JPS6266843A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a technology for detecting high-speed blood flow using the pulsed Doppler method, and in particular, to ultrasonic diagnosis suitable for detecting high-speed blood flow and displaying its detection points (sample points). It is related to the device.

[Background technology]

In ultrasonic diagnostic equipment, there are two methods for detecting high-speed blood flow in deep areas: (1) a method that uses continuous wave Doppler, and (2) a method that uses continuous wave Doppler.
) There is a method of increasing the repetition frequency using pulsed Doppler.

The sample points cannot be determined using method (1) above.

In addition, the method (2) has the problem that a tomographic image of a deep part cannot be obtained and that only a shallow part of the sample point can be determined.

[Purpose of the invention]

An object of the present invention is to provide a technique for detecting high-speed blood flow in five deep areas while confirming sample points in a tomographic image using the pulsed Doppler method.

The above and other objects and novel features of the present invention will become clear from the description of the present RIA and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, when detecting a Doppler signal, the pulse repetition period is shortened, and when detecting a tomographic image, the pulse repetition period is made longer than twice that of Doppler detection, so that the tomographic image and
The present invention is characterized by providing means for simultaneously displaying more than one pulsed Doppler sample point.

To detect high-speed blood flow, it is necessary to increase the repetition frequency, while to obtain a tomographic image of the probed area, it is necessary to lower the repetition frequency.

However, it is not necessary to detect tomographic images and blood flow Doppler signals at the same time; when detecting blood flow Doppler signals, the repetition frequency is increased, and when trying to obtain tomographic images, it is necessary to detect them at fixed intervals (1 second or The repetition frequency may be lowered to 1 cardiac cycle) and the tomographic image and Doppler sample points may be displayed.

[Embodiments of the invention]

Hereinafter, the present invention will be explained using examples and drawings.

In addition, in all the figures for explaining the embodiment, parts having the same functions are given the same reference numerals, and repeated explanations thereof will be omitted.

The schematic configuration of the system of the ultrasonic diagnostic apparatus of this example is shown in the first section.
This is shown in the block diagram of the figure.

In FIG. 1, a reflected signal due to the ultrasonic wave emitted from the ultrasonic probe l by the ultrasonic repeating signal output from the control circuit 7 passes through the ultrasonic probe 1 and the ultrasonic transmitting/receiving circuit 2, One passes through a detection circuit 3 and becomes a tomographic signal for depicting a tomographic image, and the other passes through a pulsed Doppler detection circuit 4, where Doppler beats at arbitrary depths are detected, frequency analyzed by a frequency analysis circuit 5, and become a Doppler signal.

The image switching circuit 6 stores the tomographic signal and the tomographic signal alternately in the memory of the digital scan converter 8, and the contents are displayed on the television monitor 9.

On the other hand, regarding the Doppler shift frequency by the pulsed Doppler method, the following equations (1) and (2) are related.

fd= C2vcosO/C) Xfo −(1)f
d: Doppler shift frequency V: Blood flow velocity θ: As shown in Fig. 3, the angle between the ultrasound beam and the blood flow C: Sound speed in the living body fo: Ultrasonic frequency fd = PRF/2...・・・・・・・・・
(2) 18K fdMAX: Maximum detectable Doppler frequency PRF: Ultrasonic repetition frequency Therefore, in order to detect high-speed blood flow, PRF should be made high and fo should be made low.

For example, in order to detect a blood flow velocity of 5 fil/S with 2 MHz ultrasound at 0=0, C= 1500 m/S.
If s, then (1) and (2) formula II PRF= (2X 5/+500) x2000x2=
26.7 (KI+7.), and the depth of the tomographic image that can be drawn with this repetition frequency is about 3 [3, -1] deeper parts cannot be drawn. This situation will be explained using FIG.

In order to detect high-speed blood flow, the signal is sampled repeatedly as shown in FIG. 2(C). The tomographic image obtained by this method is the shaded area in Fig. 2 (Δ), and the image of the valve ['' that is originally aimed at cannot be drawn. If the reflected signal is repeatedly sampled, the PRF becomes low and high-speed blood flow cannot be detected.

In conventional devices, in order to detect high-speed blood flow in the area indicated by the black circle (・) in Fig. 2 (A), an image of the diagonal area and sample points of individual points (x) are displayed. In this example, the tomographic image is rewritten at regular intervals according to the control signal from the control circuit 7, and when the tomographic image is not being drawn, that is, when the Doppler signal is being detected, the PRF is rewritten as shown in Figure 2 (C). The PRF is set high to detect the mixed signals of the parts (x) (・) (-) shown in Figure 2 (A), and when the tomographic image is drawn, the PRF is lowered as shown in Figure 2 (B). It is possible to display N cross-sectional images to the depths as shown in FIG. 2(A) and accurate sample points of (×)(·)(-). The reason for displaying multiple sample points is that as shown in Fig. 4 (B), when the PRF becomes high, the reflected signal from one or more previous launches and the reflected signal from the current launch are mixed and received. , to make it clear.

Next, FIG. 5 shows a control flowchart outlining mode selection and control of each mode of the ultrasonic diagnostic apparatus of this embodiment.

The Doppler mode of this embodiment is as shown in FIG.

■ Display of B-mode image (ultrasonic tomographic image), ■ Display of direction of ultrasound beam, ■ Display of sample point, ■ Fixation of ultrasound beam, (Sh; Detection of Doppler signal at sample point) It consists of steps.

In the control for displaying sample points during B mode, as shown in FIG. The relationship with o is PRT
When o≧PRT, the sample depth SB when displaying sample points and the sample depth S0 when detecting Doppler signals at sample points may be the same, but in order to detect high-speed blood flow, PRTo <PRT8. Therefore, 511=n
It becomes XP RT □ + S o.

That is, sample point Ss r = So r Ss
2=PRTO+SO, 583=2PRTO+SO・・
The most accurate display is to obtain 5IIN=(n-1)PRTo+80 and display all sample points in the B7 to D images. This is shown in a flowchart as shown in FIG.

〔Effect of the invention〕

As explained above, according to the present invention, when detecting a Doppler signal, the pulse repetition period is shortened, and when detecting a tomographic image, the pulse repetition period is made longer than twice that of Doppler detection, so that the tomographic image and By providing a means to simultaneously display two or more pulsed Doppler sample points, high-speed blood flow in deep areas can be detected while checking the sample points on a tomographic image, improving sample position accuracy and flow velocity measurement accuracy. can do. Thereby, the cutting accuracy can be improved.

It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a system of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining a PRF and a tomographic image corresponding thereto. FIG. 3 is a diagram for explaining the basic method of the Doppler method, and FIG. 4 is a diagram for explaining PRF and reflected signals. FIG. 5 is a control flowchart for explaining mode selection and control of each mode of the ultrasonic diagnostic apparatus of this embodiment; FIG. 6 is a diagram for explaining sample point display in a B-mode image; FIG. 7 is a control flowchart for displaying sample points in a B-mode image. In the figure, 1... Ultrasonic probe, 2... Ultrasonic transmitting/receiving circuit, 3... Detection circuit, 4... Pulse Doppler detection circuit, 5... Frequency analysis circuit, 6... Video switching circuit, 7
. . . control circuit, 8 . . . digital scan converter, 9 . . . television monitor.

Claims (1)

[Claims] (1) Ultrasonic probe, ultrasonic transmitter/receiver circuit, detection circuit, pulsed Doppler detection circuit, frequency analysis circuit, video switching circuit,
In an ultrasonic diagnostic device consisting of a control circuit, etc., when detecting a Doppler signal, the pulse repetition period is shortened, and when detecting a tomographic image, the pulse repetition period is made longer than twice that of Doppler detection, and the pulse repetition period is set to be twice as long as the tomographic image. 1. An ultrasonic diagnostic apparatus comprising means for simultaneously displaying more than one pulsed Doppler sample point.