JP2594959B2 - Ultrasonic Doppler meter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the speed of an object using ultrasonic waves, and more particularly to a device for measuring a blood flow velocity in a living body in real time.

[Conventional technology]

Various devices are known that determine the flow velocity of an object by the Doppler effect of sound waves. In particular, the pulse Doppler method based on phase difference detection is described, for example, in Proc. Of the Second European Congress on Ultrasonics in Medicein 1975 (Proc. Of the Second E).
uropean Congress on Ultrasonics in Medicine, 197
5.) It is described in a paper published on page 144. In the device that uses this method, it is possible to measure the speed of each part at all measurement depths in real time by measuring the phase difference of the received signal at each transmission pulse interval by making the transmission pulse burst-like It is.

[Problems to be solved by the invention]

In the above-mentioned pulse Doppler method, if the repetition frequency of transmission is T, the maximum measurable Doppler shift frequency Fd is 1 / 2T
On the other hand, if the sound wave propagation velocity is S, the measurable depth D is TS / 2. Therefore, the product of Fd and D becomes constant at S / 4, and there is a limit to the measurable speed or measurable depth.

Therefore, an object of the present invention is to provide an ultrasonic Doppler meter capable of eliminating the above-mentioned limitations and measuring a high-speed object velocity even in a deep part.

An object of the present invention is to perform quantitative cardiac function evaluation by measuring acceleration to use for diagnosis. (References, Senda: Cardiac function evaluation by Doppler echocardiography, clinical practice of ultrasound Doppler method, Medical-core, kk Japan Medical Association,
p.155, 1986) [Means for Solving the Problems] In the present invention, the phase difference (corresponding to the speed) of the received signal within the pulse interval of the ultrasonic transmission is determined in advance, and the two successive positions are determined. The difference between the phase differences, that is, the acceleration of the object is measured, and the speed is corrected using the acceleration. This makes it possible to accurately measure the speed at which air-shilling is performed at high speed.

(Example of the invention)

Hereinafter, the configuration of the present invention will be described in detail with reference to examples. In FIG. 1, reference numerals 10-1, 10-2 and 11-1, 11-2 denote a demodulator and a low-pass filter for obtaining a real part and an imaginary part of a received signal, respectively. 12 is a phase angle detector, and the phase angle θ is However, Re: the real part of the received signal, I _m: and requests the same imaginary part.

D is an input terminal, B is an output of the second subtractor 14-2, that is, an acceleration output terminal, C is a corrected second speed output terminal, and A is an output of the first subtractor 14-1 (first output). Speed),
B 'is the output of the integrator 15 and E is the input terminal for the threshold value (TH). 13-1 and 13-2 are delay circuits, 14-1 and 14-2 are subtraction circuits, and 17 is a switching circuit. The signal A is input and the output is input to the integrator 15. The other input of the integrator 15 is the signal B. Reference numeral 16 is an air shilling judging device. Here, the area shilling judging unit sets (C) = (A) when (a) | (A)-(B ') | <TH, and (2) (b) | (A)-(B') | If> TH, then (C) = (B ') (3)

F is the control signal output of the air-shilling judging unit 16, which outputs 0 in the case of the equation (2) and outputs 1 in the case of the equation (3). The switch 17 is ON when the control signal F is 0, and OFF when the control signal F is 1.

According to this configuration, the received signal input from the terminal D is decomposed into a real part and an imaginary part by the demodulator 10 and the low-pass filter 11 and input to the phase angle detector 12. The phase angle θ is obtained by the phase angle detector 12. Next, the difference Δθ (corresponding to the first speed) of the phase angle of the received signal is obtained at the point A by the first delay circuit 13-1 and the first subtractor 14-1. That is, (A) = Δθ = θ _n −θ _{n + 1} = [2ω ₀ / C] · T · v (4) where T: pulse repetition period v: blood cell velocity ω ₀ : ultrasonic frequency c: sound velocity Becomes Here, the Doppler frequency ω _i is as follows: ω _i = [2ω ₀ / C] · v = Δθ / T (5) Similarly, the second delay circuit 13-2 and the second subtraction circuit 14-2 similarly use the phase difference ΔΔθ.
Stops at point B. That is, ΔΔθ = (Δθ) _n- (Δθ) _{n + 1} (6). The phase angle difference ΔΔθ is converted by the integrator 15 into a phase angle difference Δθ (corresponding to the second speed). That is, Here, if the acceleration ΔΔθ is constant within the pulse time interval T, then: ΔΔθ · T + K where K: integration constant.

Next, the above-mentioned judgment (Equations (2) and (3)) is made by the air-shilling judging unit 16 to obtain an accurate speed (second speed).
Can be found. Here, the output A (first speed) of the switch 17 is used as the integral eigennumber K in a range where the equation (2) is satisfied. (K = (A) = ((Δθ) _n ) However, Equation (3)
Is satisfied, the control signal of the determiner 16 becomes F, the switch 17 is turned off, and the phase difference corresponding to the second speed obtained by the integrator 15 is used. (K = (B ')
= (Δθ) ' _n ).

This determination method will be described in more detail with reference to FIG.

FIG. 2A is a schematic diagram of blood flow velocity measurement, wherein 1 is an ultrasonic probe, 2 is a beam direction, P is a measurement point of interest, LA is the left atrium, LV is the left ventricle, and RV is the right ventricle. a ₀ is the artery, IVS is septum, arrows are blood flow direction. FIG. 6B shows a time change of the speed at the point P, and indicates that the phase left Δθ exceeds π and the air is being silenced because the speed is high. FIG. 3C shows a time change of the acceleration at the point P, and the acceleration is in a state where no air-silling is performed. (A) = (B ') in the range where the speed is not air-shilling
((A) is the first speed, (B ') is the speed obtained from the integration of the acceleration, that is, the second speed), and otherwise, | (A)-(B') |> TH Therefore, the corrected speed C is (C) = (B ') (shown by a dotted line).

On the other hand, FIG. 4D shows the case where air-silling is not performed and abnormal blood flow exists. In this case, the backflow is caused by the septal defect. The time changes of the speed and the acceleration at this time are shown in FIGS. In this case, | (A) − (B ′) | <TH is always satisfied, and there is no need to correct ((C) = (A)).

In the above description, the overall configuration of the ultrasonic diagnostic apparatus, for example, the transmission / reception deflection circuit of the sector scanner, the preamplifier, the probe, and the display are omitted. In FIG. 1, the description of the A / D converter, the addition processing for improving the signal-to-noise ratio, and the like are omitted.

The present invention relates to a flat plate probe and a mechanical using the same.
It is effective for scanners, sectors and linear electronic scanning devices.

In the above description, the ultrasonic wave has been described.
The present invention is also effective for general waves such as light, electromagnetic waves, and lasers. Also, various methods can be considered for obtaining the integration constant.

〔The invention's effect〕

As described above, according to the present invention, it is possible to accurately measure a high-speed blood flow velocity exceeding a limit determined by a transmission pulse interval, which is clinically beneficial.

As another effect, the acceleration parameter is effective for evaluation of cardiac function such as left ventricular contractility.

[Brief description of the drawings]

FIG. 1 is an embodiment of the present invention, and FIG. 2 is an explanatory diagram thereof. 12 ... Phase detector, 13 ... Delay circuit, 14 ... Subtractor, 15
…… integrator, 16 …… determiner, 17 …… switcher.

Continuation of the front page (72) Inventor Shizuo Ishikawa 1-280 Higashi Koigabo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (56) References JP-A-61-25527 (JP, A) JP-A-61-98243 ( JP, A)

Claims (1)

(57) [Claims] An ultrasonic Doppler meter for transmitting an ultrasonic wave to an inspection object and measuring a speed of an object in the inspection object based on a reception signal of the ultrasonic wave from the inspection object, wherein the Doppler of the reception signal is Means for determining a phase shift due to an effect and measuring a first speed; means for measuring a second speed from an integral of a difference between the successive phase shifts corresponding to the successive first speeds; When the absolute value of the difference between the first speed and the second speed exceeds a predetermined threshold,
Means for correcting the first speed to the first speed as the first speed.