JP2000225115A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically obtain the real-time accurate number of heartbeats without using an electrocardiograph. SOLUTION: This device is designed to perform scanning of a transmitted/ received ultrasonic beam by a scan controller 15, obtain successively at each scan B-mode images by a B-mode processing system 16, calculate an auto- correlation about the change with passage of time of each of the pixel data by a CPU 19, and obtain the average of the auto-correlation about the pixel belonging to a region where the change in the B-mode images is intensive. By detecting the obtained peaks of the waveform, the number of heartbeats is obtained by their intervals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus for obtaining an image of the inside of a human body or the like using ultrasonic waves.

[0002]

2. Description of the Related Art When an image of a subject is obtained by an ultrasonic diagnostic apparatus, it is sometimes necessary to measure a heart rate.
In such a case, an electrocardiograph is usually attached to the subject, and E
Although it is determined from the R-wave interval of the CG waveform, an additional electrocardiograph is required according to this. Therefore, it is also determined from the image of the ultrasonic diagnostic apparatus. That is, an M-mode image or a D-mode image is taken for the circulatory system, an operator observes the image, manually designates a peak on the image, obtains a peak-to-peak distance (time), and obtains a heart rate ( Every minute). Here, the M-mode image is obtained by capturing a temporal change in the echo signal intensity distribution of one line in the ultrasonic beam direction, and the D-mode image is obtained by capturing the speed of blood flow as a change over time. .

[0003]

However, if the operator observes the image obtained by the ultrasonic diagnostic apparatus and designates it by manual operation to obtain the heart rate as in the prior art, the operation is complicated and the burden on the operator is increased. It is large and inaccurate, and above all, cannot measure heart rate in real time.

[0004] In view of the above, it is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of automatically determining an accurate heart rate in real time from an image obtained by the ultrasonic diagnostic apparatus.

[0005]

In order to achieve the above object, means for transmitting and receiving ultrasonic waves one after another in time, means for calculating an autocorrelation relating to a temporal change of a sequentially obtained received ultrasonic signal, It is characterized in that there are provided means for obtaining a peak in the obtained autocorrelation waveform, and means for calculating a heart rate based on the interval between the obtained peaks.

[0006] Received ultrasonic signals are sequentially obtained. When an autocorrelation is calculated with respect to a temporal change of the signals, a spatio-temporal smoothing effect is obtained. Therefore, in this autocorrelation waveform, it is easy to find a peak and find the interval between the peaks, and it is possible to automatically find the peak in real time by image processing or the like. In addition, the temporal and spatial smoothing effect prevents the received signal from being affected by minute changes or noise over time, so that accuracy can be ensured. Since the interval between the peaks corresponds to the heartbeat cycle, the heart rate (per minute) can be obtained therefrom. Therefore, it is possible to obtain an accurate heart rate in real time without using any other special device only by the ultrasonic diagnostic apparatus.

[0007]

Next, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, an array type probe 11 has a number of ultrasonic transducers arranged in an array. The transmission / reception circuit 12
Consists of a number of individual transmitting and receiving circuits connected to the individual transducers. The transmission beamformer 13 supplies a drive signal to each transmission / reception circuit in the transmission / reception circuit 12 to operate a number of ultrasonic transducers of the array type probe 11 at the same time to synthesize ultrasonic waves generated from these. The receiving beamformer 14 gives a delay time to each of the received ultrasonic signals obtained from each ultrasonic transducer of the array type probe 11 and synthesizes these signals.

The scan controller 15 controls the focus and direction of the synthesized transmission ultrasonic wave by controlling the timing and the delay time of the drive signal, and also controls the focus and direction of the synthesized reception ultrasonic wave obtained by the signal synthesis. The direction is set to be the same as the above-mentioned transmission ultrasonic wave. Then, control is performed on the drive timing and the delay time that determine the direction so that the combined transmitted / received ultrasonic wave to be transmitted / received one after another scans a plane.

Therefore, the array-type probe 11 is applied to the diagnosis site of the subject, a specific cross section is scanned with the synthesized ultrasonic beam, and the received signal is processed by the B-mode processing system 16, as shown in FIG. Such a fan-shaped ultrasonic image (B-mode image) 31 is obtained. This image data is sent to a DSC (Digital Scan Converter) and an image memory 18 where it is converted into a TV video signal,
Sent to Since this image 31 is sequentially obtained for each ultrasonic beam scan, the display image is updated by setting the ultrasonic beam scan rate to be as fast as the frame rate of the TV video signal, thereby updating the display image. Can display video. This makes it possible to diagnose a moving circulatory system when the circulatory system is used as a diagnostic site.

In this B-mode image 31, data arranged on one specific line 32 in the direction of the ultrasonic beam, ie, 1
A one-dimensional array of signal intensities at each arrival time for one received ultrasonic signal is extracted. Such a one-dimensional image,
An M-mode image as shown in FIG. 3 is obtained by obtaining the B-mode images 31 obtained one after another for each scan and arranging them in the direction of the acquisition time of the B-mode images 31. In FIG. 3, the vertical axis represents the arrival time of one received ultrasonic signal, that is, the distance of the ultrasonic reflector, and the horizontal axis represents the acquisition time of a large number of B-mode images 31. This M
The mode image is a specific line 3 penetrating the internal organs of the subject.
2 represents a temporal change of a one-dimensional image (one-dimensionally arranged pixels).

Further, the Doppler processing system 17 captures the Doppler shift of the frequency of the received ultrasonic signal from a specific portion 33 on a specific line (not limited to the line 32 shown) of the B-mode image 31. The specific portion 33 may be a single pixel, or may be a certain number of pixels, and the Doppler shift obtained for each of them may be averaged to obtain speed information. The speed information is obtained for each of the sequentially obtainable B-mode images 31 and arranged in the direction of the time axis at which the B-mode images 31 are obtained, whereby a waveform (D-mode image) as shown in FIG. 4 is obtained. The D-mode image represents a temporal change of the blood flow velocity distribution in the blood vessel by designating the specific portion 33 in the blood vessel, for example.

In this way, a B-mode image 31, an M-mode image, and a D-mode image for the circulatory system are obtained, and these image data will be collected for about two cardiac cycles. Meanwhile, the frame rate (scan rate) of the image data is much higher than the heart rate (every second). Then, the CPU 19 calculates the autocorrelation of these image data.

In the case of the B-mode image 31, an autocorrelation is calculated with respect to a temporal change of data for each pixel.
Since the B-mode image 31 for the circulatory system is obtained, the change of the autocorrelation is large near the moving heart, and the change of the autocorrelation is small at the portion where there is no movement.
Therefore, for example, only the autocorrelation of the pixel for a large portion of motion corresponding to 30% of the area of the image 31 is extracted, and the average thereof is calculated. Then, an autocorrelation waveform as shown in FIG. 5 is obtained.

This waveform is a smooth waveform subjected to smoothing in space and time and space. That is, by taking the autocorrelation with respect to the temporal change of the data of each pixel, spatio-temporal smoothing is performed, and by averaging the autocorrelation of each pixel, spatial spatial smoothing is performed. As a result, the entire movement can be accurately captured without being affected by a minute temporal change and a change different for each small portion.
Therefore, if two peaks in this waveform are detected and the interval between them, that is, the time, is calculated, the time becomes a heartbeat cycle, from which a heart rate (per minute) can be obtained. These are processed by the CPU 19 and displayed on the display device 20. Therefore, the heart rate can be obtained almost in real time at the time when about two heartbeat cycles have elapsed.

In the case of an M-mode image, one line of pixel data is sequentially obtained in time, so that an autocorrelation of a time change is obtained for each of the one-dimensionally arranged pixel data.
In this way, spatio-temporal smoothing is performed. The average of the autocorrelation of each pixel obtained in this way for only one line or a portion having a large motion is calculated. Since the averaging process enables smoothing in a metric space, a smooth autocorrelation waveform as shown in FIG. 5 is eventually obtained by the smoothing in a spatio-temporal and metric space. As with the B-mode image, the autocorrelation waveform is smooth, so that it is easy to automatically detect the peak, and an accurate heart rate can be obtained in real time.

As described above, the D-mode image has a specific
FIG. 5 shows a temporal change of the blood flow velocity distribution obtained from the Doppler shift of the received signal at the specific portion 33 on the line 32. This also performs spatio-temporal smoothing by obtaining the autocorrelation similarly to the M mode. To obtain a smooth waveform. In this case, if the speed distribution indicated by the D-mode image does not indicate the speed distribution obtained from one piece of pixel data but indicates the average value of the speed distribution obtained from several pieces of pixel data, this averaging is performed. This means that metric spatial smoothing is performed by the processing.
As described above, automatic detection of a peak can be easily performed from the smooth autocorrelation waveform, and an accurate heart rate can be obtained in real time.

The above description relates to one embodiment, and the specific configuration and the like can be variously changed. For example, calculation of autocorrelation and averaging processing is performed by the CPU 1
Although the processing is performed according to step 9, it is of course possible to use a dedicated processing device.

[0018]

As described above, according to the ultrasonic diagnostic apparatus of the present invention, a sufficiently smoothed waveform is obtained by obtaining the autocorrelation of the temporal change of the data obtained by the ultrasonic diagnostic apparatus. Since a peak is detected from this waveform, accurate detection can be easily performed and can be automated, and an accurate heart rate can be obtained in real time without using other special equipment such as an electrocardiograph. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a B-mode image.

FIG. 3 is a diagram showing an M-mode image.

FIG. 4 is a diagram showing a D-mode image.

FIG. 5 is a diagram showing an autocorrelation waveform.

[Explanation of symbols]

 Reference Signs List 11 array type probe 12 transmission / reception circuit 13 transmission beamformer 14 reception beamformer 15 scan controller 16 B-mode processing system 17 Doppler processing system 18 DSC and image memory 19 CPU 20 display device 31 B-mode image 32 1 in ultrasonic beam direction Line 33 Specific part

Claims (1)

[Claims] 1. A means for transmitting and receiving ultrasonic waves one after another in time, a means for calculating an autocorrelation relating to a temporal change of a sequentially obtained received ultrasonic signal, and a means for obtaining a peak in an obtained autocorrelation waveform. Means for calculating a heart rate based on the determined peak interval.