JPS6257541A - Blood stream state display method in 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] (a) Industrial application field The present invention uses the ultrasonic Doppler effect to measure the blood flow spectrum in a living body, and can display the blood flow distribution in the depth direction in real time. The present invention relates to a method of displaying blood flow dynamics in an ultrasonic diagnostic apparatus.

(b) Prior art and its problems Conventionally, when diagnosing blood flow dynamics inside the heart, the ultrasonic pulsed Doppler method has been widely applied.

This ultrasonic pulse Doppler method utilizes the fact that when an ultrasound pulse is emitted into a living body, the frequency of the ultrasound echo reflected from inside the living body is slightly shifted from the frequency of the emitted ultrasound pulse due to the Doppler effect. It measures the blood flow velocity in the living body.

By the way, conventionally, in order to observe blood flow dynamics, one sets a sampling point at the area where the blood flow dynamics are to be measured while looking at an ultrasound tomographic image, and then the radiation direction of the ultrasound beam is set at that point. It is fixed toward the site and displays temporal changes in blood flow on a monitor or the like. This method only determines the temporal change in blood flow velocity at one point in the diagnosis target region, and when measuring the blood flow velocity at another region -M, the position of the verse sampling point is determined. It has to change. Therefore, if you want to observe the distribution of blood flow velocity in the depth direction on a tomographic image at a certain time phase of a living body, you must repeat the above operation many times and infer the distribution state from these data. It is difficult to understand blood flow distribution intuitively.

On the other hand, the Doppler signals obtained from each site in the body are subjected to fast Fourier transform to obtain a blood flow spectrum, the average surface flow velocity at each site is calculated from this blood flow spectrum, and the data of this average blood flow velocity is calculated. Once stored in memory, it is displayed in red depending on the direction of the blood flow, for example, if the blood flow is approaching the emitted ultrasound beam, it is displayed in blue if it is moving away from it, and then the average blood flow is displayed. There is a method of displaying blood flow dynamics by applying brightness modulation according to the flow velocity and superimposing it on a previously captured tomographic image.

Although this display method allows the two-dimensional distribution of blood flow to be easily observed, since the average blood flow velocity is modulated in brightness, it is difficult to read the distance change in the average blood flow velocity from the extent of this brightness change. Therefore, it is not possible to quantitatively understand the blood flow velocity distribution in the depth direction of the diagnostic site.

The present invention has been made in view of the above circumstances, and is capable of displaying distance changes in blood flow direction and blood flow velocity over a certain depth direction within a living body in real time. The purpose is to enable quantitative understanding of flow dynamics.

(C) Means for solving the problem In order to achieve the above object, the present invention sets a certain predetermined time phase based on the biological information signal, and at this time, the radiation direction of the ultrasound beam and Set multiple sampling points corresponding to the depth direction on the ultrasound beam,
Next, the Doppler signal obtained from each site in the body corresponding to each sampling point is fast Fourier transformed to obtain a blood flow spectrum at each sampling point, and one axis is calculated from these blood flow spectra. The direction and speed are displayed, and the other axis is displayed as depth.

(D) Embodiment FIG. 1 is an explanatory diagram showing the timing of acquiring Doppler signals for carrying out the method of the present invention.

The blood flow velocity distribution in the depth direction within the living body is displayed as follows. First, a trigger signal is extracted based on the R wave included in the ECG signal obtained from the electrocardiograph in synchronization with the heartbeat of the living body, and a certain period of time τ is emitted from this trigger signal. Later, an ultrasound beam is emitted into the living body and Doppler signals are collected.

Delay time τ from trigger signal. is set in advance to correspond to a predetermined time phase of the living body. For example, if you want to observe the blood flow distribution during the ejection phase of the heart,
Since the period during which the wave appears roughly corresponds to this time phase, it is a certain time τ from the R wave. After a while, when a T wave appears, an ultrasound beam is emitted and Doppler signal collection begins. In other time phases, the ultrasound beam is sector-scanned to obtain tomographic images.

When collecting Doppler signals, the radiation direction of the ultrasound beam is set to the direction of the aorta on the tomographic image, as shown in FIG. is emitted continuously, for example, 128 times. At this time, a plurality of sampling points (for example, 200 points) are set corresponding to the depth direction on the ultrasonic beam.

When an ultrasound beam is emitted into a living body, the ultrasound is reflected from various parts within the living body, and by receiving this with a transducer, an ultrasound echo signal is obtained. Then,
The ultrasonic echo signal is phase-detected to extract a Doppler signal, and the extracted Doppler signal is fast Fourier transformed (FF
T) to obtain blood flow spectra at all 200 sampling points. Based on this blood flow spectrum, as shown in Figure 2(b), the horizontal axis is the direction and velocity of the blood flow, the vertical axis is the depth of the sampling point, and the power of the blood flow spectrum is expressed as the brightness change. Display each on the monitor. At this time, the blood flow distribution is displayed superimposed on the tomographic image of that time phase or separately from the tomographic image.

In this way, an appropriate time phase is set for the trigger signal synchronized with the R wave of the ECG signal, and the ultrasonic vibrator is set under this time phase.
- By obtaining and displaying multiple blood flow spectra on a frame, distance changes in blood flow dynamics can be directly grasped.

In the above embodiment, the Doppler signal is collected every time in synchronization with the R wave, but if the Doppler signal is collected every few times and the period in between is used as the period for obtaining tomographic images, the tomographic images can be obtained continuously. Since the tomographic image is displayed as a moving image, it becomes easier to see the tomographic image. Furthermore, when a keyboard or the like is operated, the blood flow distribution may be displayed only at that time. Alternatively, the blood flow distribution may be continuously displayed by constantly collecting Doppler signals regardless of the ECG signal.

(e) Effects As described above, according to the present invention, the direction of blood flow and distance changes in ocean current speed across a certain depth within the body are displayed in real time, so blood flow dynamics can be quantitatively measured. Excellent effects such as being able to understand the information are demonstrated.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the acquisition timing of Doppler signals for implementing the method of the present invention, and FIG. 2 is a diagram showing an example of display of a tomographic image and blood flow velocity distribution on a monitor.

Claims (1)

[Claims] (1) Setting a certain predetermined time phase based on the biological information signal,
Under this time phase, multiple sampling points are set corresponding to the radiation direction of the ultrasound beam and the depth direction on the ultrasound beam at that time, and then data is obtained from each part of the body corresponding to each sampling point. The Doppler signal is fast Fourier-transformed to obtain a blood flow spectrum at each sampling point, and from these blood flow spectra, one axis is displayed as the direction and velocity of the blood flow, and the other axis is displayed as depth. A method for displaying blood flow dynamics in a sonic diagnostic device.