JP2000350729A - Method for suppressing interference artifact and ultrasonic diagnosis system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for suppressing interference artifact and an ultrasonic diagnosis system which can suppress acoustic interference artifact without deteriorating image quality. SOLUTION: This system stores data on sound ray(DSR) If1(i) in a memory by conducting scanning, with a focus position as the first focus f1 (L2). DSR If2(i) are obtained by conducting scanning on the same space, with a focus position as the second focus f2 (L3). Regarding a non-correlation region, a value of the DSR If1(i) is taken, and regarding a correlation region, a correlation of the DSR between If1(i) and If2(i) is taken, and for a data part with high correlation, a value of the DSR If1(i) is taken, and for a data part with low correlation, a value in which the DSR If1(i) are suppressed or delated is taken, and DSR Iout(i) are created (L4). On the basis of the DSR Iout(i), an ultrasonic image is created and displayed (L7). For a data part with low correlation, brightness decreases or becomes '0' and is not remarkable; therefore, an ultrasonic image in which interference artifact is suppressed is obtained. The deterioration of image quality can be prevented, because an unusable frequency band is not produced and a reception opening is not small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for suppressing interference artifacts and an ultrasonic diagnostic apparatus.
More specifically, the present invention relates to an interference artifact suppression method and an ultrasonic diagnostic apparatus capable of suppressing acoustic interference artifacts without deteriorating image quality.

[0002]

2. Description of the Related Art FIG.
5 is an ultrasound image depicting the heart in an er view (a scanning method for simultaneously depicting the right ventricle, the left ventricle, the right atrium, and the left atrium). At this time, an acoustic interference artifact Ar may appear, making it difficult to see the apical endocardium. Conventionally,
As a method for suppressing the above-described interference artifact, a frequency compound method and a spatial compound method are known.

In the frequency compounding method, two sound ray data are acquired in the same space by changing the frequency, and these sound ray data are added. An ultrasonic image is created based on the added sound ray data. . If the frequency is different, the appearance of the interference artifact is different, so that the weight of the data corresponding to the interference artifact is relatively low in the added sound ray data. Thus, an ultrasonic image in which interference artifacts are suppressed can be obtained.

In the spatial compounding method, a normal reception aperture is divided into two parts, and data of two sound rays in the same space is obtained using each of the divided one and the other reception apertures, and the sound ray data is phased. An ultrasonic image is created on the basis of the sound ray data obtained by the production and addition. If the position of the receiving aperture is different, the appearance of the interference artifacts differs, so that the weight of the data corresponding to the interference artifact becomes relatively low in the phasing-added sound ray data. Thus, an ultrasonic image in which interference artifacts are suppressed can be obtained.

[0005]

In the frequency compounding method, it is necessary to provide a considerably large gap between two frequencies to be used in order to sufficiently reduce interference artifacts. In other words, it is necessary to open a wide frequency band between two frequencies to be used. That is, a wide frequency band between the two frequencies used cannot be used. For this reason, there is a problem that image quality deteriorates. On the other hand, in the spatial compounding method, the receiving aperture is smaller than usual, so that the resolution in the horizontal direction is particularly deteriorated. That is, there is a problem that image quality deteriorates. Therefore, an object of the present invention is to provide an interference artifact suppression method and an ultrasonic diagnostic apparatus capable of suppressing acoustic interference artifacts without deteriorating image quality.

[0006]

According to a first aspect of the present invention, data of a plurality of sound rays or a plurality of frames in the same space is obtained by changing a focal position of at least one of transmission and reception of ultrasonic waves. Then, the data is correlated, the original data is weighted based on the height of the correlation, sound ray or frame data is newly generated, and an ultrasonic image is created based on the newly generated data. A method for suppressing interference artifacts is provided. In the interference artifact suppression method according to the first aspect, data is weighted based on the degree of correlation. Here, since the data from the structure does not change much even if the focal position is different, the correlation is high. On the other hand, when the focal position is different, the appearance of the interference artifact differs, so that the correlation of the data corresponding to the interference artifact is significantly reduced. That is, the weight of the data portion corresponding to the interference artifact becomes relatively significantly lower. Thus, an ultrasonic image in which interference artifacts are suppressed can be obtained. further,
According to this method, an unusable frequency band does not occur,
Further, since the receiving aperture does not become small, the image quality does not deteriorate.

According to a second aspect, the present invention provides a scanning means for scanning the same space by changing the focal position of at least one of transmission and reception of ultrasonic waves and acquiring data of a plurality of sound rays or a plurality of frames. A correlation calculating means for correlating a plurality of acquired data, a data converting means for newly generating sound ray or frame data by weighting the original data based on the height of the correlation, and a newly generated data And an ultrasonic image generating means for generating an ultrasonic image based on the ultrasonic diagnostic apparatus.
In the ultrasonic diagnostic apparatus according to the second aspect, the interference artifact suppression method according to the first aspect can be suitably implemented.

[0008] In a third aspect, the present invention obtains data of a plurality of sound rays or a plurality of frames in the same space by changing the width of an aperture for at least one of transmission and reception of ultrasonic waves, and Taking correlation, weighting the original data based on the height of the correlation, newly generating sound ray or frame data, and creating an ultrasonic image based on the newly generated data. An interference artifact suppression method is provided. In the interference artifact suppression method according to the third aspect, data is weighted based on the degree of correlation. Where the data from the structure is
Even if the width of the opening is different, the correlation does not change much, so that the correlation is high. On the other hand, when the width of the aperture is different, the appearance of the interference artifacts is different, so that the correlation of the data corresponding to the interference artifacts is extremely low. That is, the weight of the data portion corresponding to the interference artifact becomes relatively significantly lower. Thus, an ultrasonic image in which interference artifacts are suppressed can be obtained. Furthermore, according to this method,
There are no unusable frequency bands. Also, a large aperture can be used at least once. Therefore, the image quality does not deteriorate.

According to a fourth aspect, the present invention provides a scanning means for scanning the same space by changing the width of an aperture of at least one of transmission and reception of ultrasonic waves and acquiring data of a plurality of sound rays or a plurality of frames. And a correlation calculating means for correlating the plurality of acquired data, a data converting means for newly generating sound ray or frame data by weighting the original data based on the height of the correlation, and a newly generated An ultrasonic diagnostic apparatus comprising: an ultrasonic image generating unit that generates an ultrasonic image based on data.
In the ultrasonic diagnostic apparatus according to the fourth aspect, the interference artifact suppression method according to the third aspect can be suitably implemented.

As the "correlation" in the above configuration, the following may be used. (1) Point correlation One data point constituting each sound ray is made to correspond to one,
Similarity when comparing data values (2) One-dimensional correlation A plurality of one-dimensionally adjacent data points constituting each sound ray: a plurality of one-dimensionally adjacent plural data points (3) Two-dimensional correlation In the case of correlation of data of a plurality of frames, data points constituting each sound ray are considered in consideration of the spatial arrangement of a plurality of sound rays constituting the frame. Are two-dimensionally adjacent pluralities: similarities when two-dimensionally adjacent pluralities are compared and data values are compared.

As the weighting by "correlation", the following examples may be used. As a point correlation, a difference (absolute value) between data values of corresponding data points is obtained. Next, as a weight, when the difference is smaller than or equal to the first threshold, one or the average of the original data values is used as the data value of the data point, and the difference is larger than the first threshold and larger than the second threshold. When the difference is small, one of the original data values or the average is converted to a coefficient (linearly or curvedly from “1” to “0” according to the value of the difference between the first threshold value and the second threshold value). The value multiplied by (the coefficient value changes) is taken as the data value of the data point, and when the difference is greater than or equal to the second threshold value, “0” is taken as the data value of the data point.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments of the invention shown in the drawings. Note that the present invention is not limited by this.

-First Embodiment- FIG. 1 is a configuration diagram showing an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. This ultrasonic diagnostic apparatus 100
An ultrasonic probe 1, a transmission / reception unit 2 for transmitting and receiving ultrasonic waves by driving the ultrasonic probe 1, and sound ray data (B mode, Color Flow Mapping) from the received ultrasonic waves.
And a signal processing unit 3 for generating a power Dopplar Imaging mode or the like.
A memory 4 capable of storing sound ray data for sound rays, and weighting of original data based on the correlation between the sound ray data output from the signal processing unit 3 and the sound ray data stored in the memory 4 Calculation unit 5 for newly generating sound ray data
And a digital scan converter 6 for creating an ultrasonic image based on the sound ray data newly generated by the correlation operation unit 5
And a display unit 7 for displaying the created ultrasonic image, an input unit 8 for an operator to input instructions and data, and a control unit 9 for controlling the above-mentioned units. Further, the control unit 9 includes an interference artifact suppression processing unit 9a that performs an interference artifact suppression process according to the present invention.

FIG. 2 is a flowchart showing the operation of the interference artifact suppression processing according to the first embodiment of the present invention. In step L1, the sound ray number counter value i is set to "1".
Initialize to In step L2, as shown in FIG. 3A, the i-th sound ray is scanned with the focus position as the first focus f1, and the sound ray data If1 (i) of the i-th sound ray is stored in the memory 4. I do. In step L3, as shown in FIG. 3B, the focus position is set to the second focus f2, the i-th sound ray is scanned in the same space as in step L2, and the sound ray data If2 ( get i). Note that the first focus f
Specific examples of the first and second focal points f2 are 1 cm and 12 cm
Combination of 2cm and 16cm, 4cm and 1
The most effective combination for suppressing interference artifacts may be selected from a combination of 8 cm and the like.

In step L4, the correlation calculator 5 outputs
The value of the sound ray data If1 (i) is taken for the non-correlation area shown in FIG.
By taking the correlation of f1 (i) and If2 (i), the data part with high correlation takes the value of sound ray data If1 (i), and the data part with low correlation suppresses or deletes sound ray data If1 (i). The sound ray data Iout (i) of the i-th sound ray is generated by taking the obtained value.

An example of a point correlation operation (output characteristic of the correlation operation unit 5) will be described below. Abs {} is a function that takes an absolute value. Also, j represents the number of the data point. When Iout (i) j = If1 (i) j × C0 ≦ Abs {If1 (i) j−If2 (i) j} ≦ K1, C = 1 K1 <Abs {If1 (i) j-If2 (i ) j} <K2, C = 1− (Abs {If1 (i) j−If2 (i) j} −K1) / (K2−K1) K2 ≦ Abs {If1 (i) j−If2 (i) j}, C = 0 FIG. 5 illustrates the weighting coefficient C. In this example, if the correlation is large (if the difference Abs {If1 (i) j−If2 (i) j} is smaller than K1), If1 (i) is output. If there is a correlation range (if the difference is larger than K1 and smaller than K2), If
1 (i) is multiplied by a positive weighting coefficient C smaller than “1” and output. If the correlation is smaller than the range (if the difference is larger than K2), “0” is output.

In steps L5 and L6, steps L2 to L4 are repeated until the end of one frame. And
When one frame is over, repeat the same for the next frame

On the other hand, in step L7, the digital scan converter 6 and the display device 7 output the sound ray data Iout (1) to Iout for one frame output from the correlation calculator 5.
Create and display an ultrasonic image based on (LAST).

According to the ultrasonic diagnostic apparatus 100 according to the first embodiment described above, the data portion having a low correlation has low brightness or becomes "0", and thus is inconspicuous. That is, as shown in FIG. 6, an ultrasonic image in which interference artifacts are suppressed can be obtained. Further, there is no unusable frequency band and the receiving aperture is not reduced, so that the image quality does not deteriorate. Further, since the non-correlation area (area where interference artifacts do not appear) and the correlation area (area where interference artifacts appear) are separated, deterioration of image quality due to correlation processing in areas where interference artifacts do not appear can be prevented, and correlation processing can be prevented. It is possible to prevent a decrease in the frame rate due to the burden.

-Second Embodiment-The second embodiment is basically the same as the first embodiment, except that data for two frames can be stored in the memory 4 and interference artifacts are generated in frame units. Perform suppression processing.

FIG. 7 is a flowchart showing the operation of the interference artifact suppression processing according to the second embodiment. In step V1, as shown in FIG. 3A, a scan for one frame is performed with the focus position as the first focus f1,
Data Df1 (sound ray data for one frame) is stored in the memory 4. In step V2, as shown in FIG. 3B, scanning is performed for one frame with the focal position being the second focal point f2, and data Df2 (sound ray data for one frame) is stored in the memory 4. In step V3, the correlation calculator 5 calculates the data D for the non-correlation area shown in FIG.
The value of f1 is taken, and in the correlation area shown in FIG. 4, the data Df1 and Df2 are correlated, and the data portion having a high correlation takes the value of data Df1, and the data portion having a low correlation suppresses or deletes the data Df1. The data Dout of one frame is generated by taking the obtained value. Since the data Df1 and Df2 are sound ray data for one frame, they are two-dimensional data in consideration of the spatial arrangement of each sound ray. Therefore, a two-dimensional correlation operation is performed here. In step V4, the digital scan converter 6 and the display device 7
Creates and displays an ultrasonic image based on the sound ray data Dout for one frame output from the correlation calculator 5.

According to the ultrasonic diagnostic apparatus according to the second embodiment, the data portion having a low correlation has a low luminance or becomes "0", so that the interference artifact becomes inconspicuous. Further, there is no unusable frequency band and the receiving aperture is not reduced, so that the image quality does not deteriorate. Although there is a disadvantage that the capacity of the memory 4 is increased (a capacity for two frames is required) as compared with the first embodiment, there is an advantage that a two-dimensional correlation operation can be performed.

-Third Embodiment- A third embodiment is the same as the "first embodiment" of the first embodiment.
Interference artifact suppression processing is performed using “large reception aperture Al” and “small reception aperture As” shown in FIG. 9 instead of “focus f1” and “second focus f2”.

FIG. 8 is a flowchart showing the operation of the interference artifact suppression processing according to the third embodiment. This flowchart is the same as the flowchart of FIG. 2 except for steps L2 'and L3', and therefore only steps L2 'and L3' will be described. In step L2 ′, as shown in FIG.
The i-th sound ray is scanned as the large reception aperture Al, and the sound ray data If1 (i) of the i-th sound ray is stored in the memory 4. In step L3 ', as shown in FIG. 9B, the i-th sound ray is scanned in the same space as in step L2' as the small reception aperture As, and the sound ray data I of the i-th sound ray is obtained.
Obtain f2 (i).

According to the ultrasonic diagnostic apparatus according to the third embodiment, the data portion having a low correlation has a low luminance or becomes "0", so that the interference artifact becomes inconspicuous. Further, there is no unusable frequency band, and the large receiving aperture Al can be used, so that the image quality does not deteriorate.

-Fourth Embodiment- A fourth embodiment is basically the same as the third embodiment, except that data for two frames can be stored in the memory 4 and interference artifacts are generated in frame units. Perform suppression processing.

FIG. 10 is a flowchart showing the operation of the interference artifact suppression processing according to the fourth embodiment. Since this flowchart is the same as the flowchart of FIG. 7 except for steps V1 'and V2', only steps V1 'and V2' will be described. In step V1 ', as shown in FIG. 9A, a scan for one frame is performed with the large reception aperture Al, and the data Df1 is stored in the memory 4. Step V
In 2 ′, as shown in FIG. 9B, the small reception aperture As
The scan for one frame is performed, and the data Df2 is stored in the memory 4.

According to the ultrasonic diagnostic apparatus of the fourth embodiment, since the data portion having a low correlation has low luminance or becomes "0", the interference artifact becomes inconspicuous. Further, there is no unusable frequency band, and the large receiving aperture Al can be used, so that the image quality does not deteriorate. Although there is a disadvantage that the capacity of the memory 4 is increased as compared with the third embodiment, there is an advantage that a two-dimensional correlation operation can be performed.

Fifth Embodiment In the first embodiment or the third embodiment, the capacity of two sound rays is secured in the memory 4 and the sound ray data If2 (i)
Is also stored in the memory 4, and the sound ray data If1 (i), If2 (i)
Is performed.

[0030]

According to the method for suppressing interference artifacts and the ultrasonic diagnostic apparatus of the present invention, acoustic interference artifacts and acoustic noise can be suppressed.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an interference artifact suppression process according to the first embodiment of the present invention.

FIG. 3 is an exemplary diagram of a first focus and a second focus.

FIG. 4 is an exemplary diagram of a non-correlation area and a correlation area.

FIG. 5 is a diagram illustrating an example of a correlation height and a weight coefficient;

FIG. 6 is an exemplary diagram of an ultrasonic image obtained by the present invention.

FIG. 7 is a flowchart illustrating an interference artifact suppression process according to a second embodiment of the present invention.

FIG. 8 is a flowchart illustrating an interference artifact suppression process according to a third embodiment of the present invention.

FIG. 9 is an exemplary diagram of a large reception aperture and a small reception aperture.

FIG. 10 is a flowchart illustrating an interference artifact suppression process according to a fourth embodiment of the present invention.

FIG. 11 is an exemplary view of a conventional ultrasonic image.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 ultrasonic diagnostic apparatus 1 ultrasonic probe 2 transmission / reception unit 3 signal processing unit 4 memory 5 correlation operation unit 6 digital scan converter 7 display device 9 control unit 9a interference artifact suppression processing unit f1 first focus f2 second focus Al large Reception aperture As small reception aperture

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4C301 AA01 CC02 EE07 EE20 HH13 HH25 JB22 JB23 JB28 JB29 JB32 JC14 KK02 KK22 LL03 LL04 LL06 5B057 AA08 BA05 CA08 CA12 CA16 CB08 CB12 CB16 CE09 DB02 DC09 DC09

Claims (4)

[Claims] 1. A method of acquiring data of a plurality of sound rays or a plurality of frames in the same space by changing a focal position of at least one of transmission and reception of an ultrasonic wave, correlating the data, and setting a correlation height A method for suppressing interference artifacts, comprising: generating new sound ray or frame data by weighting the original data based on the original data; and generating an ultrasonic image based on the newly generated data. 2. A scanning unit that scans the same space by changing the focal position of at least one of transmission and reception of ultrasonic waves to acquire data of a plurality of sound rays or a plurality of frames, and a correlation between the acquired plurality of data. And a data conversion means for newly generating sound ray or frame data by weighting the original data based on the height of the correlation, and creating an ultrasonic image based on the newly generated data. An ultrasonic diagnostic apparatus comprising: an ultrasonic image creating unit that performs the operation. 3. Acquiring data of a plurality of sound rays or a plurality of frames in the same space by changing the width of an aperture in at least one of transmission and reception of ultrasonic waves, correlating the data, and calculating the height of the correlation. A new method for generating sound ray or frame data by weighting the original data on the basis of, and creating an ultrasonic image based on the newly generated data. 4. A scanning unit that scans the same space by changing the width of an aperture in at least one of transmission and reception of ultrasonic waves to acquire data of a plurality of sound rays or a plurality of frames, and Correlation calculation means for obtaining correlation, data conversion means for newly generating sound ray or frame data by weighting the original data based on the height of the correlation, and converting the ultrasonic image based on the newly generated data. An ultrasonic diagnostic apparatus comprising: an ultrasonic image generating means for generating.