JP2659748B2 - Ultrasonic Doppler device - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial application field) The present invention relates to an ultrasonic Doppler device capable of measuring a flow rate of a fluid using the Doppler effect of an ultrasonic wave.

(Prior Art) The color Doppler flow mapping method is expected to be a method capable of non-invasively quantifying reflux, instead of cardiovascular imaging. However, at present, there is no established method for grading backflow by the color Doppler method. The methods proposed so far perform grading based on geometric characteristics such as the length, width, and area of the backflow jet, but not based on the absolute flow rate of the backflow jet.

(Problem to be Solved by the Invention) The flow rate of the jet is given by (flow velocity × cross-sectional area). However, it is difficult to accurately measure the areas of the backflow port, the short circuit port, and the valve port of the valve regurgitation / short flow / stenosis flow.

Accordingly, it is an object of the present invention to provide an ultrasonic Doppler apparatus capable of determining a jet flow rate without measuring a cross-sectional area by using the properties of a free jet.

[Structure of the Invention] (Means for Solving the Problems) In a first invention, a flow velocity of a fluid at a first measurement point set at an ejection port position on a color Doppler image is calculated from a result of ultrasonic transmission / reception. A first flow velocity calculating means for calculating a flow velocity of the fluid at a second measurement point set at an arbitrary position distant from the ejection port on the color Doppler image in the fluid ejection direction from the ultrasonic transmission / reception result; The apparatus comprises a flow velocity calculating means, a distance calculating means for calculating the distance between the first and second measurement points, and a flow rate calculating means for calculating an ejection flow rate of a fluid based on a calculation result of each of the calculating means.

According to a second aspect of the present invention, there is provided a flow velocity calculating means for calculating a flow velocity of a fluid at a measurement point set at an ejection port position on a color Doppler image, a flow velocity information inputting means for inputting desired flow velocity information, and A distance measuring means for averaging the fluctuation of the corresponding position of the input flow velocity information on the color Doppler image to obtain a distance between the averaged position and the measurement point; a measurement result of the distance measuring means and the flow velocity calculation; And a flow rate calculating means for calculating an ejection flow rate of the fluid based on the calculation result of the means and the flow rate information input by the flow rate information inputting means.

When you ejected from an orifice (created for) the free turbulent jet with uniform velocity V _N, a distance L in the spout in the center of the region in which the fluid has not yet mixed around the fluid has been ejected jet (This is called a laminar core). In this laminar core, the flow rate is kept at Vn (see FIG. 8). Assuming that the shape of the ejection port is a circle, its diameter is D, and an arbitrary distance M (>
It is known that if the flow velocity on the central axis of the jet separated by L) is Vx, the following relationship holds.

L = 6.8D (1) Vx / Vn = L / M (2) The jet spreads in a conical shape with a half-apex angle of about 10 °.
The following equation is obtained from the equations (1) and (2).

Vn · D = [Vx / 6.8] M (3) If Vx is the minimum speed that can be detected by a certain device,
If there is no angle dependence, M can be regarded as the range of the jet aimed by the device. At this time, since Vx is a constant value inherent to the device, Vn · D∝M (4) This relationship has been experimentally confirmed by Wranne et al.
Since Vn ・ D is neither the flow rate nor the size of the spout,
The reverse flow rate or the size of the reverse flow port cannot be graded only by the reaching distance M. However, (4)
In equation (5) obtained by dividing the equation by V ₀ , D∝M / Vn (5) It is shown that a value obtained by dividing the reaching distance X by the ejection velocity Vn can be an index of the size of the backflow port. Jetting flow rate Q of the jet becomes ([pi] D ^2/4) · given by Vn, but (3) the use of ^{formula, Q = 0.017 (Vx) 2} (M 2 / Vn) ... (6). Here, assuming that Vx is the minimum detectable speed, the jet spreads conically at a constant half apex angle (approximately 10 °), so that the area S captured by the flow mapping is proportional to M ² . Therefore, Q∝S / Vn (7) This relationship indicates that a value obtained by dividing the jet spreading area S by Vn is an index for grading the flow rate Q.

 The following equation is obtained by modifying the equation (6).

Q = 0.017 (M · Vx) ² / Vn (8) Here, the ejection speed Vx and the distance M from the ejection port (>
If the velocity Vx on the central axis at a position separated by L) can be measured, the flow rate Q can be obtained.

Therefore, in the first invention, the fluid flow velocity (Vn, Vx) at the first and second measurement points and the distance (M) between the first and second measurement points are obtained, and the ejection flow rate (Q ) Is calculated.

Here, since the flow of the fluid is diffused near the second measurement point, it may be difficult to measure the fluid flow velocity at the second measurement point with high accuracy. Therefore, in the second invention, arbitrary fluid information is input, and corresponding position fluctuations of the input information on the color Doppler image (flow mapping) are averaged.
1. A distance (M) corresponding to the second distance between measurement points is obtained. Note that the flow rate (Q) calculation itself based on Vn, Vx, and M is the same as in the first embodiment.

When the fluid is blood, that is, when this device is used for abnormal diagnosis, the flow rate of the blood spout can be reduced without measuring the area of the regurgitant port, the shunt port, and the valve port of the valve regurgitation / short-circuit flow / stenosis flow You can ask.

(Examples) Hereinafter, the present invention will be described specifically with reference to examples.

 FIG. 1A shows an embodiment of the first invention.

Reference numeral 1 denotes an input unit. The input unit 1 includes first measurement point setting means 2 and second measurement point setting means 3. First
The measurement point setting means 2 sets a first measurement point (N) at the position of an ejection port (for example, a valve opening of a heart) on a color Doppler image, and the second measurement point setting means 3 The second measurement point (X) is set at an arbitrary position in the Doppler image that is away from the ejection port in the fluid ejection direction. This first
As the second measurement point setting means 2, 3, for example, a trackball provided on an operation panel is applied.

Reference numeral 4 denotes a blood flow imaging unit. The blood flow imaging unit 4 uses a single ultrasonic probe to perform blood flow information and tomographic image (B-mode image) information by using an ultrasonic Doppler method and a pulse reflection method. (Detailed later).

Reference numeral 5 denotes a jet flow rate calculation unit, which calculates the flow velocity and flow rate of blood (described in detail later).

The blood flow imaging unit 4 and the jet flow calculation unit 5 are CP
It is connected to the U bus 7.

The blood flow information obtained by the blood flow imaging unit 4 and the calculation result of the jet flow calculation unit 7 are transferred to the display control unit 8 via the CPU bus 7, and under the control of the display control unit 8. The information is displayed on the display unit 9.
A CRT display is applied to the display unit 9.

A CPU (Central Processing Unit) 6 controls the operation of the entire device of this embodiment.

Next, based on FIG.
Will be described.

The jet flow rate calculator 5 functionally includes a first flow rate calculator 5a, a second flow rate calculator 5b, a distance calculator 5c, and a flow rate calculator 5d.

The first flow velocity calculating means 5a calculates the blood flow velocity (Vn) at the first measurement point (N) set by the first measurement point setting means 2. Second flow velocity calculating means 5b
Calculates the blood flow velocity (Vx) at the second measurement point (X) set by the second measurement point setting means 3. The distance calculation means 5c calculates the distance (M) between the first and second measurement points. Also, the flow rate calculating means 5d
Calculates the jetting flow rate (Q) of blood based on the calculation plan of each of the calculation means 5a, 5b, 5c. The calculation of the ejection flow rate (Q) is based on the execution of the calculation of the equation (8).

Here, the algorithm of the first and second flow velocity calculating means 5a, 5b will be described.

In FIG. 3, reference numeral 11 denotes an ultrasonic probe, which forms a B-mode image and a blood flow distribution image of a subject (heart in this case) based on a reception echo of the ultrasonic wave transmitted from the probe 11, and The blood flow distribution image (color) is superimposed and displayed on the mode image (black and white) (this display image is a “color Doppler image”). When the first measurement point (N) is set on this color Doppler image, the first flow velocity calculating means 5a
Calculates the flow velocity (Vn) at the first measurement point (N) by executing the calculation of the equation (9).

When the second measurement point (X) is established on the color Doppler image, the second flow velocity calculating means 5b executes the calculation of the equation (10) to execute the calculation at the second measurement point (X). Calculate the flow velocity (Vx).

(9) and (10), fd _n, fd _x ultrasonic propagation velocity Doppler shift frequency, C is in the body (sound velocity), f ₀
Is the center frequency of the ultrasonic wave. Further, θ _x and θ _n are obtained from the angle between the points N and X and the scanning line with the position of the ultrasonic probe 11 as the origin.

Note that the distance between the first and second measurement points (M) is obtained based on the coordinate information of the first and second measurement points (N, X).

Next, the detailed configuration of the blood flow imaging unit 4 in FIG. 1A will be described with reference to FIG.

Reference numeral 11 denotes an ultrasonic probe for transmitting / receiving ultrasonic pulses to / from a subject, and 12 denotes an analog section of a sector electronic scanning device, which includes a preamplifier 13, a pulser 14, an oscillator 15, a delay line 16, and an adder.
17, a detector 18 is provided. 19 is a DSC (digital scan converter), 20 is a color processing circuit, 35
Is a control circuit, and 29 is a marker generator.

One of the signals output from the adder 17 is a detector 18,
The data is sent to the DSC 19 via the line 37, and is used to display a tomographic image (monochrome B-mode image). The other is sent below line 39 and serves to display a blood flow image. line
The signal added from 39 is split into two, mixers 24a and 24b, respectively.
Is added to Each mixer 24a, 24b has a 90 ° phase shifter 2
Reference signal f ₀ from the oscillator 15 by 5 is added each to have a 90 ° phase difference. As a result, the low-pass filters 26a and 26
The b receives the Doppler shift frequency component fd and the (2f ₀ + fd) signal, and the high-pass components are removed by the low-pass filters 26a and 26b to obtain only the Doppler shift frequency component fd. This is a phase detection output signal for forming a blood flow distribution image and calculating the flow velocities Vn and Vx.

The phase detection output signal includes not only blood flow information but also unnecessary reflected signals (referred to as clutter) from slow-moving objects such as the heart wall. Therefore, the clutter is removed. Phase detection output is MTI (Moving Targ
et Indicator) calculation unit 27.

The MTI operation unit 27 includes an A / D converter, a multi-line memory, an MTI
Filter, autocorrelator, average speed calculator, variance calculator,
It is composed of a power calculation unit.

Therefore, the value calculated for each point is DSC19
After the data is interpolated and converted into color information by the color processing circuit 20. For example, the flow approaching the probe 11 is converted to reddish, and the flow away from the probe is converted to blued.

In addition, the marker generation unit 29 is provided with the first and second
This generates information for forming a marker indicated at a measurement point (N and X) set position by the measurement point setting means 2 and 3 (see FIG. 1 (a)).
At 9 the image is superimposed on the color Doppler image. The first,
The second measurement setting information is transmitted to the jet flow rate calculation unit 5 via the control circuit 35.

Next, the operation of the embodiment device configured as described above will be described.

Under the control of the control circuit 35 shown in FIG. 2, ultrasonic transmission / reception is performed by the sector electronic scanning analog section 12, and the B
A mode image and a blood flow distribution image are formed and are displayed on the display unit 9 under the control of the display control unit 8 in FIG. FIG. 4 shows an example of this display.

The operator measures the first and second measurement points (N and X) on this display image (color Doppler image) by operating the input unit 1. Then, the flow velocity Vn at the first measurement point (N) is obtained by the first flow velocity calculation means 5a in FIG. 1 (b) (by executing the calculation of the formula (9)), and the second flow velocity calculation means is obtained. The flow velocity Vx at the second measurement point (X) is obtained by 5b (by executing the calculation of the expression (10)). Further, the distance (M) between the first and second measurement points is obtained by the distance calculation means 5c. Further, the flow rate calculating means 5d obtains the first measurement point (N), that is, the flow rate (Q) of the blood passing through the valve port which is the ejection port, based on the calculation results of the respective calculating means 5a, 5b, 5c (before ( 8) by executing the calculation of the equation). Then, the required M,
Vn, Vx and Q are numerically displayed on the display screen of the display unit 9 under the control of the display control unit 8 (see FIG. 4).

As described above, according to the present embodiment, valve regurgitation, short-circuit flow,
It is possible to determine the blood ejection flow rate without measuring the area of the reverse flow port, short-circuit port, and valve port of the stenotic flow.

FIG. 1 (c) shows an embodiment of the second invention.
In FIG. 1C, components having the same functions as those shown in FIG. 1A are denoted by the same reference numerals.

The device of the embodiment shown in FIG. 1 (c) is greatly different from the device shown in FIG. 1 (a) in the configuration of the input section 41 and the jet flow rate calculation section 45.

The input unit 41 includes a measurement point setting unit 42 and a flow velocity information input unit 43. The measurement point setting means 42 sets the measurement point (N) at the position of the ejection port (for example, the valve port of the heart) on the color Doppler image. A trackball or the like is applied in the same manner as the above.
The flow velocity information input means 43 is for inputting desired flow velocity information, and a keyboard or the like is applied to the flow velocity information input means 43.

Further, as shown in FIG. 1 (d), the jet flow rate calculation unit 45 functionally includes a flow rate calculation unit 45a, a distance measurement unit 45b,
It has a flow rate calculating means 45c. The flow velocity calculating means 45a calculates the blood flow velocity (Vn) at the measurement point (N) set by the measurement point setting means 42. This flow rate (V
The calculation of n) is based on the execution of the calculation of the equation (9) as in the case of the first flow velocity calculating means 5a in FIG. 1B. The distance measuring means 45b averages the fluctuation of the corresponding position on the flow velocity distribution (that is, the color Doppler image) of the flow velocity information input by the flow velocity information inputting means 43, and calculates the difference between the averaged position and the measurement point (N). The distance (M) between them is determined. At the second measurement point (X) in the above embodiment, since the blood flow is diffused, the measurement accuracy of the flow velocity (Vx) may be deteriorated.
Therefore, as described above, the flow velocity (Vx) at the position corresponding to the second measurement point (X) is set first, and the distance (M) is determined in reverse, so that the ejection flow rate calculation accuracy is improved. Is increasing. The corresponding position of the flow velocity information on the color Doppler image is as shown by 21 in FIG. 5, which fluctuates. If a special color is assigned to this, the distance (M) Can be measured on the display screen.

In FIG. 1 (d), the flow rate calculation means 45c takes in the above Vx, Vn, M and calculates the ejection flow rate (Q) by executing the calculation of the equation (8).

The display of Vx, Vn, M, Q and the like are the same as those shown in FIG.

Next, a model experiment performed by the inventor of the present application will be described.

A jet is created in a phantom device (water bath) using four types of nozzles having an inner diameter of 1.4, 2.0, 3.0, and 4.0 mm (see FIG. 6), and Vn, while changing the flow rate in the range of 0.2 to 2.2 / min. Vx, M was measured. In the measurement, the apparatus shown in FIG. 1A was used, and a combined CW probe (2.5 MHz) capable of detecting a high flow rate as the ultrasonic probe 11 was used. In particular, the measurement of Vx
Due to poor stability, the color shift was performed using the zero shift function. In addition, the angle between the ultrasonic beam and the jet is set to be 60 ° or less because the error increases when the angle is 70 ° or more. Further, for the flow measurement for comparison, an ultrasonic flow meter manufactured by Transonic Systems (measured from the difference in arrival time of ultrasonic waves between two points sandwiching the fluid; accuracy: 2%) was used.

The measured flow rate (estimated flow-rate) obtained by substituting the actually measured Vn, Vx, and M into equation (8) and the flow rate (me
Fig. 7 shows the relationship with the asured flow-rate). A good linear relationship of Y = 1.01X + 0.06 (r = 0.96, SE = 0.19) was established between the two, regardless of the difference in nozzle diameter.

From these experimental results, it is clear that in the case of a free turbulent jet, the jet flow rate can be obtained with high accuracy from the above equation (8) even if the sectional area of the jet port is not known. In order to be a free turbulent jet, the number of Reynolds nozzles must be about 2500 or more. For left heart regurgitation, the pressure difference is 80
It is considered that the above condition is often satisfied because the flow velocity reaches about 4 mm / s or more around mmHg.

The first and second embodiments of the present invention have been described above.
The first and second inventions are not limited to the above embodiment, and needless to say, various modifications can be made.

For example, a plurality of second measurement points are provided, and for each point, the flow velocity (Vx) and the distance (M) are obtained, and two or more ejection flow rates (Q)
May be calculated and averaged to obtain the final ejection flow rate (Q). In this way, the measurement accuracy of the ejection flow rate can be further improved.

[Effects of the Invention] As described above in detail, according to the first and second aspects of the present invention, it is possible to obtain the ejection flow rate of the liquid without measuring the cross-sectional area by using the properties of the free jet. An ultrasonic Doppler device can be provided.

[Brief description of the drawings]

FIG. 1 (a) is a block diagram showing an embodiment of the first invention, FIG. 1 (b) is a detailed configuration block diagram of a jet flow rate calculation unit in FIG. 1 (a), and FIG. 1 (c). FIG. 1D is a block diagram showing an embodiment of the second invention, FIG. 1D is a detailed block diagram of the jet flow rate calculation unit in FIG. 1C, and FIG. 2 is a blood diagram in FIG. 1A. FIG. 3 is a detailed block diagram of the flow imaging unit, FIG. 3 is an explanatory diagram of a main algorithm in the jet flow rate calculation unit in FIGS. 1 (a) and (b), and FIG. 4 is a table of a display unit in FIG. 1 (a). FIG. 5 is an explanatory diagram of an example of the display, FIG. 5 is an explanatory diagram of a display example of the display unit in FIG. 1 (b), FIG. 6 and FIG. FIG. 8 is an explanatory diagram of a free turbulent jet. 2... First measurement point setting means 3... Second measurement point setting means 4... Blood flow imaging unit 5a... First flow velocity calculation means 5 b. 5c: distance calculation means, 5d: flow rate calculation means, 9: display unit (display means), 42: measurement point setting means, 43: flow velocity information input means, 45a: flow velocity calculation means, 45b ... Distance measuring means, 45c ... Flow rate calculating means.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-96233 (JP, A) JP-A-51-89463 (JP, A)

Claims (3)

(57) [Claims] 1. An ultrasonic Doppler apparatus for obtaining a color Doppler image based on a reception port of an ultrasonic wave transmitted toward a jet port and a fluid jetted from the jet port, the jet port on the color Doppler image. First flow velocity calculating means for calculating the flow velocity of the fluid at the first measurement point set at the position from the ultrasonic transmission / reception result, and set at an arbitrary position separated from the ejection port on the color Doppler image in the fluid ejection direction. Second flow velocity calculating means for calculating the fluid flow velocity at the second measurement point obtained from the ultrasonic transmission / reception result, distance calculating means for calculating the distance between the first and second measurement points, and each of the calculating means An ultrasonic Doppler device comprising: a flow rate calculating means for calculating a flow rate of ejected fluid based on a result of the calculation. 2. An ultrasonic Doppler apparatus for obtaining a color Doppler image based on a jet port and a reception echo of an ultrasonic wave transmitted toward a fluid jetted from the jet port, the jet port on the color Doppler image. A flow velocity calculating means for calculating the flow velocity of the fluid at the measurement point set at the position based on the ultrasonic transmission / reception result; a flow velocity information inputting means for inputting desired flow velocity information; and the flow velocity information inputted by this means. Distance measurement means for averaging the variation of the corresponding position on the color Doppler image and determining the distance between the averaged position and the measurement point,
An ultrasonic wave having flow rate calculating means for calculating the flow rate of fluid ejection based on the measurement result of the distance measuring means, the calculation result of the flow rate calculating means, and the flow rate information input by the flow rate information inputting means. Doppler device. 3. The ultrasonic Doppler device according to claim 1, wherein said fluid is blood.