JP3662835B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to adaptive automatic setting of a region of interest (ROI).
[0002]
[Prior art]
The integrated backscatter (IB) value is mainly used as an index value for diagnosing and evaluating hardening or fibrosis of the myocardium or blood vessel wall. Various methods have been proposed for obtaining the IB value.
[0003]
For example, when obtaining the IB value for a part of the myocardium, the echo power from the part is integrated along the time axis (depth) direction or within a certain region, and the integrated value is obtained. The IB value is defined as a ratio to the reference (as related applications, Japanese Patent Application No. 10-329108, Japanese Patent Application No. 10-329109, Japanese Patent Application No. 10-330343). Since the IB value varies with time according to the cardiac cycle, the difference (or ratio) between the maximum value and the minimum value becomes an index value representing the properties of the myocardium. Generally, it is called a cyclic variation (CV) (hereinafter CV-IB) value.
[0004]
[Problems to be solved by the invention]
However, conventionally, in order to obtain the IB value and the CV-IB value, it is necessary to manually set the ROI for each frame of the ultrasonic image, and manually specify the maximum value and the minimum value. It was necessary to do this, and it was extremely complicated. Moreover, there was a problem in measurement accuracy because of such manual work. Furthermore, conventionally, since only one ROI can be set, CV-IB values cannot be obtained simultaneously for a plurality of sites on the myocardium. Also, in other image processing, it is generally complicated to manually set the ROI.
[0005]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to realize adaptive setting of a region of interest according to a moving tissue.
[0006]
Another object of the present invention is to improve the measurement accuracy of an IB value or a CV-IB value.
[0007]
Another object of the present invention is to make it possible to simultaneously evaluate the properties of a plurality of parts of a target tissue.
[0008]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention provides binarization means for forming a binarized image from which an object is extracted based on data obtained by transmission / reception of ultrasonic waves, A first image processing means for applying a first image processing for defining a first offset line along the contour inside the contour of the object to the binarized image; and an image after the first image processing. Second image processing means for performing a second image processing for defining a second offset line further inside along the first offset line, based on the first offset line and the second offset line And a region of interest is set.
[0009]
According to the said structure, a 1st offset line is defined along the outline of a target object, a 2nd offset line is defined along the 1st offset line, and a region of interest is set based on them. Here, the first offset line has a shape corresponding to the contour shape of the object, and the shape of the second offset line also follows it. Therefore, the first offset line is adaptive to the inside according to the shape of the object itself. It is possible to automatically set the region of interest. For this reason, there is an advantage that the region of interest can be automatically set for each frame. In addition, there is an advantage that a region of interest can be set according to an objective standard.
[0010]
Preferably, the region of interest is set as a region sandwiched between the first offset line and the second offset line. That is, the two offset lines form part of the outline of the region of interest.
[0011]
Desirably, it includes means for setting a processing range on a data capture region where the ultrasonic wave is transmitted and received, and is within the processing range and is sandwiched between the first offset line and the second offset line The region of interest is set as follows.
[0012]
According to this configuration, the region of interest can be automatically set inside the processing range as the maximum range. For example, if a plurality of processing ranges are set for each part on the heart wall that is a diagnosis target, the region of interest can be set adaptively for each part.
[0013]
Preferably, a plurality of processing ranges are set in the data capture area, and the region of interest is set for each processing range. That is, since a plurality of regions of interest can be set simultaneously in the same frame, the problem caused by the time difference can be solved when comparing evaluation values. The processing range defines an outer edge of processing, and the setting is basically performed artificially, but may be automated. Also, if the processing range is manually set in advance and the processing range is uniformly applied to a series of frames, the complexity of the setting can be largely eliminated.
[0014]
Preferably, the region of interest is adaptively set for each frame in accordance with the motion of the object.
[0015]
(2) Moreover, in order to achieve the said objective, this invention was obtained by the power calculation means which calculates power based on the data obtained by transmission / reception of an ultrasonic wave, and the said ultrasonic transmission / reception Binarization means for forming a binarized image from which an object is extracted based on the data, and a first offset line along the contour inside the contour of the object with respect to the binarized image; First image processing means for performing a first image processing for determining the second image, and a second image for determining a second offset line further to the inner side along the first offset line than the image after the first image processing. A second image processing unit that performs processing, a region of interest setting unit that sets a region of interest as a region sandwiched between the first offset line and the second offset line, and an integrated value of power in the region of interest. Characterized in that it comprises a a first evaluation value calculation means for calculating a first evaluation value for evaluating the properties of the object.
[0016]
According to the above configuration, the first evaluation value is calculated based on the power in the region of interest that is automatically set. The first evaluation value is for evaluating the properties of the object, but may be, for example, the IB value described above. In that case, the power of each echo data in the region of interest is integrated, the integrated value may be an IB value, the integrated value divided by a predetermined value may be the IB value, or the integrated object is integrated. An IB value obtained by dividing the value by the integrated value for the comparative object separately obtained may be used as the IB value.
[0017]
The power is obtained, for example, by orthogonally detecting a received signal and converting it to a complex signal, and adding the square of the real part and the square of the imaginary part.
[0018]
Preferably, a second evaluation value calculating means for calculating a second evaluation value by averaging the first evaluation values is included. According to such an average, noise can be effectively removed. Note that the second evaluation value may be an average IB value.
[0019]
Desirably, a determination means for determining a maximum value and a minimum value in a time variation of the first evaluation value or the second evaluation value, and a third evaluation value for calculating a third evaluation value based on the maximum value and the minimum value Computing means. Here, the third evaluation value is, for example, the above CV-IB value. Note that the CV-IB value may be obtained based on the time change of the IB value instead of the average IB value.
[0020]
Preferably, the maximum value and the minimum value are determined based on a biological signal. That is, the search range of the maximum value and the minimum value can be narrowed by a biological signal such as an electrocardiogram signal, or the timing thereof can be determined.
[0021]
Desirably, at least one of the first evaluation value, the second evaluation value, and the third evaluation value is represented as a display mode of the region of interest. For example, if the magnitude of the evaluation value is expressed by a change in hue, a change in luminance, etc., the magnitude can be intuitively recognized.
[0022]
Preferably, at least one of the first evaluation value, the second evaluation value, and the third evaluation value is displayed in a graph.
[0023]
(3) In order to achieve the above object, the present invention includes a binarization unit that forms a binarized image from which an object is extracted based on data obtained by transmission and reception of ultrasonic waves. By scanning the binarized image with a first operator for edge detection having a size of n × n pixels, a first offset line is formed along the contour inside the contour of the object. A first image processing means for performing a first image processing for determining the image, and scanning an image after the first image processing with a second operator for edge detection having a size of m × m pixels. Second image processing means for performing a second image processing for defining a second offset line further inside along the first offset line, based on the first offset line and the second offset line Region of interest It is characterized by being. Desirably, means for variably setting at least one of n and m is included.
[0024]
By changing the value of n, the separation width (offset amount) from the contour edge to the first offset line can be freely changed. Further, by changing the value of m, the separation width (ROI width) from the first offset line to the second offset line can be freely changed.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0026]
First, the principle of the image processing method according to the present embodiment will be described with reference to FIGS.
[0027]
In FIG. 1, a binarized image 10 is shown. The binarized image 10 corresponds to a processing area set in a two-dimensional echo data capturing area, and power is calculated for each data in the processing area, and the power is set to a predetermined threshold. It is an image generated by comparing with a value, that is, by performing a binarization process. Here, if the myocardium is an object, for example, the data on the myocardium is 1 (ie, Hi), while the blood data is 0 (ie, Low). That is, the myocardium that is the object is extracted by this binarization processing. A tissue boundary 12 exists between the myocardium and the blood flow, and this corresponds to, for example, the intima of the myocardium.
[0028]
As will be described later, for example, four processing regions are set for the myocardium as the left ventricle in the present embodiment, and image processing as described below is applied to each.
[0029]
As shown in FIG. 2, the operator 14 is scanned for the binarized image 10. The operator 14 has a size of n × n pixels centered on the target pixel 16, and a surrounding pixel group 18 exists around the target pixel 16. This operator 14 is an operator that sets the target pixel data to 1 only when the target pixel value is 1 and 0 and 1 are mixed in the peripheral pixel group, and otherwise sets the target pixel value to 0. .
[0030]
When such an operator 14 is scanned with respect to the binarized image 10 shown in FIG. 1, an image as shown in FIG. 2 is obtained as a result. That is, 1 is given as the pixel value in a band-like region from the tissue boundary 12 to a portion that has entered the tissue by a predetermined pixel. One side of the band-like region is a tissue boundary 12, and the other side is an offset line 20. The offset line 20 forms a part of the outer shape of the ROI (region of interest) that is finally set.
[0031]
Next, an exclusive OR (XOR) operation is executed for each pixel between the image shown in FIG. 1 and the image shown in FIG. 2, and as a result, an image as shown in FIG. 3 is obtained. . That is, 1 is given to the pixels existing inside the tissue with the offset line 20 as a boundary, and 0 is given to the other pixels.
[0032]
Then, an operator 22 as shown in FIG. 4 is scanned with respect to the image shown in FIG.
[0033]
Here, the operator 22 is an operator for setting an offset line similarly to the operator 14 shown in FIG. 2, and the size thereof is m × m pixels with the target pixel 24 as the center. In the operator 22, a surrounding pixel group 26 exists around the target pixel 24.
[0034]
The operator 22 has a calculation function that sets the value of the target pixel to 1 only when the value of the target pixel is 1 and 1 and 0 are mixed in the peripheral pixel group, and sets the value of the target pixel to 0 in other cases. Yes.
[0035]
Therefore, when the operator 22 is scanned with respect to the image shown in FIG. 3, the image shown in FIG. 4 is obtained. That is, an offset line 30 is generated at a position separated by a predetermined distance from the offset line 20 toward the inside of the tissue, and a value of 1 is given to the pixels sandwiched between the offset lines 20 and 30, otherwise For the pixels of 0, 0 is given as the value.
[0036]
The region having the value 1 shown in FIG. 4 becomes the ROI 32, that is, the adaptive and automatic setting of the ROI 32 is realized by the above process.
[0037]
If the tissue boundary 12 is a part of the outer shape of the ROI, there is inevitably more room for noise and the like. However, according to the image processing described above, the offset line is positioned at a certain distance from the tissue boundary 12 toward the inside of the tissue. 20, and an offset line 30 is set along the offset line 20 as a reference. As a result, the ROI 32 can be defined as a region surrounded by the two offset lines 20 and 30. Here, the ROI 32 has a band-like region, and both ends thereof are limited by the outer frame of the processing range described above.
[0038]
In the above-described embodiment, the binarization process is performed on the power of each pixel in the processing range, and the various image processes as described above are applied. However, the normal echo data is not used instead of such power. On the other hand, it is possible to apply the same method as described above, and even in this case, automatic ROI setting can be realized. Incidentally, image processing such as smoothing and compression processing may be performed on the original image prior to the binarization processing.
[0039]
Therefore, according to the present embodiment, for example, as shown in FIG. 5, for example, four processing regions 34 to 40 that are adjacent to the annular left ventricular wall are set, and in each processing region 34 to 40 It is possible to automatically set the regions of interest 34A to 40A. Incidentally, with respect to the processing region 34, an offset line 20 is set in the tissue inner direction of the tissue boundary 12, and an offset line 30 is set along the offset line 20, and the region surrounded by the two offset lines 20 and 30 is as follows. A region of interest 34A is defined.
[0040]
In the example shown in FIG. 5, four processing areas 34 to 40 are set. Of course, more processing areas may be set, or only one processing area may be set. It may be. In the present embodiment, an IB value is calculated for each processing region.
[0041]
In the processing described above, the distance from the tissue boundary 12 to the offset line 20 can be variably set by changing the size of the operator 14, that is, the value of n. Similarly, by setting the size of the operator 22, that is, the value of m to a desired value, the distance from the offset line 20 to the offset line 30, that is, the size or width of the ROI can be variably set. It is possible. Furthermore, the threshold value for the binarization process may be appropriately determined according to the power level of the target tissue.
[0042]
FIG. 6 is a block diagram showing the main configuration of the ultrasonic diagnostic apparatus according to this embodiment.
[0043]
The power data memory 70 stores power data output from a power calculator (not shown) for one frame.
[0044]
Here, the power calculation will be described. Quadrature detection is performed on the received signal acquired by ultrasonic transmission / reception, and the square of the real part and the square of the imaginary part in the complex signal after the quadrature detection are calculated. The power data is calculated as a sum of these values. Such power data is stored in the power data memory 70 as described above. The processing range setting unit 72 sets, for example, a plurality of processing ranges as shown in FIG. 5 on the display coordinate system based on the coordinates set by the input unit 74. Specifically, each processing range Reading control of power data belonging to the range is performed.
[0045]
The input device 74 is composed of, for example, a keyboard or a trackball. The input device 74 is used to set a processing range by manual operation, or to set a threshold value K, a distance n from the edge, and an ROI. The value of each parameter of size m can be set.
[0046]
The binarization circuit 76 inputs power data in a specific processing area output from the power data memory 70, applies binarization processing to them, and results in binarization as shown in FIG. It is a circuit that generates a digitized image 10. In that case, each power data is compared with the threshold value K, and a value 1 is given only to the power data exceeding the threshold value K, and a value 0 is given to the other power data. ing.
[0047]
The ROI edge detection unit 78 is a circuit that executes the processing shown in FIGS. 2 and 3. That is, the ROI edge detection unit 78 scans the binarized image after the binarization processing with the operator 14 shown in FIG. 2. This is a circuit that generates an image with a clear offset line by executing image processing and further performing an exclusive OR operation as shown in FIG. In that case, the size of the operator 14 is determined by the parameter n output from the input device 74.
[0048]
An image as shown in FIG. 3 is stored in the ROI edge data memory 80, and the image is read out and output to the ROI determination circuit 82.
[0049]
The ROI determination circuit 82 is a circuit that executes the image processing shown in FIG. 4, that is, the operator 22 shown in FIG. 4 is scanned with respect to the image output from the ROI edge data memory 80. In this circuit, the offset line 30 is clarified along the line 20, and the ROI is finally determined as a region defined by the offset line and the outer frame of the processing range.
[0050]
The coordinates of the outer diameter of the ROI determined as described above are stored in the ROI coordinate memory 84.
[0051]
Next, the IB processing circuit 85 will be described. The IB value calculation circuit 86 receives power data within a specific processing range output from the power data memory 70. The IB value calculation circuit 86 uses only the power data belonging to the ROI based on the coordinate data output from the ROI coordinate memory 84 among the input power data, and integrates them. The IB value is calculated. Of course, various methods can be applied as a method for calculating such an IB value. For example, by integrating power data along the time axis direction for each pixel or integrating power along the ultrasonic beam direction. The IB value may be obtained. However, in the present embodiment, as described above, the power data is integrated in the ROI, and thereby the IB value is obtained. The addition average circuit 88 is a circuit that adds the IB values calculated by the IB value calculation circuit 86 over a plurality of frames and calculates the average value. The average IB value obtained thereby is output to the difference circuit 90.
[0052]
An electrocardiogram signal as a biological signal from the electrocardiograph is input to the difference circuit 90, and the difference circuit 90 calculates the maximum value and the minimum value in the time variation of the average IB value based on such an electrocardiogram signal. I have identified. Specifically, since the electrocardiogram signal can specify the range where the average IB value is approximately the maximum and the minimum, the positive maximum value and the negative maximum value within the two limited ranges. By specifying the value, the maximum value and the minimum value are obtained. The difference circuit 90 outputs the CV-IB value as the difference between the maximum value and the minimum value. The memory 92 stores the above-described IB value, average IB value, and CV-IB value. Specifically, as shown in FIG. 5, a plurality of processing areas are set on one frame, and ROIs are individually set for each processing area. Correspondingly, the IB value, the average IB value and the CV-IB value are stored.
[0053]
On the ultrasonic image information memory 98, a B-mode image as an ultrasonic image output from the B-mode processing circuit is stored. The image information of the B mode image is output to the synthesis circuit 94.
[0054]
In addition to this image information, ROI coordinate data output from the ROI coordinate memory 84 and information stored in the memory 92 are input to the combining circuit 94. In the present embodiment, the combining circuit 94 has a function of combining, for example, an ROI image representing the average IB value on the B-mode image. Such an ROI image has a form similar to the outer shape of the ROI, and the luminance or hue inside the ROI image corresponds to the average IB value. Therefore, when such a composite image is displayed on the monitor 100, the magnitude of the average IB value can be intuitively recognized from the brightness or hue of the ROI. Of course, numerical values may be displayed for each ROI on the monitor 100 for each of the IB value, the average IB value, and the CV-IB value, and various other display forms may be employed. The graph creation circuit 96 is a circuit that creates a graph for each ROI based on the average IB value output from the memory 92.
[0055]
FIG. 7 shows four graphs 50 to 56 thus created. Each of the graphs 50 to 56 corresponds to the four processing regions 34 to 40 illustrated in FIG. 5. In each graph, the horizontal axis is a time axis and the vertical axis is an average IB value. That is, the above-described CV-IB value is obtained from the maximum value and the minimum value on such a graph. Therefore, if such a graph display is performed, there is an advantage that the calculation process of the CV-IB value can be confirmed.
[0056]
For example, two processing regions 62 and 64 can be set for a specific heart wall or blood vessel wall as shown in FIG. According to such setting, it is possible to automatically set two ROIs 66 and 68 in the tissue 60 by the above-described image processing, and two ROIs are set simultaneously on the same frame. There is an advantage that the calculation accuracy can be improved when the values obtained by use are compared with each other or the ratio thereof is calculated. In the above embodiment, if one or a plurality of processing regions are initially set, and an ultrasound image of each frame is obtained thereafter, the region of interest is individually set in real time for each frame. , The complexity associated with individual ROI settings can be greatly eliminated, and since ROI is automatically set under objective criteria, the calculation accuracy when performing calculations using the ROI can be improved. There is also an advantage that the reproducibility of the measurement can be improved.
[0057]
In the embodiment described above, the IB value is defined as the integrated value of the power in the ROI. However, if the IB value is defined more strictly, the ROI having the same size is set on the blood flow. If the power integrated value for the heart wall is normalized by the power integrated value on the blood flow, a more exact IB value can be calculated. Such normalization is not limited to the above, and normalization may be performed according to the size of the ROI itself.
[0058]
【The invention's effect】
As described above, according to the present invention, it is possible to realize adaptive setting of a region of interest according to a moving tissue. Further, according to the present invention, there are advantages that the calculation accuracy of the evaluation value can be improved, and further, the property evaluation can be performed for each of a plurality of parts of the target tissue.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a binarized image.
FIG. 2 is a diagram for explaining an edge detection operator;
FIG. 3 is a diagram illustrating a binarized image from which offset lines have been extracted.
FIG. 4 is a diagram for explaining an operator for detecting a second offset line.
FIG. 5 is a diagram showing a plurality of processing regions set for the myocardium.
FIG. 6 is a block diagram showing a main configuration of the ultrasonic diagnostic apparatus according to the present embodiment.
FIG. 7 is a diagram showing a graph display of average IB values.
FIG. 8 is a diagram for explaining two processing areas set across organizations;
[Explanation of symbols]
10 binary image, 12 tissue boundary, 14 operator, 20 offset line (inside), 22 operator, 30 offset line (outside), 32 ROI (region of interest), 70 power data memory, 72 processing range setter, 74 input device, 76 binarization circuit, 78 ROI edge detection unit, 80 ROI edge data memory, 82 ROI determination circuit, 84 ROI coordinate memory, 86 IB value calculation circuit, 88 addition average circuit, 90 difference circuit, 92 memory, 94 synthesis circuit, 96 graph creation circuit.

Claims (14)

Based on data obtained by transmission and reception of ultrasonic waves, binarization means for forming a binarized image from which an object is extracted;
A first image processing means for performing a first image processing for defining a first offset line along the contour inside the contour of the object with respect to the binarized image;
Second image processing means for performing second image processing for defining a second offset line along the first offset line and further on the inner side of the image after the first image processing;
Including
A region of interest is set based on the first offset line and the second offset line. The apparatus of claim 1.
The ultrasonic diagnostic apparatus, wherein the region of interest is set as a region sandwiched between the first offset line and the second offset line. The apparatus of claim 2.
Means for setting a processing range on a data capture area where the ultrasonic wave is transmitted and received,
The ultrasound diagnostic apparatus, wherein the region of interest is set as a region within the processing range and sandwiched between the first offset line and the second offset line. The apparatus of claim 3.
A plurality of processing ranges are set in the data capture area,
The ultrasonic diagnostic apparatus, wherein the region of interest is set for each processing range. The apparatus of claim 1.
The ultrasonic diagnostic apparatus, wherein the region of interest is adaptively set for each frame according to the motion of the object. Power calculation means for calculating power based on data obtained by transmission and reception of ultrasonic waves;
Binarization means for forming a binarized image from which an object is extracted based on data obtained by transmission and reception of the ultrasonic waves;
A first image processing means for performing a first image processing for defining a first offset line along the contour inside the contour of the object with respect to the binarized image;
Second image processing means for performing second image processing for defining a second offset line along the first offset line and further on the inner side of the image after the first image processing;
A region of interest setting means for setting a region of interest as a region sandwiched between the first offset line and the second offset line;
First evaluation value calculating means for calculating a first evaluation value for evaluating the property of the object based on an integrated value of power in the region of interest;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 6.
2. An ultrasonic diagnostic apparatus comprising: a second evaluation value calculating means for calculating a second evaluation value by averaging the first evaluation values. The apparatus of claim 6.
Means for determining a maximum value and a minimum value in a time variation of the first evaluation value;
Third evaluation value calculating means for calculating a third evaluation value based on the maximum value and the minimum value;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 7.
Determining means for determining a maximum value and a minimum value in time variation of the second evaluation value;
Third evaluation value calculating means for calculating a third evaluation value based on the maximum value and the minimum value;
An ultrasonic diagnostic apparatus comprising: The device according to claim 8 or 9,
The ultrasonic diagnostic apparatus, wherein the maximum value and the minimum value are determined based on a biological signal. The device according to claim 8 or 9,
At least one of the plurality of evaluation values is represented as a display mode for the region of interest. The device according to claim 8 or 9,
An ultrasound diagnostic apparatus, wherein at least one of the plurality of evaluation values is displayed in a graph. Based on data obtained by transmission and reception of ultrasonic waves, binarization means for forming a binarized image from which an object is extracted;
By scanning the binarized image with a first operator for edge detection having a size of n × n pixels, a first offset line is formed along the contour inside the contour of the object. First image processing means for performing first image processing for determining
By scanning a second operator for edge detection having a size of m × m pixels with respect to the image after the first image processing, further inward along the first offset line. Second image processing means for performing second image processing for defining a second offset line;
Including
A region of interest is set based on the first offset line and the second offset line. The apparatus of claim 13.
An ultrasonic diagnostic apparatus comprising means for variably setting at least one of the n and m.

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