JP2003299653A - Ultrasonic diagnostic equipment having bloodstream information acquiring function and transmission control method for ultrasonic pulse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ultrasonic diagnostic equipment capable of monitoring low bloodstream speed with high frame rate and high image quality. <P>SOLUTION: This ultrasonic diagnostic equipment comprises a probe 101 for transmitting the ultrasonic pulse toward the predetermined number of scanning lines, and receiving its reflected wave, an ultrasonic wave sending and receiving control part 110 for controlling sending and receiving the ultrasonic pulse for tomography information by the probe 101, and sending and receiving the ultrasonic pulse for bloodstream information, and the like. The ultrasonic sending and receiving control part 110 controls the probe 101 to repeat the scan for successively transmitting the ultrasonic pulse for bloodstream information at transmitting intervals Tc to the plurality of scanning lines, while changing the plurality of scanning lines as objects, to disperse the transmission of the ultrasonic pulses for tomography information to the different scanning line, to the plurality of scans at a transmitting interval Tb different from the transmitting interval Tc, and to transmit a part of the ultrasonic pulses for bloodstream information in scan at a transmitting interval Tc' different from the transmitting interval Tc. <P>COPYRIGHT: (C)2004,JPO

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 and the like, and more particularly to an ultrasonic diagnostic apparatus having a function of acquiring blood flow information of a subject by utilizing the Doppler effect of ultrasonic pulses.

[0002]

2. Description of the Related Art As a method of using an ultrasonic diagnostic apparatus, blood flow information of a subject is acquired by utilizing the Doppler effect of ultrasonic pulses, and a blood flow image generated from the blood flow information is superimposed on a tomographic image. Display is clinically useful and is widely used. Hereinafter, acquisition of blood flow information and superimposition display of a blood flow image generated from blood flow information on a tomographic image in a conventional ultrasonic diagnostic apparatus will be described with reference to the drawings.

FIG. 9 shows an example of the configuration of an ultrasonic diagnostic apparatus. In FIG. 9, the ultrasonic diagnostic apparatus includes an ultrasonic transmission / reception control unit 10 for controlling an ultrasonic pulse transmission method, a scanning line for transmitting / receiving ultrasonic pulses, and an ultrasonic pulse transmission interval.
0, the probe 101 and the probe 10 that transmit and receive ultrasonic waves while scanning them under the control of the ultrasonic wave transmission and reception control unit 100
1. The tomographic information acquisition processing unit 102 that acquires the tomographic information data from the ultrasonic data received by No. 1 and the blood flow information acquisition processing unit 103 that acquires the blood flow information data from a plurality of received data of the same scan line received by the probe 101. , A frame memory 104 for holding at least one frame of tomographic information data and blood flow information data, and converting one frame of tomographic information data and blood flow information data stored in the frame memory 104 into an image in a screen format DSC (Digital Scan Converter) 10
5, an image combining unit 106 that superimposes the tomographic image and the blood flow image generated by the DSC 105, and a display monitor 107 that displays the superimposed tomographic image and the blood flow image. Here, the scanning line means a line indicating the direction of the ultrasonic pulse emitted from the probe 101, as shown in the scanning diagram of FIG.

The operator applies the probe 101 to the examination site of the subject. An ultrasonic pulse is transmitted from the probe 101 under the control of the ultrasonic transmission / reception control unit 100, and the pulse reflected in the body of the subject is received by the probe 101. The ultrasonic pulse to be transmitted includes an ultrasonic pulse for tomographic information and an ultrasonic pulse for blood flow information, and can be transmitted a plurality of times for the same scanning line.

Generally, the ultrasonic pulse for the tomographic information and the ultrasonic pulse for the blood flow information have different conditions such as a waveform, and these conditions are controlled by the ultrasonic wave transmission / reception control unit 100. In addition, the ultrasonic pulse for blood flow information is transmitted and received a plurality of times on the same scanning line, and at this time, the ultrasonic transmission / reception control unit 100 controls the transmission interval of these ultrasonic pulses to be constant. The received ultrasonic data for tomographic information is subjected to signal processing by the tomographic information acquisition processing unit 102, and the obtained tomographic information data is stored in the frame memory 104.

Further, in the blood flow information acquisition processing unit 103, the Doppler shift frequency component is extracted by subjecting the received ultrasonic data for blood flow information to quadrature detection, and the received data of the same scanning line is received a plurality of times. Blood flow information such as the average, variance, and power of the blood flow velocity is obtained from the Doppler shift frequency component obtained from

The obtained blood flow information data is stored in the frame memory 104. Signal processing of these ultrasonic pulse transmission and reception data is performed by scanning lines 0, 1, 2, 3, ..., L-1 (L is the number of scanning lines in one frame, as shown in FIG. ) Are sequentially performed. The probe shown in FIG. 10 and FIG. 11 described later is a type called a sector probe, but the same applies to the case of a linear probe or a convex probe.

When one frame of tomographic information data and one frame of blood flow information data are stored in the frame memory 104,
These data are read out and converted into images in the screen format by the DSC 105, respectively, and the image synthesizing unit 106
Are superimposed and displayed on the display monitor 107.

The time required for the ultrasonic pulse transmitted from the probe to be reflected at the depth D and to reach the probe again is c · 2D, where c is the transmission speed of the ultrasonic pulse. Therefore, when the maximum depth of field is Dmax, the time from the transmission of an ultrasonic pulse to the transmission of the next ultrasonic pulse, that is, the transmission interval T of ultrasonic pulses, must satisfy T ≧ c · 2Dmax. .

Here, the relationship between the maximum field depths of blood flow information and tomographic information will be described with reference to FIG. Now
A region of interest (ROI) 108 for acquiring blood flow information is shown in FIG.
It is assumed that the position is set as shown in. In this case, the maximum visual field depth Dcmax of the blood flow information is smaller than the maximum visual field depth Dbmax of the tomographic information. Therefore, when the transmission interval of the ultrasonic pulse for tomographic information is Tb and the transmission interval of the ultrasonic pulse for blood flow information is Tc, Tc <Tb can be satisfied.

The blood flow velocity is calculated according to the following principle. When the frequency of the transmitted ultrasonic pulse is ft, the frequency of the reflected wave in blood changes due to the Doppler effect due to the blood flow. This frequency change, that is, the Doppler shift frequency is defined as fd,
When the ultrasonic pulse transmission speed is c, the blood flow velocity is v, and the blood flow direction and the ultrasonic pulse transmission direction are θ, the relationship of fd = (2v · cos θ · ft) / c is established. That is, if the Doppler shift frequency fd is known, the blood flow velocity v can be obtained. Doppler shift frequency f
d can be obtained by quadrature detection of received ultrasonic data with a signal of frequency ft, and performing frequency analysis on the signal obtained by applying a low-pass filter.

Actually, ultrasonic pulses are transmitted a plurality of times at the sampling interval (repeated transmission interval) Tr to the same scanning line, and the above processing is performed on the received signals of these plurality of times. Normally, the repeated transmission interval Tr needs to be constant due to operational restrictions in the blood flow information acquisition processing unit 103.

Assuming that the number of transmissions of ultrasonic pulses for blood flow information to the same scanning line a plurality of times, that is, the number of samplings is N, the frequency resolution Δfd of this sampling signal is Δfd = 1 / (N · Tr when Fourier analysis is performed ). That is, it is understood that the transmission interval Tr or the number of transmissions N may be increased in order to reduce the value of the frequency resolution Δfd and enable detection of the low blood flow velocity.

Further, when the average frequency analysis is performed using the autocorrelation method, the longer the observation time N · Tr of the sampling signal, the more stable the result obtained. Further, the slower the blood flow, the longer the cycle of the sampling signal, so it is necessary to observe for a longer time in order to obtain a stable result. Therefore, also in this case, in order to detect the low blood flow velocity, the transmission interval T
It is sufficient to increase r or the number of transmissions N.

However, when N scan lines are sequentially transmitted N times, Tc = Tr. Therefore, when the number of scan lines in one frame is L, the frame rate Fr is Fr = 1 / (Tb.L + Tc.N).・ L) = 1 / (Tb ・
L + Tr · N · L), and simply increasing Tr and N leads to a decrease in frame rate.

As a method of improving this problem, there has been proposed a method of transmitting an ultrasonic pulse for one frame by repeating scanning in which ultrasonic pulses are sequentially transmitted to a plurality of scanning lines (special feature). Technology described in Japanese Patent Publication No. 6-13031). As a result, Tc <Tr can be set, and at this time, Fr = 1 / (Tb · L + Tc · N · L)> 1 / (Tb ·
L + Tr · N · L), the frequency resolution Δfd can be increased while maintaining the frame rate.

Next, referring to FIGS. 12, 13 and 14,
The transmission order of the ultrasonic pulse in the above conventional technique will be described. In these figures, the horizontal direction represents the scanning direction and the vertical direction represents the time axis. In the example of FIG. 12, Tb: Tc: T
r = 2: 1: 6, and the number N of repeated transmissions of ultrasonic pulses for blood flow information to the same scanning line is 8. The black dots in the drawing represent the transmission timing of the ultrasonic pulse for tomographic information, and the white dots in the drawing represent the transmission timing of the ultrasonic pulse for blood flow information.

The transmission order of FIG. 12 is as follows. First, in the first scan, the transmission interval Tb = 2Δt
With (Δt is a constant), ultrasonic pulses for tomographic information are transmitted in the order of scanning lines 0 → 1 → ... → 5. Next, in the second scan, ultrasonic pulses for blood flow information are transmitted at the transmission interval Tc = Δt by scanning lines 0 → 1 → ... → 5 → 0 → ・
・ ・ → 5 → 0 ... Then
Scanning (transmission) of scan lines 0 to 5 in the third scan
When all are completed, the scanning of the scanning lines 6 to 11 is similarly repeated. Thereafter, the scanning is repeated in the order shown by the scanning lines 12 to 17 ..., Thus, one frame is scanned.

In this case, compared to the case where N = 8 times are sequentially transmitted to one scanning line, ultrasonic pulses are transmitted once to each of the six scanning lines, considering only the transmission of blood flow information. Since this is repeated 8 times, the frame rate is increased by 6 times (actually, since there is also transmission for tomographic information, 6
Less than double). However, with this transmission method,
There is a large time difference for every 6 scanning lines (for example, the difference between the time when the scanning for scanning lines 0 to 5 is performed and the time when the scanning for scanning lines 6 to 11 is performed). It has the drawback of producing continuity.

A transmission method for improving discontinuity caused by such a time difference is the transmission method shown in FIG. Note that, in this figure, the dots in a grid pattern represent ultrasonic pulse transmission (dummy transmission) for blood flow information in which the received data is discarded while the transmitted data is discarded. Note that in dummy transmission, you can artificially leave a transmission interval (empty transmission) without actually transmitting,
This also includes the case of transmitting a pulse under a condition different from the ultrasonic pulse for blood flow information. Further, if the influence of the residual echo is not considered, the case of transmitting to an arbitrary scanning line and discarding the received data is also included.

The transmission order of FIG. 13 is as follows. First, in the first scan, ultrasonic pulses for tomographic information are continuously transmitted for one frame from the scan line 0 at the transmission interval Tb = 2Δt. When this scanning is completed, the transmission interval Tc
= Ultrasonic pulse for blood flow information (including dummy transmission) at Δt scanning line 0 → -5 → -4 → ・ ・ ・ → 1 → -4 → ・ ・
By repeating the scanning in the order shown in the figure, →→ 2 → −3 → ..., One frame is scanned. That is, ultrasonic pulse transmission for blood flow information is repeated for 6 or 7 consecutive scanning lines, but the leading scanning line at that time is shifted one by one. According to this transmission method,
Since the time difference for each scanning line becomes a small value that is almost constant, discontinuity in the image within the frame is eliminated.

However, since the scanning of the ultrasonic pulse transmission for the tomographic information and the scanning of the ultrasonic pulse transmission for the blood flow information are separated, the ultrasonic pulse transmission for the tomographic information and the ultrasonic pulse transmission for the blood flow information are performed. There is a problem in that there is a large time difference between the tomographic images and the tomographic image and the blood flow image that are displayed in a superimposed manner, and there is a time lag.

FIG. 14 shows an example of a transmission method in which the time phase difference for each scanning line is substantially constant and there is almost no time difference between the ultrasonic pulse transmission for tomographic information and the ultrasonic pulse transmission for blood flow information. The transmission order of FIG. 14 is as follows in detail. First, in the first scan, the transmission interval Tb = 2
At Δt, an ultrasonic pulse for tomographic information is transmitted to scan line 0. Next, in the second scan, the ultrasonic pulse (including dummy transmission) for blood flow information is transmitted as the scanning line -2 → -1 → 0 at the transmission interval Tc = 2Δt.

Next, in the third scanning, after transmitting the ultrasonic pulse for blood flow information (including dummy transmission) at the scanning interval Tc = 2Δt as scanning line -2 → -1 → 0, An ultrasonic pulse for tomographic information is transmitted to the scanning line 1 at the transmission interval Tb = 2Δt. Then, in the fourth scan, ultrasonic pulses for blood flow information are repeated at the transmission interval Tc = 2Δt in the order shown below, such as scan line -1 → 0 → 1 → -1 → 0 → ... Transmission is performed and scanning for one frame is performed.

Japanese Patent Laid-Open No. 9-66055 also discloses a method of transmitting ultrasonic pulses for shortening the time difference, but the transmission without dummy transmission at the beginning and end of the frame disclosed therein. The method is also inevitably in the form of this example because the scanning of the ultrasonic pulse transmission for tomographic information and the scanning of the ultrasonic pulse transmission for blood flow information cannot be separated.

According to this transmission method, the ultrasonic pulse for the tomographic information is not collectively transmitted for one frame but is mixed and transmitted during the ultrasonic pulse transmission for the blood flow information. The time phase difference between the transmission of the ultrasonic pulse for information and the transmission of the ultrasonic pulse for blood flow information is reduced, and the time lag between the tomographic image displayed superimposed and the blood flow information is shortened.

[0027]

However, in this transmission method, in order to make the repeated transmission interval Tr constant, the transmission intervals for both the ultrasonic pulse for the tomographic information and the ultrasonic pulse for the blood flow information must be aligned. Of course, for that reason, it is unavoidable to match the longer one of the transmission intervals. As a result, in this example, Tc = Tb = 2Δt must be set, and there is a problem that the frame rate is almost halved compared to the transmission method shown in FIG.
The ultrasonic pulse transmission interval means not only a time interval in the case of repeatedly transmitting the same type of ultrasonic pulse, but also a different type of ultrasonic pulse is transmitted after transmitting the ultrasonic pulse. It also means the time interval of those ultrasonic pulses in the case.

Here, for reference, in order to avoid a decrease in frame rate, the transmission interval Tb for tomographic information is set to 2Δt while maintaining the transmission order shown in FIG. 13, and the transmission interval for blood flow information is set. FIG. 15 shows a transmission pattern when Tc is Δt. As can be seen from this figure, with such a transmission interval, the repeated transmission interval Tr is not constant (becomes 5Δt or 6Δt), and the processing in the blood flow information acquisition processing unit 103 is It will be impossible.

As described above, according to the conventional technique, in observing a low blood flow velocity, if it is attempted to prevent the deterioration of the image quality such as the discontinuity in the image in the frame and the deviation between the tomographic image and the blood flow image, There is a problem that the rate drops. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of observing a low blood flow velocity with a high frame rate and high image quality, and an ultrasonic pulse transmission control method in such an ultrasonic diagnostic apparatus.

[0030]

In order to achieve the above object, an ultrasonic diagnostic apparatus according to the present invention has a function of acquiring blood flow information of a subject by utilizing the Doppler effect of ultrasonic pulses. An ultrasonic diagnostic apparatus, comprising: scanning means for transmitting ultrasonic pulses to a predetermined number of scanning lines and receiving reflected waves thereof; transmission / reception of ultrasonic pulses for tomographic information and blood flow information by the scanning means. Transmission / reception control means for controlling transmission / reception of the ultrasonic pulse, and tomographic information acquisition means for acquiring tomographic information based on the reflected wave for the ultrasonic pulse for tomographic information received by the scanning means, and the scanning means for receiving An ultrasonic diagnostic apparatus comprising: a blood flow information acquisition unit that acquires blood flow information based on a reflected wave for an ultrasonic pulse for blood flow information, wherein the transmission / reception control unit is for a plurality of scanning lines. Scanning for sequentially transmitting ultrasonic pulses for blood flow information at the transmission interval Tc is repeated while shifting a plurality of target scanning lines, and a plurality of transmissions of ultrasonic pulses for tomographic information to different scanning lines are performed. Of transmission intervals Tb different from the transmission interval Tc while being dispersed in the scanning of
The scanning means is controlled so that a part of the ultrasonic pulse for blood flow information in the scanning is transmitted at a transmission interval Tc ′ different from the transmission interval Tc. .

Here, the transmission / reception control means may control the scanning means so that the transmission interval Tc ′ becomes equal to the transmission interval Tb, and the last transmission in the scanning is for tomographic information. The scanning means may be controlled so that the ultrasonic pulse is transmitted or the ultrasonic pulse for the blood flow information of the transmission interval Tc ′ is transmitted, or the ultrasonic pulse for the tomographic information included in each of the scans is transmitted. The scanning means may be controlled so that the total number of transmissions and the number of transmissions of the ultrasonic pulse for blood flow information at the transmission interval Tc ′ are equal.

Further, the transmission / reception control means may further control the scanning means so as to perform dummy transmission of at least one ultrasonic pulse for blood flow information at the head of the scanning. Here, as the dummy transmission, an ultrasonic pulse for blood flow information may be transmitted, and the received data may be discarded, or an empty transmission in which no ultrasonic pulse is transmitted may be performed. The ultrasonic pulse different from the ultrasonic pulse for information may be transmitted.

The present invention can be realized not only as an ultrasonic diagnostic apparatus as described above but also as a transmission control method in which the characteristic constituent elements of such an ultrasonic diagnostic apparatus are steps, that is, It may be realized as a method for controlling transmission of ultrasonic pulses in an ultrasonic diagnostic apparatus, or may be realized as a program for causing a computer to execute such a transmission control method. Needless to say, the program can be distributed via a recording medium such as a CD-ROM or a transmission medium such as the Internet.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) An ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to this embodiment. This ultrasonic diagnostic apparatus includes an ultrasonic wave transmission / reception control unit 110, a probe 101,
Tomographic information acquisition processing unit 102, blood flow information acquisition processing unit 10
3, a frame memory 104, a DSC 105, an image synthesizing unit 106, and a display monitor 107, and has the same configuration as the conventional ultrasonic diagnostic apparatus shown in FIG. 9 except for the ultrasonic wave transmission / reception control unit 110. The same components as those of the related art are designated by the same reference numerals and the description thereof will be omitted.

The ultrasonic wave transmission / reception control unit 110 is an ultrasonic wave transmission / reception control unit 100 of the conventional ultrasonic diagnostic apparatus shown in FIG.
In addition to having a control function provided by, the transmission interval T different from the transmission interval Tc of the normal ultrasonic pulse for blood flow information.
A blood flow information special transmission unit that transmits an ultrasonic pulse for blood flow information at c ′ (hereinafter, such transmission of an ultrasonic pulse for blood flow information is referred to as “special blood flow information special transmission”). 110a
Have. For example, while the transmission interval Tc of the normal ultrasonic pulse for blood flow information is Δt, the special transmission unit 110a for blood flow information sets the transmission interval Tc ′ to 2Δt, and Send an ultrasonic pulse.

FIG. 2 shows an example of the transmission sequence (scanning lines for transmitting ultrasonic pulses and transmission interval) by the ultrasonic transmission / reception control unit 110. The horizontal direction in the figure represents the scanning direction, and the vertical direction represents the time axis. In this example, Tb: Tc: Tr = 2:
The ratio is 1: 6, and the number of repeated transmissions of the ultrasonic pulse for blood flow information to the same scanning line is N = 8. The black dots in the figure are ultrasonic pulse transmissions for tomographic information, the white dots in the figure are ultrasonic pulse transmissions for blood flow information, and the points with a grid pattern are transmitted, but the received data is discarded for blood flow information. It represents ultrasonic pulse transmission (dummy transmission).

In the dummy transmission, a pseudo transmission interval may be provided (idle transmission) without actually transmitting, or a pulse having a condition different from the ultrasonic pulse for blood flow information may be transmitted. Further, if the influence of the residual echo is not considered, the received data can be discarded by transmitting to any scanning line.
Also, the hatched points indicate special transmission for blood flow information, that is, ultrasonic pulse transmission for blood flow information, but transmission with a different transmission interval from the normal ultrasonic pulse for blood flow information (blood flow information For special transmission). In this example, the transmission interval Tc ′ of this special transmission for blood flow information is equal to the transmission interval of the ultrasonic pulse for tomographic information, and Tc ′ = Tb.

The transmission order of FIG. 2 is as follows in detail. That is, the transmission control by the ultrasonic transmission / reception control unit 110 is as follows. First, in the first scan, ultrasonic pulses for tomographic information are transmitted to the scan line 0 at the transmission interval Tb = 2Δt. Next, in the second scan, the ultrasonic pulse (including dummy transmission) for blood flow information is similarly scanned at the transmission interval Tc = Δt on the scanning line -4 → -3 → ...
-> Send in order of 0. Then, the transmission interval Tb = 2Δt
Then, an ultrasonic pulse for tomographic information is transmitted to the scanning line 1.

Next, in the third scanning, the ultrasonic pulse for blood flow information is transmitted at the transmission interval Tc = Δt on the scanning line -3 →
---> Send in order of 0. Then, the transmission interval Tc ′ =
An ultrasonic pulse for blood flow information is transmitted to the scan line 1 at 2Δt (that is, special transmission for blood flow information is performed). Hereinafter, the ultrasonic pulse for blood flow information is scanned at the transmission interval Tc = Δt.
The scanning for one frame is performed by repeating the scanning in the order shown, such as 3 → -2.

As described above, the ultrasonic wave transmission / reception control unit 110 according to the first embodiment of the present invention sets the transmission interval Tc ′ of a part of the ultrasonic pulse for blood flow information to the normal ultrasonic pulse for blood flow information. It has a function of controlling so that the interval is different from the transmission interval Tc (for example, the same interval as the ultrasonic pulse for tomographic information). That is, the ultrasonic wave transmission / reception control unit 110
(1) The ultrasonic pulses for tomographic information are not collectively transmitted as one scan as in the conventional technique shown in FIG. 13, but are dispersed in the scan for blood flow information and the end of the scan is performed. And (2) in the final transmission of each scan, the transmission is controlled to be tomographic information transmission or special transmission for blood flow information.

By this control, the repeated transmission interval Tr
While Tc <Tb, that is, the ultrasonic pulse for the tomographic information and the ultrasonic pulse for the blood flow information can be respectively set to the optimum transmission interval while keeping the value constant (6Δt), it is possible to realize the substantially same frame rate as in the case of FIG. Furthermore, since the time difference between each scanning line is almost constant, discontinuity does not occur in the image within the frame, and there is almost no time difference between the ultrasonic pulse transmission for tomographic information and the ultrasonic pulse transmission for blood flow information. Since it does not exist, there is no deviation between the tomographic image and the blood flow image.

Since the number of transmission of ultrasonic pulses for blood flow information is far greater than the number of transmission of ultrasonic pulses for tomographic information, when compared with FIG. 14, it is possible to obtain Tc <Tb. The effect of improvement is great.

Note that, instead of controlling the ultrasonic pulse transmission interval Tc 'itself, it is possible to adjust the transmission interval as a result by performing dummy transmission at an appropriate transmission interval and number of times, but this is essentially It does not depart from the spirit of the invention. For example, as in the transmission pattern shown in FIG. 3, in the first scan, ultrasonic pulses for tomographic information are transmitted twice, and at the end of the second and third scans (two transmissions). ), Special transmission for blood flow information and transmission for tomographic information are performed, and at the end of the fourth scan (transmission twice)
In the above, the same effect can be obtained even if the transmission for tomographic information is performed twice.

The number of scanning lines in each scan, the transmission interval of ultrasonic pulses, the number of transmission of ultrasonic pulses for blood flow information to the same scanning line, and the like may be different from those in FIG. For example, as in the transmission pattern shown in FIG. 3, Tb: Tc: Tr = 2: 1: 10, Tc ′ = Tb,
The transmission may be N = 6, or Tb: Tc: Tr = 1.5: 1: as in the transmission pattern shown in FIG.
The transmission may be 9, Tc ′ = Tb, N = 6.

Although not shown, when transmitting an ultrasonic pulse for tomographic information a plurality of times for the same scanning line (during multi-stage focusing, etc.), transmitting an ultrasonic pulse for tomographic information and blood flow information The present invention can also be applied to the case where the scanning line densities of the ultrasonic pulse transmissions are different. Further, the scanning line for transmitting the ultrasonic pulse for tomographic information does not need to be as shown in FIG. 2 or FIG. 3, and for example, the scanning line i shown in the drawing may be used.
The transmission may be controlled to be transmitted to the scanning line i + 1 at the transmission timing.

Further, as shown in FIG. 5, in the transmission control in this embodiment, the arrangement of scanning lines and the scanning are shifted with respect to the transmission order of ultrasonic pulses disclosed in Japanese Patent Laid-Open No. 3-39147. The present invention is also applicable to a transmission method in which the arrangement of scanning lines corresponding to which direction is reversed, and a transmission method shown in Japanese Patent Laid-Open No. 9-66055 that does not include dummy transmission at the beginning and end of a frame. That is, in each transmission scan, transmission is performed in the order from the scan line with the highest scan line number to the scan line with the lowest scan line, and such individual transmission scans are shifted from the scan line with the low scan line number toward the high scan line. Regardless of the transmission order, the characteristic transmission control in this embodiment, that is, the total number of tomographic information transmissions and blood flow information special transmissions included in each transmission scan, should be the same. It is possible to apply the transmission control in which the individual transmission scan includes the special transmission for blood flow information. In addition,
L in the figure is the number of scanning lines in one frame.

(Second Embodiment) Next, an ultrasonic diagnostic apparatus according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to this embodiment. This ultrasonic diagnostic apparatus includes an ultrasonic wave transmission / reception control unit 120, a probe 101, a tomographic information acquisition processing unit 102, a blood flow information acquisition processing unit 103, a frame memory 104, a DSC 105, and an image synthesis unit 106.
And the display monitor 107, and has the same configuration as the ultrasonic diagnostic apparatus of the prior art shown in FIG. 9 except the ultrasonic wave transmission / reception control unit 120.

The ultrasonic wave transmission / reception control unit 120 is an ultrasonic wave transmission / reception control unit 100 of the conventional ultrasonic diagnostic apparatus shown in FIG.
Embodiment 1 in addition to having the control function of
The blood flow information special transmission unit 110a has the same function as the blood flow information special transmission unit 120a, and at least one ultrasonic pulse for blood flow information is always placed at the beginning of the scanning by the ultrasonic pulse for blood flow information. And a dummy blood flow information dummy transmission unit 120b for dummy transmission.

FIG. 7 shows an example of the transmission sequence (scanning lines for transmitting ultrasonic pulses and transmission interval) by the ultrasonic transmission / reception control unit 120. The horizontal direction in the figure represents the scanning direction, and the vertical direction represents the time axis. Black dots in the figure are ultrasonic pulse transmissions for tomographic information, white points in the figure are ultrasonic pulse transmissions for blood flow information,
The dots in the square pattern represent ultrasonic pulse transmission (dummy transmission) for blood flow information in which the received data is discarded but the received data is discarded.

In the dummy transmission to the scanning line with the scanning line number less than 0, the transmission pulse is not actually transmitted but a pseudo transmission interval is provided (empty transmission), or the ultrasonic pulse for blood flow information is used. It is possible to send pulses under different conditions,
Considering the influence of the residual echo on the scan line 0, it is desirable to transmit the ultrasonic pulse for blood flow information and discard the received data. Although not shown in FIG. 7, the same applies to dummy transmission to a scanning line having the number of scanning lines L or more (L is the number of scanning lines in one frame).

Further, the shaded points indicate the ultrasonic pulse transmission for blood flow information, but the transmission interval is different from the normal ultrasonic pulse for blood flow information, that is, the special transmission for blood flow information. Represent In this example, the transmission interval Tc ′ is equal to the transmission interval of the ultrasonic pulse for tomographic information, and Tc ′ = Tb.

The transmission order of FIG. 7 is as follows in detail. That is, the transmission control by the ultrasonic transmission / reception control unit 120 is as follows. First, in the first scan, ultrasonic pulses for tomographic information are transmitted to the scan line 0 at the transmission interval Tb = 2Δt. Next, in the second scanning, the ultrasonic pulse (dummy transmission) for blood flow information is similarly sent at the transmission interval Tc = Δt on the scanning line -4 → -3 → ... →
After transmitting in the order of −1, the ultrasonic pulse for blood flow information is transmitted to the scan line 0 at the transmission interval Tc ′ = 2Δt as in the first embodiment. Hereinafter, ultrasonic pulses (including dummy transmission) for blood flow information are transmitted at the transmission interval Tc = Δt on the scanning line -4 → −.
Repeatedly transmitted as 3 ... (Third to ninth scanning).

Then, at the end of the ninth scanning,
After transmitting the ultrasonic pulse for tomographic information to the scan line 4,
In the next tenth scanning, the ultrasonic pulse for blood flow information is dummy-transmitted to the scan line 0 at the transmission interval Tc = Δt, and then the ultrasonic pulse for blood flow information is transmitted for the scan line 1 → 2.
... and continue. Thereafter, the transmission is repeated in the order shown in the figure to scan one frame.

As described above, the ultrasonic wave transmission / reception control unit 120 according to the second embodiment of the present invention has, in addition to the functions of the first embodiment, 1 to 1 at the beginning of ultrasonic pulse transmission for blood flow information in each scan. It has a function of controlling dummy transmission several times.

By this control, the influence of the residual echo of the immediately preceding ultrasonic pulse transmission can be made relatively the same with respect to the ultrasonic pulse for blood flow information to the same scanning line a plurality of times. That is, according to the transmission in the present embodiment, regardless of which blood flow information transmission is performed, blood flow information transmission (including dummy transmission) is always performed immediately before the transmission.

Therefore, even if there is a residual echo of the immediately preceding ultrasonic pulse transmission at the time of transmitting the ultrasonic pulse for blood flow information, the ultrasonic pulse transmission for blood flow information to the same scanning line is performed a plurality of times. Since the difference in the influence of the residual echo is not detected as the phase difference, it hardly affects the obtained blood flow information.

Further, since it is possible to control so that the transmission immediately after the ultrasonic pulse transmission for blood flow information whose transmission interval is Tc 'is either dummy transmission or ultrasonic pulse transmission for tomographic information, transmission is possible. Different intervals (mixed transmission of blood flow information and special transmission for blood flow information) do not cause a difference in the influence of residual echo on ultrasonic pulse transmission for blood flow information. As a result, artifacts in the finally obtained blood flow image are reduced.

The two characteristic transmission methods in the present embodiment, namely, (1) provision of special transmission for blood flow information, and (2) the dummy transmission at the beginning of each scan must be performed. What is included is interrelated,
This has the effect of suppressing the decrease in the frame rate and reducing the artifacts of the blood flow image. That is, without performing the special transmission for blood flow information in (1) above,
Such a synergistic effect cannot be obtained simply by performing the dummy transmission of (2) above.

For reference, when the transmission of (2) is performed without performing the transmission of (1), that is, the transmission intervals of the ultrasonic pulse for blood flow information are all the same, and the same scanning is performed. FIG. 8 shows an example in which dummy transmission is performed so that the influence of the residual echo on the transmission of the ultrasonic pulse for blood flow information to the line a plurality of times is the same.

In the transmission pattern shown in FIG. 8, Tb =
The conditions of 2Δ, Tr = 6Δ, and N = 8 are the same as those shown in FIG. 7, and Tc = Tb in order to keep Tr constant. As can be seen by comparing FIG. 7 and FIG. 8, the number of times of dummy transmission to the same scanning line is smaller in the transmission pattern shown in FIG. That is, with the two characteristic transmission methods (1) and (2) in the present embodiment, it is possible to reduce the artifact of the blood flow image while suppressing the decrease in the frame rate due to the dummy transmission.

The two characteristic transmission methods in the present embodiment are applicable to the case where the ultrasonic pulse for tomographic information is transmitted to the same scanning line a plurality of times (in multi-stage focusing, etc.).
Alternatively, when the scanning line densities of the ultrasonic pulse transmission for the tomographic information and the ultrasonic pulse transmission for the blood flow information are different, the transmission method without dummy transmission at the beginning and the end of the frame is also applicable.

As described above, according to the ultrasonic diagnostic apparatus of the present invention, in the transmission scan of the ultrasonic pulse for the blood flow information for the plurality of scanning lines, the blood flow information of the transmission interval different from the normal transmission interval is obtained. Low blood flow velocity can be observed at high frame rate and high image quality by mixing special transmissions for blood flow and additionally transmitting dummy ultrasonic pulse for blood flow information at the beginning of scanning. .

The present invention is not limited to Embodiments 1 and 2 above, and the number of scanning lines in each scan and the transmission interval of ultrasonic pulses are the same as those in these Embodiments. Different transmission patterns may be used. In addition, it goes without saying that the present invention can be implemented in various forms without departing from the scope of the present invention.

[0064]

As is apparent from the above description, the ultrasonic diagnostic apparatus according to the present invention has the function of acquiring blood flow information of a subject by utilizing the Doppler effect of ultrasonic pulses. A scanning means for transmitting ultrasonic pulses to a predetermined number of scanning lines and receiving reflected waves thereof, transmission / reception of ultrasonic pulses for tomographic information by the scanning means, and ultrasonic waves for blood flow information A transmission / reception control unit that controls transmission / reception of pulses, a tomographic information acquisition unit that acquires tomographic information based on a reflected wave for the ultrasonic pulse for tomographic information received by the scanning unit, and a blood flow received by the scanning unit. An ultrasonic diagnostic apparatus comprising: blood flow information acquisition means for acquiring blood flow information based on a reflected wave for an ultrasonic pulse for information, wherein the transmission / reception control means is a transmission interval for a plurality of scanning lines. The scanning in which the ultrasonic pulse for blood flow information is sequentially transmitted at c is repeated while shifting a plurality of target scanning lines, and the transmission of the ultrasonic pulse for tomographic information to different scanning lines is performed for the plurality of Transmitting at a transmission interval Tb different from the transmission interval Tc while being dispersed in the scanning,
For some of the ultrasonic pulses for blood flow information in the scan, a transmission interval T different from the transmission interval Tc is used.
The scanning means is controlled to transmit at c '.

As a result, the scanning is repeated while shifting the target scanning lines, so that the time difference between the plurality of scanning target scanning lines can be suppressed and
Since the ultrasonic pulse for tomographic information is dispersed and transmitted in a plurality of scans, the time difference between the tomographic information and blood flow information is also suppressed, and moreover, of the ultrasonic pulse for blood flow information in the scan, Since some of them are transmitted at a transmission interval Tc ′ different from the transmission interval Tc, ultrasonic waves are transmitted with the transmission interval Tb for tomographic information transmission and the transmission interval Tc for blood flow information transmission set to different values. Pulses can be transmitted and a drop in frame rate is avoided.

That is, the ultrasonic pulse for the tomographic information and the ultrasonic pulse for the blood flow information are respectively transmitted at the optimum transmission intervals without the deterioration of the image quality such as the discontinuity in the image within the frame or the deviation between the tomographic image and the blood flow image. Can be Here, the transmission / reception control means may further control the scanning means so as to perform dummy transmission of at least one ultrasonic pulse for blood flow information at the beginning of the scanning.

As a result, just before the transmission of the ultrasonic pulse for blood flow information, the ultrasonic pulse for blood flow information is always transmitted, and the influence of the residual echo becomes equal, so that finally Artifacts in the obtained blood flow image are reduced. That is, it is possible to reduce the artifact of the blood flow image while suppressing the decrease in the frame rate. As described above, according to the present invention, an ultrasonic diagnostic apparatus capable of observing a low blood flow rate with a high frame rate and high image quality is realized, and its practical value is extremely high.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of a scanning order according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an example of a scanning order according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an example of a scanning order according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an example of a scanning order according to the first embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to Embodiment 2 of the present invention.

FIG. 7 is a diagram showing an example of a scanning order according to the second embodiment of the present invention.

FIG. 8 is a diagram showing an example of a scanning order when a part of the characteristics of the scanning order according to the second embodiment of the present invention is missing.

FIG. 9 is a block diagram showing a configuration of a conventional ultrasonic diagnostic apparatus.

FIG. 10 is a diagram showing scanning lines for transmitting and receiving ultrasonic pulses in one frame.

FIG. 11 is a diagram showing an example of a relationship between a region of interest of blood flow information and maximum visual field depths of tomographic information and blood flow information.

FIG. 12 is a diagram showing an example of a scanning order in a conventional ultrasonic diagnostic apparatus.

FIG. 13 is a diagram showing an example of a scanning order in a conventional ultrasonic diagnostic apparatus.

FIG. 14 is a diagram showing an example of a scanning order in a conventional ultrasonic diagnostic apparatus.

FIG. 15 is a diagram showing an example of a scanning order.

[Explanation of symbols]

100, 110, 120 Ultrasonic wave transmission / reception control unit 100 Ultrasonic wave transmission / reception control unit 101 probe 102 Fault information acquisition processing unit 103 Blood flow information acquisition processing unit 104 frame memory 105 DSC 106 image composition section 107 display monitor Region of interest for blood flow information 110a, 120a Blood flow information special transmission unit 120b Dummy transmitter for blood flow information

Claims (12)

[Claims] 1. An ultrasonic diagnostic apparatus having a function of acquiring blood flow information of a subject by utilizing the Doppler effect of ultrasonic pulses, the ultrasonic pulse being transmitted toward a predetermined number of scanning lines. Scanning means for receiving the reflected wave, transmission / reception control means for controlling transmission / reception of ultrasonic pulses for tomographic information and transmission / reception of ultrasonic pulses for blood flow information by the scanning means, and tomographic information received by the scanning means Information acquisition means for acquiring tomographic information based on the reflected wave for the ultrasonic pulse for blood flow, and blood flow information for acquired based on the reflected wave for the ultrasonic pulse for blood flow information received by the scanning means An ultrasonic diagnostic apparatus comprising blood flow information acquisition means, wherein the transmission / reception control means performs scanning in which ultrasonic pulses for blood flow information are sequentially transmitted to a plurality of scanning lines at a transmission interval Tc. versus Repeatedly shifting multiple elephant scanning lines to transmit ultrasonic pulse for tomographic information to different scanning lines.
The transmission interval Tc is distributed to the plurality of scans.
And a transmission interval Tb different from the transmission interval Tc for a part of the ultrasonic pulse for blood flow information in the scanning.
An ultrasonic diagnostic apparatus characterized in that the scanning means is controlled so as to transmit at c '. 2. The transmission / reception control means is configured to transmit the transmission interval T.
The ultrasonic diagnostic apparatus according to claim 1, wherein the scanning unit is controlled so that c ′ becomes equal to the transmission interval Tb. 3. The transmission / reception control means performs the scanning so that the last transmission in the scanning is transmission of an ultrasonic pulse for tomographic information or transmission of an ultrasonic pulse for blood flow information at a transmission interval Tc ′. The ultrasonic diagnostic apparatus according to claim 2, characterized in that the means is controlled. 4. The transmission / reception control means makes the sum of the number of transmissions of the ultrasonic pulse for tomographic information included in each of the scans and the number of transmissions of the ultrasonic pulse for blood flow information at the transmission interval Tc ′ equal to each other. The ultrasonic diagnostic apparatus according to claim 2, wherein the scanning means is controlled as described above. 5. The transmission / reception control unit controls the scanning unit so as to perform dummy transmission of at least one ultrasonic pulse for blood flow information at the head of the scanning. The ultrasonic diagnostic apparatus according to any one of 4 above. 6. The ultrasonic diagnostic apparatus according to claim 5, wherein the dummy transmission is to transmit an ultrasonic pulse for blood flow information and discard the received data. 7. The ultrasonic diagnostic apparatus according to claim 5, wherein the dummy transmission is an empty transmission that does not transmit an ultrasonic pulse. 8. The ultrasonic diagnostic apparatus according to claim 5, wherein the dummy transmission is transmission of an ultrasonic pulse different from the ultrasonic pulse for blood flow information. 9. An ultrasonic pulse transmission control method in an ultrasonic diagnostic apparatus having a function of acquiring blood flow information of a subject by utilizing the Doppler effect of an ultrasonic pulse, the ultrasonic diagnostic apparatus comprising: The transmission control method includes scanning means for transmitting ultrasonic pulses to a predetermined number of scanning lines and receiving reflected waves thereof, wherein the transmission control method uses ultrasonic waves for blood flow information at transmission intervals Tc for a plurality of scanning lines. A first control step of controlling the scanning means so as to repeat scanning in which pulses are sequentially transmitted while shifting a plurality of target scanning lines, and transmission of ultrasonic pulse for tomographic information to different scanning lines. ,
The transmission interval Tc is distributed to the plurality of scans.
A second control step of controlling the scanning unit to transmit at a transmission interval Tb different from that, and a part of the ultrasonic pulse for blood flow information in the scanning that is different from the transmission interval Tc. Interval T
and a third control step of controlling the scanning means so as to transmit at c '. 10. The ultrasonic pulse transmission control method according to claim 9, wherein in the third control step, the scanning means is controlled so that the transmission interval Tc ′ becomes equal to the transmission interval Tb. . 11. The transmission control method further controls the scanning means so as to dummy-transmit an ultrasonic pulse for blood flow information at least once at the beginning of the scanning.
11. The method according to claim 9, further comprising a control step.
A method for controlling transmission of an ultrasonic pulse as described. 12. A program for an ultrasonic diagnostic apparatus having a function of acquiring blood flow information of a subject by utilizing the Doppler effect of ultrasonic pulses, and the program according to claim 9. A program for causing a computer to execute the steps in the method for controlling transmission of ultrasonic pulses described.