JP4253070B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to echo data conversion processing.
[0002]
[Prior art]
When the boundary (contour) is emphasized on the ultrasonic image, for example, a differential filter represented by a Sobel filter is used. Such a filter uses a two-dimensional mask, calculates a difference between the density values inside and outside the boundary within the mask, and converts the value of the echo data of interest according to the difference value.
[0003]
However, there is a problem in that an ultrasonic image includes a lot of noise, and when boundary enhancement is performed according to differentiation processing as described above, noise is also enhanced at the same time.
[0004]
Incidentally, there is a request for boundary enhancement in both a two-dimensional ultrasonic image and a three-dimensional ultrasonic image, and the latter image processing method is disclosed in Japanese Patent Laid-Open No. 10-33538. In such a method, a predetermined volume rendering operation is performed on the echo data continuous along the ultrasonic beam in a time-series order, and a pixel value corresponding to the ultrasonic beam is satisfied when a predetermined end condition is satisfied. Is determined.
[0005]
When a three-dimensional image is formed by such processing, it has been pointed out that it is difficult to clearly express the surface of a thin tissue such as a fetal fold.
[0006]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to realize ultrasonic image processing capable of enhancing a boundary (for example, an organ surface) without enhancing noise.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an extraction means for extracting a plurality of echo data in a mask centering on the echo data of interest from an echo data string, and a centroid based on the plurality of echo data in the mask. Using the center-of-gravity position calculation means for calculating the position, the conversion means for converting the value of the echo data of interest in accordance with the difference between the center position in the mask and the position of the center of gravity, and each converted echo data And an image processing means for forming an ultrasonic image.
[0008]
According to the above configuration, the centroid position is calculated based on the plurality of echo data in the mask, and the difference between the centroid position and the center position where the target echo data exists is calculated. Then, the value of the echo data of interest is converted using the difference.
[0009]
Since the position of the center of gravity is used, the contribution can be reduced even if noise is included in the mask, and the noise in the ultrasonic image often exists throughout the entire image. Seems to have much less influence on the calculation of the center of gravity. The barycentric position represents the tendency of the luminance distribution in the mask, and the difference between it and the mask center position corresponds to the probability that the mask center position is on the tissue boundary. Therefore, if the value of the target echo data is converted according to the size of the difference, boundary enhancement can be performed without being affected by noise.
[0010]
Preferably, the converting means converts the value of the echo data of interest according to the difference and its polarity. The polarity of the difference is inverted when the mask moves from a tissue with a large echo data value to a small tissue and vice versa. Therefore, the polarity is used for the conversion process.
[0011]
Preferably, the converting means converts the value of the attention echo data according to the difference only when the difference has a positive polarity. For example, when clarifying a part of an amniotic fluid such as a fetus's eyelid, it is desirable to perform conversion under this condition, and it is possible to prevent the problem that other parts stand out unnecessarily.
[0012]
Preferably, the conversion means converts the value of the attention echo data according to the absolute value of the difference. In general boundary emphasis processing, it is desirable to perform conversion under this condition. The user can select whether to use the difference as it is or its absolute value, or the condition can be automatically changed according to the measurement condition (for example, diagnosis part or subject). .
[0013]
Preferably, the conversion means selects a conversion characteristic according to the difference from a plurality of different conversion characteristics, a conversion unit that performs conversion according to the selected conversion characteristic, Have Preferably, the plurality of conversion characteristics include a logarithmic characteristic.
[0014]
Preferably, the echo data string is composed of a plurality of echo data along an ultrasonic beam, and the mask is a one-dimensional mask. If the mask is scanned along the ultrasonic beam, rapid filtering becomes possible.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
[0016]
FIG. 1 illustrates the principle of the present invention. (A) shows an echo data string. The vertical axis indicates the address of the echo data, and the horizontal axis indicates the value of the echo data, that is, the density value. In this embodiment, this echo data string is composed of a plurality of echo data in time series order existing on the ultrasonic beam.
[0017]
In the image processing method according to the present embodiment, a one-dimensional mask M is used, and a plurality of echo data in the mask are extracted. This is shown in (B). In the figure, 2n + 1 echo data are cut out by the one-dimensional mask M. Here, the center of the mask is the target pixel, that is, the target echo data, and n echo data are extracted in both directions from the center of the mask. Incidentally, the one-dimensional mask M is scanned along the echo data string shown in FIG. For example, scanning is performed along an ultrasonic beam.
[0018]
In this embodiment, the calculation of the center of gravity position shown in (C) is executed, and the center of gravity position of the mask is specified. Here, the calculation formula of the center of gravity position shown in (C) is equivalent to the calculation formula for calculating the center of gravity position of a physical object. Then, a difference δ between the obtained center of gravity position and the center position of the mask is calculated. The value of the echo data of interest is converted using this difference δ.
[0019]
FIG. 2 shows a state where the region I and the region II are separated by a boundary on the ultrasonic image. In such a model, when the one-dimensional mask M is scanned as shown, the result shown in FIG. 3 is obtained. That is, in FIG. 3, when the density value of region I is smaller than the density value of region II, the value of difference δ becomes positive, and the value of difference δ peaks when the mask center position is on the boundary. Reach. On the other hand, when the density value of the region I is larger than the density value of the region II, the result is the reverse of the above, that is, the difference δ takes a negative value, and the negative value of the difference δ is maximum on the boundary. Become.
[0020]
Since the difference δ has such a property, for example, when emphasizing the surface of the fetus in the amniotic fluid, it is possible to perform boundary enhancement using only the positive difference δ. Of course, if the absolute value of the difference δ is used, there is an advantage that each boundary between tissues can be emphasized.
[0021]
In this embodiment, when converting the value of the echo data of interest (input density value), for example, the characteristics shown in FIG. 4 are used. In the graph shown in FIG. 4, the horizontal axis is the input density value, and the vertical axis is the output density value. The graph includes a plurality of conversion characteristics 100 to 106, and the conversion characteristics are selected and used according to the magnitude of the value of + δ. Here, the conversion characteristic 100 is a linear characteristic, and the conversion characteristics 102 to 106 have logarithmic characteristics. When the conversion characteristics 102 to 106 are selected, the boundary is emphasized as the shift amount from the center position of the center of gravity is larger, that is, as the gradient of the density value on the boundary line is steeper. . Incidentally, when the logarithmic characteristic is used, the smaller the input density value is, the more the output density value is doubled. As a result, the boundary line having a small density difference is emphasized in a region where the input density value is small. Incidentally, as described above, since the position of the center of gravity in the one-dimensional mask is used as the feature amount, there is an advantage that it is hardly affected by noise.
[0022]
Next, the configuration of an ultrasonic diagnostic apparatus to which the above principle is applied will be described. FIG. 5 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to this embodiment.
[0023]
The probe 10 is used in contact with the surface of a living body or inserted into a body cavity. An ultrasonic beam is scanned two-dimensionally or three-dimensionally by the probe 10, and as a result, a two-dimensional data capturing area or a three-dimensional data capturing area is formed.
[0024]
The transmission / reception unit 12 is a circuit that supplies a transmission signal to the probe 10 and performs processing such as phasing addition on the reception signal from the probe 10.
[0025]
The image processing unit 14 is a circuit that forms a desired ultrasonic image in accordance with the obtained received signal, that is, echo data. The image processing unit 14 uses the two-dimensional tomographic image, a three-dimensional image having a three-dimensional expression, or the like. Is configured. In this case, an image processing method based on the volume rendering method described in Japanese Patent Laid-Open No. 10-33538 may be applied. However, the above-described principle is not limited to such three-dimensional processing, and the above-described effect can be obtained even when a B-mode image or an M-mode image is formed.
[0026]
The image processing unit 14 has a filter unit 16. This filter unit 16 is a circuit that executes the above-described principle, and an ultrasonic image filtered by the filter unit 16 is output to the display unit 18 as it is, or an ultrasonic image preprocessed by the filter unit 16 is Thereafter, the image is output to the display unit 18 through other image processing.
[0027]
FIG. 6 shows a specific configuration example of the filter unit 16 shown in FIG. The center-of-gravity position calculation unit 20 receives 2n + 1 echo data in the mask. That is, the echo data sequence cut out by the one-dimensional mask is sent to the gravity center position calculation unit 20. The center-of-gravity position calculation unit 20 executes the center-of-gravity position calculation shown in FIG. 1C, and outputs the resulting center-of-gravity position G.
[0028]
The differencer 22 receives the center address C of the mask, which is the address of the echo data of interest, and calculates the position difference δ by subtracting the center position C from the center of gravity position G. The difference δ is output to the image density value converter 24. Further, it is output to the absolute value calculator 23 as necessary, and the absolute value of the difference δ is output to the image density conversion unit 24.
[0029]
Here, as shown in FIG. 2, for example, when viewed along the moving direction of the one-dimensional mask M, the boundary is emphasized under the condition that the mask scan is performed from the area where the echo data is small to the area where the echo data is large. In this case, the image density value converter 24 uses only the difference δ having a positive value. Further, when performing enhancement processing for all the boundaries, the image density value conversion unit 24 uses the absolute value of the difference output from the absolute value calculator 23. Which value is used is selected artificially or automatically in accordance with the diagnostic conditions such as the diagnostic subject and the diagnostic site.
[0030]
FIG. 7 shows a specific configuration example of the image density value conversion unit 24 shown in FIG. The difference δ is input to the LUT selection unit 26, and the LUT selection unit 26 selects one of the look-up tails (LUT) from the table group 30. Here, LUT1 to LUT4 correspond to the conversion characteristics 100 to 106 shown in FIG. As a result, a lookup table is first selected according to the magnitude of the difference δ, and then the value of the echo data of interest is converted.
[0031]
【The invention's effect】
As described above, according to the present invention, it is possible to enhance the boundary without enhancing noise.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the principle of an image processing method according to the present invention.
FIG. 2 is a diagram illustrating scanning of a one-dimensional mask.
FIG. 3 is a diagram illustrating a change in difference when a one-dimensional mask is scanned on the model illustrated in FIG. 2;
FIG. 4 is a diagram illustrating characteristics of density value conversion.
FIG. 5 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 6 is a diagram illustrating a specific configuration example of a filter unit.
FIG. 7 is a diagram illustrating a specific configuration example of an image density value conversion unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Probe, 12 Transmission / reception part, 14 Image processing part, 16 Filter part, 18 Display part, 20 Center-of-gravity position calculation part, 22 Difference unit, 23 Absolute value calculation part, 24 Image density value conversion part, 26 LUT selection part, 30 tables.

Claims (7)

Extraction means for extracting a plurality of echo data in a mask centered on the echo data of interest from the echo data string,
Centroid position calculating means for calculating a centroid position based on a plurality of echo data in the mask;
Conversion means for converting the value of the echo data of interest according to the difference between the center position in the mask and the position of the center of gravity;
Image processing means for forming an ultrasonic image using each converted echo data;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
The ultrasonic diagnostic apparatus characterized in that the conversion means converts the value of the echo data of interest according to the difference and its polarity. The apparatus of claim 1.
The ultrasonic diagnostic apparatus according to claim 1, wherein the conversion means converts the value of the echo data of interest according to the difference only when the difference has a positive polarity. The apparatus of claim 1.
The ultrasonic diagnostic apparatus characterized in that the conversion means converts the value of the echo data of interest according to the absolute value of the difference. The apparatus of claim 1.
The converting means includes
A selection unit that selects one of the conversion characteristics according to the difference from a plurality of different conversion characteristics;
A conversion unit for performing conversion according to the selected conversion characteristic;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 5.
An ultrasonic diagnostic apparatus characterized in that a logarithmic characteristic is included in the plurality of conversion characteristics. The apparatus of claim 1.
The echo data string is composed of a plurality of echo data along the ultrasonic beam,
The ultrasonic diagnostic apparatus, wherein the mask is a one-dimensional mask.

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