JPH034842A - Ultrasonic doppler diagnostic device - Google Patents

Abstract

PURPOSE:To detect vector velocity showing an exact motion state and to display information concerning this vector velocity in the past before a present time point by pictures as well by providing plural frame memories, etc., to successively store two-dimensional Doppler information in a reagent. CONSTITUTION:The vector velocity is calculated according to the information in the plural frame memories and a frame memory controller 71 is provided to control to read memory in frame memories 70. On the other hand, a tangential velocity memory 73 is provided to store tangential velocity and a tangential velocity averaging circuit 74 is provided. The absolute value of this vector velocity and a vector angle, etc., are averaged concerning the prescribed number of data by a vector velocity averaging circuit 78 and supplied to a display device 28. Accordingly, as the vector velocity information, both the not-averaged velocity and the averaged velocity can be selectively displayed by the pictures on a CRT display. Thus, the vector velocity information before the lapse of a prescribed time can be read.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an ultrasonic Doppler diagnostic device, in particular, an ultrasonic Doppler diagnostic device that emits ultrasonic waves into a subject, receives velocity information due to the Doppler effect, and detects motion reflectors within the subject. The present invention relates to an ultrasonic Doppler diagnostic device that accurately displays the movement state of a person on a screen.

[Prior Art] Ultrasonic Doppler diagnostic equipment is well known, which displays an image of the state of intracardiac blood flow using a moving reflector that emits an ultrasonic pulse beam or the like into a subject such as a living body. The velocity distribution state of the blood flow is determined by receiving the reflected echo of the blood flow from within the subject and detecting the Doppler effect received by the reflected echo as a frequency shift of the ultrasound carrier frequency.

[Problem to be solved by the invention] By the way, in such conventional devices, the velocity obtained with a single beam is only the velocity component moving in the ultrasound beam direction (radial direction in sector scanning), and the actual velocity is There is a problem in that it is difficult to display accurate speed according to the direction of movement.

Therefore, conventionally, multiple ultrasonic pulse beams are emitted from different positions a certain distance apart to the same position on the subject, and the obtained multiple velocity signals are synthesized to calculate the velocity including the direction of motion of the motion reflector. It is done to find out.

However, this method not only complicates the equipment, but also
In particular, it has the disadvantage that it is difficult to apply to a region such as the heart where the position and angle at which the ultrasonic pulse beam can be inserted are limited.

In addition, in the ultrasonic transmission/reception direction in sector scanning, vector velocity can be determined by comparing and calculating velocity signals obtained by emitting two ultrasonic pulse beams having a minute deflection angle difference. This is proposed in the No. 152437 publication.

According to this, an ultrasonic pulse beam is first emitted several times in a predetermined direction, and then an ultrasonic pulse beam is emitted multiple times in a direction that is slightly different from the predetermined direction by a small deflection angle. By calculating the tangential velocity in real time from the two velocity signals in the radial direction having , it is possible to finally obtain the vector velocity.

However, in this case, although it is possible to calculate the vector velocity in real time and display an image, it is not possible to display the previous motion state as an image again after displaying the motion state.

When performing image diagnosis, there are cases where it is desired to compare and observe two diagnostic images after a predetermined period of time has elapsed, and it is desired to be able to display an image of the past speed state that has already been obtained.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to detect a vector velocity indicating an accurate motion state in a sector scanning device, and to obtain past information on this vector velocity before the present time. Another object of the present invention is to provide an ultrasonic Doppler diagnostic device that can also display images.

Another object of the present invention is to provide an ultrasonic Doppler diagnostic device that clearly displays the calculated vector velocity using arrows and allows the velocity state to be easily grasped on the screen.

[Means for Solving the Problems] In order to achieve the above object, the present invention scans sectors within a subject with an ultrasonic pulse beam at a constant repetition period, demodulates the reflected echo signals obtained as a result, and demodulates the reflected echo signals obtained as a result. In an ultrasonic Doppler diagnostic device that detects the velocity of a motion reflector by detecting the velocity of a motion reflector, a plurality of frame memories sequentially store two-dimensional Doppler information within a subject in a radial direction in a sector arc to be scanned, and a selected frame memory. A tangential velocity calculator extracts Doppler information with minute deflection angle differences in the ultrasound beam direction and calculates the tangential velocity in the sector arc from this Doppler information, and a vector velocity is calculated from this tangential velocity and the radial velocity in the radial direction. A vector velocity calculator that calculates. Further, in the invention of claim (2), the tangential velocity computing unit comprises a difference signal computing unit and a multiplier, and the vector velocity computing unit computes the vector angle by calculating the arctangent of the ratio of the tangential velocity to the radial velocity. and an absolute value calculator that calculates the square root of the sum of the squares of the tangential velocity and the radial velocity.

Furthermore, the invention according to claim (3) is characterized in that, in addition to the above configuration, a display device is provided for displaying the vector velocity calculated by the vector velocity calculation unit as an arrow in the tomographic image.

[Operation] According to the above configuration, the ultrasound pulse beam is sector-scanned within the subject at a predetermined deflection angle, and the radial velocity in the ultrasound beam direction obtained by this sector scanning is 1. Each frame is sequentially stored in the frame memory.

Then, the tangential velocity is first calculated using an arbitrarily selected frame memory.
This will be explained based on the diagram.

In the figure, the actual speed (vector speed) is, for example, 0-4 in any direction in one frame memory.
The tangential velocity V is calculated from the radial velocity "rl" of a and the radial velocity "r2" in the direction ob-b which is separated by a small deflection angle Δφ from the 0-1-3 direction. That is, for example, by calculating the difference When performing
1 cos θ - cos (θ + Δφ month -・Δφ Δφ (1hi 1: absolute value of vector velocity, θ: angle formed between actual velocity direction and ultrasound beam direction)
...(1) Here, if Δφ(1), the above (1
) formula becomes ΔV−1 sin θ·Δφ. Therefore, by multiplying this ΔV by the coefficient -1/Δφ, the tangential velocity V perpendicular to the ultrasound beam direction
is required.

-ΔV·(−1/Δφ) −ly l sinθ −(2) The tangential velocity thus obtained is subjected to vector calculation together with the radial velocity. That is, the angle indicating the actual velocity direction, that is, the vector angle θ, and the absolute value of the vector velocity are determined by the following equation.

1 θ〜j an (V t / V r t )
...(3) υ1-par 'υ-1...(4) rl t In this way, the vector velocity indicating the actual velocity is obtained, and the absolute velocity and direction of motion of the motion reflector can be accurately imaged. It becomes possible to display.

The vector velocity calculation in this case is performed using the information in the frame memory, and past velocity information can be extracted by using the information in the frame memory slightly before the current time.

In addition, this vector velocity is displayed by indicating the direction of motion (vector direction) with an arrow and its absolute value by the length of the arrow, thereby making it possible to clearly indicate the actual velocity state.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a circuit block diagram of the main components of an ultrasonic Doppler diagnostic apparatus according to a first embodiment of the present invention, in which an ultrasonic pulse beam is emitted from a probe 1O toward a subject 11. Ru. In order to radiate this ultrasonic pulse beam, a transmitting/receiving section 12, a scanning control section 13, and a timing generating section 14 are provided, and the timing generating section 14 generates an ultrasonic transmission frequency signal and Generates timing signals for transmission and reception. The transmitting/receiving section 12 controls the output of the ultrasonic pulse beam based on the control of the scanning control section 13. In addition, the transmitting/receiving section 12
A velocity calculation unit 16 is connected to the ultrasonic beam direction radial velocity obtained by sector scanning, and the velocity calculation unit 16 calculates the radial velocity in the ultrasound beam direction from the Doppler shift frequency of the reflected echo signal.

This radial velocity information is stored in frame 100 (j~100(j!+k)) in which the radial velocity for each tomographic image is stored.
is stored in the frame memory 70, but this radial velocity information may be frequency shift information that has not yet been converted into a velocity value.

It can be calculated using the following calculation.

In other words, the Doppler shift frequency is fo, and the absolute value of the flow velocity is 1.
Hi1. The angle between the fluid flow direction and the ultrasound beam is θ,
When the sound speed is C2 and the transmission frequency of ultrasonic wave is f, the radial velocity V is Or V −1υl cosθ−(fd/2fo)c...
(5) The radial velocity is calculated using this equation (5).

The characteristic feature of the present invention is that the vector velocity is determined using information in a plurality of frame memories.
．． In the embodiment, the frame memory 70 is capable of storing frame information for 64 frames or 32 frames.

Therefore, a frame memory controller 71 is provided to control reading of the memory in the frame memory 70, and on the other hand, a tangential velocity calculator 72 is provided to calculate the tangential velocity. Since the absolute flow velocity is calculated, a tangential velocity memory 73 and a tangential velocity averaging circuit 74 are provided to store the tangential velocity for this purpose.

Further, the present invention calculates a vector velocity based on the tangential velocity and radial velocity determined by the tangential velocity calculator 72, but for this purpose, the radial velocity stored in the frame memory 70 is averaged. an averaging circuit controller 76 that controls the radial velocity averaging circuit 75;
, a vector velocity calculator 77, a vector velocity averaging circuit 78 for computing an average value of vector velocity, and an averaging circuit il controller 79 for controlling this vector velocity averaging circuit 78.

Furthermore, a display device 28 using a CRT display is provided to display the calculated vector velocity superimposed on the tomographic image.

FIG. 3 shows the internal circuit of the tangential velocity calculator 72, which calculates the difference between the radial velocity Vr1 in a certain direction and the radial velocity Vr2 in a direction shifted by a slight deflection angle. a code converter 30 and an adder 31 for (-1/Δφ
). The sign converter 30 inverts the sign of the radial velocity vr2 and outputs it as -vr2 to the adder 31, and the adder 31 converts the sign to the radial velocity vr1.
As a result, a difference operation is performed.

Further, FIG. 4 shows the internal circuit of the vector velocity calculator 77, which includes the radius vector, velocity vr1 (3)
t to calculate jan-1(V/V) of the equation
rl Consists of an angle calculator 36.

As shown in FIG. 10, since the angle θ calculated by the above method is an angle with respect to the radial velocity direction on which the calculation is based, when actually displaying it, a reference line is set and, for example, It is preferable to use the center line OP in the figure as a reference line and to indicate the vector angle by the angle φ with respect to the reference line. That is, if the scanning angle with respect to the center line OP is β, then φ−θ−
By calculating β, the angle φ can be calculated, which allows accurate vector angle display.

The first embodiment has the above configuration, and its operation will be explained below.

By sequentially transmitting and receiving ultrasonic waves into the subject, velocity information for each frame 100 is stored in the frame memory 70. Here, for example, frame 10 of a certain time
0i) to find the vector velocity.

In this case, the scanning line m in the frame 1001)
The radial velocity vr1 at the depth d of the scan line m+1 (direction 0-a in FIG. 10) and the scanning line m+1 (direction 0-1- in FIG. 10).
Direction 0-4b separated from the a direction by a small deflection angle Δφ)
The radial velocity "r2" at the depth d is supplied to the tangential velocity calculator 72. Then, the sign converter 30 and the adder 31 perform the difference calculation of the equation (1), and then the multiplier 32
Accordingly, the difference calculation of the above equation (2) is performed, and the tangential velocity V 2 is calculated.

After this tangential velocity V is stored in the tangential velocity memory 73, the tangential velocity averaging circuit 74 calculates, for example, the tangential velocity obtained in frames (1) to (j!+k) within a predetermined time. The average value is calculated. On the other hand, the average value of the radial velocity is calculated in the radial velocity averaging circuit 75 in the same manner as in the case of the tangential velocity, and both average values are supplied to the vector velocity calculator 77.

In this vector velocity calculator 77, the radial velocity Vr1
The absolute value of the vector velocity is calculated from the average value of and the average value of the tangential velocity V0 by the above equation (4), and the above (
3) The vector angle will be calculated using the equation. In this embodiment, the absolute value of the vector velocity and the vector angle are also averaged by the vector velocity averaging circuit 78 for a predetermined number of data, and then supplied to the display device 28. Therefore, CR selectively uses both unaveraged and averaged vector velocity information.
7 images can be displayed on the display.

According to the first embodiment, vector velocity information from a predetermined time ago can be read out, and when applied to the heart, for example, the velocity state at a desired time during one cycle of heartbeat can be extracted. By performing the arithmetic processing twice, there is an advantage that a plurality of pieces of speed information at different times can be compared simultaneously on the screen.

FIG. 2 shows a second embodiment of the present invention, which has a simple structure and can improve the accuracy of the vector velocity value obtained.

That is, a radial velocity averaging circuit 75 is provided immediately after the frame memory 70, and the tangential velocity is determined from the average value of the radial velocity.

For example, in the radial velocity averaging circuit 75, (1) to (j
! The average value of the radial velocity obtained in the frames up to +k) is first calculated, and the averaging circuit controller 80 calculates the average value of the radial velocity ()
) to l+k), the depth d of the mth scan line of the frame
The radial velocity V of the scanning line m+1st depth d of the frame from rlm (1) to (12+lc) is defined as the tangential velocity r,
m+1 times are supplied to the arithmetic unit 72.

Therefore, the tangential velocity and vector velocity are calculated based on the averaged radial velocity, and highly accurate velocity information can be obtained within an allowable predetermined time.

Next, FIG. 5 shows a third embodiment of the present invention,
This third embodiment is characterized in that the tangential velocity calculator 72 has a circuit configuration based on complex calculations.

That is, the third embodiment has a complex signal converter 44a consisting of a cosine signal converter 40a and a sine signal converter 42a, a complex signal converter 44b consisting of a cosine signal converter 40b and a sine signal converter 42b, The signal converter 40 converts the radial velocity signal into an eO8 signal, and the sine signal converter 4 converts the radial velocity signal into an eO8 signal.
2, the phase of the radial velocity signal is shifted by 90 degrees and converted into a sine signal.

This multi-line signal converter 44 includes four multipliers 46a.

46b, 46C, 46d, a code converter 48, and two adders 50a, 50b are provided, and complex operations described below are performed by these.

It also includes an arctangent calculator 52 that calculates the arctangent of the ratio of the imaginary part I to the real part R of the complex signal, and a multiplier 54 that multiplies (-1/ by Δφ). A multiple search operation is performed by , and an accurate velocity in the orthogonal direction can be determined.

The operation shown in FIG. 5 will be explained using an arithmetic expression.

As shown in FIG. 10, the radial velocity Vr1 in the direction 0-a and the radial velocity Vr2 in the 0-b direction separated by a minute deflection angle Δφ are expressed by the following equations.

Vrl"'hi cosθ...(6)v
r2−′hi1cos(θ+<6)−(7) Here, Vrl and vr2 (or frequency deviation) in equations (6) and (7) are complex when the Doppler signal is expressed as a complex number. Since the value is proportional to the argument of the phase of the Doppler signal, if we consider the Doppler signal as a complex number of magnitude 1 with the argument of this phase, each complex Doppler signal Z 1
, Z 2 are expressed by the following equations (8) and (9).

Z, mcos (kV, 1) +1 sin (kV,
1) −cos (kVcos θ) +1sin (kVcos θ) ・ (8
)Z −cos (kVr2) 11sIn (kV
r2) 2 −cos ((kVcos (θ + Δφ)) + 1s
ln f(kVcos (θ+Δφ))... (
9) However, k is a proportionality constant expressed by the following formula.

k=(4πf/cf) r Here, f: Ultrasonic transmission frequency f: Ultrasonic repetition frequency C: Sound speed in the living body Find the tangential velocity ■ (-hi sin θ).

That is, when the complex conjugate product of Zl and Z2 is determined, the values of its real part R and imaginary part can be obtained from the following equations (11) and (13).

R[Z fist Z *] 2 -R[(cos kV + 1sin kV, ■)"
1 (cos kV −1sln kVr2) ]2 = cos k (V, 1−Vr2) −(10
)::cos (kVΔφsinθ) R-(11
) I [Z-Z ”] 2 = I [(cos kV +1sin kV, ■)
"1 (cos kV -1sin kVr2) ]2-8ink (■r1-vr2)...(12)::si
n (kVΔφsin θ) I ・ (
13) Then, by substituting equations (11) and (13) into the following equation (14), the tangential velocity v0 can be calculated.

V - (Δφ in 1/) tan -' (1/R) - 1υl sin θ - (14) Therefore, according to the third embodiment, the velocity data of a frame at a certain time selected in the frame memory 70 is is converted into a complex signal by supplying it to a complex signal converter 44,
The tangential velocity {circle over (1)} can be determined by performing the calculation of equation (14) using the real part R and the imaginary part {circle over (1)} of the complex signal.

Then, from this tangential velocity ■ and radial velocity ■r1, the vector angle and the absolute value of the vector velocity are determined by the vector velocity calculator 77, and the vector angle θ and the absolute value 1υ1 of the vector velocity are The angle θ is the angle φ (Fig. 10) with respect to the center line OP, and the angle θ
−β.

This process is performed in the same way for each other point, and is performed sequentially for all points in one frame, but it may also be limited to an arbitrary area, and by specifying the area with a cursor etc., the desired area can be selected. It is also possible to extract the vector velocity of

According to the third embodiment, the tangential velocity can be accurately determined by calculating the complex conjugate product, and therefore the accuracy of the vector velocity is also improved.

The vector velocity determined in the above manner is displayed as an image superimposed on the tomographic image, and as shown in Fig. 6,
Divide the angle into 4 parts, θ degrees and 90 degrees.

Set a predetermined color for each of 180 degrees and 270 degrees,
It is also suitable to display angles between these by changing the mixing ratio of the interposed colors. In this case, the absolute value of the vector velocity is displayed by the magnitude of brightness, and according to this, the greater the velocity, the brighter the color will be displayed.

Another invention is characterized in that the angle of the vector velocity is indicated by an arrow, and as shown in FIG. 7, it is preferable that the angle is indicated by an arrow and the absolute value is indicated by the length of the arrow.

Furthermore, as shown in FIG. 8, angles can be indicated by arrows and absolute values can be indicated by numerical values.

Furthermore, as shown in FIG. 9, both the absolute value and the angle may be displayed numerically, and by selecting the desired point with the cursor display, accurate information on the specific point of interest can be retrieved. I can do it. Note that this numerical display and the arrow display in FIG. 7 may be performed simultaneously.

According to such a display, the direction and absolute value of the vector velocity are clearly displayed, making it possible to provide accurate information for diagnosis.

[Effects of the Invention] As explained above, according to the present invention, vector velocity can be determined using velocity information with minute deflection angle differences between multiple frame memories. In addition to information, vector velocity information before the current time can be displayed as an image, and it is possible to compare the past motion state with the current motion state or the motion state at multiple related times, making it useful for diagnosis. It becomes possible to provide information.

For example, when observing intracardiac blood flow, the vector velocity at each time in the heartbeat cycle can be displayed as an image, and the vector velocity information can also be used to perform other detailed analyses. This makes it possible to provide information that is useful for various types of diagnosis.

Further, according to the invention of claim (3), there is an advantage that the vector velocity is displayed in an easy-to-understand manner, and accurate information regarding the motion direction (vector angle) and velocity value can be easily determined.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing a schematic configuration of an ultrasonic Doppler diagnostic device according to a first embodiment of the present invention, and FIG. 2 is a circuit block diagram showing a schematic configuration of an ultrasonic Doppler diagnostic device according to a second embodiment of the present invention. Circuit block diagram, Fig. 3 is a block diagram showing the internal circuit of the tangential velocity calculator, Fig. 4 is a block diagram showing the internal circuit of the vector velocity calculator, and Fig. 5 is related to other internal circuits of the tangential velocity calculator. A block diagram showing the third embodiment. Figure 6 is an explanatory diagram of color display of vector velocity. Figure 7 is an explanatory diagram of vector velocity displayed with arrows. Figure 8 is an illustration of vector velocity displayed with arrows and numerical values. FIG. 9 is an explanatory diagram when the vector velocity is displayed numerically. FIG. 10 is an explanatory diagram showing the relationship between the actual velocity (vector velocity), radial velocity, and tangential velocity. 10... Probe 12... Transmission/reception unit 13... Scanning control unit 16... Speed calculation unit 28... Display device code converter adder multiplier Absolute value calculator Angle calculator Frame memory Frame memory control tangential velocity calculator tangential velocity memory tangential velocity averaging circuit radial velocity averaging circuit vector velocity computing unit vector velocity averaging circuit.

Claims (1)

[Claims] (1) Sector-scanning an ultrasonic pulse beam within the subject at a constant repetition period and demodulating the resulting reflected echo signal to detect the velocity of a moving reflector within the subject. In an ultrasound Doppler diagnostic device, a plurality of frame memories sequentially store two-dimensional Doppler information within a subject in the radial direction in a sector arc to be scanned, and a minute deflection angle difference in the ultrasound beam direction in a selected frame memory. A tangential velocity calculator that extracts certain Doppler information and calculates a tangential velocity in a sector arc from this Doppler information, and a vector velocity calculator that calculates a vector velocity from this tangential velocity and a radial velocity in a radial direction. An ultrasonic Doppler diagnostic device characterized by: (2) In the device according to claim (1), the tangential velocity calculator comprises a difference signal calculator and a multiplier,
The vector velocity calculator is an angle calculator that calculates the vector angle by calculating the arctangent of the ratio of the tangential velocity to the radial velocity;
An ultrasonic Doppler diagnostic device comprising: an absolute value calculator that calculates the square root of the sum of squares of tangential velocity and radial velocity. (3) Ultrasonic Doppler diagnostic equipment that scans sectors within the subject with an ultrasonic pulse beam at a constant repetition rate, demodulates the resulting reflected echo signals, and detects the velocity of the moving reflector within the subject. , a tangential velocity calculator that calculates the tangential velocity in the sector arc from Doppler information with a minute deflection angle difference in the ultrasound beam direction, and a vector that calculates the vector velocity from this tangential velocity and the radial velocity in the radial direction. An ultrasound Doppler diagnostic device comprising: a velocity calculator; and a display device that displays the vector velocity calculated by the vector velocity calculator as an arrow in a tomographic image.