M (t) and the thickness change waveform y (t). Adjust the period of M (t). In the present embodiment, the period adjustment unit 140 detects the period of the R wave of the electrocardiogram waveform, and expands or contracts the reference waveform M (t) generated by the reference waveform generation unit 117 in the time direction. A reference waveform expanded and contracted in the time direction is represented by the following equation.

  M ′ (t) = M (t · Ty / Tm) (15)

  If t · Ty / Tm is not an integer, an interpolated value is generated using the relationship between t and M (t). It is also possible to store the value of M (t) in a sufficiently fine sampling unit and use the nearest value as a substitute value.

  When the thickness change amount estimation unit 118 detects that a time phase difference between M ′ (t) and y (t) is shifted by a correlation calculation between M ′ (t) and y (t) or the like. Can be adjusted by appropriately shifting the timing for reading the reference waveform from the reference waveform generator 117.

  After matching the period of the reference waveform M ′ (t) and the period of the thickness change waveform y (t) in this manner, the thickness change amount estimation unit 118 determines the maximum thickness of the thickness change waveform y (t). The amount of change can be obtained as described in the first embodiment.

  As described above, according to the present embodiment, by adjusting the reference waveform generated by the reference waveform generation unit 117 to the stress cycle of the subject by the period adjustment unit 140, more precise thickness change amount and elastic modulus value can be obtained. Calculation is possible.

  In this embodiment, the cycle of the reference waveform is adjusted. However, the cycle of the thickness change waveform is adjusted so that the cycle of the thickness change waveform obtained from the thickness change waveform calculation unit 116 matches the cycle of the reference waveform. May be. In the ultrasonic diagnostic apparatus 202 ′ illustrated in FIG. 7, the cycle adjustment unit 140 receives the thickness change waveform obtained from the thickness change waveform calculation unit 116. And the information regarding the stress applied to the subject obtained from the period detection unit 141 is received, and the period of the thickness change waveform is adjusted. Even if such a configuration is used, the above-described effects can be obtained.

Further, when the cardiac cycle of the subject differs between heartbeats due to arrhythmia or the like and the cycle of the thickness change waveform is not constant, the cycle adjustment unit 140 adjusts to the shortest cycle among the cycles of the thickness change waveform. The period of the thickness change waveform may be made constant by extracting data of each period. Specifically, when the shortest cardiac cycle is T _min , the cycle adjustment unit 140 extracts data during the period _Tmin from each cardiac cycle of the thickness change waveform using the R wave of the electrocardiographic waveform as a trigger. By doing so, the period of the thickness change waveform may be made constant.

  In this case, since the R wave is observed at the beginning of the systole, such a data extraction also causes a cardiac cycle in which a part of the data in the diastole is lost. However, when the cardiac cycle is different between heartbeats in the same subject, the length of the systole during the cardiac cycle hardly changes and the length of the diastole varies mainly. Further, the maximum value and the minimum value of the thickness change amount necessary for measuring the elastic property are observed in the systole. Therefore, even if data in the diastole is missing, it is considered that there is no significant effect on the measurement of elastic modulus. After making the period of the thickness change waveform constant, the period of the reference waveform and the thickness change waveform may be matched as described above, if necessary.

(Third embodiment)
Hereinafter, a third embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described. FIG. 8 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 203. The ultrasonic diagnostic apparatus 203 is different from the ultrasonic diagnostic apparatus 202 ′ of the second embodiment in that it further includes an averaging unit 170. The transmission unit 102, reception 103, calculation unit 151, thickness variation estimation unit 118, and period adjustment unit 140 of the ultrasonic diagnostic apparatus 203 are the same as the corresponding components of the ultrasonic diagnostic apparatus 202 ′ of the second embodiment. To work.

  The averaging unit 170 obtains an average waveform in a plurality of cycles of the thickness change waveform whose cycle is adjusted. FIG. 9A shows a waveform of information relating to the deformation cycle of the subject obtained from the cycle detection unit 141. As in the second embodiment, the information regarding the deformation cycle of the subject is, for example, an electrocardiogram waveform. FIG. 9B shows two periods indicated by y′1 (t) and y′2 (t) of the thickness change waveform y ′ (t) whose period is adjusted by the period adjusting unit 140. .

  The averaging unit 170 obtains an average over a plurality of cycles of the waveform for each cycle of the thickness change waveform y ′ (t). If the thickness change waveform after averaging is Y (t), the following equation (16) is obtained.

Here, y ′ _i (t) indicates the thickness change waveform of the i-th cardiac cycle, and L indicates the number of cardiac cycles to be averaged. The averaged thickness change waveform Y (t) obtained by the averaging unit 170 is input to the thickness change amount estimation unit 118, and the maximum thickness change amount is the same as described in the first embodiment. Calculated. Since the thickness change waveform with the cycle adjusted is input to the averaging unit 170, each cycle of the thickness change waveform is constant, and the averaging unit 170 performs the calculation of Expression (16) by simple addition. Is possible.

  The number of cardiac cycles to be averaged can be arbitrarily selected. An average over the entire measured period may be obtained, or an average for a plurality of periods may be obtained while shifting the cardiac cycle for calculating the average in real time. Further, in Equation (16), a simple addition average is obtained, but a weighted addition average may be obtained.

  According to the present embodiment, the random noise included in the thickness change waveform is reduced by the averaging in the averaging unit 170. For this reason, the thickness variation estimation unit 118 can estimate the maximum thickness more accurately, and the calculation accuracy of the elastic modulus is further improved.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described. FIG. 10 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 204. In the ultrasonic diagnostic apparatus described so far, the maximum thickness change amount is estimated from the entire thickness change waveform using a reference waveform obtained in advance by measurement. In contrast, the ultrasonic diagnostic apparatus 204 generates a reference waveform from the movement waveform of the measurement site obtained by measuring the subject. For this purpose, the ultrasonic diagnostic apparatus 204 includes a reference waveform generation unit 117 ′ that generates a reference waveform based on the movement waveform obtained from the movement waveform calculation unit 115.

  FIG. 11 schematically shows a cross section of the subject 12 measured by the probe 101. The subject 12 includes an arterial blood vessel, and ultrasonic beams 20a, 20b, and 20c are transmitted from the probe 101 so as to measure a cross section perpendicular to the axis of the arterial blood vessel. In the scanning section, the arterial blood vessel includes a blood vessel front wall 31, a blood vessel cavity 32 and a blood vessel rear wall 33.

  The blood vessel front wall 31 and the blood vessel rear wall 33 receive stress from the blood due to a change in pressure of blood flowing through the blood vessel cavity 32, and the expansion and contraction are periodically repeated. In the blood vessel region 21a of the blood vessel front wall 31 having a minute width on the ultrasonic beam 20c, it is considered that the thickness change, which is a change in the distance between the two points p1 and p2, occurs due to the movement of the intima side end 22a. Therefore, it is considered that the tissue movement waveform of the intima side end 22a is similar to the layer thickness change waveform between p1 and p2.

  FIG. 12A shows, for example, the movement waveform n (t) of the intima side end 22a obtained from the movement waveform calculation unit 115, and FIG. 12B shows the movement waveform n (t) based on the movement waveform n (t). The reference waveform M (t) generated in the reference waveform generation unit 117 ′ is shown. Here, t represents the sampling time. When the number of sampling points is N, t is an integer satisfying t = 0, 1,... N−1. The movement waveform n (t) has a positive direction when the measurement point moves in the direction in which the blood vessel diameter increases. These waveforms show only one cardiac cycle. When the maximum value in one cardiac cycle of the movement waveform n (t) is Nmax and the minimum value is Nmin, the reference waveform generator 117 calculates the reference waveform M (t) from the movement waveform n (t) by the following equation.

  Thereby, the reference pattern waveform M (t) is proportional to the waveform n (t) of the intima side end 22a and becomes a waveform having an amplitude of 1.

  FIG. 13 shows the actually measured thickness change waveform y (t) for one cardiac cycle output from the thickness change waveform calculation unit 116. This thickness change waveform y (t) is obtained, for example, by calculating the difference between the movement waveform obtained at the measurement position p1 in FIG. 11 and the movement waveform obtained at the measurement position p2.

  As shown in FIG. 11, both the reference waveform M (t) and the thickness change waveform y (t) are based on the received echo signal obtained from the ultrasonic beam 20c. However, the thickness change waveform y (t) is a minute distance change between two points, whereas the reference waveform M (t) is based on the movement waveform n (t). As shown in FIG. 12A, the amplitude D1 of the movement waveform n (t) is, for example, about several hundred μm, whereas the amplitude D2 of the thickness change waveform y (t) is about several tens of μm. For this reason, the noise influence is much smaller in the reference waveform M (t) than in the thickness change waveform y (t).

  Therefore, by using the reference waveform generated in this manner, the thickness change amount estimation unit 118 suddenly obtains the maximum change amount from the entire thickness change waveform as described in the first embodiment. The maximum thickness change amount or the elastic modulus can be obtained with high accuracy without being affected by noise such as spike noise that is mixed. In particular, according to this embodiment, the reference waveform M (t) and the thickness change waveform y (t) are both based on the same received echo signal. For this reason, even if a period adjustment unit is not provided, the periods of the two waveforms are the same, and the maximum thickness change amount can be obtained with high accuracy. In addition, since an external signal indicating the stress cycle of the subject such as an electrocardiograph or a blood pressure monitor is not required, measurement can be performed easily.

(Fifth embodiment)
The fifth embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described below. FIG. 14 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 205. The ultrasonic diagnostic apparatus 205 is different from the ultrasonic diagnostic apparatus 204 of the fourth embodiment in that it further includes a blood vessel diameter calculation unit 142.

  The blood vessel diameter calculation unit 142 receives the movement waveform from the movement waveform calculation unit, and calculates a blood vessel diameter waveform of the inner diameter or outer diameter of the arterial blood vessel in the subject. The reference waveform generation unit 117 receives the blood vessel diameter waveform from the blood vessel diameter calculation unit 142 and generates a reference waveform based on the blood vessel diameter waveform. More specifically, first, in order to define the blood vessel cavity 32, as shown in FIG. 11, for example, the positions of the intima side end 22a and the intima side end 22b of the blood vessel wall are specified. The position is specified by observing a cross-sectional image of the arterial blood vessel displayed on the image display unit 106 by the operator and designating the position on the cross-sectional image, or by analyzing the received echo signal. The unit 100 may perform this automatically. When the movement waveform of the intima side end 22a is ia (t) and the movement waveform of the intima side end 22b is ib (t), the blood vessel diameter waveform L (t) is expressed by the following equation (18).

  L (t) = ia (t) + ib (t) (18)

  Here, the signs of ia (t) and ib (t) are positive in the direction in which the blood vessel diameter increases. As described above, the blood vessel outer diameter change waveform may be obtained.

  The reference waveform generation unit 117 receives the blood vessel diameter waveform L (t) and generates the reference waveform M (t) using the blood vessel diameter waveform L (t) instead of the movement waveform n (t) in Expression (17). . Thereby, the maximum thickness change amount or the elastic modulus can be obtained in the same manner as in the fourth embodiment.

  In the present embodiment, the blood vessel diameter waveform used for generating the reference waveform indicates a change in the blood vessel diameter and has a strong correlation with the pressure of blood flowing through the blood vessel. Further, the deformation or thickness change of the blood vessel wall has a correlation with the blood pressure. Therefore, a change in thickness, which is a change in distance between two points in the blood vessel wall, has a correlation with a change in blood vessel diameter, and the blood vessel diameter waveform can be suitably used for generating a reference waveform.

  In particular, since the intima side end 22a and the intima side end 22b that define the blood vessel diameter move in opposite directions depending on blood pressure, the amplitude of the blood vessel diameter waveform L (t) is the movement waveform ia (t) or the movement waveform ib ( t) which is approximately twice that of t). For this reason, the influence of noise is suppressed in the blood vessel diameter waveform L (t), and the influence of noise in the generated reference waveform is also small. Accordingly, it is possible to calculate the thickness change amount and the elastic modulus value more precisely.

(Sixth embodiment)
The sixth embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described below. FIG. 15 is a block diagram showing a configuration of the ultrasonic diagnostic apparatus 206. In the fourth embodiment, the reference waveform generation unit 117 ′ generates the reference waveform based on the movement waveform. In the present embodiment, the reference waveform generation unit 117 ″ receives a blood pressure waveform from the outside and generates a reference waveform based on the blood pressure waveform.

  The blood pressure waveform input to the reference waveform generation unit 117 ″ indicates a blood pressure change in the arterial blood vessel of the subject and is acquired by the real-time sphygmomanometer 150 or the like.

  FIG. 16 shows an example of a blood pressure waveform. The change in blood pressure almost coincides with the movement waveform n (t) shown in FIG. The reference waveform generation unit 117 ″ receives the blood pressure waveform and generates a reference waveform M (t) according to Expression (17). A change in thickness, which is a change in distance between two points in the blood vessel wall, is caused by a change in blood pressure. Since the change in thickness and the change in blood pressure are correlated, the blood pressure waveform can be suitably used for generating a reference waveform. For this reason, it is possible to calculate a more precise thickness change amount and elastic modulus value using the generated reference waveform.

  In each of the above embodiments, the distance (thickness) change waveform between any two measurement sites in the subject is used as the reference waveform. However, the velocity between any two measurement sites in the subject is used. Even if the difference waveform is used as the reference waveform, the same effect can be obtained. In this case, a velocity difference waveform between two measurement sites may be obtained from a plurality of subjects in advance, or a velocity difference waveform may be obtained by time-differentiating the blood vessel diameter waveform. Further, the speed difference waveform may be obtained by time differentiation of the blood pressure waveform.

  The ultrasonic diagnostic apparatus of the present invention is suitable for measurement of property characteristics such as thickness variation, strain, and elastic characteristics of a tissue constituting a subject.

1 is a block diagram showing a first embodiment of an ultrasonic diagnostic apparatus according to the present invention. The reference waveform produced | generated in the reference | standard waveform generation part of the ultrasonic diagnosing device of FIG. 1 is shown. The thickness change waveform output from the thickness change waveform calculation part of the ultrasonic diagnostic apparatus of FIG. 1 is shown. It is a figure explaining the information contained in a thickness change waveform. It is a block diagram which shows 2nd Embodiment of the ultrasonic diagnosing device by this invention. (A), (b), and (c) are obtained from the electrocardiogram waveform obtained from the period detector, the thickness change waveform obtained from the thickness change waveform calculator, and the reference waveform generator in the second embodiment. Each reference waveform is shown. It is a block diagram which shows the modification of 2nd Embodiment of the ultrasonic diagnosing device by this invention. It is a block diagram which shows 3rd Embodiment of the ultrasonic diagnosing device by this invention. (A) And (b) has each shown the electrocardiogram waveform obtained from a period detection part, and the thickness change waveform obtained from a period adjustment part in 3rd Embodiment. It is a block diagram which shows 4th Embodiment of the ultrasonic diagnosing device by this invention. A cross section of a subject measured by a probe is schematically shown. (A) And (b) has each shown the position waveform input in a reference waveform generation part and the reference waveform produced | generated in a reference waveform generation part in 4th Embodiment. In 4th Embodiment, the thickness change waveform output from the thickness change waveform calculation part is shown. It is a block diagram which shows 5th Embodiment of the ultrasonic diagnosing device by this invention. It is a block diagram which shows 6th Embodiment of the ultrasonic diagnosing device by this invention. An example of a blood pressure waveform used in the sixth embodiment is shown. It is a figure explaining the method of tracking a structure | tissue from the phase difference of an ultrasonic echo signal. A cross section of a subject measured by a probe is schematically shown. It is a figure explaining the method of calculating | requiring a distortion amount from the tracking waveform of a subject tissue. It is a figure explaining an error arising in the maximum thickness change amount when noise is superimposed on the thickness change waveform.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Subject 31 Blood vessel front wall 32 Blood vessel cavity 33 Blood vessel rear wall 100 Control part 101 Probe 102 Transmission part 103 Reception part 104 Tomographic image generation part 105 Image composition part 106 Image display part 115 Moving waveform calculation part 116 Thickness change waveform Calculation unit 117, 117 ′, 117 ″ Reference waveform generation unit 118 Thickness change estimation unit 119 Sphygmomanometer 120 Elastic modulus calculation unit 140 Period adjustment unit 141 Period detection unit 142 Blood vessel diameter calculation unit 150 Calculation unit 170 Averaging unit 201 202, 203, 204, 205, 206 Ultrasonic diagnostic apparatus

Claims (24)

A transmitter that generates a drive signal for driving the probe in order to transmit ultrasonic waves to a subject that is periodically deformed by stress;
A reception unit that receives an echo obtained by the reflection of the ultrasonic wave at the subject by the probe and generates a reception echo signal;
A calculation unit that calculates a thickness change waveform indicating a change in distance between any two measurement sites in the subject based on the received echo signal;
A reference waveform generation unit for generating a reference waveform;
Using the reference waveform, a thickness change amount estimation unit that calculates a maximum change amount of the thickness change waveform from the entire thickness change waveform;
An ultrasonic diagnostic apparatus comprising:   The thickness change amount estimation unit obtains a coefficient by which the thickness change waveform or the reference waveform is multiplied so that a matching error between the thickness change waveform and the reference waveform is minimized, and the coefficient and the reference waveform The ultrasonic diagnostic apparatus according to claim 1, wherein a maximum change amount of the thickness change waveform is calculated from an amplitude.   The ultrasonic diagnostic apparatus according to claim 1, wherein the reference waveform generation unit includes a storage unit that stores data of the reference waveform.   The ultrasonic diagnostic apparatus according to claim 3, wherein the reference waveform is an average of thickness change waveforms acquired in advance from a plurality of subjects. A cycle adjustment unit that adjusts the cycle of the reference waveform based on the deformation cycle of the subject;
The ultrasonic diagnostic apparatus according to claim 4, wherein the thickness change amount estimation unit calculates a maximum change amount of the thickness change waveform based on a reference waveform whose period is adjusted and the thickness change waveform. A cycle adjustment unit for adjusting a cycle of the thickness change waveform based on a cycle of deformation of the subject;
The ultrasonic diagnostic apparatus according to claim 4, wherein the thickness change amount estimation unit calculates a maximum change amount of the thickness change waveform based on a thickness change waveform whose period is adjusted and the reference waveform.   An averaging unit that obtains an average of a plurality of cycles of the thickness change waveform with the cycle adjusted is further provided, and the maximum change amount of the thickness change waveform is calculated based on the averaged thickness change waveform and the reference waveform. The ultrasonic diagnostic apparatus according to claim 5.   When the period of the thickness change waveform is not constant, the period adjustment is performed so that the data of each period is extracted in accordance with the shortest period among the periods of the thickness change waveform and the period of the thickness change waveform is made constant. The ultrasonic diagnostic apparatus according to claim 1, further comprising a unit.   The calculation unit includes a movement waveform calculation unit that calculates a movement waveform that indicates a change in position of a plurality of measurement sites in the subject based on the received echo signal, and the two measurement sites based on the movement waveform The ultrasonic diagnostic apparatus according to claim 1, further comprising an arithmetic unit that calculates a thickness change waveform therebetween.   The ultrasonic diagnostic apparatus according to claim 9, wherein the reference waveform generation unit generates the reference waveform based on the movement waveform.   The blood vessel diameter calculation unit further calculates a change waveform of a blood vessel diameter included in the subject based on the movement waveform, and the reference waveform generation unit generates the reference waveform based on the change waveform. 9. The ultrasonic diagnostic apparatus according to 9.   The ultrasonic diagnostic apparatus according to claim 1, wherein the reference waveform generation unit generates the reference waveform based on a blood pressure change waveform of the subject.   The ultrasonic diagnostic apparatus according to claim 1, further comprising an elastic modulus calculation unit that receives information on a stress difference of the stress generated in a deformation cycle of the subject and obtains an elastic modulus from the maximum change amount. . A method of controlling an ultrasonic diagnostic apparatus by a control unit of the ultrasonic diagnostic apparatus,
(A) transmitting the ultrasonic wave by driving the probe;
Receiving by the probe an echo obtained by the reflection of the ultrasonic wave in a subject that is periodically deformed by stress;
Calculating a thickness change waveform indicating a change in distance between any two measurement sites in the subject based on the received echo signal (C);
Generating a reference waveform (D);
(E) calculating a maximum change amount of the thickness change waveform from the entire thickness change waveform using the reference waveform;
A method for controlling an ultrasonic diagnostic apparatus including:   The step (E) obtains a coefficient by which the thickness change waveform or the reference waveform is multiplied so that a matching error between the thickness change waveform and the reference waveform is minimized, and based on the coefficient and the amplitude of the reference waveform. The method for controlling an ultrasonic diagnostic apparatus according to claim 14, wherein a maximum change amount of the thickness change waveform is calculated.   The method of controlling an ultrasonic diagnostic apparatus according to claim 14 or 15, wherein the reference waveform is an average of thickness change waveforms acquired in advance from a plurality of subjects. Further comprising adjusting the period of the reference waveform based on the period of deformation of the subject;
15. The method of controlling an ultrasonic diagnostic apparatus according to claim 14, wherein the step (E) calculates a maximum change amount of the thickness change waveform based on a reference waveform whose period is adjusted and the thickness change waveform. Adjusting the cycle of the thickness change waveform based on the deformation cycle of the subject;
The method of controlling an ultrasonic diagnostic apparatus according to claim 16, wherein the step (E) calculates a maximum change amount of the thickness change waveform based on the thickness change waveform whose period is adjusted and the reference waveform. Further comprising calculating an average of a plurality of periods of the thickness-change waveform with the period adjusted;
The method of controlling an ultrasonic diagnostic apparatus according to claim 18, wherein a maximum change amount of the thickness change waveform is calculated based on the averaged thickness change waveform and the reference waveform. The step (C) calculates a moving waveform that indicates a change in position of a plurality of measurement sites in the subject based on the received echo signal; and
The method for controlling the ultrasonic diagnostic apparatus according to claim 14, further comprising: calculating a thickness change waveform between the two measurement sites based on the movement waveform.   21. The method of controlling an ultrasonic diagnostic apparatus according to claim 20, wherein the step (D) generates the reference waveform based on the movement waveform. Further comprising calculating a blood vessel diameter change waveform included in the subject based on the movement waveform;
The method according to claim 20, wherein the step (D) generates the reference waveform based on the change waveform.   The method of controlling an ultrasonic diagnostic apparatus according to claim 14 or 15, wherein the step (D) generates the reference waveform based on a blood pressure change waveform of the subject. The control of the ultrasonic diagnostic apparatus according to any one of claims 14 to 23, further comprising a step of receiving information on a stress difference of the stress generated in the deformation cycle of the subject and obtaining an elastic modulus from the maximum change amount. Method.

Images