JPH04276246A - Ultrsonic diagnostic device - Google Patents

Abstract

PURPOSE:To obtain true power spectrum and a central frequency by removing distortion due to statistical fluctuation. CONSTITUTION:An ultrsonic diagnostic device is furnished with a cine-memory 6, an addition circuit 7, an mean buffer 8, and with a monitor 12. The cine- memory 6 stores blood flow data for plural heartbeats. Both the addition circuit 7 and the mean buffer 8 obtain the average data of the blood data for the plural heartbeats based on the blood data stored in the cine-memory 6.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an ultrasonic diagnostic apparatus, and particularly an ultrasonic diagnostic apparatus that detects blood flow data from reflected echo signals from within a living body and displays information related to the detected blood flow data. Regarding.

0002

[Prior Art] Generally, an ultrasonic diagnostic device transmits ultrasonic waves from an ultrasonic transducer called a probe into a living body such as a human body, and analyzes reflected echo signals from within the living body. It is used to obtain information on the internal tissue structure and blood flow of the body.

[0003] In this type of ultrasonic diagnostic apparatus, a Doppler signal obtained by orthogonal detection of a reflected echo signal is subjected to fast Fourier transform (FFT), its power spectrum is obtained, and it is sequentially displayed as blood flow information. The center frequency of the obtained Doppler signal is calculated by performing an autocorrelation calculation, and the diagnostic site is colored according to the obtained center frequency to display blood flow information as a color Doppler signal. All of these data are power spectra at a certain point in time and center frequencies.

On the other hand, echo signals reflected from blood are mainly reflected from red blood cells. It is known that the distribution of red blood cells has a spread in both time and space, and the spread is Gaussian random. As a result, statistical fluctuations called speckles occur in the power spectrum of the Doppler signal obtained from the reflected echo signal.
Similarly, the center frequency also varies.

[0005]

[Problems to be Solved by the Invention] The presence of speckles in the power spectrum means that the true spectrum is distorted by statistical fluctuations. The same applies to the estimated value of the center frequency in color Doppler. Therefore, the power spectrum does not represent the actual blood flow information sufficiently accurately, and the center frequency also varies as if it had fluctuated, even though it has not actually fluctuated.

An object of the present invention is to provide an ultrasonic diagnostic apparatus that can eliminate the distortion caused by the above-mentioned statistical fluctuations, determine the true power spectrum and center frequency, and accurately display blood flow information.

[0007]

[Means for Solving the Problems] An ultrasonic diagnostic apparatus according to the present invention emits an ultrasonic beam into a living body, detects blood flow data from a reflected echo signal from the living body, and detects blood flow data from a reflected echo signal from the living body. It displays information related to data, and includes a storage means, an average calculation means, and a display means. The storage means has a capacity to store blood flow data for at least one heartbeat, and stores blood flow data for a plurality of heartbeats. The average calculation means calculates average data of the blood flow data of a plurality of heartbeats using the blood flow data stored in the storage means. The display means displays the average data obtained by the average calculation means.

[0008]

In the present invention, when a reflected echo signal is obtained from within the living body, blood flow data is detected from the reflected echo signal, and blood flow data for a plurality of heartbeats is stored in the storage means. Based on the blood flow data stored in the storage means, the average calculation means calculates the average data of the blood flow data of a plurality of heartbeats, and the display means displays the average data calculated by the average calculation means.

In other words, the present invention focuses on the fact that the human body's blood flow system has extremely good periodicity due to heartbeat, and utilizes this periodicity to calculate blood flow data obtained for each heartbeat cycle. By averaging, more accurate blood flow data is displayed.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the general configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. The probe 1 is composed of a plurality of micro vibrators, and is connected to a wave transmitting/receiving circuit 2. The transmitting/receiving circuit 2 includes a high-frequency pulse oscillator for transmitting an ultrasonic beam, a receiver for receiving and processing reflected echoes, a delay circuit and a delay amount selection circuit for performing electronic scanning, and the like. Transmission/reception circuit 2
The output is input to the Doppler detection circuit 3. The Doppler detection circuit 3 includes a 90° phase shifter, a mixer, an A/D conversion circuit, and the like. The Doppler detection circuit 3 performs orthogonal detection of the reflected echo signal from within the living body received by the wave transmitting/receiving circuit 2, and obtains separate Doppler signals of a real part and an imaginary part. The Doppler detection circuit 3 is connected to the FFT 4 and the blood flow calculation circuit 5. FFT4 is to obtain the power spectrum of the Doppler signal from the obtained Doppler signal. Further, the blood flow calculation circuit 5 performs an autocorrelation calculation on the detected Doppler signal to obtain its center frequency.

The output of the FFT 4 is input to one input terminal of a two-input one-output switch circuit 9, and is also input to the cine memory 6. The output of the blood flow calculation circuit 5 is input to one input terminal of a two-input one-output switch circuit 10 and to the cine memory 6.

The cine memory 6 stores the FFT 4 for multiple heartbeats and blood flow data from the blood flow calculation circuit 5, and the electrocardiograph 15 outside the device.
It stores the electrocardiographic waveform data from and while updating them sequentially. The cine memory 6 is provided with separate areas for storing these three types of data. The output of the cine memory 6 is input to an adder circuit 7, and the output of the adder circuit 7 is input to an average buffer 8. Note that the cine memory 6 is
When a diagnostic image is frozen, blood flow data for a predetermined period near the freeze timing is stored, so by reading and playing back the contents after freezing,
Blood flow data and electrocardiogram waveforms before and after the freeze timing can be diagnosed. The adding circuit 7 performs an average calculation for each heartbeat of the blood flow data stored in the cine memory 6. Further, the average buffer 8 stores the output of the adding circuit 7 for one heartbeat.

The output of the average buffer 8 is sent to a switch circuit 9.
, 10 and is input to the other input terminals of the switch circuit 9.
, 10 are input to the DSC 11. DSC
11 converts the blood flow data selected by the switch circuits 9 and 10 into a television signal. The converted television signal is given to the monitor 12 and displayed.

The above-mentioned components are connected to the CPU 13 and controlled thereby. Further, a keyboard 14 is connected to the CPU 13. The keyboard 14 is used to specify, for example, freezing of a diagnostic image, and when freezing of a diagnostic image is specified, the CPU 13 outputs a signal to switch circuits 9 and 10 to switch to other input terminals.

Next, the operation of the ultrasonic diagnostic apparatus configured as described above will be explained. First, the probe 1 is driven by the wave transmitting/receiving circuit 2, and an ultrasound beam is transmitted from the probe 1 into the living body. The reflected echo signal from within the living body is received again by the probe 1 and input to the wave transmitting/receiving circuit 2. In the wave transmitting/receiving circuit 2, processing such as amplification is performed on the reflected echo signal, and the signal is sent to the Doppler detection circuit 3. In the Doppler detection circuit 3, the obtained reflected echo signal is subjected to orthogonal detection, and after cutting high frequency components with a filter (not shown),
After A/D conversion, the real part and the imaginary part obtained by shifting the phase of the real part by 90°
generate two digital Doppler signals.

The generated Doppler signal is given to the FFT 4 and blood flow calculation circuit 5. In FFT4, the generated Doppler signal is subjected to fast Fourier transform, and the power spectrum (frequency distribution) of the Doppler signal is calculated. Further, the blood flow calculation circuit 5 performs autocorrelation calculation processing on the generated Doppler signal to obtain its center frequency.

The power spectrum blood flow data obtained by the FFT 4 and the center frequency blood flow data obtained by the blood flow calculation circuit 5 are separately provided to a cine memory 6 and also to switch circuits 9 and 10. Here, when it is desired to display real-time blood flow data on the monitor 10, the switch circuits 9 and 10 are switched to one input terminal side by a switch signal from the CPU 13 by operating the keyboard 14, and the FFT 4 or blood flow calculation circuit 5 is switched to the one input terminal side. Blood flow data is DS
The signal is converted into a television signal at C11 and displayed on the monitor 10. On the other hand, when displaying the image in the cine memory 6, the switch circuits 9 and 10 are switched to the other input terminal side by a switch signal from the CPU 13.

FIG. 2 is a diagram showing the contents of data stored in the cine memory 6. The cine memory 6 is divided into I+1 addresses from i=0 to I between the R wave of one heartbeat and the R wave of the next heartbeat in the electrocardiogram waveform, and each address is further divided into I+1 addresses from i=0 to I. It is divided into J+1 addresses from ~J.

The address of j indicates the frequency direction of each blood flow data. For example, when power spectrum data from FFT4 is stored, the power data of the center frequency is shown in the hatched area in FIG. Further, power data of the surrounding area is stored in the vicinity thereof in the j direction. Further, when the blood flow data at the center frequency from the blood flow calculation circuit 5 is stored, the blood flow data at the center frequency is stored only in the hatched portion. Therefore, the cine memory 6 is (I+1)×(J+1)
Each heartbeat has 1 address space, and when storing data for N heartbeats, an address space N times the address space described above is required.

Here, the stored data for each heartbeat has extremely good periodicity in accordance with the periodicity of the heartbeat. Therefore, the blood flow data stored in the cine memory 6 is read out,
The adder circuit 7 adds the addresses for each address divided in the time axis direction, and the average of the sums is calculated using Equation 1.

[0021]

[Math 1]

The average data obtained by the adder circuit 7 is provided to an average buffer 8. FIG. 3 is a diagram showing the storage state of the average buffer 8. The average buffer 8 has an area capable of storing average data for one heartbeat, and shows respective areas for the FFT 4 and the blood flow calculation circuit 5. The average data stored here is the switch circuit 9, 10
is given to D, and when the switch circuits 9 and 10 are switched to the other input terminal side by a command from the CPU 13,
It is sent to the SC 11 and displayed on the monitor 12.

As described above, in this embodiment, the blood flow data of a plurality of heartbeats are stored in the cine memory 6 and the average data is obtained from the data, so that statistical fluctuations in the power spectrum and center frequency of the Doppler signal are reduced. Highly accurate calculated values can be obtained when calculating maximum flow velocity and flow rate. Furthermore, since the cine memory 6 is used, a special memory for obtaining average data is not required.

[Other Embodiments] In the above embodiments, the data of multiple heartbeats is stored in the cine memory, but the present invention is not limited to this, and it is also possible to have a separate memory for calculating average blood flow data. good. In this case, it may have a capacity for one heartbeat. That is, this is achieved by operating the memory as an accumulator and adding sequentially input data at each address in the time axis direction. Then, by dividing the obtained result by the heart rate, the average value can be obtained.

[0025]

[Effects of the Invention] In the present invention, blood flow data for multiple heartbeats are stored, and the periodicity of the heartbeats is used to calculate the average of the bloodflow data. It is possible to suppress statistical fluctuations in the center frequency, obtain values close to the true power spectrum and true center frequency, and display accurate blood flow data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing one line of data stored in a cine memory.

FIG. 3 is a diagram showing the storage state of an average buffer.

[Explanation of symbols]

3 Doppler detection circuit 4 FFT 5 Blood flow calculation circuit 6 Cine memory 7 Adder circuit 8 Average buffer 9,10 Switch circuit 12 CRT monitor

Claims (1)

[Claims] 1. An ultrasonic diagnostic apparatus that emits an ultrasonic beam into a living body, detects blood flow data from reflected echo signals from the living body, and displays information related to the detected blood flow data, comprising: A storage means having a capacity to store blood flow data for at least one heartbeat and storing blood flow data for a plurality of heartbeats, and an average of the bloodflow data of the plurality of heartbeats by the bloodflow data stored in the storage means. An ultrasonic diagnostic apparatus comprising an average calculation means for calculating data, and a display means for displaying information related to the average data calculated by the average calculation means.