JP4398024B2 - Ultrasonic diagnostic device and thrombus imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an apparatus capable of imaging information related to a thrombus.
[0002]
[Prior art]
When a power spectrum is displayed based on an echo signal from a blood flow flowing through a blood vessel in the brain, a high-luminance portion (instantaneous peak) may be observed occasionally. Here, the power spectrum is a graph with the horizontal axis representing the time axis and the vertical axis representing the velocity axis, and the luminance corresponds to the power of the Doppler component. The portion of high brightness observed in such a power spectrum is generally called HITS (High Intensity Transient Signal). Clinically, it is known that a person with a higher frequency of HITS is more likely to have a cerebral infarction. However, the generation mechanism has many unknown parts. In any case, the occurrence frequency of HITS is estimated to be an index of the risk of potential thrombus occurrence in each person.
[0003]
Conventionally, when observing the frequency of HITS, an ultrasonic probe for intracerebral diagnosis is brought into contact with the vicinity of the temple of the head, and ultrasonic pulses are transmitted and received by the ultrasonic probe. A Doppler component (Doppler signal) corresponding to blood flow motion information is extracted from the received signal thus obtained, and a power spectrum is calculated by calculating the power of the Doppler component. The power spectrum displayed on the screen is visually observed for a certain time (for example, 30 minutes), and the number of occurrences of the HITS is manually counted.
[0004]
[Problems to be solved by the invention]
However, according to the long-time visual observation as described above, the burden on the observer is very large. In addition, there is a problem in diagnosis because it is difficult to obtain objective data because each person's judgment standard varies depending on how high the brightness is regarded as HITS.
[0005]
In particular, in the past, since HITS was monitored on the power spectrum, it was impossible to recognize in which part of the living body it occurred and how it moved.
[0006]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to make it possible to spatially recognize the occurrence and movement of HITS, which is said to have a correlation with thrombus.
[0007]
Another object of the present invention is to form a new image representing the possible presence of a thrombus.
[0008]
[Means for Solving the Problems]
(1) In order to achieve the above-mentioned object, the present invention scans an ultrasonic beam to form a two-dimensional or three-dimensional data capturing area, and the intensity of a received signal from the transducer. Instantaneous peak determination means for determining a predetermined instantaneous peak based on information, and forming a two-dimensional or three-dimensional instantaneous peak image corresponding to the two-dimensional or three-dimensional data capture area based on the instantaneous peak And an instantaneous peak image forming means.
[0009]
According to the above configuration, an instantaneous peak (HITS) that seems to have a correlation with a thrombus can be determined in the data capture region, and a two-dimensional image or a three-dimensional image including the instantaneous peak can be formed. Therefore, on the image, it is possible to grasp the moving direction of the instantaneous peak, the speed or distribution of the movement, and the like.
[0010]
Preferably, power receiving means for calculating power based on the received signal is included, and the intensity information of the received signal is the power of the received signal. Preferably, the power calculation means calculates the power of the Doppler component in the received signal. Preferably, the received signal strength information is an amplitude value of the received signal.
[0011]
Preferably, it includes speed calculating means for calculating a speed from the received signal, and the instantaneous peak determining means determines the instantaneous peak based on the intensity information and the speed. According to this configuration, since the instantaneous peak can be determined not only by intensity information but also by speed information, the determination accuracy can be improved.
[0012]
Preferably, on the basis of the received signal, an ultrasonic image forming unit that forms a two-dimensional or three-dimensional ultrasonic image corresponding to the two-dimensional or three-dimensional data capture area, the instantaneous peak image, and the supersonic peak image Image synthesizing means for synthesizing the sound wave image and forming a synthesized image.
[0013]
According to the above configuration, the presence of an instantaneous peak can be visualized on a conventional two-dimensional image or three-dimensional image, and the movement and behavior of the instantaneous peak can be grasped in correlation with other organs and blood vessel running states.
[0014]
Preferably, the image processing apparatus includes afterimage processing means for performing afterimage processing of an instantaneous peak between frames on the instantaneous peak image. According to this configuration, when the instantaneous peak disappears in a short time or when the moving speed of the instantaneous peak is large and the frame is out of the frame in a short time, the presence or locus can be clearly expressed.
[0015]
(2) In order to achieve the above object, the present invention includes a transmission / reception unit for transmitting / receiving ultrasonic waves, and a logarithmic compressor for performing logarithmic compression on a received signal from the transmission / reception unit. First image forming means for forming an ultrasonic image that has undergone processing, and second image processing for forming an instantaneous peak image based on a branch received signal extracted from a path between the transmission / reception means and the logarithmic compression means Means, and image synthesis means for synthesizing the ultrasonic image and the instantaneous peak image.
[0016]
In a normal ultrasonic diagnostic apparatus, logarithmic compression is performed on a received signal because of the relationship with the dynamic range of the signal. However, such logarithmic compression may reduce the accuracy of instantaneous peak discrimination. . Therefore, the instantaneous peak is determined for a received signal that has not been subjected to such logarithmic compression.
[0017]
Preferably, the second image processing means includes instantaneous peak discrimination means for discriminating a strong reflector present in the blood vessel as the instantaneous peak based on the waveform of the branch reception signal.
[0018]
Preferably, the instantaneous peak discriminating unit determines that a peak exceeding a predetermined threshold is present in the region where the level of the branch reception signal falls below a predetermined threshold as the instantaneous peak.
[0019]
Echoes from the bloodstream are inherently weaker than echoes from other real tissues (such as blood vessel walls), while the intensity of instantaneous echoes is high. Therefore, using such characteristics, the discrimination accuracy of the instantaneous peak is improved.
[0020]
(3) In order to achieve the above object, the thrombus imaging device according to the present invention scans an ultrasonic beam and forms a scanning surface, and based on a reception signal from the transmission / reception unit, An instantaneous peak image forming means for determining an instantaneous peak correlated with a thrombus and forming an instantaneous peak image representing the instantaneous peak on the scanning plane; and a display means for displaying the instantaneous peak image. Features.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0022]
FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention. This ultrasonic diagnostic apparatus has a thrombus imaging function, that is, a mode for imaging an instantaneous peak correlated with a thrombus.
[0023]
The probe 10 is an ultrasonic probe that transmits and receives ultrasonic waves, and the probe 10 is brought into contact with the surface of the living body 8. Of course, the probe 10 may be a probe inserted into a body cavity. The probe 10 has an array transducer composed of a plurality of transducer elements, and an ultrasonic beam is electronically scanned by performing electronic scanning on the array transducer. In FIG. 1, the ultrasonic beam is indicated by reference numeral 12, and the scanning surface 14 is formed by electronically scanning the ultrasonic beam 12. Incidentally, as the electronic scanning method, for example, electronic sector scanning and electronic linear scanning are known.
[0024]
In the present embodiment, the two-dimensional scanning plane 14 is formed as a data capture area, but the present invention can also be applied to the case where a three-dimensional data capture area is formed.
[0025]
The transmission unit 20 is a circuit that supplies a transmission signal to the probe 10. The receiving unit 22 is a circuit that executes a phasing addition process on the reception signal output from the probe 10. The transmission beam is electronically formed by the action of the transmission unit 20, and the reception beam is electronically formed by the action of the reception unit 22. The receiving unit 22 preferably has a so-called digital beam former.
[0026]
The tomographic image forming unit 24 is a circuit that forms a tomographic image, that is, a B-mode image based on the received signal. The tomographic image 100 formed by the tomographic image forming unit 24 is output to the synthesizing unit 32.
[0027]
The Doppler image forming unit 26 is a circuit that forms a two-dimensional Doppler image (color Doppler image) based on the received signal. The Doppler image 101 is output to the synthesis unit 32.
[0028]
The instantaneous peak image forming unit 28 is a circuit that detects the above-described instantaneous peak, that is, HITS, and forms a two-dimensional image representing the instantaneous peak as the instantaneous peak image 102.
[0029]
The afterimage processing unit 30 is a circuit that performs inter-frame correlation processing on the instantaneous peak image 102, thereby executing the afterimage processing of the instantaneous peak. The instantaneous peak image 103 that has been subjected to the afterimage processing is output from the afterimage processing unit 30 to the combining unit 32.
[0030]
The combining unit 32 has a function of combining the instantaneous peak image 103 with one or both of the tomographic image 100 and the Doppler image 101. In this case, it is desirable to perform highlight display or coloring on the instantaneous peak so that the instantaneous peak stands out from other images at least on the synthesized image 104. The composite image 104 is output to the display unit 34, and the composite image is displayed on the display unit 34. Of course, any one of the images 101, 100, and 103 may be displayed on the display unit 34 alone.
[0031]
FIG. 2 conceptually shows the operation of the combining unit 32. The tomographic image 100 and the Doppler image 101 are images corresponding to the scanning plane 14, and the instantaneous peak image 103 is also an image corresponding to the scanning plane 14. These images are combined by the combining unit 32 to form a combined image 104. In the composite image 104, the instantaneous peak is clearly displayed on the cross section of the living tissue as the background. Therefore, according to such an image, it is possible to easily grasp the place where the instantaneous peak occurs and the behavior thereof. In particular, in the present embodiment, the afterimage processing for the instantaneous peak is performed by the afterimage processing unit 30, and therefore, the movement locus of the instantaneous peak can be observed. As described above, the probability of occurrence of an instantaneous peak is generally very low. For this reason, when the instantaneous peak is visually observed simply on the Doppler power spectrum in the past, there is a high possibility that the instantaneous peak will be overlooked. However, according to the present embodiment, there is an advantage that the instantaneous peak can be easily and reliably specified on the composite image 104.
[0032]
Therefore, according to the apparatus according to the present embodiment, it is possible to accurately identify an instantaneous peak correlated with a thrombus and accurately diagnose the degree of danger such as cerebral infarction. In addition, it is possible to clearly recognize in which part of the living body a thrombus is generated or moving, and for example, it is possible to make a diagnosis such as clogging or retention of a thrombus in a stenotic region of a blood vessel.
[0033]
Next, specific contents of each configuration shown in FIG. 1 will be described.
[0034]
FIG. 3 shows a specific configuration example of the tomographic image forming unit 24 shown in FIG. The tomographic image forming unit 24 includes a detector 36 and a Log compressor 38. The detector 36 is a circuit that detects a received signal and outputs an envelope signal. The Log compressor 38 is a circuit that executes logarithmic compression processing on the envelope signal. That is, it is a circuit that performs processing for further increasing the intensity of the low signal intensity component and relatively suppressing the high signal intensity component. Incidentally, signal detection may be performed after logarithmic compression. The circuit configuration itself shown in FIG. 3 is a known configuration.
[0035]
FIG. 4 shows a specific configuration example of the Doppler image forming unit 26.
[0036]
The received signal is input to the quadrature detector 40, and reference signals that are 90 degrees out of phase with each other are mixed with the received signal, thereby converting the received signal into a complex signal. Incidentally, the complex signal passes through a predetermined low-pass filter, so that only the component in the baseband region is output as a complex signal.
[0037]
The wall motion filter 42 is a filter that passes only a high frequency component in a complex signal in order to remove a huge echo component from a low-speed moving body such as a heart wall.
[0038]
As is well known, the autocorrelator 44 performs an autocorrelation operation on the complex signal after quadrature detection. The autocorrelation result is averaged by the averaging circuit 46 and then input to the speed calculator 48. The speed calculator 48 is a circuit that calculates the speed by detecting the phase from the result after autocorrelation. The circuit configuration itself shown in FIG. 4 is a known configuration.
[0039]
5 and 6 show specific configuration examples of the instantaneous peak image forming unit 28. FIG.
[0040]
In the example shown in FIG. 5, the received signal is first input to the comparator 50, and the received signal is compared with the threshold value α. This threshold value α is set to a predetermined level for discriminating instantaneous peaks. Therefore, an instantaneous peak (or a signal having the possibility) is output as the output of the comparator 50, and the detector 52 performs detection on the signal output from the comparator 50. As a result, an instantaneous peak image having the same region as that of a normal B-mode image is formed. In the example shown in FIG. 5, the detector 52 is provided at the subsequent stage of the comparator 50, but their arrangement may be reversed. A configuration example in that case is shown in FIG.
[0041]
In the example shown in FIGS. 5 and 6, the instantaneous peak is determined based on the level, that is, the intensity of the received signal. However, the instantaneous peak may be determined based on the strength (power) of the Doppler component included in the received signal.
[0042]
FIG. 7 shows a configuration example of the afterimage processing unit 30 shown in FIG. A signal output from the instantaneous peak image forming unit 28 is input to the frame memory 54 via the adder 58, where information for one frame is stored. A signal output from the frame memory 54 is input to a weighting circuit 56, and the signal is multiplied by a weighting value β. This β is set to a value lower than 1. The weighted signal is added to the signal output from the instantaneous peak image forming unit 28 in the adder 58. Then, the added signal is stored in the frame memory 54, and the above steps are repeated. As a result, information of the latest frame and a plurality of previous frames are mixedly stored in the frame memory 54, that is, an afterimage process for an instantaneous peak can be performed. In addition to the circuit configuration shown in FIG. 7, other circuit configurations for performing afterimage processing may be employed.
[0043]
8, 10, and 11 illustrate other configuration examples of the instantaneous peak image forming unit 28 illustrated in FIG. 1.
[0044]
In order to explain the operation of the configuration shown in FIG. 8, first, referring to FIG. 9, FIG. 9A shows an example of a received signal. Here, reference numerals 201 and 202 denote portions corresponding to the blood vessel wall, and reference numeral 203 denotes a blood flow portion between the blood vessel walls. Reference numeral 204 represents a thrombus existing in the blood flow portion, that is, an instantaneous peak.
[0045]
By the way, in a normal tomographic image forming process, a logarithmic compression process is performed on a received signal as shown in FIG. A signal that has undergone such logarithmic compression processing is shown in FIG. As shown in the drawing, the instantaneous peak 206 is buried in other signal components, and it is difficult to determine the instantaneous peak 206.
[0046]
Therefore, an instantaneous peak is determined before logarithmic compression processing is performed. FIG. 9C shows a signal after detection for the signal shown in FIG. Here, reference numeral 208 indicates an instantaneous peak. As is clear from the comparison between (B) and (C), according to the received signal before logarithmic compression, the discrimination accuracy of the instantaneous peak can be improved. However, in addition to the instantaneous peak, a relatively strong signal component corresponding to the blood vessel wall is generated, and a device for discriminating only the instantaneous peak is required. Therefore, in the present embodiment, the instantaneous peak 208 is specified by pattern recognition of a strong signal surrounded by weak signals.
[0047]
That is, as shown in (C), when a strong signal exists among weak signals on the time axis, it is specified as an instantaneous peak 208 as shown in (D).
[0048]
The circuit configuration shown in FIG. 8 is for realizing the operation shown in FIG. Detection is performed on the received signal in the detector 60, and the received signal after the detection is input to two low-pass filters (LPF) 62 and 64. Here, the low-pass filter 62 is a circuit for removing noise from the received signal. The filtered received signal is input to the moving averaging circuit 66, and a moving average process is performed on the received signal. The processed signal is input to the selector 70.
[0049]
On the other hand, the low-pass filter 64 smoothes the received signal to the extent that the inside and outside of the blood vessel can be identified. The smoothed received signal is input to the comparator 68, and the threshold value α is compared with the received signal. Then, a signal component exceeding the threshold value α is input to the pattern discriminator 72. As described above, the pattern discriminator 72 is a circuit that determines a momentary peak when there is a strong signal in a weak signal. When an instantaneous peak is determined, a gate pulse synchronized with the instantaneous peak timing is output to the selector 70. The selector 70 passes the input signal only during the pulse period of the gate pulse. As a result, only the signal component corresponding to the instantaneous peak existing in the blood vessel is output from the selector 70. Therefore, if the instantaneous peak image is formed by the circuit configuration shown in FIG. 8, it is advantageous that ones from the thrombus can be effectively selected and those other than the thrombus can be effectively excluded.
[0050]
In the configuration example shown in FIG. 10, the received signal is input to the quadrature detector 74, and the received signal is converted into a complex signal by the quadrature detection as described above. After the complex signal passes through the wall motion filter 76, it is input to the autocorrelator 78, and autocorrelation is performed on the complex signal. The autocorrelation result is output to the speed calculator 82 via the averaging circuit 80, and the speed calculator 82 calculates the speed from the autocorrelation result. Incidentally, each of the above-described configurations is the same as that of the Doppler image forming unit 26 shown in FIG. 4, and therefore, the Doppler image forming unit 26 and the configurations 74 to 82 can be used together.
[0051]
On the other hand, the received signal is input to the comparator 84, and the received signal is compared with the threshold value α. Then, a signal component exceeding the threshold value α is input to the detector 86, which is the same as the processing shown in FIG. The selector 88 is a circuit that selects only a signal component having a speed within a predetermined speed range from among the signal components output from the detector 86. That is, not all instantaneous peaks are imaged, but only the instantaneous peaks satisfying a predetermined speed condition are specified in consideration of the moving speed of the thrombus. The configuration example shown in FIG. 10 has an advantage that the thrombus identification accuracy can be further improved.
[0052]
FIG. 11 also shows a configuration example of the instantaneous peak image forming unit 28, and the same components as those shown in FIG. In this configuration example, the output of the wall motion filter 76 is input to the amplitude calculator 89. The amplitude calculator 89 is a circuit that calculates the amplitude (power) by adding the squares of the real part and imaginary part of the complex signal to each other and calculating the square root of the addition result. The calculation result is output to the selector 92 via the averaging circuit 90. The selector 92 satisfies the condition that the speed belongs within a predetermined speed range among the signal components output from the detector 86, and the power belongs within the predetermined power range (or more than the predetermined power). This is a circuit that passes only the signal component that satisfies the condition. According to the circuit configuration shown in FIG. 11, the discrimination accuracy of the instantaneous peak corresponding to the thrombus can be further increased.
[0053]
Incidentally, in each of the above configuration examples, the received signal and the threshold value α are compared, and the instantaneous peak is discriminated. Of course, as described above, the power and threshold value of the Doppler component included in the received signal are as described above. The instantaneous peak may be discriminated by comparing. In that case, in the circuit configuration shown in FIG. 11, the signal output from the averaging circuit 90 may be compared with a threshold value. In that case, if the comparison operation is also performed in the selector 92, the comparator 84 and the detector 86 become unnecessary.
[0054]
In the above embodiment, an instantaneous peak image as a two-dimensional image is synthesized with an ultrasonic image as a two-dimensional image. However, an ultrasonic image as a three-dimensional image is synthesized as a three-dimensional image. You may make it synthesize | combine an instantaneous peak image. According to such a configuration, there is an advantage that, for example, the heart is represented in three dimensions, and a thrombus flowing in the heart can be visualized in three dimensions.
[0055]
【The invention's effect】
As described above, according to the present invention, an image capable of spatially recognizing the occurrence and movement of an instantaneous peak can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 is a diagram for explaining synthesis of an ultrasonic image and an instantaneous peak image.
FIG. 3 is a diagram illustrating a configuration example of a tomographic image forming unit illustrated in FIG. 1;
4 is a diagram illustrating a configuration example of a Doppler image forming unit illustrated in FIG. 1; FIG.
FIG. 5 is a diagram illustrating a configuration example of an instantaneous peak image forming unit illustrated in FIG. 1;
6 is a diagram illustrating another configuration example of the instantaneous peak image forming unit illustrated in FIG. 1. FIG.
7 is a diagram illustrating a configuration example of an afterimage processing unit illustrated in FIG. 1. FIG.
FIG. 8 is a diagram showing another configuration example of the instantaneous peak image forming unit shown in FIG. 1;
9 is a diagram for explaining the operation of the configuration shown in FIG. 8. FIG.
10 is a diagram showing another configuration example of the instantaneous peak image forming unit shown in FIG.
FIG. 11 is a diagram illustrating another configuration example of the instantaneous peak image forming unit illustrated in FIG. 1;
[Explanation of symbols]
8 biological body, 10 probe, 12 ultrasonic beam, 14 scanning plane (data acquisition area), 24 tomographic image forming unit, 26 Doppler image forming unit, 28 instantaneous peak image forming unit, 30 afterimage processing unit, 32 combining unit, 34 Display section.

Claims (11)

A transducer that scans an ultrasonic beam to form a two-dimensional or three-dimensional data acquisition area;
Based on the intensity information of the received signal from the transducer, an instantaneous peak determination means for determining an instantaneous peak correlated with a thrombus ,
Based on the instantaneous peak, instantaneous peak image forming means for forming a two-dimensional or three-dimensional instantaneous peak image corresponding to the two-dimensional or three-dimensional data capture area;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
Power calculating means for calculating power based on the received signal,
The ultrasonic diagnostic apparatus, wherein the intensity information of the received signal is the power of the received signal. The apparatus of claim 2.
The ultrasonic diagnostic apparatus, wherein the power calculation means calculates the power of a Doppler component in the received signal. The apparatus of claim 1.
The ultrasonic diagnostic apparatus, wherein the received signal intensity information is an amplitude value of the received signal. The apparatus of claim 1.
Speed calculation means for calculating the speed from the received signal,
The ultrasonic diagnostic apparatus, wherein the instantaneous peak determination means determines the instantaneous peak based on the intensity information and the speed. The apparatus of claim 1.
Ultrasonic image forming means for forming a two-dimensional or three-dimensional ultrasonic image corresponding to the two-dimensional or three-dimensional data capture area based on the received signal;
Image synthesizing means for synthesizing the instantaneous peak image and the ultrasonic image and forming a synthesized image;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
An ultrasonic diagnostic apparatus comprising afterimage processing means for performing afterimage processing between frames on the instantaneous peak image. Transmission / reception means for transmitting / receiving ultrasonic waves;
A first image forming unit that includes a logarithmic compressor that performs logarithmic compression on a received signal from the wave transmitting / receiving unit, and that forms an ultrasonic image that has undergone logarithmic compression processing;
A second image processing means for forming an instantaneous peak image including an instantaneous peak correlated with a thrombus, based on a branched received signal taken from a path between the transmission / reception means and the logarithmic compression means;
Image synthesizing means for synthesizing the ultrasonic image and the instantaneous peak image;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 8.
The ultrasonic diagnostic apparatus characterized in that the second image processing means includes instantaneous peak discrimination means for discriminating a strong reflector present in a blood vessel as the instantaneous peak based on the waveform of the branch reception signal. The apparatus of claim 9.
The ultrasonic diagnostic apparatus according to claim 1, wherein the instantaneous peak determination unit determines a peak exceeding a predetermined threshold in an area where the level of the branch reception signal falls below a predetermined threshold as the instantaneous peak. Wave transmitting / receiving means for scanning an ultrasonic beam to form a scanning surface;
Instantaneous peak image forming means for determining an instantaneous peak correlated with a thrombus based on a received signal from the wave transmitting / receiving means and forming an instantaneous peak image representing the instantaneous peak on the scanning plane;
Display means for displaying the instantaneous peak image;
A thrombus imaging device comprising:

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