JPH04208142A - Ultrasonic diagnosis device - Google Patents

Abstract

PURPOSE:To reduce measurement errors by electronically scanning each divided oscillator group, receiving plural ultrasonic beams from the same region, gaining angles between the plural ultrasonic beams and blood flows in the region on the positions of the oscillator groups and the region, and gaining each maximum blood flow speed by plural signals from reception means. CONSTITUTION:Divided oscillator groups 1a-1c each are electronically scanned, plural ultrasonic beams are received from the same region, angles between the plural ultrasonic beams and blood flows in the region are gained on the positions of the oscillator groups 1a-1c and the region, maximum blood flow speeds each are gained by plural signals from reception means 3C, 3D, and effective and ineffective components of blood flow speeds are gained from the respective angles and the respective maximum blood flow speeds. This can reduce measurement errors in the blood flow speeds, even when the angles become large, and can dispense with the operation for setting the angles, resulting in shortening the inspection time.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to ultrasonic waves that can detect or measure the speed of moving reflectors such as blood flow in the heart or blood vessels. Related to diagnostic equipment.

(Prior Art) The ultrasonic Doppler method utilizes the ultrasonic Doppler effect in which when an ultrasonic wave is reflected by a moving object, the frequency of the reflected wave shifts in proportion to the moving speed of the object. By transmitting ultrasonic rate pulses to a living body and obtaining the frequency shift due to the Doppler effect from the phase change of the reflected wave echo, it is possible to obtain motion information of a moving object at the depth position where the echo was obtained. According to this, it is possible to know the direction of the flow of blood at a position in the living body and the state of the flow, whether it is turbulent or regular.

Specifically, first, the wave transmitting/receiving circuit is driven to repeatedly transmit ultrasonic pulses from the ultrasonic probe to the blood flow in the living body of the subject a predetermined number of times. Center frequency f of the transmitted ultrasound beam
c is scattered by the flowing blood cells and changes by the frequency f d due to the Doppler shift (7, the transmitter/receiver circuit changes the receiving frequency f
=fc+fd is received. Note that the frequencies fc, fdl;j
It becomes as follows.

fd=2Vcos θ-fc/niko, ■ is the blood flow velocity, θ is the angle between the ultrasound beam and the blood vessel, and C is the speed of sound.

Since this frequency fd is a function of blood flow velocity ■,
By detecting and processing the Doppler shift frequency fd, the blood flow velocity ■ can be obtained.

As a method of measuring this blood flow velocity, for example,
-204653 is already known. This technical content will be explained with reference to FIG. The velocity of blood flowing through a certain blood vessel V
Two ultrasound beams A and B are applied to an arbitrary part S1 of
When radiating from different directions, two ultrasonic beams A
, B are automatically set in advance to a predetermined angle Δθ. Then, two reflected echoes from the same site S are received by the same transducer group 17, two Doppler shift frequencies are detected based on these received signals, and two Doppler shift frequencies corresponding to these are detected.
The two velocities V and ■ are determined by calculation.

Furthermore, as can be seen from FIG. 6, there is a relationship expressed by the following equation.

v=v, °
It is. Here, x and y are two ultrasound beams A.

It is a unit vector on B, θ1 is the angle formed by velocity V and velocity V 2 , and θ2 is an angle formed by velocity 2 and velocity 2. In other words, by calculating the above equation, the blood velocity V and the angle θ1 are obtained from the two velocities ■, ■2 and the intersection angle Δθ of the ultrasound beams A and B.
Since it is possible to determine the size and direction of blood flow in blood vessels, it is possible to determine the size and direction of blood flow within the blood vessels. According to this, it is possible to accurately determine the absolute speed while automatically setting the intersection angle.

However, in an example related to -, there were the following problems. This will be explained below. First, in the ultrasonic Doppler method, as shown in Fig. 7, among the temporal changes in blood flow velocity, the maximum deviation frequency fdm from the maximum blood flow velocity v max
Find aX. Further, the power relative to the blood flow velocity is as shown in FIG.

Then, using the tomographic image shown in FIG. 9, the angle θ between the blood vessel direction P and the ultrasound beam direction and the tube diameter 2r are measured. Further, if the range gate width is matched to the blood vessel and this length is ρ, then it becomes 2r−ρCO8θ.

Furthermore, the blood flow g Q that is clinically desired is: Q=VA=Vmax/2 ・yr r2 However, Vma
x = c-fdmax/(2f-cosθ),
f is the ultrasonic frequency and C is the speed of sound. Here CO
The angle is corrected by Sθ.

(Problem to be Solved by the Invention) However, as shown in FIG. 10, as the angle θ increases, the maximum flow velocity value VfflaX becomes
``It starts to show a large value even though the blood flow mQ is low.Therefore, there was a problem that the blood flow mQ was overestimated.

The cause of this is thought to be the influence of turbulence components. FIGS. 11(a) and 11(b) are diagrams showing this type of =5- blood flow state. In blood flow, Figure 11 (a)
There are two states: laminar flow shown in FIG. 11(b) and turbulent flow shown in FIG. 11(b). The laminar flow is expressed as V(x)=Vmax(1-(x/R)2). Here, R is the pipe diameter (radius).

Further, the turbulent flow is V (x) −Vmax (1−(x/R)) ”
” is displayed. Here, the opening changes depending on the Reynolds number. R is the pipe diameter (radius). At this time, the flow is V (
x) There are other directions besides the direction.

Next, the conditions for the occurrence of the turbulent flow are: (1) When the Reynolds number RD increases: RD-4Qρ/πDη Here, Q is the flow rate and ρ is the fluid density. D is the tube diameter (diameter) and η is the fluid viscosity.

(2) When the conditions inside the pipe change, the inlet region 2 curves the pipe (development of secondary flow). (3) When the time changes, pulsatile flow is considered.

In this way, many blood vessels are considered to have turbulent flow, and this turbulence causes the velocity component in the direction along the blood vessel and the blood flow component in other directions to be synthesized, so that the maximum blood flow velocity v ma
X looked like a jonin and was not listening.

Further, as shown in FIG. 12, the flow in the blood flow direction is assumed to be . This V. is the southward velocity of the flow rate "C tomorrow", which is a function of the position The velocity during flow is Vo=Vmax (1-x/R)''. Here, Vll1aX is the maximum value of Vo.

Turbulent flow has a velocity Vr that moves in random directions within a microvolume depending on the flow rate. Think about it separately. Overall, it flows at a speed Vo, but when viewed microscopically, the scatterers (red blood cells) move in an ulterior manner, but statistically they are balanced, so they are closer to JS. No. Zunawa appears to be coming towards us at a speed of Vr from any angle.

Therefore, the Doppler detection speed on the ultrasound beam is Vocos θ+Vr, as shown in FIG. Sol~
If we take this as an angle iT', then Vmax-(Voc
osθ+Vr) / cosθ=Vo+Vr/
cos θ. In other words, as shown in FIG.
I'll go. As the angle θ becomes larger in this way, the measured values Vma and Reproducibility was poor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that can reduce measurement errors in blood flow velocity even when the angle becomes large.

(Means for Solving the Problems) The present invention has taken the following measures in order to solve the problems and achieve the objects set forth in item 1. The present invention transmits and receives ultrasonic waves to and from a subject. Extract Doppler signals from received signals L-+IA In ultrasound diagnostic equipment that measures blood flow 1:1 based on Doppler signals, an ultrasound probe with multiple transducers is Divide into groups [each vibration divided into 7 J' 7! means for electronically scanning 'f and receiving a plurality of ultrasound beams from the same region; and calculation means for calculating the maximum blood flow velocity from each of the plurality of signals from the receiving means and calculating the effective component and invalid component of the blood flow velocity from each of the angles and the maximum blood flow velocity. It is characterized by:

(Effects) By taking such measures, the following effects are achieved. Each divided transducer group is electronically scanned to receive multiple ultrasound beams from the same region, and the formation between the multiple ultrasound beams and the blood flow flowing to the region is based on the position of the transducer group and the position of one region. The angle is determined, the maximum blood flow velocity is determined from multiple signals from the receiving means, and the effective and inactive components of the blood flow velocity are determined from each angle and maximum blood flow velocity. Speed measurement errors can be reduced, and inspection time can be shortened because angle setting operations are no longer necessary.

(Example) Specific examples of the present invention will be described below. FIG. 1 is a schematic block diagram showing the first embodiment of the ultrasonic diagnostic apparatus according to the present invention, and FIG. 2 is the angle between the blood flow direction and the M raster at an arbitrary observation point on the M raster of the monitor. FIG. 3 is a diagram for explaining the settings, and FIG. 3 is a diagram for explaining the operation of the embodiment.

As shown in FIG. 1, the ultrasonic diagnostic apparatus includes an ultrasonic probe 1
, transmission system 2 (, pulse generator 2A, transmission delay circuit 2
B. Pulsar 2C1 The reception system 3 includes a preamplifier 3A and a reception delay circuit 3B. The device also includes an envelope detection circuit 4A as a B-mode processing system 4, a phase detection circuit 5A as a Doppler mode processing system, a range gate circuit 5B, and an FFT 5C.

The arithmetic circuit 5D1 has a DSC 6A (digital scan converter) as a display system 6, a TV monitor 6B, and a controller 17 as a control system.

Ultrasonic probe 1 has multiple ultrasonic and wave vibrations (channels).
In order to perform the sector electronic scanning shown in Fig. 2, the excitation timing of each transducer is set in the desired direction so that the transmission direction of the ultrasonic beam sequentially changes in a fan shape for each pulse of the ultrasonic beam. We will change it accordingly. That is, first, when the pulse generator 2A receives a clock pulse (not shown), it generates a rate pulse corresponding to the ultrasonic repetition frequency and outputs it to the transmission delay circuit 2B.

The transmission delay circuit 2B sets a predetermined delay time for each channel so that the ultrasonic wave is transmitted from the ultrasonic probe T-1 in a desired direction. The pulser 2C is the transmission delay circuit 2B
A drive pulse is generated from the delayed rate pulse outputted from the ultrasonic probe 1, and each transducer of the ultrasound probe 1 is driven.

Thus, the ultrasound probe 1 generates ultrasound and transmits the ultrasound into the living body via the living body surface 5. This ultrasonic wave is partially reflected by blood vessels within the cow's body and blood flow (mainly red blood cells) within the blood vessels, and the echo signals thereof are received by the same transducer.

The preamplifier 3A amplifies the echo signal input from the ultrasound probe 1-, and then transmits this echo signal to the reception delay circuit 3.
Output to B. The reception delay circuit 3B provides a delay time, and then an adder (not shown) adds the signals of each channel. The added signal is then output to an envelope detection circuit 4A and a phase detection circuit 5A. The envelope detection circuit 4A performs envelope detection on the received signal from the reception delay circuit 3B, and outputs B-mode image data (tomographic image data) to the DSC 6A.

The phase detection circuit 5A inputs the echo signal input from the reception delay circuit 3B and a reference signal (not shown), performs phase detection, and obtains phase information, that is, a Doppler shift frequency consisting of a Doppler signal and a clutter component.

This signal is converted into a digital signal by an A/D converter (not shown), and clutter components are removed by a filter (not shown) to obtain a Doppler signal. Then, in order to extract the Doppler signal only at the depth of the blood flow in the living body, the Doppler signal is manually input to the range gate circuit 5B.

Here, as shown in Figure 2, on the monitor is a fan shape = 1
2--shaped tomographic image and blood flow information are displayed simultaneously, and a raster M is set so that it intersects with the blood flow S. Further, a sample volume SV (range gate position) is set near the intersection, and a mark R is displayed so as to rotate around the center O. This mark R is rotated by an arbitrary angle θ about the center O by rotating an encoder (not shown).

Then, the angle θ is determined by aligning the mark R with the estimated blood flow direction 17.

Further, when the encoder is manually rotated in an arbitrary direction, the controller 10 rotates the mark R in conjunction with this, calculates the angle θ, and outputs this angle to the calculation circuit 5D. As shown in FIG. 2, the range gate circuit 5B detects the sampling volume SV (also referred to as the range gate position) on any rask M displayed on the TV monitor.
Apply a range gate to extract only Doppler signals within this range. The FFT 5C as a frequency divider converts the Doppler signal from the range gate circuit 5B into a frequency solution +11
Obtain temporal changes in blood flow velocity.

Next, the features of the first embodiment will be explained with reference to FIG. The feature of this embodiment is that, as shown in FIG. Angle θ with the sound wave beam
, θ2 is determined by controller 0, and this angle θ θ and 1°
2 The apparent maximum flow velocity at this angle is Vmaxl.

an arithmetic circuit 5 for calculating an effective blood flow component from which invalid blood flow components have been removed based on vmaχ2, that is, a true maximum flow velocity value;
It is at the point where D was set.

That is, first, the Doppler maximum velocity Vmaxl at the angle θ1 between the ultrasonic beam and the blood flow on the biological surface a1
is detected by FFT5C. Next, the ultrasound probe 1 is moved to the living body surface a2 to detect the Doppler maximum velocity v max2 at the angle θ2 between the ultrasound beam and the blood flow.

Then, the calculation circuit 5D calculates the angle θ from the controller 0.
, θ2, and the maximum speed is Vmaxi, and Vmax2 is FF.
Starting from T5C, the respective values are substituted into Vmax-Vo+Vr/cosθ. Then, Vmaxl = Vo + V
r/co sθIVmax2=Vo+V r/
It becomes c o sθ2.

Solving the above equation, the effective component V and the reactive component Vr are Vo-(
Vmaxlocos θ, −Vmax2°eO8θ2
)/(cos θ −eO8θ2) Vr−cose −coθ2 (V maxi −V
max2)/(cos θ2-cos θ1).

Furthermore, the blood vessel diameter 2 obtained by range game 1/circuit 5B
Using R, the calculation circuit 5D calculates the cross-sectional area A of the blood vessel at the observation point from A=πr2.

Then, the calculation circuit 5D calculates the blood flow ff1Q as Q = A'
It can be obtained from V o /2.

Thus, the effective component V and the invalid component V from the arithmetic circuit 5D
r, blood flow rate Q, and B-mode image data from the envelope detection circuit 4A are simultaneously displayed on the TV monitor 6B via the DSC 6A.

−15= In other words, the effective component of blood flow velocity is 0. The ineffective component is 0.

Vr and blood flow ff1Q can be displayed simultaneously. In other words, if you measure the maximum speed from two angles, Vo, Vr
can be found. This can improve the accuracy of the blood flow needle placement. Furthermore, since the flow status can be displayed, such as displaying the active component V and the reactive component Vr, the reliability of the device can be improved.

As described above, according to this example, the active ingredient (2). .

Since the invalid component Vr can be separated, angle dependence is eliminated and the true blood flow rate can be determined. From this, for example, in a blood vessel near the body surface, although the ultrasound beam angle θ is large, the true blood flow rate can be determined without increasing the flow m fllll constant error.

Next, a second embodiment of the present invention will be described. The first thing mentioned above
In the example, the angle-dependent error for determining the flow rate was regarded as a turbulence component, and the true value of the blood flow velocity was determined. However, the angle between the blood flow direction and the ultrasound beam must be manually set on the B mode, which is a difficult operation.

Therefore, the second embodiment solves this problem. This second embodiment will be explained below.

FIG. 4 is a block diagram showing the main parts of the second embodiment. In the second embodiment, the aperture plane of the ultrasound beam 1 is divided into three transducer groups 1a, lb, and lc, and the transducer group 1c is driven to transmit, and the reflected echo from the transducer group IC is received. A receiving circuit 3D receives reflected echoes from the transducer group 1a, and a receiving circuit 3C receives reflected echoes from the transducer group 1b. Further, FFT5C-1 performs frequency analysis on the signal from the receiving circuit 3D, FFT503 performs frequency analysis on the signal from the receiving circuit 3C,
FFT5C that analyzes the frequency of the signal from the transmitter/receiver circuit 2E
2, and an arithmetic circuit 5D that calculates the true blood flow velocity based on the outputs from these FFTs 5C1 to 5C3. That is, in the second embodiment, the transmitting/receiving circuit 2E and the receiving circuit 3C
, 3D, and receives reflected echoes in parallel and simultaneously in real time.

Next, the operation of the second embodiment will be explained. By driving the transducer group IC by the transmitting/receiving circuit 2E, ultrasonic waves are transmitted from the transducer group IC toward the living body. Then, the ultrasonic waves reflected at the pressure site S of the living body (assumed to be the blood flow velocity V) are transmitted through the transducer group 1a at an angle θ with respect to the blood flow velocity V, and a velocity f corresponding to the velocity The signal is received by the receiving f0 circuit 2D.

Further, the reflected ultrasonic waves are received by the transmitting/receiving circuit 2E via the transducer group IC as a signal corresponding to the angle θ relative to the blood flow velocity V and the velocity Vd2. Furthermore, the reflected ultrasound waves pass through the transducer group 1b at an angle θ with respect to the blood flow velocity V.
, the signal corresponding to the speed Vd3 is received by the receiving circuit 3C. Furthermore, each echo signal is subjected to each FFT
5C1, 5C2°5C3, and the maximum blood flow velocity Vmaxi, Vmax2. Vma
x3 is required. After that, the arithmetic circuit 5D performs FFT
Maximum blood flow velocity V m of 5C1, 5C2, 5C3'lJ)
axi, V max2. V max3 and angle θ
Based on ~θ, the following equation is calculated.

Vd1=Vocosθt+Vr Vd2=Vocosθ2+VrVd3−Vocosθ3+Vr...(2
)Δ01=01-02 Δθ2=02-θ3 Here, V Vr is unknown and Δθ1.

0” Δθ2 is known.

θ2=θ1−Δ~03″″θ2−Δθ2 =θ1−Δθ1−Δθ2 (3). Here, the relationship between θ, θ, and θ3 is the depth position of one non-digital gate and the aperture surface (geometric position) of the vibrator.
required from. For example, as shown in Figure 5, the opening center O
Since the arbitrary transducer position X, range lead depth d, and angle θb are known, Δθ=tan ((x
The angles Δθ and Δθ2 are automatically determined in advance from +dslnθb)/deosθb)-θb.

Therefore, by substituting equation (3) into equation (2) and solving the three-dimensional linear simultaneous equations in real time, θ, V, and Vr can be obtained.

O As described above, according to the second embodiment, each of the divided transducer groups 1a to 1c is electronically scanned to receive a plurality of ultrasound beams from the same region, and the positions of the transducer groups] a to 1c are 1 part S
Receiving circuits 3C and 3D calculate the angles θ, θ, and θ between the plurality of ultrasonic beams and the blood flow flowing in region S1 based on the position of point S1.

The maximum blood flow velocity V m is determined from multiple signals from the transmitter/receiver circuit 2E.
axi, V max2. Find V max3 and each angle.

Since the effective component V and the invalid component Vr of the blood flow velocity are calculated in real time from the maximum blood velocity, even if the angle becomes large, the measurement error of blood flow velocity can be reduced, and there is no need to set the angle. , inspection time can be shortened.

This can improve the accuracy of blood flow measurement. Angle detection can also be performed in real time, and changes in angle caused by vibration of the ultrasonic probe or body movement can be tracked. Therefore, by determining the cross-sectional area from the range gate width, a great effect can be obtained in flow rate display. Furthermore, in areas such as the rabbit artery (for example, areas where shallow blood vessels parallel to the body surface are diagnosed using a large-diameter ultrasound probe such as a linear electric r-scanning ultrasound probe), this implementation Examples are particularly useful.

Note that the present invention is not limited to the embodiments described above. The present invention is also applicable to linear electronic scanning type ultrasound probes as described above. Furthermore, the method of dividing the vibrator group is not limited to this embodiment. Of course, various modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] According to the present invention, each divided transducer group is electronically scanned to receive a plurality of ultrasound beams from the same part, and a plurality of ultrasound beams are received based on the position of one part of the transducer group. Determine the angle between the ultrasound beam and the blood flow flowing through the site, determine the maximum blood flow velocity from multiple signals from the receiving means, and calculate the effective component and invalid component of the blood flow velocity from each angle and maximum blood velocity. Therefore, even if the angle becomes large, the measurement error of blood flow velocity can be reduced.
Moreover, since the operation for setting the angle is not required, it is possible to provide an ultrasonic diagnostic apparatus that can shorten the examination time.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing a first embodiment of the ultrasonic diagnostic apparatus according to the present invention, and FIG. 2 is an angle setting between the blood flow direction and the M raster at an arbitrary observation point on the M raster of the monitor. 3 is a diagram for explaining the operation of the device shown in FIG. 1, FIG. 4 is a schematic block diagram showing the second embodiment of the present invention, and FIG. FIG. 6 is a diagram for explaining an example of a conventional method for determining blood flow velocity, FIG. 7 is a diagram showing temporal changes in blood flow velocity, and FIG. is a diagram showing the relationship between blood flow velocity and power, Figure 9 is a diagram to explain blood flow measurement, and Figure 1 is a diagram showing the relationship between blood flow velocity and power.
Figure 0 is a diagram showing the relationship between the angle between the ultrasound beam and the blood flow direction and the blood flow velocity, Figure 11 is a diagram showing laminar flow and turbulent flow,
Figure 12 is a diagram showing the flow state of blood flow, Figure 13 is a diagram to explain the effective component and invalid component of blood flow velocity, and Figure 14 is a diagram showing the angle between the ultrasound beam and the blood flow direction and blood flow. FIG. 3 is a diagram showing the relationship between the flow velocity and the ineffective component. 1...Ultrasonic probe, 2 people...Pulse generator, 2B...
... Transmission delay circuit, 2C ... Pulser, 2E ... Transmission and reception circuit, 3A ... Preamplifier, 3B ... Reception delay circuit, 3C, 3D ... Receiving circuit, 4A ... Envelope detection circuit, 5A...Phase detection circuit, 5B...Range gate circuit, 5C, 5C1, 5C2, 5C3...FFT. 5D...Arithmetic circuit, 6A...DSC, 6B...T
V monitor, 10...controller. Applicant's agent Patent attorney Takehiko Suzue JP-A-4-2081.42 (8)

Claims (1)

[Claims] An ultrasound probe equipped with multiple transducers in an ultrasound diagnostic device that transmits and receives ultrasound waves to and from a subject, extracts a Doppler signal from the received signal, and measures blood flow based on the Doppler signal. means for dividing the transducer into a plurality of transducer groups and electronically scanning each of the divided transducer groups to receive a plurality of ultrasound beams from the same region; means for determining the angle between the plurality of ultrasonic beams and the blood flow flowing in the region based on the method, and determining the maximum blood flow velocity from the plurality of signals from the receiving means, and calculating the maximum blood flow velocity from each of the angles and the maximum blood flow velocity. An ultrasonic diagnostic apparatus characterized by comprising a calculation means for determining an effective component and an inactive component of flow velocity.