WO2015107993A1

WO2015107993A1 - Diagnostic ultrasound apparatus and pulse wave measurement method

Info

Publication number: WO2015107993A1
Application number: PCT/JP2015/050497
Authority: WO
Inventors: 川畑　健一; 吉川　秀樹; 田中　智彦
Original assignee: 日立アロカメディカル株式会社
Priority date: 2014-01-15
Filing date: 2015-01-09
Publication date: 2015-07-23
Also published as: JP2017070317A

Abstract

Provided is a diagnostic ultrasound apparatus capable of obtaining more reliable pulse wave information with a relatively small number of measurements. The calculation unit of the diagnostic ultrasound apparatus is provided with a pulse wave measurement unit for measuring pulse waves that move inside a blood vessel in a living body using echo signals that are reflected at two locations of the blood vessel wall when multiple ultrasound beams are irradiated at a slant relative to the blood vessel. The pulse wave measurement unit obtains, for the multiple ultrasound beams, the respective temporal changes of a first echo signal reflected from the side of the blood vessel that is closer to the probe and a second echo signal reflected from the side that is further from the probe and calculates the pulse wave velocity using the difference in time that changes arising from the pulse wave occur at the respective reflection origins (measurement points) and the distance between measurement points in the direction in which the blood vessel runs.

Description

Ultrasonic diagnostic apparatus and pulse wave measuring method

The present invention relates to an ultrasonic diagnostic apparatus. In particular, the present invention relates to a technique for measuring and diagnosing the state of a specific part of a blood vessel using ultrasound.

The speed of the pulse wave that travels through the blood vessels is closely related to blood pressure, the degree of arteriosclerosis, etc., and accurate measurement of the pulse wave transmission speed is very important for health management and understanding the health status of patients. . As a method of measuring the pulse wave transmission speed, there is a method of measuring and calculating the time required for the pulse wave to reach the upper arm and ankle using a blood pressure cuff against an electrocardiogram. Based on the blood pressure ratio of the upper arm and ankle obtained by this method, CAVI (Cardio Angular Vascular Index), which is an index indicating the blood vessel-specific hardness independent of blood pressure, is calculated.

The pulse wave transmission speed required by this method (CAVI method) is an average value over a long distance from the heart to the ankle, but in reality, changes in the inner diameter of the blood vessel and arteriosclerosis are localized in a part of the long path. In many cases. As a technique for grasping local changes in blood vessel properties, a method using an ultrasonic diagnostic apparatus has also been proposed (Patent Document 1). In this method, ultrasonic pulses are transmitted toward two points along the direction of blood vessel travel, and a temporal change in the amount of tissue movement is detected from the ultrasonic signals reflected from these two points. The pulse wave transmission speed is calculated from the distance between the points.

JP 2005-52424 A

The technique described in Patent Document 1 has a drawback in that an error becomes larger than the conventional CAVI method because the pulse wave transmission speed is measured based on the measured pulse wave transmission time between two points. In general, errors can be reduced by increasing the number of measurements. In this case, however, the measurement time becomes longer, and the positional relationship between the ultrasound probe brought into contact with the living body and the living body, that is, the relationship between the blood vessels can be maintained. There is also a high probability that this will not occur, thereby causing an error.

An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of obtaining pulse wave information with higher reliability with a relatively small number of measurements.

The present invention uses an echo signal obtained from a side closer to the ultrasonic probe and a side far from the ultrasonic probe when the ultrasonic beam is irradiated obliquely relative to the blood vessel in the living body, A plurality of measurement data with different pulse wave movement distances is acquired with a small number of measurements.

That is, the ultrasonic diagnostic apparatus of the present invention uses an ultrasonic probe that transmits an ultrasonic beam into a living body and receives an echo signal from the living body, and an echo signal received by the ultrasonic probe. A calculation unit that calculates biological information, and the calculation unit is close to the ultrasonic probe of the blood vessel when the ultrasonic beam is irradiated obliquely relative to the blood vessel in the living body. Pulse wave measurement for measuring a pulse wave moving in a blood vessel using a first echo signal reflected from the side and a second echo signal of the blood vessel reflected from the side far from the ultrasonic probe It has the part.

According to the present invention, it is possible to provide an ultrasonic diagnostic apparatus capable of obtaining more reliable pulse wave information with a relatively small number of measurements.

Functional block diagram showing a first embodiment of an ultrasonic diagnostic apparatus of the present invention The figure which shows the pulse wave measurement procedure of 1st embodiment It is a figure explaining the angle of the ultrasonic beam with respect to the blood vessel, (a) is the case of the pulse wave measurement of 1st embodiment, (b) shows the case of the conventional pulse wave measurement. The figure which shows the case where the running direction of the blood vessel is diagonal The figure which shows the time change of the echo signal with respect to one ultrasonic beam FIG. 5 is a graph in which the pulse wave travel time is plotted against the pulse wave travel distance, where (a) is a pulse wave measurement of the first embodiment, (b) is a conventional pulse wave measurement, and (c) is a second implementation. The case of the pulse wave measurement of a form is shown. Functional block diagram showing a second embodiment of the ultrasonic diagnostic apparatus of the present invention The figure which shows the pulse wave measurement procedure of 2nd embodiment It is a figure explaining the direction of the mode ultrasonic beam in 2nd embodiment, (a) shows the case of wide mode, (b) shows the case of narrow mode. The figure which shows the relationship between an ultrasound probe and a coupling material of the ultrasound diagnosing device of 3rd embodiment. Functional block diagram showing a fourth embodiment of the ultrasonic diagnostic apparatus of the present invention Functional block diagram showing a fifth embodiment of the ultrasonic diagnostic apparatus of the present invention The figure which shows the pulse wave measurement procedure of 5th embodiment

The ultrasonic diagnostic apparatus of the present embodiment includes an ultrasonic probe (1) that transmits an ultrasonic beam into a living body and receives an echo signal from the living body, and an echo that is received by the ultrasonic probe (1). A calculation unit (4) that calculates biological information using the signal, and a display unit (6) that displays the biological information calculated by the calculation unit (4). The calculation unit (4) includes a first echo signal reflected from a side of the blood vessel close to the ultrasonic probe (1) when the ultrasonic beam is irradiated relatively obliquely to the blood vessel in the living body. A pulse wave measurement unit (40) for measuring a pulse wave moving in the blood vessel using the second echo signal reflected from the side of the blood vessel far from the ultrasonic probe (1).

The pulse wave measurement unit (40) uses temporal changes of the first echo signal and the second echo signal, and the distance in the blood vessel traveling direction between the side of the blood vessel close to the ultrasonic probe and the side far from the ultrasonic probe. And a pulse wave velocity calculating unit (45) for calculating the pulse wave propagation velocity.

In this embodiment, the ultrasound probe (1) is an ultrasound probe that includes a plurality of arranged transducers and emits a plurality of ultrasound beams, and the pulse wave measurement unit (40) includes a plurality of A pulse wave is measured using the first echo signal and the second echo signal generated corresponding to each of the ultrasonic beams.

Note that “the ultrasonic beam is oblique with respect to the blood vessel” means that the ultrasonic beam is directed in the blood vessel traveling direction when the ultrasonic beam is irradiated in a direction orthogonal to the blood vessel traveling direction. This means that the light is incident at an angle smaller than 90 °, and the angle formed between the probe surface and the ultrasonic beam is not synonymous.
In the following description, “pulse wave transmission speed” is also simply referred to as “pulse wave speed”.

<First embodiment>
Hereinafter, the ultrasonic diagnostic apparatus of the first embodiment will be described with reference to the drawings.

As shown in FIG. 1, the ultrasonic diagnostic apparatus of the present embodiment has a plurality of transducers (not shown) arranged in a one-dimensional or two-dimensional direction, and transmits ultrasonic beams to a living body and reflected echoes from the living body. A probe (ultrasonic probe) 1 that receives an ultrasonic signal, a transmitter 2 that drives a transducer of the probe 1 and transmits an ultrasonic beam from the probe 1, and an ultrasonic wave that the probe 1 receives A receiving unit 3 that performs signal processing such as amplification and phasing on the signal, a calculation unit (pulse wave measurement unit) 4 that calculates information on the pulse wave using a signal output from the receiving unit 3, and a calculation unit 4 A display unit 6 for displaying the calculated pulse wave information and an input unit 7 for inputting conditions necessary for measurement, parameters necessary for calculation, and the like are provided. The display unit 6 includes a display control unit 61 that controls a display image.

The probe 1 is, for example, an electronic scanning probe 1 that performs beam focusing by electronically switching a plurality of vibrators, and a known type such as a linear type, a convex type, or a sector type can be used. The transmitter 2 includes an ultrasonic signal transmission circuit 21 that drives a plurality of transducers included in the probe 1 at a predetermined frequency, and a transmission signal transmitted from the ultrasonic signal transmission circuit with a predetermined delay with respect to the plurality of transducers. A delay control unit (beamformer) 23 that supplies the signals in a related manner is provided, and the direction and depth (focus position) of the ultrasonic beam are adjusted by controlling the delay time given to each transducer. be able to.

The delay control unit 23 adjusts the direction and depth of the ultrasonic beam based on the designation of the region of interest and the beam angle input via the input unit 7. For example, the operator can set a region of interest including a blood vessel to be examined based on a B-mode image, and can set an angle with respect to the blood vessel as a beam angle. For this reason, the input unit 7 includes a frequency setting unit (not shown) for setting the frequency of the transmission signal and a gain setting unit (not shown) for setting the gain of the amplifier, a region of interest setting unit 71, an angle setting unit 72, a plurality of A beam interval setting unit 73 is provided for setting an interval (beam interval) between the ultrasonic beams. The input unit 7 includes buttons, a keyboard, a trackball, and the like for performing various settings, and some of them can be configured with a touch panel.

The receiving unit 3 includes an amplifying unit 31 that amplifies a signal from each transducer, and a delay process that performs delay processing (phasing) corresponding to a delay time given to each transducer by the delay control unit 23 of the transmitting unit 2. A unit 32, an apodization processing unit 33, an addition unit (not shown), and the like are provided. The receiving unit 3 generates a reception signal corresponding to the transmission beam by the processing of these units. The received signal is subjected to processing such as unnecessary wave component removal and spectrum calculation as necessary, and is then configured by the display control unit 61 into a display image in B mode, M mode, or Doppler mode. In order to create these display images, although not shown in FIG. 1, elements included in a general ultrasonic diagnostic apparatus, such as a B-mode processing unit, a DSC (Digital Scan Converter), and further a Doppler processing unit are signaled. You may provide as a process part.

The pulse wave measurement unit 40 includes a pulse wave arrival time calculation unit 41, a distance calculation unit 42, a pulse wave velocity calculation unit 45, and the like in order to calculate a pulse wave velocity. In the present embodiment, measurement is performed in a mode in which the temporal position change of the reflection source is recorded, and the pulse wave arrival time calculation unit 41 determines the pulse wave arrival time based on the time change of the received signals from the plurality of reflection sources. Calculate The distance calculation unit 42 calculates, for example, the moving distance of the pulse wave within the region of interest from the B mode image, specifically, the distance between a plurality of measurement points of the blood vessel. The pulse wave velocity calculator 45 calculates the pulse wave velocity using the pulse wave arrival time calculated by the pulse wave arrival time calculator 41 and the distance calculated by the distance calculator 43.

Next, based on the above configuration, the operation of the ultrasonic diagnostic apparatus of the present embodiment will be described focusing on the operation of the pulse wave measurement unit 40. FIG. 2 shows the operation procedure.

First, the operator sets a region of interest including a target blood vessel via the region of interest setting unit 71 of the input unit 7 (S201). The region of interest can be set using the ultrasonic image (B mode image) displayed on the display unit 6 so that the target blood vessel is included in the region of interest. If necessary, set the measurement conditions that allow the target blood vessel to be visualized well. For example, the ultrasonic intensity and frequency are set in a range where an echo signal from the blood vessel wall can be measured.

Next, the angle of the ultrasonic beam irradiated from the probe 1 with respect to the target blood vessel is set (S202). As shown in FIG. 3B, when the target blood vessel 300 is running substantially parallel to the body surface of the subject, the target blood vessel 300 is in contact with the body surface (skin) 305, The surface (the surface in contact with the body surface of the subject) is parallel to the target blood vessel 300, and the angle formed between the

ultrasonic beams

310 and 320 irradiated perpendicularly from the surface of the probe 1 and the blood vessel 300 is about 90 °. . In the present embodiment, as shown in FIG. 3A, the angles of the

ultrasonic beams

310 and 320 irradiated from the probe 1 are adjusted so that the

ultrasonic beams

310 and 320 are obliquely irradiated to the blood vessel 300. To.

The angle θ formed between the

ultrasonic beams

310 and 320 and the traveling direction of the blood vessel 300 differs depending on the thickness of the blood vessel 300, and the point A1 where the ultrasonic beam 310 hits the blood vessel wall 300-1 closer to the body surface and the body The difference L in the blood vessel traveling direction from the point A2 where the ultrasonic beam 310 strikes on the blood vessel wall 300-2 far from the table is set to a predetermined value or more. With respect to the predetermined value L, the traveling direction between the points A1 and A2 takes into account that the displacement of the blood vessel wall due to the pulse wave includes a frequency component of up to about 60 Hz and the arrival at a specific part is detected in phase. It is preferable that the difference in position is approximately 0.5 mm or more. The angle θ is preferably set so that L is 0.5 mm or more. The points A1 and A2 are points (reflection sources) that generate reflected echoes, and are hereinafter referred to as measurement points.

Specifically, when the diameter D of the blood vessel and the difference in the position in the blood vessel traveling direction between the measurement points A1 and A2 (distance in the traveling direction) is L, the angle θ is
[Equation 1]
θ ≧ arctan (D / L) (1)
It becomes. Since the diameter D of the blood vessel can be grasped from the B-mode image, the angle can be determined using this value. Specifically, L (0.5 mm) may be set as a specified value, designation of a target blood vessel may be accepted when setting a region of interest, and the ultrasonic beam angle θ may be automatically set. The operator may input the value of L and change it.

Note that FIG. 3 shows a case where the blood vessel travels substantially parallel to the body surface, but the blood vessel 300 may travel diagonally in the depth direction with respect to the body surface 305 as shown in FIG. In this case, the sum of the inclination angle α of the blood vessel 300 with respect to the body surface and the angle θ between the target blood vessel 300 and the irradiation beam in the cross section where the blood vessel 300 travels is the angle θp of the ultrasonic beam with respect to the surface of the probe 1. The angle θp of the ultrasonic beam may be set so that

Next, the interval W0 between a plurality of, for example, two ultrasonic beams irradiated from the probe 1 is set (S203). Hereinafter, a case where the ultrasonic beam is two parallel beams will be described as an example. The interval between the ultrasonic beams is such that the interval W between the points where the two ultrasonic beams enter the blood vessel (A1 and B1 in FIG. 3) is twice or more than the interval L between the measurement point A1 and the measurement point A2. It is preferable to set so that. As shown in FIG. 3, when the probe 1 is a linear type and the two ultrasonic beams are parallel beams, the beam interval is substantially equal to the interval W between the points where the two ultrasonic beams are incident on the blood vessel. . The values L and W set in steps S202 and S203 are recorded in a memory (not shown) and used for calculation by the pulse wave velocity calculation unit 45.

Thus, after setting the irradiation angle θ of the ultrasonic beam and the interval W between the irradiation beams, the irradiation of the ultrasonic beam is started, and echo signals from the two ultrasonic beams are continuously received (S204). The interval between the ultrasonic beams and the angle of the ultrasonic beam, that is, the irradiation direction, are controlled by a delay control unit 23 that controls the drive and delay relationship of the transducer of the probe 1.

FIG. 5 shows the time change of the received signal corresponding to one ultrasonic beam. In the graph of FIG. 5, the horizontal axis represents depth, and the vertical axis represents signal intensity. As shown in the figure, the received signal has two peaks corresponding to the measurement points A1 and A2, and the respective peak positions are shifted in the horizontal axis direction due to the propagation of the pulse wave. That is, the position in the vibration direction changes. Here, since the ultrasonic beam is obliquely incident on the blood vessel, the measurement point A1 and the measurement point A2 are at positions shifted in the traveling direction of the blood vessel, and the time at which the pulse wave propagates is different. For example, in FIG. 5, the pulse wave reaches the measurement point A2 when Δt has elapsed from time t0, and the pulse wave has reached the measurement point A1 when 4Δt has elapsed from t0. Thus, by continuously acquiring echo signals (received signals) from two ultrasonic beams, four measurement points A1, A2, B1, B2 (A2 in the order of travel direction) shown in FIG. , A1, B2, B1), the position change in the depth direction and the time when it occurred can be obtained.

The pulse wave measurement unit 40 first determines the pulse wave propagation time of each measurement point A2, A1, B2, B1 using the received signal (S205). The pulse wave transmission time is calculated, for example, by providing a spatial gate centering on the average position of each measurement point of the blood vessel, and setting the time when the position of the measurement point is shifted outward from the spatial gate as the pulse wave arrival time. After determining the pulse wave arrival time at each measurement point, the movement time of the pulse wave moving between the measurement points is calculated (S206). Finally, the pulse wave transmission speed Vn is calculated using the distance Ln between the measurement points and the movement time ΔTn (S207).
[Equation 2]
Vn = Ln ÷ ΔTn (2)

In equation (2), the subscript “n” is 1, 2, 3... N (N is an integer of “number of measurement points−1”, and when the number of measurement points is 4 as described above, Three speeds V1, V2 and V3 are calculated corresponding to three different distances, ie, distance L1 between A2 and A1, distance L2 between A2 and B2, and distance L3 between A2 and B1. , L2 and L3 are calculated by the distance calculation unit 42 using the blood vessel diameter D (obtained from the B-mode image), the set angle θ of the ultrasonic beam, and the beam interval W. The ultrasonic beam is a parallel beam. A simple example in which a blood vessel runs parallel to the body surface is as follows.
The distance L1 between A2 and A1 is L1 = D ÷ tanθ
The distance L2 between A2 and B1 is L2 = L1 + [Distance between A1 and B1] = L1 + W
The distance L3 between A2 and B2 is L3 = L2 + [distance between B2 and B1] = L2 + L1.

The three velocities calculated in this way should be the same if the velocity of the pulse wave in the region of interest is uniform, but have some variation due to restrictions on device accuracy. The average value of the multiple velocities obtained here (three in this case) may be obtained and used as the pulse wave velocity, or the relationship between Ln and tn may be approximated by a linear function, and the slope of the linear function may be used as the pulse wave velocity. Good. Since the pulse wave repeatedly appears, it is possible to improve the accuracy by adding the pulse wave velocity measured a plurality of times within a predetermined time.

The calculated pulse wave velocity is displayed on the display unit 6 (S208). The display form of the pulse wave velocity on the display unit 6 can take various forms. For example, the pulse wave velocity may be displayed as a numerical value, or may be displayed as a relative evaluation with respect to a standard pulse wave velocity. It is also possible to display the pulse wave velocity in a superimposed manner or in parallel on the same screen as the ultrasonic image (B mode image).

The effect of this embodiment over the prior art will be described with reference to FIGS. 3 (a), 3 (b) and FIG. FIG. 3A shows measurement points when the ultrasonic beam is irradiated obliquely to the blood vessel according to the present embodiment. FIG. 6A is a diagram in which the pulse wave travel time obtained in the present embodiment is plotted against the travel distance, and the slope of the graph of FIG. 6A is the pulse wave velocity. FIG. 3B shows a pulse wave measurement technique using a conventional ultrasonic diagnostic apparatus. FIG. 6B is a diagram in which the pulse wave travel time obtained by the prior art is plotted against the travel distance.

In the prior art, as shown in FIG. 3B, since the ultrasonic beam is irradiated perpendicularly to the blood vessel 300, there are four measurement points A1, A2, B1, and B2, but the pulse wave is Since it is observed as the displacement of the blood vessel in the direction orthogonal to the traveling direction of the blood vessel, the arrival times of the pulse waves are the same at the measurement points A1 and A2 and the measurement points B1 and B2. Therefore, as can be seen from FIG. 6B, only one set of information can be obtained in one measurement, the distance between A1 and B1 and the travel time of the pulse wave moving between A1 and B1. This is low independence between the information using the distance between A2 and B1 and the pulse wave travel time between A2 and B1, and the information using the distance between A1 and B1 and the pulse wave travel time between A1 and B1. Because.

On the other hand, in the present embodiment, information of a score three times that of the prior art can be obtained by the same single measurement, and the accuracy of the calculated pulse wave velocity can be improved. Thus, in the present embodiment, it is possible to obtain more data in the same measurement time as the measurement for obtaining a set of data necessary for conventional pulse wave transmission speed calculation. As a result, the number of data points can be increased without increasing the measurement time, and the accuracy of the calculated pulse wave transmission speed can be increased.

In the above-mentioned example, the distance L1 between A2 and A1, the distance L2 between A2 and B2, and the distance L3 between A2 and B1 are obtained as the movement distance of the pulse wave, and the pulse wave velocity is calculated from these three distances. Although the case of calculation has been described, for example, three distances between A2 and A1, between A1 and B2, and between B2 and B1 may be used. In this case also, the number of calculated pulse wave velocities can be increased. , Can improve accuracy.

In this embodiment, since the pulse wave is observed from the displacement of the blood vessel, it is not affected by the direction of the blood flow flowing through the blood vessel. That is, the present embodiment can be similarly applied to the case where the blood flow is directed in either direction.

<Second embodiment>
The ultrasonic diagnostic apparatus of the present embodiment also irradiates a plurality of ultrasonic beams obliquely relative to the traveling direction of the blood vessel, as in the first embodiment. It is characterized in that the measurement is performed in a plurality of measurement modes with different beam intervals.

That is, the ultrasonic diagnostic apparatus according to the present embodiment includes a control unit that controls driving of the ultrasonic probe, and the control unit has two measurement modes in which combinations of ultrasonic beams are different, the first measurement mode and the second measurement mode. The measurement mode is provided. In the first measurement mode, the first ultrasonic beam and the second ultrasonic beam separated from the first ultrasonic beam in the transducer arrangement direction are simultaneously irradiated. In the second measurement mode, the first ultrasonic beam is irradiated with the first ultrasonic beam. The ultrasonic beam and the third ultrasonic beam separated from the first ultrasonic beam in the direction of transducer arrangement are simultaneously irradiated. The interval between the first ultrasonic beam and the third ultrasonic beam is different from the interval between the first ultrasonic beam and the second ultrasonic beam. The pulse wave measurement unit measures a pulse wave by using a plurality of sets of first echo signals and second echo signals respectively measured in the first measurement mode and the second measurement mode. Of the first measurement mode and the second measurement mode, a measurement mode having a wider width (interval) between beams is referred to as a wide mode, and a measurement mode having a narrow width between beams is referred to as a narrow mode.

In the ultrasonic diagnostic apparatus of the present embodiment, the control unit sets the distance between the first ultrasonic beam and the second ultrasonic beam to the ultrasonic probe of the blood vessel through which the same ultrasonic beam passes. It is set longer than the distance in the blood vessel traveling direction between the near side and the far side.

Also, the ultrasonic diagnostic apparatus of the present embodiment includes an adjusting unit that adjusts the irradiation direction of the ultrasonic beam by the ultrasonic probe. The adjusting means is, for example, a beam former that adjusts the direction of the ultrasonic beam emitted by each transducer of the ultrasonic probe.

Furthermore, in the ultrasonic diagnostic apparatus of the present embodiment, the pulse wave measurement unit can include a determination unit (comparison unit) that determines the accuracy of the measured pulse wave information.

Hereinafter, this embodiment will be described in detail with reference to FIGS. In FIG. 7, the same elements as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

The ultrasonic diagnostic apparatus of the present embodiment is substantially the same as the ultrasonic diagnostic apparatus of the first embodiment shown in FIG. 1, but includes a control unit 5 for operating the apparatus in a plurality of measurement modes. Is different. The plurality of measurement modes are, for example, a wide mode and a narrow mode, and the control unit 5 sends commands to the transmission unit 2, the reception unit 3, and the calculation unit 4 so as to perform these two measurement modes in succession. The input unit 7 is provided with a measurement mode selection unit 75 that selects measurement in a plurality of measurement modes.

The transmission unit 2 varies the beam intervals of the plurality of ultrasonic beams emitted from the probe 1 in the wide mode and the narrow mode according to the command from the control unit 5. The beam intervals in the wide mode and the narrow mode may be set in advance, or may be set / changed by the operator via the input unit 7.

The receiving unit 3 sends the reception signal of each measurement mode to the calculation unit 4, and the calculation unit 4 calculates the pulse wave arrival time and the pulse wave velocity using the reception signals of both measurement modes. In addition, the calculation unit 4 includes a first comparison unit 43 that compares measurement values in one measurement mode and a second comparison unit 44 that compares measurement values between measurement modes in order to continuously operate both measurement modes. ing. The comparison results of the first comparison unit 43 and the second comparison unit 44 are transferred to the control unit 5 and the display unit 6, whereby the measurement mode is switched or redone.

Based on the above configuration, the operation of the ultrasonic diagnostic apparatus of this embodiment will be described. FIG. 8 shows an operation procedure. In FIG. 8, the same steps as those in FIG. 2 are denoted by the corresponding reference numerals, and redundant description is omitted.

First, a region of interest is set (S201), and an irradiation angle of the ultrasonic beam with respect to the target blood vessel is set (S202). The beam irradiation angle θ with respect to the blood vessel is the blood vessel between the blood vessel position on the body surface side (measurement point A1) and the blood vessel position on the side far from the body surface (measurement point A2), as in the first embodiment. It is preferable that the position difference in the traveling direction is set to be a predetermined value (for example, 0.5 mm or more). If the above conditions are satisfied, the beam irradiation angle θ may be the same or different between the wide mode and the narrow mode.

Next, for each of the wide mode and the narrow mode, beam intervals W1 and W2 of a plurality of, for example, two ultrasonic beams are set (S801). FIGS. 9A and 9B show the relationship between the two ultrasonic beams in the two measurement modes. Here, in order to simplify the description, the case where the blood vessel 300 is traveling substantially parallel to the body surface 305 is shown. The angle between the sound beam and the blood vessel 300 is set to be the same as the angle when the blood vessel 300 is parallel to the body surface 305. In the wide mode shown in FIG. 9A, a point where one of the two

ultrasonic beams

310 and 320 is incident on the side closer to the body surface of the blood vessel is A1, and a point where the one is incident on the far side is A2. Let B1 be the point where the other 320 of the sound beam is incident on the side closer to the body surface of the blood vessel, and B2 be the point where it is incident on the far side. It is assumed that the probe 1 is not moved while the two measurement modes are performed, and one of the ultrasonic beams 310 in the narrow mode shown in FIG. 9B is the same as the ultrasonic beam 310 in the wide mode and is a blood vessel. Are incident on positions A1 and A2. In the narrow mode, the point where the other 330 of the ultrasonic beam is incident on the side close to the body surface of the blood vessel is C1, and the point where the other 330 is incident on the far side is C2.

The beam interval W2 in the narrow mode (equal to the distance between A1 and C1 in the case of a parallel beam) is preferably larger than the distance L1 between the A1 and A2 blood vessels, and the beam interval W1 in the wide mode is the beam in the narrow mode. It is larger than the interval W2. That is, the beam interval is set so that L1 <W2 <W1. As an example, W2 is set to about twice L1, and W1 is set to about twice W2.

After setting the ultrasonic beam angle and the beam interval in this way, first, measurement is started a predetermined number of times (n times: n is an integer of 1 or more) in the wide mode (S802). That is, the measurement of transmitting and receiving the

ultrasonic beams

310 and 320 is repeated n times for a predetermined time. At this time, the interval and angle of the ultrasonic beam are controlled by the delay control unit 23 of the transmission unit 2 as in the first embodiment.

The calculation unit 4 inputs the reception signal continuously received by the reception unit 3 and calculates the pulse wave velocity (S803). This calculation is the same as in the first embodiment, and the pulse wave velocity is calculated using the three distances (A2-A1, A2-B2, A2-B1) calculated in advance.

When the measurement reaches n times, the first comparison unit 43 obtains a deviation of the pulse wave velocity obtained by the n times of measurement and compares it with a preset threshold value (S804). The threshold value is, for example, about 10% of the n measurement values. When the obtained deviation is larger than a preset threshold value, the control unit 5 determines that the measurement is defective, and changes the beam angle and / or the beam interval to change the position of all or part of the measurement points. Change and measure again n times in wide mode. When the obtained deviation is smaller than a preset threshold value, it is determined that the measurement is good, and then the measurement shifts to the narrow mode (S805).

In the narrow mode, the

ultrasonic beams

310 and 330 are transmitted / received for a preset number of times (m times: m is an integer of 1 or more). The movement speed of the pulse wave is calculated using the reception signal obtained by each reception of m times (S806). This calculation is the same as in the first embodiment, and the pulse wave velocity is calculated using the three distances (A2-A1, A2-C2, A2-C1) calculated in advance. When the measurement reaches m times, the first comparison unit 43 obtains a deviation of the pulse wave velocity obtained by the m times of measurement and compares it with a preset threshold value (S807). When the obtained deviation is larger than a preset threshold value, it is determined that the measurement is defective, and the position of the measurement points C1 and C2, that is, the position of the ultrasonic beam 330 with respect to the ultrasonic beam 310 is changed and the narrow mode is again performed. To measure m times. If the obtained deviation is smaller than a preset threshold value, it is determined that the measurement is good, and the flow proceeds to pulse wave velocity calculation (S808). In step S808, the pulse wave velocity is calculated from the obtained wide mode and narrow mode data.

In step S808, the n pulse wave velocities calculated in the wide mode and the m pulse wave velocities calculated in the narrow mode can be calculated as a pulse wave velocity by simple averaging or weighted averaging. In the case of weighting, one (for example, wide mode) may be weighted more heavily than the other (narrow mode), or may be set according to the number of repetitions (n, m).

Also, instead of averaging the pulse wave velocities obtained in the two modes at once, the pulse wave velocities calculated in the wide mode or the two modes are averaged for each mode, and weighted and added according to each variance. Also good. Further, when obtaining the average value for each mode, the second comparison unit 44 can compare the results of the wide mode and the narrow mode, and in this case, a message prompting the display unit 6 to restart the measurement according to the comparison result. You may make it display.

The display of the finally calculated pulse wave moving speed on the display unit 6 in an arbitrary display form is the same as in the first embodiment (S208).

According to the present embodiment, the number of measurements can be increased and obtained without changing the position of the probe 1 with respect to the subject (region of interest) by performing measurement in two modes with different beam intervals. The accuracy of the pulse wave moving speed can be improved. Measurement data corresponding to the present embodiment is shown in FIG. It can be seen that the number of data points is further increased compared to FIG.

In the second embodiment, the case where the measurement in the wide mode and the narrow mode is continuously performed on the assumption that the probe 1 is not moved has been described. However, for example, the probe 1 has a function of making the interval between the ultrasonic beams variable. If not, two measurements can be performed using two probes with different beam intervals. Alternatively, two measurements can be performed using two probes, and the position of one probe can be fixed during the two measurements, and the position of the other probe (interval with respect to the fixed probe) can be varied. In any case, by using measurement data in which the irradiation angle of the ultrasonic beam is inclined with respect to the blood vessel, information on a plurality of pulse wave movement distances and arrival time difference information can be obtained for each measurement. The accuracy of pulse wave velocity measurement can be increased.

Moreover, although the example provided with the determination part (comparison part) which determines the accuracy of pulse wave information in each of several measurement modes (wide mode and narrow mode) was demonstrated, accuracy is determined about one measurement mode There may be cases. For example, in the case of a single measurement mode as in the first embodiment, a comparison unit may be provided to determine the accuracy of the pulse wave information calculated by the pulse wave velocity calculation unit 45, and according to the result. The beam interval W and the beam angle θ may be adjusted.

<Third embodiment>
In the first and second embodiments, the ultrasonic probe controls the angle of the ultrasonic beam by the transmitter 2 (delay controller 23) of the probe 1 as an adjustment unit that adjusts the irradiation direction of the ultrasonic beam. In the present embodiment, the coupling material 10 that changes the angle of the probe 1 is employed between the probe 1 and the subject. Since other configurations are the same as those of the first or second embodiment, description thereof is omitted.

FIG. 10 shows the relationship between the probe 1 and the coupling material 10. As shown in the figure, the coupling material 10 has a triangular shape when viewed from the side, and the bottom surface 10b that contacts the subject's skin and the top surface 10a that is fixed to the probe 1 have a predetermined angle β. ing. When such a coupling material 10 is fixed to the surface of the probe 1, the ultrasonic beam emitted perpendicularly from the probe surface is [90 ° -β] with respect to the blood vessel 300 traveling substantially parallel to the body surface. Incident at an angle. Therefore, in the case where measurement is performed by obliquely irradiating an ultrasonic beam with respect to a blood vessel at an angle θ, desired oblique irradiation can be achieved by using a coupling material having an inclination of [90 ° −θ].

As already described, the range of the angle θ depends on the target blood vessel diameter D, but since there is a certain tolerance, the effect of the present invention can be obtained even if the coupling material 10 having a fixed inclination is used. Obtainable.

<Fourth embodiment>
In addition to pulse wave velocity measurement, the ultrasonic diagnostic apparatus of the present embodiment obtains information related to blood vessel properties other than pulse wave velocity from ultrasonic images obtained by ultrasonic imaging and measurement results of measurement devices other than ultrasonic measurement. It is characterized by having a function (normality calculation unit) for calculating the normality of the tissue using the pulse wave velocity and the characteristics relating to the blood vessel properties.

For this reason, the calculation unit includes a vascular property calculation unit that calculates a blood vessel property using an echo signal received by the ultrasound probe, and the normality calculation unit relates to the vascular property calculated by the vascular property calculation unit. The normality of the tissue is calculated using the information and the pulse wave information measured by the pulse wave measuring unit. The normality calculation unit inputs blood pressure information and / or pulse wave information measured by the external measurement device, and uses information from the external measurement device and pulse wave information measured by the pulse wave measurement unit to Normality can be calculated.
In the present embodiment, the apparatus configuration relating to pulse wave velocity measurement can be the same as any one of the first to third embodiments. Hereinafter, on the basis of the apparatus configuration of the second embodiment, description of overlapping elements will be omitted, and different points will be mainly described.

FIG. 11 shows a functional block diagram of the ultrasonic diagnostic apparatus of this embodiment. In FIG. 11, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. As shown in FIG. 11, the ultrasonic diagnostic apparatus of the present embodiment is characterized in that the calculation unit 4 includes a vascular property calculation unit 47, and the vascular property calculation unit 47 includes a measurement result of the external measurement device 9. Can be input directly from an external device or via the input unit 7. The display unit 6 displays the blood vessel normality calculated by the blood vessel property calculating unit 47.

The calculation performed by the blood vessel property calculating unit 47 includes a function related to the shape such as the diameter of the blood vessel or the thickness of each film such as the inner membrane, the inner membrane, and the outer membrane of the blood vessel, and a function obtained from the change over time of the blood vessel wall. An example of an index related to the function of a blood vessel is, for example, a stiffness parameter (β parameter) obtained from a temporal variation of a blood vessel wall. The β parameter is given by:

[Equation 3]
β = {ln (Ps / Pd)} / (ΔD / Dd) (3)
In the formula, Ps and Pd are systolic blood pressure (maximum blood pressure) and diastolic blood pressure (minimum blood pressure), respectively, and ΔD is the difference between the maximum blood vessel diameter Ds (at the maximum blood pressure) and the minimum blood vessel diameter Dd (at the time of minimum blood pressure). . Ps and Pd may be input from the input unit 7 that have been measured in advance, or blood pressure measurement may be performed in parallel with the ultrasonic measurement, and the measurement result from the sphygmomanometer (measurement device 9) may be captured. Good. Ds and Dd can be measured from an ultrasonic image.

The blood vessel property calculating unit 47 may display the numerical value related to the calculated shape such as the blood vessel diameter and the function-related indicator on the display unit 6 together with the pulse wave velocity, or may display an indicator that combines the plurality of indicators and the pulse wave velocity. It is also possible to determine the normality of blood vessels based on the index and display the result.

In parallel with ultrasonic imaging, measurement by the CAVI method is performed, and both the local pulse wave velocity obtained in the present embodiment and the average pulse wave velocity of the whole body measured by the CAVI method are used to calculate blood vessels. The degree of normality may be calculated. For example, the vascular property calculation unit 47 compares the average pulse wave velocity of the whole body with the local pulse wave velocity, determines that the arteriosclerosis is progressing in a region where the pulse wave velocity is high, and displays the result. To do.

According to this embodiment, in addition to the pulse wave velocity, it is possible to provide information related to the properties of the blood vessel, which can contribute to the diagnosis of blood vessel normality by the ultrasonic diagnostic apparatus.

<Fifth embodiment>
The ultrasonic diagnostic apparatus of this embodiment is characterized by having a function of storing locally measured pulse wave velocities, and using a plurality of pulse wave velocities measured at different sites and at different times, the pulse wave It is characterized by providing speed change information and pulse wave velocity distribution. In the present embodiment, the apparatus configuration relating to pulse wave velocity measurement can be the same as any one of the first to third embodiments. Hereinafter, on the basis of the apparatus configuration of the second embodiment, description of overlapping elements will be omitted, and different points will be mainly described.

FIG. 12 shows a functional block diagram of the ultrasonic diagnostic apparatus of this embodiment. In FIG. 12, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. As shown in FIG. 12, the ultrasonic diagnostic apparatus of the present embodiment stores a result of calculating the pulse wave velocity of a predetermined part obtained by one or several measurements with respect to the apparatus of FIG. And a velocity distribution creating unit 48 for creating a pulse wave velocity distribution using a plurality of pulse wave velocity information stored in the storage unit 8. Instead of the velocity distribution creating unit 48 or in addition to the pulse wave velocity distribution creating unit 48, a pulse wave velocity temporal information creating unit 49 may be provided.

The storage unit 8 includes information (subject ID, part, measurement time, etc.) attached to the data of one or more sets of measurement data performed on the same subject (region of interest). ). The pulse wave velocity distribution creating unit 48 creates a pulse wave distribution based on the pulse wave velocities of a plurality of blood vessels (regions of interest) measured for the same subject. The pulse wave distribution is created as a distribution map, for example. The pulse wave velocity temporal information creation unit 49 creates a graph or the like showing long-term or short-term changes in pulse wave velocity in the same blood vessel of the same subject. The distribution map created by the pulse wave velocity distribution creating unit 48 and the graph created by the pulse wave velocity temporal information creating unit 49 are displayed on the display unit 6 together with or independently of the ultrasonic image.

Next, based on the above configuration, the operation procedure of the ultrasonic diagnostic apparatus of the present embodiment will be described. FIG. 13 shows the operation procedure. In the flow of FIG. 13, the same steps as those of FIG. 2 and FIG.

First, a region of interest (ROI) is set, and an angle of an ultrasonic beam with respect to a blood vessel included in the region of interest and an interval between a plurality of ultrasonic beams are set (S201 to S203). Next, measurement is started (S204). When the measurement is performed in two types of modes, the wide mode and the narrow mode, the measurement is performed in steps S801 to S807 in FIG. 8 to calculate the pulse wave velocity (S206, S808). The calculated pulse wave velocity is recorded in the storage unit 8 in association with the set ROI (S1301). At this time, when blood pressure, a CAVI value, or the like is input from an external measurement device (FIG. 11), the information is recorded together.

Thereafter, the ROI is changed, and the above steps are repeated until the measurement of all target ROIs is completed (S1302). After all ROI measurements are completed, a pulse wave velocity distribution is obtained (S1303). The pulse wave velocity distribution may be displayed as a table of ROI and pulse wave velocity as it is, but a distribution map is created and displayed superimposed on the ultrasonic image or the whole body model image. (S1304). The distribution chart can be created by, for example, relativizing the pulse wave velocity for each ROI based on the pulse wave velocity (average value of the whole body) obtained by the CAVI method and assigning a predetermined color or gradation to the relative value. By displaying such a distribution map, it is possible to confirm at a glance a portion where the pulse wave velocity is particularly fast or slow, and can provide information for diagnosis of arteriosclerosis or the like.

The example shown in FIG. 13 is a case where the pulse wave velocity data for each ROI is accumulated and the pulse wave velocity distribution is obtained. However, the pulse wave velocity data measured over time for the same subject is accumulated, It is also possible to obtain data of changes in the pulse wave velocity of the subject over time (long-term or short-term changes). Information indicating changes over time can be displayed on the display unit 6 in the same manner as the distribution chart. It is also possible to create or display other diagnostic information obtained by further processing this information.

According to the present embodiment, the pulse wave velocity measured by the ultrasonic diagnostic apparatus is further increased by including the storage unit that records the pulse wave velocity for each measurement and the unit that tabulates the data accumulated in the storage unit. It can be provided in a form that is easy to use for diagnosis.

As mentioned above, although each embodiment of the ultrasound diagnosing device of the present invention was described, these embodiments can be carried out in combination as appropriate, and the functions of the conventional ultrasound diagnosing device are added or changed appropriately. It is also possible.

According to the present invention, highly accurate pulse wave information can be obtained in a relatively short measurement time, and information effective for diagnosis of blood vessel normality can be provided.

DESCRIPTION OF SYMBOLS 1 ... Probe, 2 ... Transmission part, 3 ... Reception part, 4 ... Calculation part, 5 ... Control part, 6 ... Display part, 7 ... Input part, 8 * ..Storage unit, 9 ... external measuring device, 10 ... coupling material, 21 ... ultrasound signal transmission circuit, 23 ... delay control unit (beamformer), 31 ... amplification unit , 32 ... Delay processing section, 33 ... Apodization processing section, 40 ... Pulse wave measurement section, 41 ... Pulse wave arrival time calculation section, 42 ... Distance calculation section, 43 ... 1 comparison unit, 44 ... second comparison unit, 45 ... pulse wave velocity calculation unit, 47 ... blood vessel property calculation unit, 48 ... pulse wave velocity distribution creation unit, 49 ... pulse wave velocity Time information creation unit.

Claims

An ultrasonic probe that transmits an ultrasonic beam into a living body and receives an echo signal from the living body;
A calculation unit that calculates biological information using an echo signal received by the ultrasonic probe, wherein the calculation unit irradiates the ultrasonic beam obliquely relative to a blood vessel in the living body. Using a first echo signal reflected from the side of the blood vessel close to the ultrasound probe and a second echo signal reflected from the side of the blood vessel far from the ultrasound probe, An ultrasonic diagnostic apparatus comprising a pulse wave measurement unit that measures a pulse wave moving in a blood vessel.
The ultrasonic diagnostic apparatus according to claim 1,
The pulse wave measurement unit calculates a time change of the first echo signal and the second echo signal, and a distance in the blood vessel traveling direction between the side of the blood vessel close to the ultrasonic probe and the side far from the ultrasonic probe. An ultrasonic diagnostic apparatus comprising a pulse wave velocity calculation unit that calculates a pulse wave velocity using the pulse wave velocity.
The ultrasonic diagnostic apparatus according to claim 1,
The ultrasonic probe is an ultrasonic probe that includes a plurality of arranged transducers and emits a plurality of ultrasonic beams,
The ultrasonic diagnostic apparatus, wherein the pulse wave measurement unit measures a pulse wave using a first echo signal and a second echo signal generated corresponding to each of a plurality of ultrasonic beams.
The ultrasonic diagnostic apparatus according to claim 3,
A control unit for controlling the driving of the ultrasonic probe;
The control unit simultaneously irradiates a first ultrasonic beam and a second ultrasonic beam separated from the first ultrasonic beam in a transducer arrangement direction, and the first ultrasonic beam. A second measurement mode for simultaneously driving a sound beam and a third ultrasonic beam separated from the first ultrasonic beam in the direction of transducer arrangement, and the first ultrasonic beam and the second ultrasonic beam. The interval between the ultrasonic beams is different from the interval between the first ultrasonic beam and the third ultrasonic beam.
The pulse wave measurement unit measures a pulse wave using a plurality of sets of the first echo signal and the second echo signal respectively measured in the first measurement mode and the second measurement mode. A characteristic ultrasonic diagnostic apparatus.
The ultrasonic diagnostic apparatus according to claim 4,
The control unit is configured such that the interval between the first ultrasonic beam and the second ultrasonic beam is the interval between two positions of the blood vessel through which both beams pass, and the blood vessel through which one ultrasonic beam passes is provided. The ultrasonic diagnostic apparatus is set to be longer than the interval in the blood vessel traveling direction between the side closer to the ultrasonic probe and the side farther from the ultrasonic probe.
The ultrasonic diagnostic apparatus according to claim 1,
The ultrasonic diagnostic apparatus, wherein the ultrasonic probe includes an adjusting unit that adjusts an irradiation direction of the ultrasonic beam.
The ultrasonic diagnostic apparatus according to claim 6,
The ultrasonic diagnostic apparatus according to claim 1, wherein the adjustment means is a coupling material attached to and detached from a contact surface of the ultrasonic probe with a living body.
The ultrasonic diagnostic apparatus according to claim 6,
The ultrasonic diagnostic apparatus, wherein the adjusting means is a beam former that adjusts a direction of an ultrasonic beam emitted by each transducer of the ultrasonic probe.
The ultrasonic diagnostic apparatus according to claim 1,
The ultrasonic diagnostic apparatus, wherein the pulse wave measurement unit includes a determination unit that determines the accuracy of measured pulse wave information.
An ultrasonic probe that transmits an ultrasonic beam into a living body and receives an echo signal from the living body;
Using an echo signal received by the ultrasonic probe, a calculation unit that calculates biological information;
A display unit that displays biological information calculated by the calculation unit, and the calculation unit irradiates the ultrasonic beam relatively obliquely with respect to the blood vessel in the living body. Using the first echo signal reflected from the side closer to the probe and the second echo signal reflected from the side of the blood vessel far from the ultrasonic probe, the pulse wave moving in the blood vessel is measured. An ultrasonic diagnostic apparatus comprising a pulse wave measurement unit that performs the above operation.
The ultrasonic diagnostic apparatus according to claim 10,
The pulse wave measurement unit includes a normality calculation unit that calculates the normality of the tissue using the measured pulse wave information, and displays the normality calculated by the normality calculation unit on the display unit. Ultrasonic diagnostic equipment.
The ultrasonic diagnostic apparatus according to claim 11,
The calculation unit includes a blood vessel property calculation unit that calculates a blood vessel property using an echo signal received by the ultrasound probe, and the normality calculation unit is a blood vessel property calculated by the blood vessel property calculation unit. An ultrasonic diagnostic apparatus characterized in that a normality level of a tissue is calculated using information related to information and pulse wave information measured by the pulse wave measurement unit.
The ultrasonic diagnostic apparatus according to claim 11,
The normality calculation unit inputs blood pressure information and / or pulse wave information measured by an external measurement device, and uses information from the external measurement device and pulse wave information measured by the pulse wave measurement unit, An ultrasonic diagnostic apparatus characterized by calculating normality of a tissue.
The ultrasonic diagnostic apparatus according to claim 10,
A storage device for storing pulse wave information measured by the pulse wave measurement unit for a plurality of sites;
An ultrasonic wave further comprising: a pulse wave velocity distribution creating unit that creates a pulse wave velocity distribution using pulse wave information of a plurality of parts accumulated in the storage device and displays the pulse wave velocity distribution on the display unit Diagnostic device.
A blood vessel in a living body is irradiated with a plurality of ultrasonic beams obliquely with respect to the blood vessel, and a pulse is generated using two echo signals generated by a single ultrasonic beam at a pair of blood vessel walls having different positions in the depth direction. A method of measuring waves,
Adjusting an interval between the plurality of ultrasonic beams;
Adjusting the angle of the ultrasound beam relative to the blood vessel;
Using the time change of two echo signals obtained for each of the plurality of ultrasonic beams, the propagation distance and propagation time of the pulse wave are calculated, and the pulse wave information of the number of measurement points twice the number of ultrasonic beams is obtained. A pulse wave measuring method comprising: a step of acquiring; and a step of calculating a pulse wave propagation velocity using the pulse wave information.
The pulse wave measuring method according to claim 15,
The step of acquiring the pulse wave information includes the step of plotting the pulse wave information at a plurality of measurement points on a graph showing the relationship between the propagation distance and the propagation time,
The step of calculating the pulse wave propagation velocity includes calculating the pulse wave propagation velocity from the slope of the graph.