JP2001070304A - Ultrasonic diagnostic apparatus and ultrasonic transmission method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a method of quantifying the degree of contrast of a contrast agent by changing an intermittent transmission interval based on a flash echo imaging method, intermittent transmission is reliably performed even at a short interval of one heartbeat or less. Do. A transmitting means (2) for transmitting an ultrasonic pulse signal is provided.
1, 12), a heartbeat detecting means (14, 32) for detecting a heartbeat signal representing a periodic beat of the subject's heart, and a transmitting means for transmitting a first ultrasonic pulse signal for eliminating the contrast agent And a transmission controller 31 for transmitting the second ultrasonic pulse signal to the transmitting means in synchronization with a desired time phase of the periodic pulsation after the transmission. The desired time phase is determined by a desired delay time of the heartbeat signal (ECG signal) from the reference wave (R wave). The transmission control means includes a first transmission and a second transmission.
The interval between the second transmission is changed under a certain rule. For example, this time interval includes a time interval of one heart beat or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus which administers an ultrasonic contrast agent to a subject and performs transmission based on a flash echo imaging (FEI) method which is a form of a contrast echo method. Transmission method.
In detail, the function of imaging the blood flow dynamic information of the blood vessel part using the echo signal reflected by the contrast agent, the function of imaging the information of the hemodynamics of the organ parenchyma level by detecting perfusion, and their quantification The present invention relates to an ultrasonic diagnostic apparatus having various image processing functions for the purpose of evaluation and an ultrasonic transmission method thereof, and in particular, to higher precision and higher definition of these various functions.

[0002]

2. Description of the Related Art Medical applications of ultrasonic signals cover various fields, and ultrasonic diagnostic apparatuses are one of them. An ultrasonic diagnostic apparatus is an apparatus that obtains an image signal by transmitting and receiving an ultrasonic signal, and is used in various modes utilizing the non-invasiveness of the ultrasonic signal.

[0003] The mainstream of this ultrasonic diagnostic apparatus is of a type in which a tomographic image of a soft tissue of a living body is obtained using an ultrasonic pulse reflection method. This imaging method can obtain a tomographic image of tissue non-invasively, and it can be displayed in real time compared to other medical modalities such as X-ray diagnostic equipment, X-ray CT scanner, MRI equipment, and nuclear medicine diagnostic equipment, It has many advantages, such as a small and relatively inexpensive device, no exposure to X-rays and the like, and blood flow imaging based on the ultrasonic Doppler method. Therefore, it is widely used in the diagnosis of the heart, abdomen, mammary gland, urology, obstetrics and gynecology, and the like. In particular, the simple operation of simply touching the ultrasonic probe to the body surface makes it possible to observe the heartbeat and the movement of the fetus in real time. It also has various advantages that it can be easily inspected by being moved to a different location.

[0004] In the field of the ultrasonic diagnostic apparatus, a contrast echo method for evaluating the blood flow dynamics by injecting an ultrasonic contrast agent from a vein when examining a heart or abdominal organs has recently attracted attention. I'm taking a bath. The method of injecting a contrast agent from a vein is less invasive than the method of injecting it from an artery, and diagnosis by this evaluation method is becoming widespread. The main component of the ultrasonic contrast agent is microbubbles (microbubbles), which serve as a reflection source for reflecting ultrasonic signals. The higher the injection amount or the concentration of the contrast agent, the greater the contrast effect. However, due to the nature of the bubbles of the contrast agent, there are cases where the time of the contrast effect is shortened by ultrasonic irradiation. In view of such a situation, a persistent and pressure-resistant contrast agent has been developed in recent years, but there is a concern that a long stay of the contrast agent in the body may lead to an increase in invasiveness.

When the contrast echo method is performed, a contrast agent is supplied to a region of interest of a subject part by blood flow one after another. For this reason, even if the bubbles are once erased by irradiating the ultrasonic waves, it is assumed that the contrast effect is maintained if new bubbles have flowed into the region of interest at the time of the next ultrasonic irradiation. However, in practice, the transmission and reception of ultrasonic waves are usually performed several thousand times per second, and given the existence of blood flow dynamics in organ parenchyma and relatively small blood vessels, which have low blood flow velocity. On the diagnostic image of, the bubbles disappear one after another before confirming the brightness enhancement by the contrast agent, and the contrast effect is instantaneously reduced.

[0006] Among the diagnostic methods using a contrast agent, the most basic diagnostic method is to determine the presence or absence of blood flow at the diagnostic site by checking for the presence or absence of brightness enhancement by the contrast agent. More advanced diagnostic methods include a method of knowing the temporal change in the spatial distribution of the contrast agent from the extent of the luminance change and the degree of luminance enhancement at the diagnostic site, and the time from when the contrast agent is injected to when it reaches the region of interest, And time change of echo intensity due to a contrast agent in the ROI (Time Intensity).
Curve: TIC) or a method of obtaining the maximum luminance.

[0007] The contrast echo method can also be effectively implemented by a harmonic imaging method in which an image is formed using a non-fundamental wave component of an ultrasonic echo signal. The harmonic imaging method is an imaging method that separates and detects only a non-fundamental wave component due to a nonlinear behavior generated when a microbubble, which is a main component of a contrast agent, is excited by ultrasonic waves. Since a living organ is relatively unlikely to cause nonlinear behavior, a contrast agent image having a good contrast ratio can be obtained by this harmonic imaging method.

Further, utilizing the phenomenon in which microbubbles disappear by irradiation of ultrasonic waves as described above, flash echo imaging (Flash Echo Image) is performed.
An imaging method called a “ging method” (or also called a transient response imaging method) has been proposed, and it has been reported that luminance enhancement can be improved by this method (for example, see the literature “67-95 Study of Flash Echo Imaging Method ( 1), Naohisa Kamiyama et al., 67th Annual Meeting of the Japanese Society of Ultrasonics, June 1996, or JP-A-8-280674). In principle, this imaging method replaces the conventional continuous scan of several tens of frames per second with intermittent transmission of one frame every few seconds. This is a technique for eliminating high-echo signals by eliminating microbubbles that have occurred at once.

Further, conventionally, there has been proposed a method of quantifying the degree of contrast of the contrast agent by changing the interval of the intermittent transmission.
Since the contrast medium disappears by irradiating the ultrasonic waves, the echo luminance observed at the time of the intermittent transmission depends on the amount of the microbubbles flowing into the scan plane within the transmission stop time of the ultrasonic waves. As an example, the interval between intermittent transmissions is one heartbeat,
When two heartbeats are changed,..., The change in the contrast luminance of the region of interest (ROI) set in the myocardial part is conceptually represented as shown in FIG. 10 (for example, the document “Sanjiv Kaul,
“Myocardial contrast echo
cardigraphy ", Current Pro
blems in Cardiology, Vol.
22, Nob. 11, 1997 pp. 611-616
""reference).

As shown in FIG. 1, as the heart rate (intermittent transmission interval time) increases, the contrast brightness curve becomes saturated. When the curve becomes flat, the brightness becomes equal to the total blood volume of the region of interest. The slope of the curve before flattening is proportional to the flow rate and correlates with the inflow velocity of blood (contrast agent). Therefore, in the case of FIG. 10, comparing the blood flow dynamics in both regions of interest where the curves 1 and 2 are obtained, the blood flow dynamics corresponding to the curve 2 is compared with the blood flow dynamics corresponding to the curve 1, This indicates that the speed is low and the total blood flow is small.

Further, the present inventor has already disclosed a device and a scanning method having a function of automatically measuring the curve shown in FIG. 10 by sequentially changing the intervals of the intermittent transmission described above by Japanese Patent Application Laid-Open No. H11-155958 ( Japanese Patent Application No. 9-324772
No. application).

On the other hand, a conventional ECG-gated method (ECG-g
Imaging that obtains an image based on an image is frequently performed. As a reference trigger when using the electrocardiogram synchronization method, an R wave detected as a waveform having the maximum intensity in the electrocardiogram cycle is usually used (a waveform indicated by an arrow A in FIG. 11). When an image synchronized with a cardiac phase other than the R-wave is required, the operator appropriately sets a delay time from the reference trigger (R-wave), and performs scanning in synchronization with the elapse of the delay time. For example, if the operator wants to observe an image of the end systole of the heart, the operator sets the delay time to, for example, 0.
The image is set to 2 seconds (the time between arrows AB in FIG. 11), and an image synchronized with the time phase at the end of the T wave (see arrow B in FIG. 11) is obtained.

For this reason, when the heartbeat time phase is fixed using the electrocardiogram synchronization method and the interval of intermittent transmission is changed in accordance with this phase, the interval of intermittent transmission is one heartbeat because the reference trigger is an R wave. It can be changed in units such as two heartbeats.

[0014]

However, in the method of quantifying the contrast of a contrast agent by changing the transmission interval of the above-mentioned intermittent transmission method, the following unsolved problems are left unsolved. Was. This problem will be described with reference to FIG.

In FIG. 1, the ultimate contrast luminance when the intermittent transmission interval of curves 1 and 2 becomes zero is a 1, a 2 (y
Intercept), and the luminance is not zero. The reason why the luminance value becomes larger than zero is that there is a stationary echo component which is imaged before the dyeing. Even if the echo component derived from the tissue is removed (not imaged) using the harmonic imaging method, a harmonic component, that is, a so-called tissue harmonic component is generated due to the non-linear effect of the ultrasonic signal during propagation in the living body. This tissue harmonic component is reflected in the echo signal, and raises the luminance value.

In the case of the conventional method, the contrast luminance value obtained by actual measurement is a value at each of the intermittent transmission intervals (one heartbeat, two heartbeats, three heartbeats,...) Indicated by black circles in FIG. . For this reason, it is very difficult to estimate the entire curve in the figure from the measured values. In particular, the behavior of the curve in the intermittent transmission interval of one heartbeat or less remains very vague. If the curve passes through the origin (0,0), the curve fitting may be performed relatively easily and the whole image of the curve may be grasped with high accuracy. However, as described above, since the tissue harmonic component exists, the origin may be changed. Can not be used. For this reason, even if you do curve fitting,
The probability of including many errors becomes extremely large.

Therefore, there is a problem that the ambiguity of the curve portion in the intermittent transmission interval of one heartbeat or less is large, and the accuracy of the inflow velocity of the blood flow obtained from the curve slope is extremely low.

An object of the present invention is to provide a method for quantifying the degree of contrast of a contrast agent by changing an intermittent transmission interval based on a flash echo imaging method. An ultrasonic diagnostic apparatus and an ultrasonic transmission method capable of performing transmission, thereby enabling more accurate quantification of information on blood flow dynamics of a blood vessel portion and information on hemodynamics at an organ substantial level by detection of perfusion. To provide.

[0019]

According to one aspect of the present invention, an ultrasonic pulse signal is transmitted inside a subject to which an ultrasonic contrast agent has been administered, in order to achieve the above-described various objects.
In an ultrasonic diagnostic apparatus configured to obtain a tomographic image of the subject using an echo signal accompanying the transmission, a transmission unit that transmits the ultrasonic pulse signal and a periodic pulse of a heart of the subject are represented. Heartbeat detection means for detecting a heartbeat signal;
The transmitting means transmits the first ultrasonic pulse signal for eliminating the ultrasonic contrast agent, and after the transmission, the second ultrasonic pulse signal is synchronized with a desired time phase of the periodic beat. Transmission control means for transmitting the sound wave pulse signal to the transmission means.

By transmitting the ultrasonic pulse signal twice as described above, intermittent transmission at a time interval shorter than one heartbeat can be performed. The contrast agent can be positively erased in the first transmission, and then the contrast agent (blood flow) that has flowed in can be imaged under the flash echo imaging method in the second transmission. Since the image signal is observed with fine control up to the intermittent transmission interval in the range of less than one heartbeat, the TI
The data amount of the C (luminance change curve) measurement particularly in a range where the elapsed time is short is increased, and the accuracy of the quantitative evaluation of the TIC data is improved.

Further, as the preferred embodiments of the present invention, the following can be provided.

Preferably, the transmission control means includes the first
This is means for transmitting the second ultrasonic pulse signal asynchronously with the periodic beat.

Preferably, the desired time phase is a cardiac time phase determined by a desired delay time from a reference wave of the heartbeat signal. For example, the heartbeat signal is an ECG (electrocardiogram) signal, and the reference wave is an R wave of the ECG signal.

More preferably, the transmission control means sets a time interval between the transmission of the first ultrasonic pulse signal and the transmission of the second ultrasonic pulse signal in accordance with a certain rule. An interval changing means for changing the interval is provided. For example, the time interval is any time interval including a real multiple of the heartbeat cycle. In this case, the time interval may include a time interval of one heart beat or less.

[0025] Preferably, the spacing changing means are the time intervals t, when the delay time that determines the transmission time phase of the second round of the ultrasonic pulse signal is a t _0, the condition of t ≦ t ₀ is A determination means for determining whether or not the condition is satisfied is provided, and a delay time t _DELAY from the R wave corresponding to a transmission time phase of the first ultrasonic pulse is calculated according to the determination result.

According to a specific mode, the interval changing means is
The stage is t ≦ t₀When the condition is satisfied, t
_DELAY= T₀-T to calculate the delay time t
_DELAYAnd a delay time t
_DELAYAnd the time interval t or the delay time t₀According to
Transmission of the first and second ultrasonic pulse signals
Transmission command means for commanding after the appearance of one R wave;
While t> t₀When the condition of
t_DELAY= T- (tt₀) (T: heart cycle)
Calculation to calculate the delay time t_DELAYThe second performance that seeks
Calculation means and the delay time t _DELAYAccording to the first
The transmission of the second ultrasonic pulse signal after the appearance of one R wave
And the second time according to the time interval t.
The transmission of the ultrasonic pulse signal of the eye extends over the appearance of the next R wave
And second transmission command means for commanding in an inoperative state.

According to still another aspect, a measuring means for measuring an actual value of a transmission time interval of the first and second ultrasonic pulse signals instructed by the second transmission instructing means, A replacement means for retroactively replacing the value measured by the measurement means with the value of the time interval may be provided.

On the other hand, a time interval setting means for arbitrarily selecting or arbitrarily setting the time interval from predetermined values may be provided.

[0029] Also, a receiving means for receiving the echo signal obtained with the transmission of the second ultrasonic pulse signal and a data processing means for generating and recording image data based on the echo signal are provided. The data processing means includes means for recording information indicating the time interval between the transmission of the first and second ultrasonic pulse signals involved in the generation of the image data together with the image data. You may comprise.

In this case, preferably, there is provided a measuring means for measuring data representing the intensity change curve of the echo signal or the luminance change curve of the image luminance over time based on the luminance of the image data. For example, the measurement unit is a unit that creates data representing the change curve using information representing the time interval.

According to another aspect of the present invention, an ultrasonic pulse signal is transmitted to the inside of a subject to which an ultrasonic contrast agent has been administered, and an echo signal accompanying the transmission is used. In the ultrasonic transmission method of the ultrasonic diagnostic apparatus so as to obtain a tomographic image of the subject, transmitting the first ultrasonic pulse signal for eliminating the ultrasonic contrast agent, after the transmission, the A second ultrasonic pulse signal is transmitted into the subject in synchronization with a desired time phase of a periodic heartbeat of the subject.

According to this transmission method, as described above,
The contrast agent can be positively erased in the first transmission, and then the contrast agent (blood flow) that has flowed in can be imaged under the flash echo imaging method in the second transmission.

Preferably, the first ultrasonic pulse signal is transmitted asynchronously with the periodic beat, and the desired time phase is a cardiac time phase determined by a desired delay time from a reference wave of the heartbeat signal. It is. More preferably, the time interval between the transmission of the first ultrasonic pulse signal and the transmission of the second ultrasonic pulse signal is changed under a certain rule.

At this time, it is preferable that the time interval is an arbitrary time interval including a time interval of one heart beat or less. Specifically, the time interval t, the delay time that determines the transmission time phase of the second round of ultrasonic pulse signal when the t _0, to determine whether a condition of t ≦ t ₀ is satisfied The delay time t _DELAY from the reference wave corresponding to the transmission time phase of the first ultrasonic pulse according to the determination result.
Is calculated.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The ultrasonic diagnostic apparatus according to this embodiment can be applied to all sites of interest when administering an ultrasonic contrast agent to a subject and observing a blood flow state based on the degree of contrast, but hereinafter, the liver parenchyma or the heart An ultrasonic diagnostic apparatus that obtains blood flow dynamics based on the degree of contrast of a contrast agent (perfusion) flowing into muscle and identifies an abnormal site will be described.

FIG. 1 schematically shows the entire configuration of the ultrasonic diagnostic layer apparatus according to the first embodiment. The ultrasonic diagnostic apparatus shown in FIG. 1 includes an apparatus main body 11, an ultrasonic probe 12, an operation panel 13, and an EC connected to the apparatus main body 11.
G (electrocardiograph) 14.

The operation panel 13 is used for giving various instructions and information from the operator to the apparatus main body 11, and includes a keyboard 13A, a trackball 13B, a mouse 13C, and a scan sequence for TIC measurement described later. An execution button 13D for starting is provided. The trackball 13B is used, for example, to function as a pointing device on a monitor screen and to set an ROI (region of interest) on an image. By operating the keyboard 13A or the like, the imaging mode is changed to “B mode imaging” or “CFM (Col.
or FlowMapping) mode imaging. The CFM mode imaging is an imaging mode in which a blood flow state is displayed as a two-dimensional color image, and an image in the CFM mode is displayed so as to be superimposed on an image in the B mode.

The ultrasonic probe 12 is a device that transmits and receives ultrasonic signals to and from the subject, and has a piezoelectric vibrator such as a piezoelectric ceramic as an electromechanical reversible conversion element. As a preferred example, a plurality of piezoelectric vibrators are arranged in an array and mounted at the tip of the probe, and a phased array type probe 12 is configured. As a result, the probe 12 converts the pulse drive voltage supplied from the apparatus main body 11 into an ultrasonic pulse signal and transmits the ultrasonic pulse signal in a desired direction inside the subject, while correspondingly transmitting the ultrasonic echo signal reflected from the subject. Is converted to an echo signal of a voltage.

The ECG 14 is used mainly in contact with the body surface of the subject to obtain electrocardiographic waveform data of the subject.

The apparatus main body 11 includes a probe 12 as shown in FIG.
Unit 21 and receiving unit 2 connected to
2. A receiver unit 23 placed on the output side of the receiving unit 22, a B-mode DSC (digital scan converter) 24, an image memory 25, a TIC operation unit 26, a Doppler unit 27, a display data synthesizer 28, and A display 29 is provided. The TIC operation unit 26 has an external output device 3 placed outside the diagnostic device.
0 is connected. The external output device is configured by, for example, a printer, a magnetic storage medium, a personal computer via a network, and the like. The apparatus main body 11 further includes a transmission controller 31 for controlling the transmission timing of the ultrasonic signal by the transmission unit 21 and a heartbeat detection unit 32 for receiving an ECG (electrocardiogram) signal detected by the ECG 14.

The configuration and operation of each circuit of the apparatus main body 11 will be further described.

The transmission unit 21 has a pulse generator, a transmission delay circuit, and a pulser (not shown). The pulse generator has a rate frequency fr [Hz] of, for example, 5 kHz.
(Period 1 / fr [sec]) is generated. This rate pulse is distributed to the number of transmission channels and sent to the transmission delay circuit. A timing signal for determining a delay time is supplied to the transmission delay circuit for each transmission channel. As a result, the transmission delay circuit adds a command delay time to the rate pulse for each channel. A rate pulse with a delay time is supplied to the pulser for each transmission channel. The pulsar receives the rate pulse and the piezoelectric vibrator (transmission channel) of the probe 12 at the timing.
A voltage pulse is given every time. As a result, an ultrasonic signal is emitted from the probe 12. The ultrasonic signal transmitted from the ultrasonic probe 12 is converged in a beam shape in the subject, and is set in the scan direction in which the transmission directivity is commanded.

As described above, the ultrasonic pulse signal is transmitted via the probe 12 by driving the transmission unit 21, and the timing is controlled by the transmission controller 31 as described later. The transmission controller 31 is a component that constitutes one of the features of the present invention.

In the subject, beamforming is performed according to the above-described delay time. The transmitted ultrasonic pulse signal is reflected by a discontinuous surface of acoustic impedance in the subject. This reflected ultrasonic signal is transmitted to the probe 12 again.
And is converted into an echo signal of a corresponding voltage amount. This echo signal is taken into the receiving unit 22 from the probe 12 for each receiving channel.

The receiving unit 22 includes a preamplifier, a receiving delay circuit, and an adder in order from the input side. Each of the preamplifier and the reception delay circuit has a built-in amplifier circuit or delay circuit for the reception channel. The delay time of the reception delay circuit is given as a signal of a delay time pattern according to a desired reception directivity. For this reason,
The echo signal is amplified by a preamplifier for each reception channel, given a delay time by a reception delay circuit, and then added by an adder. By this addition, the reflection component from the direction corresponding to the desired reception directivity is emphasized. By integrating the performances of the transmission directivity and the reception directivity, the overall performance of the transmitted and received ultrasonic beams can be obtained.

The output terminal of the adder of the receiving unit 22 reaches the display data combiner 28 via the receiver unit 23 and the B-mode DSC 24 in order.

Although not shown, the receiver unit 23
A logarithmic amplifier, an envelope detector, and an A / D converter are provided. In the case of an apparatus that performs the harmonic imaging method, the receiver unit 27 is additionally equipped with a band-pass filter that allows only a high frequency component, for example, twice the transmission frequency of the ultrasonic pulse signal to pass. With this receiver unit, echo data in the direction given the reception directivity is formed in a digital amount, and the B mode DSC
24.

The B-mode DSC 24 converts echo data from a raster signal sequence of an ultrasonic scan into a raster signal sequence of a video format, and sends this to a display data synthesizer 28.

The image memory 25 is a B-mode DSC 24
And a memory element for recording the processing signal of the DSC (either a raster signal sequence of an ultrasonic scan or a raster signal sequence of a video format) and a write / read control circuit therefor. The echo data recorded in the memory element is read out on a frame basis during or after imaging. The read data is sent to the display 29 via the B-mode DSC 24 and the display data synthesizer 28 for display.

The read output terminal of the image memory 25 is also connected to a TIC operation unit 26, so that data read from the memory can be taken into the operation unit 26. The TIC operation unit 26 includes a work memory and an operation circuit such as a CPU, and uses a TIC (Time Inten) based on the echo data read into the work memory.
(Site Curve) data, and the calculated data can be output to the display data synthesizer 28 and, if necessary, the external output device 30. Thereby, the TIC data is displayed on the display 29 and the external output device 30.
Displayed or output to

The Doppler unit 27 includes the receiving unit 22
Receive the added echo signal processed by Although not shown, the unit 27 includes a quadrature detector, an A / D converter, a clutter removal filter, a Doppler shift frequency analyzer, an arithmetic unit such as an average speed, a DSC, a color processing circuit, and the like.
The Doppler shift frequency, that is, blood flow velocity information and its power information are obtained as color flow mapping data (CFM data). The color flow mapping data is subjected to processing such as noise cancellation by a DSC built in the Doppler unit 27, and its scanning method is converted and sent to the display data synthesizer 28. This color flow mapping data can also be sent to the image memory 25 and stored.

The heartbeat detection unit 32 receives the ECG signal supplied from the ECG 14 and sends out the ECG waveform data to the display data synthesizer 28 for display, while the heartbeat synchronized with the R wave for ECG synchronization. A signal is generated, and the heartbeat signal is sent to the transmission controller 31.

The display data synthesizer 28 has a B-mode DSC
B-mode image data (gray scale image) sent from the Doppler unit 27 and CF sent from the Doppler unit 27
M mode image data (color flow image), electrocardiogram waveform data sent from the heartbeat detection unit 32, TIC
The arithmetic data of the arithmetic unit 26 and / or desired setting parameters are reconstructed into image data of one frame by processing such as arranging or overlapping. The frame image data is sequentially read out by the display 29.
The display unit 29 converts the image data into an analog amount by a built-in D / A converter, and displays a tomographic image of the tissue shape of the subject on a display such as a TV monitor.

Further, the transmission controller 31 includes an A / D converter 41 and a CPU (Central Processing Unit) 42 for receiving an operation signal from the operation panel 13 and a CPU 42
And a memory 43 connected to the memory 43. In the memory 43, a protocol for setting a protocol of the intermittent transmission method based on the flash echo imaging method according to the present invention (here, a transmission timing sequence) and a program for executing a scan sequence according to this protocol are previously stored. Is stored. CPU 42 is A / D / D / A
The operation panel 13, the heartbeat detection unit 32, the transmission unit 21, and the image memory 25 are connected via the converter 41 and the interface 44, and perform processing shown in FIGS.

Here, the principle of the protocol of the intermittent transmission method according to the present invention will be described with reference to FIGS.

Now, the delay value t ₀ of the cardiac phase to be observed, ie, to obtain an image relating to the blood flow dynamics, is set to an appropriate value, and the protocol of the intermittent transmission method according to the present invention is, for example, the intermittent transmission interval t. Column from the initial value to the final value of

## EQU1 ## t = 0.05, 0.1, 0.15, 0.2,
.., 0.9, 1, 2,..., 4 (heart rate). Although this protocol is expressed in terms of the heart rate, it may be converted into a timing sequence in units of time. For example, if the heart rate is 60 heart beats / minute, one heart beat corresponds to 60/60 = 1 second.

This protocol is divided into a range in which the intermittent transmission interval t is less than one heartbeat (see FIG. 3) and a range in which the intermittent transmission interval t is one heartbeat or more (see FIG. 2).

[0058] Similar to the prior art for the latter range, one heartbeat integral multiple of time has been determined as intermittent transmission interval t, in synchronization with the delay value t ₀ after the elapse each heartbeat several minutes intermittently Transmission is commanded. The first transmission of the first heartbeat can use intermittent transmission for the previous 0.9 heartbeat.

On the other hand, the interval train in the range of less than one heartbeat is a feature of the present invention. As shown in FIG. 3, one intermittent transmission interval is defined by two transmissions of the ultrasonic pulse signal.
For example, the interval is controlled so as to gradually increase. The first transmission (first transmission) is performed to eliminate the contrast agent (microbubbles) on the scan section, and the second transmission is performed.
Times th transmission (second transmission) is performed for the image generated by the observation time phase t ₀ as described above. Therefore, the first transmission only needs to be performed under transmission conditions (transmission sound pressure or the like) sufficient to eliminate the microbubbles, and it is not always necessary to generate an image using this echo signal.

[0060] The transmission shifting the timing to change the spacing of the intermittent transmission a first transmission for microbubble loss, the second transmission of the image generation is fixed to the specified time phase t ₀ (i.e., always the same Hemodynamics are observed at the time phase).

As can be seen from FIG. 3, FIG.
In the case (c), since t ≦ t ₀ is satisfied, it is relatively easy to determine the interval t between the first transmission and the second transmission.
That is, as shown in FIG. 4A, the adjustment delay value t _{DEL AY based} on the R wave (reference wave) is _calculated by:

[ _Mathematical formula-see original _document ] The operation is performed by t _DELAY = t ₀ -t. Then, from the peak value of the R wave, “t ₀ −t”
The first transmission: 1 is performed after time, and the second transmission is performed after t time.
The transmission may be performed (type I processing).

On the other hand, in the cases shown in FIGS. 6D and 6E, t ≦ t ₀ is not satisfied, and the first transmission is currently focused on R
Because it enters the time zone before the wave, the first transmission and the second transmission
Determining the transmission interval t cannot be realized by relying on one R wave.

[0063] Therefore, when the t> t _0, to control the spacing t of the intermittent transmission in a state of over two R waves. Specifically, as shown in FIG. 4B, the adjustment delay value t _{DELAY based} on the first R wave one heartbeat before is set as:

Calculated as t _DELAY = T− (t−t ₀ ). Here, T is a cardiac cycle, and it is assumed that the heart rate is constant. Then, when the adjustment delay value t _DELAY has elapsed from the first R wave, the first transmission is commanded, and thereafter, after the appearance of the second R wave, the interval t
, The second transmission is instructed (type II processing).

Thus, even when t> t ₀ , the first and second transmission timings can be reliably controlled by specifying the intermittent transmission interval.

A protocol of the intermittent transmission method set based on the above principle and a scan sequence performed based on the protocol will be described.

The CPU 42 sets the protocol of the intermittent transmission method based on the flash echo imaging method according to the present invention according to the procedure shown in FIG.

First, the CPU 42 determines whether or not to use a fixed intermittent transmission interval type protocol as the intermittent transmission protocol based on operation information from the operation unit 13 (step S1). When the determination is YES, that is, when it is determined that the fixed type is to be used, the processing of steps S2 to S5 is sequentially performed.

In step S 2, the CPU 42 inputs the delay value t ₀ of the cardiac time phase for observing, ie, obtaining an image relating to the blood flow dynamics, from the operation information of the operation unit 13. R of the delay value _{t 0} is the ECG signal as shown in FIGS. 2-4
It is specified as the delay time from the peak value time of the wave. Delay value _{t 0} is specified, for example, 0.2 seconds, the cardiac cycle T
Adjusted to the end of the wave.

Next, in step S3, the CPU 42
Selects a desired protocol from one or a plurality of types of protocols recorded in the memory 43 in advance, and reads out the selected protocol into the work area. As this protocol, for example, a column from the initial value to the final value of the intermittent transmission interval t is

## EQU4 ## t = 0.05, 0.1, 0.15, 0.2,
.., 0.9, 1, 2,..., 4 (heart rate). The interval t may be changed from a large value of the heart rate to a small value. This protocol, according to the principles described above, features one of the features of the present invention.
Includes interval columns that fall below the heart rate. Alternatively, it may be set by designating the initial value of the intermittent transmission interval and its increment (one or more types of increments for each range).

[0070] Next, at step S4, the delay value t ₀ defining the observation time phase is determined whether or the value that is currently set. When it is necessary to make a correction, the process returns to step S2, and when no correction is necessary, the determined protocol is stored in the memory 43 (step S5).

On the other hand, if the determination in step S1 is NO,
That is, when the operator does not select the fixed type protocol and determines that the operator manually specifies the protocol parameters one by one, the CPU 42 proceeds to steps S6 to S6.
The processing of S11 is performed sequentially.

First, the above-described delay value t ₀ of the observation time phase is set.
Is input from the operation information (step S6), and the increment Δt of the intermittent transmission interval t is input from the operation information (step S7),
Further, the maximum value of the intermittent transmission interval t is input from the operation information (step S8). Thereby, the CPU 42, for example,

## EQU5 ## t = 0.1, 0.2, 0.3,..., 0.9,
An interval sequence (ie, protocol) such as 1, 2,..., 4 (heart rate) is set and displayed on the display 29 (step S9).

Then, the CPU 42 asks the operator whether or not the protocol set manually as described above is acceptable (step S10). When the information of OK is obtained, the protocol is stored in the memory 43 (step S1).
1). Conversely, when the user wants to modify the protocol, the process returns to step S6.

Next, a scan sequence executed by the CPU 42 will be described with reference to FIG.

The CPU 42 reads from the memory 43 the protocol of the intermittent transmission method (including the delay value t ₀ of the observation time phase) set through the processing of FIG. 5 described above, and reads the minimum value of the intermittent transmission interval t of the protocol. The value is read (steps S21, S22). This minimum value reading is for intermittent transmission in order from the one with the smallest interval, but conversely, the maximum value may be read and intermittent transmission may be performed in order from the one with the largest interval.

Further, the CPU 42 determines whether or not the read interval t satisfies t ≧ 1 heartbeat with respect to a preset one heartbeat value (step S23). If NO in the determination (when the interval t is less than one heartbeat), then for a delay value t ₀ at the time of observation phase and the interval t, t ≦ t ₀
It is determined whether or not (step S24).

If t ≦ t ₀ (YES) holds in this determination, a series of processing of type I is performed based on the above-described principle. That is, the adjustment delay value t _DELAY =
t ₀ -t is calculated (step S25), and it is determined from the heartbeat signal whether an R wave as a reference wave has appeared (step S26). When the R wave appears, it is determined whether or not the adjustment delay value t _DELAY has elapsed from the appearance (step S27). This adjustment delay value t
Immediately after _DELAY has elapsed, the first transmission for the first disappearance of microbubbles is instructed to the transmission unit 21 (step S28).

As a result, the transmission unit 21 transmits the probe 12 under the transmission conditions such as the transmission sound pressure appropriately set.
To transmit an ultrasonic pulse signal to the subject. As a result, the contrast agent (microbubbles) existing on the scan section temporarily disappears.

Thereafter, it is determined whether or not the currently designated intermittent transmission interval t has elapsed (step S29). If the determination is YES, the second observation second transmission is transmitted to the transmission unit 21. Command is issued (step S30).

Thus, the transmitting unit 21 drives the probe 12 to transmit an ultrasonic pulse signal to the subject under the transmission conditions for imaging, and scans a cross section with the ultrasonic beam. The echo signal obtained by this is sent to the receiving unit 22 via the probe 12, and is beam-formed and processed into an echo signal. The echo signal is further processed into B-mode image data by the receiver unit 23 and sent to the B-mode DSC 24. The scanning mode of the image data is converted by the B-mode DSC 24, and the image data is stored in the image memory 25. Since information representing the intermittent transmission interval t of the currently generated image data is sent from the transmission controller 31 to the image memory 25, the interval t is stored in association with the image data.

The echo signal from the receiving unit 22 is also sent to the Doppler unit 27. Therefore, color flow mapping data of the blood flow is generated by the Doppler unit 27, and this mapping data is also stored in the image memory 25 in association with the B-mode image data and the information on the intermittent transmission interval t.

The B-mode image data generated by the B-mode DSC 24, the CFM mode image data generated by the Doppler unit 27, the electrocardiogram waveform data sent from the heartbeat detection unit 32, and the like are reconstructed by the display data synthesizer. , Are displayed on the display 29 almost in real time.
At this time, the image in the CFM mode is displayed, for example, superimposed on the image in the B mode.

After the second transmission command in step S30, the CPU 42 determines whether or not the final transmission has been performed (step S30).
31), if the determination is NO, the next intermittent transmission interval t
Is read out (step S32), and the process returns to step S23.

If it is determined in step S23 that t> t ₀ (NO) while the processing in steps S23 to S31 is repeated, a series of processing corresponding to the type II described above is performed in steps S33 to S38. Be executed.

That is, as described above, the adjustment delay value t
Calculate _DELAY = T− (t−t ₀ ) (Step S3)
3) It is determined from the heartbeat signal whether or not the first R wave as a reference wave has appeared (step S34). When this R wave appears, the adjustment delay value t
_It is determined whether _DELAY has elapsed (step S3).
5). Immediately after the adjustment delay value t _DELAY elapses, the first transmission for the first disappearance of the microbubbles is instructed to the transmission unit 21 (step S36). As a result, the contrast agent on the scan section is once erased in the same manner as described above.

Thereafter, it is determined whether or not the next R wave has appeared (step S37). And YES in this judgment
Or not (second occurrence R wave) whether has elapsed then the time of the observation time phase t ₀ minutes R-wave appearance of the second case made is determined (step S38). When the determination is YES, the second transmission for the next observation is instructed to the transmission unit 21 (step S39). As a result, the scan on the cross section by the ultrasonic beam is executed as described above, the echo signals are collected, and the image data of the B mode and the color flow mapping are stored and displayed.

[0087] In the process of step S36 to S39, the second transmission may be performed while waiting only intermittent transmission interval t from the first transmission priority that always constant observation time phase t ₀ If, is better from the second R-wave were measured lapse of t ₀ is advantageous.

Thereafter, the flow shifts to step S31 to determine whether or not the final transmission is completed. If the determination is NO, the process returns to step S23. Then, steps S23 and S2
4. While repeating the processing routine of S33 to S39 and S31, YES in step S23, that is, the interval t
≧ 1 heartbeat is determined. At this time, intermittent transmission in synchronization with the observation time phase t ₀ according to the heart rate of the read interval t = integer value from protocol is commanded (see FIG. 2, step S40). Thus, similarly to the above, the image data in the B mode and the CFM mode are collected and stored together with the intermittent transmission interval t, and both images and the electrocardiogram waveform are displayed.

If it is determined in step S31 that the final transmission command has been completed, the CPU 42 ends the execution of the scan sequence shown in FIG.

On the other hand, the TIC operation unit 26 performs an operation for obtaining TIC data at an appropriate timing after the end of the above-described scan sequence, for example. When the scan sequence is completed, the image data obtained by the second transmission is stored in the image memory 25, and is read out by the TIC operation unit 26. For example, the first image is displayed in a frozen state, and the ROI is set at a desired position on this image.

The TIC calculation unit 26 calculates a luminance value (for example, an average luminance value) based on the pixel values in the ROI for each image frame, and performs a curve fitting process on the entire TIC based on the discrete luminance values to smoothly perform the smoothing. Based on the curve data, information on the hemodynamics at the organ parenchyma level by perfusion detection, such as the total blood flow and the inflow velocity of the blood flow, is imaged and quantitatively evaluated from the curve data. As a result, as shown in FIG. 7, when the heart rate (that is, time) is plotted on the horizontal axis, TIC data representing the temporal change of the luminance value in the ROI and quantitative evaluation information are obtained. The data and information are displayed on the display 29 via the display data synthesizer 28 and stored in the external output device 30.

As can be seen from FIG. 7, the luminance value calculated by the TIC calculation unit 26 can be measured for the intermittent transmission interval not only for the time range of one or more heartbeats but also for the time range of less than one heartbeat as in the related art. Done, and a luminance value is obtained. That is, an actual measurement value is also provided for a time range of less than one heartbeat that critically affects the accuracy of the curve fitting process. Therefore, TIC
The accuracy of the curve fitting processing by the arithmetic unit 26 becomes extremely high, and the y-axis intercept a3, that is, the limit luminance value at the heart rate = 0, can be accurately estimated with high accuracy while being affected by the above-mentioned tissue harmonic component. it can.

In this manner, the behavior of the brightness value curve in a range of less than one heartbeat can be obtained with high accuracy without any modification. Therefore, the inflow velocity of the blood flow into the ROI correlated with the slope of the curve can be accurately measured, and together with the total blood flow in the ROI based on the brightness value at the time when the curve reaches flatness, the perfusion The function of imaging information on hemodynamics at the level of organ parenchyma by detection and the function of quantitatively evaluating them are fully demonstrated.

As described above, in addition to the intermittent transmission method based on the flash echo imaging method, the ultrasonic transmission in which the microbubbles are positively eliminated in a region where the intermittent transmission interval is short, particularly in a region of one heart beat or less, is added. The scope of the flash echo imaging method can be further expanded than the conventional method, the function of imaging the blood flow dynamic information of the blood vessel part using the echo signal reflected by the contrast agent, the function of organ real level by detecting perfusion The function of imaging hemodynamic information and various image processing functions for quantitative evaluation thereof can be exhibited with higher accuracy and higher definition.

[0095] Further, according to this embodiment, as shown in FIG. 5, when using a fixed protocol, the operator inputs the observation time phase t _0, the only need of operations to execute the scan sequence after Therefore, the simplicity of operation is maintained.

The present invention is not limited to the configuration of the above-described embodiment, but can be embodied in various forms.

As a first modification, a configuration can be provided in which the intermittent transmission interval is retrospectively determined. Aforementioned Protocol Configuration Type II processes, i.e., the delay value t in the case of t> t ₀
Calculation of _DELAY = T− (t−t ₀ ) is performed. At this time, it is assumed that the cardiac cycle T (heart rate) is constant.
However, the cardiac cycle T is not constant depending on the subject,
Since it may change, an accurate luminance time curve is obtained even in such a case.

Therefore, a timer 51 for measuring the actual interval between the first transmission and the second transmission by the transmission unit 21 is provided. This timer may also serve as an existing timer or measuring means inside the apparatus. Then, the measurement interval value t by the timer 51 is sent to the image memory 25. When the transmitted measurement interval value t is different from the designated interval value t provided from the transmission controller 31, the image memory 25 replaces the measurement interval value t with the measurement interval value t from the timer 51 and stores it.

The setting of the protocol of the intermittent transmission method and the scan sequence control by this protocol are executed in the same manner as described above.

Therefore, in the case of this configuration, even if the heartbeat period T is not constant, the heartbeat period T
The TIC data which is not affected by the change is measured and displayed as shown in FIG. In particular, the influence of the fluctuation of the cardiac cycle T is great in a range of one heart beat or less, but in such a sensitive range, the TIC data is plotted and calculated with the transmission interval value t obtained retrospectively. Accordingly, accurate TIC data can be obtained regardless of the fluctuation of the cardiac cycle T, and the items of TIC measurement such as the inflow speed of blood flow can be quantified with high accuracy.

Another variation relates to the protocol. In the above-described embodiment, the setting of the fractional value of the heart rate in the intermittent transmission interval is limited to a range of less than one heartbeat.

(Equation 6) For example, an interval of any real value that takes a fraction may be set for a range of one or more heartbeats.

The protocol according to the present invention includes:
A sequence of one cycle based on the intermittent transmission interval t may be repeated for a plurality of cycles.

Further, even for a protocol corresponding to this repetition, for example,

(Equation 7) For example, an interval sequence in which the same interval continues a plurality of times may be set.

The above-described embodiments and their modifications are merely examples, and are not intended to limit the scope of the present invention. The scope of the present invention is determined according to the description of the claims, and various types of ultrasonic diagnostic apparatuses can be implemented without departing from the scope of the present invention.

[0105]

As described above, according to the ultrasonic diagnostic apparatus and the ultrasonic transmission method according to the present invention, the degree of contrast of the contrast agent is quantified by changing the intermittent transmission interval based on the flash echo imaging method. In particular, the intermittent transmission can be performed by reliably controlling the transmission interval even in a short interval of one heartbeat or less, and thereby, the information on the blood flow dynamics of the blood vessel and the organ by detecting the perfusion can be obtained. Hemodynamic information at a substantial level can be quantified with higher precision and higher definition. As a result, detailed information can be provided for quantification of blood flow information and differential diagnosis.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an intermittent transmission interval of one or more heartbeats.

FIG. 3 is a diagram illustrating an intermittent transmission interval of less than one heartbeat.

Figure 4 is a graph showing a relation between the ECG waveform and time parameters when classified according to the magnitude relationship of the observation time phase t ₀ and intermittent transmission interval t.

FIG. 5 is a diagram illustrating a schematic flowchart of protocol setting performed by a transmission controller.

FIG. 6 is a schematic flowchart showing a scan sequence executed by a transmission controller.

FIG. 7 is a diagram illustrating a state in which TIC data obtained based on the present invention is plotted and curve fitting is performed.

FIG. 8 is a block diagram of an ultrasonic diagnostic apparatus according to another embodiment of the present invention.

FIG. 9 is a diagram illustrating a state in which TIC data is plotted based on intermittent transmission intervals obtained retrospectively and curve fitting is performed according to another embodiment.

FIG. 10 is a diagram illustrating a state in which TIC data obtained based on a conventional example is plotted and curve fitting is performed.

FIG. 11 is a view for explaining a relationship between an ECG waveform and an observation time phase.

[Explanation of symbols]

Reference Signs List 11 apparatus main body 12 ultrasonic probe (transmitting means) 13 operation panel (time interval setting means) 14 ECG sensor (heartbeat detecting means) 21 transmitting unit (transmitting means) 22 receiving unit (receiving means) 23 receiver unit (receiving means) 24 B-mode DSC (data processing means) 25 Image memory (data processing means, replacement means) 26 TIC operation unit (measuring means) 27 Doppler unit (receiving means) 28 display data synthesizer (data processing means) 29 display (data processing) Means) 31 Transmission controller (transmission control means, time interval setting means) 32 Heartbeat detection unit (heartbeat detection means) 42 CPU 43 Memory 51 Timer (measurement means)

Claims (19)

[Claims] 1. An ultrasonic diagnostic apparatus which transmits an ultrasonic pulse signal inside a subject to which an ultrasonic contrast agent has been administered, and obtains a tomographic image of the subject using an echo signal accompanying the transmission. Transmitting means for transmitting the ultrasonic pulse signal, heartbeat detecting means for detecting a heartbeat signal representing a periodic beat of the heart of the subject, and a first time for eliminating the ultrasonic contrast agent Causing the transmitting means to transmit an ultrasonic pulse signal,
An ultrasonic diagnostic apparatus comprising: a transmission control unit that transmits the second ultrasonic pulse signal to the transmission unit in synchronization with a desired time phase of the periodic beat after the transmission. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein said transmission control means is means for transmitting said first ultrasonic pulse signal asynchronously with said periodic pulsation. Ultrasonic diagnostic equipment. 3. The ultrasonic diagnostic apparatus according to claim 1, wherein the desired time phase is a cardiac time phase determined by a desired delay time from a reference wave of the heartbeat signal. apparatus. 4. The ultrasonic diagnostic apparatus according to claim 3, wherein the heartbeat signal is an ECG (electrocardiogram) signal, and the reference wave is an R wave of the ECG signal. . 5. The ultrasonic diagnostic apparatus according to claim 4, wherein the transmission control unit sets a time between transmission of the first ultrasonic pulse signal and transmission of the second ultrasonic pulse signal. An ultrasonic diagnostic apparatus comprising an interval changing means for changing an interval according to a certain rule. 6. The ultrasonic diagnostic apparatus according to claim 5, wherein the time interval is an arbitrary time interval including a real number multiple of a heartbeat cycle. 7. The ultrasonic diagnostic apparatus according to claim 6, wherein the time interval includes a time interval of one heart beat or less. 8. The ultrasonic diagnostic apparatus according to claim 7, wherein the interval changing unit sets the time interval to t, and sets a delay time to determine a transmission time phase of the second ultrasonic pulse signal to t _0.
And a determining means for determining whether or not a condition of t ≦ t ₀ is satisfied. According to a result of the determination, a determination is made from the R wave corresponding to the transmission time phase of the first ultrasonic pulse. An ultrasonic diagnostic apparatus wherein a delay time t _DELAY is calculated. 9. The ultrasonic diagnostic apparatus according to claim 8, wherein
And the interval changing means is t ≦ t₀When the condition of
Is t_DELAY= T ₀-T is calculated and
Interval t_DELAYFirst calculating means for calculating
Interval t_DELAYAnd the time interval t or the delay time t₀To
Of the first and second ultrasonic pulse signals
First transmission commander that commands transmission after the appearance of one R-wave
And t> t₀When the condition is satisfied, t_DELAY= T
-(Tt₀) (T: heartbeat cycle) is calculated and
Delay time t_DELAYSecond calculating means for calculating
Delay time t_DELAYThe first ultrasonic pal according to
Signal transmission after the appearance of one R wave
And the second ultrasonic pulse according to the time interval t.
Command to transmit the source signal while straddling the appearance of the next R wave
And second transmission command means for performing
Ultrasound diagnostic device. 10. The ultrasonic diagnostic apparatus according to claim 9, wherein an actual value of a transmission time interval between the first and second ultrasonic pulse signals instructed by the second transmission instruction unit is measured. An ultrasonic diagnostic apparatus comprising: a measuring unit; and a replacing unit that retroactively replaces a value measured by the measuring unit with the value of the time interval. 11. The ultrasonic diagnostic apparatus according to claim 5, further comprising a time interval setting means for arbitrarily selecting or arbitrarily setting the time interval from predetermined values. 12. The ultrasonic diagnostic apparatus according to claim 5, wherein the receiving unit receives the echo signal obtained with the transmission of the second ultrasonic pulse signal, and image data based on the echo signal. And data processing means for generating and recording the information. The data processing means stores information representing the time interval between the first and second transmissions of the ultrasonic pulse signal related to the generation of the image data. An ultrasonic diagnostic apparatus comprising means for recording the image data together with the image data. 13. The ultrasonic diagnostic apparatus according to claim 12, further comprising: a measuring unit that measures data representing the intensity change curve of the echo signal or the luminance change curve of the image luminance over time based on the luminance of the image data. An ultrasonic diagnostic apparatus, comprising: 14. The ultrasonic diagnostic apparatus according to claim 13, wherein said measuring means is means for creating data representing said change curve using information representing said time interval. apparatus. 15. An ultrasonic diagnostic apparatus which transmits an ultrasonic pulse signal inside a subject to which an ultrasonic contrast agent has been administered, and obtains a tomographic image of the subject using an echo signal accompanying the transmission. In the ultrasonic transmission method, the first ultrasonic pulse signal for eliminating the ultrasonic contrast agent is transmitted, and after this transmission, the ultrasonic pulse signal is synchronized with a desired time phase of a periodic beat of the heart of the subject. Transmitting the second ultrasonic pulse signal to the inside of the subject. 16. The ultrasonic transmission method according to claim 15, wherein the first ultrasonic pulse signal is transmitted asynchronously with the periodic beat, and the desired time phase is obtained from a reference wave of the heartbeat signal. An ultrasonic transmission method characterized by a cardiac phase determined by the desired delay time. 17. The ultrasonic transmission method according to claim 16, wherein a time interval between the transmission of the first ultrasonic pulse signal and the transmission of the second ultrasonic pulse signal is set to a predetermined rule. An ultrasonic transmission method characterized by being changed back. 18. The ultrasonic transmission method according to claim 17, wherein the time interval is an arbitrary time interval including a time interval of one heart beat or less. 19. The ultrasonic transmission method of claim 18, the time interval t, when the delay time that determines the transmission time phase of the second round of the ultrasonic pulse signal is a t _0, t ≦ t ₀
It is determined whether or not the condition is satisfied, and the delay time t _DELAY from the reference wave corresponding to the transmission time phase of the first ultrasonic pulse is calculated according to the determination result. Characteristic ultrasonic transmission method.