JP2005319081A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quantify the extent of the regression of the marginal region of the liver in ultrasonic diagnostic equipment receiving a reflected wave of an ultrasonic wave transmitted to an organism and obtaining an ultrasonic tomographic image. <P>SOLUTION: This ultrasonic diagnostic equipment transmits and receives the ultrasonic wave relative to the liver by an ultrasonic probe 20 and obtains the ultrasonic tomographic image based on the received waves. This equipment sets a region 16 of interest adjacent to the hepatic marginal region (an interest region setting part 28) and the longest edge in the region is defined as the outline of the liver (an outline detecting part 38). This equipment finds two straight lines estimated to be two sides constituting the hepatic marginal region. A site surrounded with the two straight lines and the outline is defined as the site blunted by the involution and the area of the site is calculated (a blunted site area measuring part 42). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic diagnostic apparatus that receives an ultrasonic reflected wave transmitted into a living body and obtains an ultrasonic tomographic image based on the reflected wave.

  An ultrasonic diagnostic apparatus that receives an ultrasonic reflected wave transmitted into a living body and obtains an ultrasonic tomographic image based on the reflected wave is known, and is used for various examinations and diagnoses because the burden on the subject is small. Yes. One of such tests and diagnoses is liver function diagnosis. As the function of the liver decreases, the homogeneity of the liver parenchyma, the smoothness of the liver surface, the sharpness of the liver margin, and the clarity of the intravascular image of the liver are lost. The examiner obtains these states from a tomographic image of the liver and makes a diagnosis in consideration of the results of other examinations. Note that the liver margin corresponds to the lower edge portion of a human when the human is standing.

  Patent Document 1 below discloses a diagnosis of liver function based on a change in the liver parenchyma of an ultrasonic tomographic image.

Japanese Patent Laid-Open No. 2001-23884

  Patent Document 1 discloses the examination and diagnosis of liver function based on changes in the liver parenchyma, but the diagnosis of liver function includes the uniformity of the liver parenchyma as described above, the smoothness of the liver surface, Considering the sharpness of the liver margin and the clarity of intravascular images, the examiner makes a diagnosis based on the experience. Patent Document 1 does not disclose any observation object other than the uniformity of the liver parenchyma.

  The present invention relates to an examination and diagnosis of liver function, and provides an ultrasonic diagnostic apparatus that supports evaluation by performing evaluations on characteristic items different from Patent Document 1.

  The ultrasonic diagnostic apparatus of the present invention includes a tomographic image acquisition unit that obtains an ultrasonic tomographic image of the liver, and a blunting degree calculating unit that calculates a blunting degree that is a value indicating the degree of blunting of the liver margin in the tomographic image. have.

  Further, the blunting degree calculating means extracts two sides constituting the liver margin, obtains approximate lines for each of them, and based on the portion surrounded by the approximate straight line and the outline of the liver margin, the blunting degree Can be calculated.

  Further, the blunting degree calculating means may calculate the blunting degree based on an area of a portion surrounded by the approximate straight line and the contour line.

  The blunting degree may be a value obtained by normalizing an area of a portion surrounded by the approximate straight line and the contour line by dividing the area by the approximate straight line.

  The blunting degree calculating means extracts two sides constituting the liver margin, calculates approximate straight lines for each of them, and calculates the blunting degree based on the intersection of the approximate straight lines and the shortest distance between the contour lines. It can be.

  The ultrasonic diagnostic apparatus may provide an image in which a color is given to a portion surrounded by the approximate straight line and the contour line.

  It is also preferable to provide an ultrasonic tomographic image in which a color is given to this portion.

  By quantifying the degree of hepatic marginal retraction, an index for diagnosing liver function can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic appearance of a human liver 10. FIG. 1 is drawn in a direction when a human is standing, with the front side of the paper being the front of the human, the back of the paper being the back, and the top of the paper being the top. The portion of the lower edge of the liver (the edge indicated by reference numeral 12 in FIG. 1) is particularly called the liver margin. When obtaining an ultrasonic tomographic image, the image is obtained by bringing the ultrasonic probe into contact with the rib from below the rib slightly upward. In FIG. 1, a tomographic image is obtained by applying a probe from a slightly lower side toward the upper side on the front side of the drawing. The tomographic images taken along the alternate long and short dash line 14 in FIG. 1 are shown in FIGS. 2 and 3, the position directly above is the position of the ultrasound probe, and therefore, the upper side of FIG. 2 is the front side surface of the human and the lower side is the back side surface. Moreover, the liver margin 12 mentioned above becomes a right end.

  FIG. 2 is an ultrasonic tomographic image of a normal liver, and the liver margin 12 has a shape with a sharp tip. FIG. 3 is an image of the liver in which the medical condition has progressed. Compared to FIG. 2, it can be seen that the tip of the liver margin 12 is retracted and the tip is rounded and blunted. The two sides that intersect at the liver margin 12 are substantially straight when normal, and even if the tip of the liver margin 12 is blunted and rounded, the portion connected to the blunted and rounded portion is almost straight.

  As described above, in the normal liver, the liver margin 12 appears at an acute angle in the tomographic image, but as the hardening progresses, the tip of the liver margin retracts and becomes rounded. The symptom can be estimated by obtaining the degree of roundness, that is, the degree of blunting.

  Hereinafter, a method for quantifying the degree of blunting of the liver margin 12 will be described. FIG. 4 shows a functional block diagram related to the quantification process of liver margin regression in the ultrasonic diagnostic apparatus. The ultrasonic probe 20 is controlled by the transmission / reception unit 22 to transmit an ultrasonic wave into the living body, receives a reflected wave thereof, and converts it into a reception signal. The received signal is sent from the transmission / reception unit to the digital scan converter (DSC) 24, where an ultrasonic tomographic image is formed. Based on this ultrasonic tomographic image, the blunting degree calculation unit 26 calculates a value indicating the degree of blunting (blunting degree).

  Details of the blunting degree calculation unit 26 will be described below. For the ultrasonic tomographic image of the liver cross section as shown in FIG. 2 or FIG. 3, a region of interest 16 is set in a portion corresponding to the liver margin 12 as shown in FIG. The region of interest 16 is set by the region of interest setting unit 28. The region of interest can be set by the examiner directly entering the position and size of the region of interest on the screen numerically, or by inputting with a pointing device, etc. The examiner looks at the displayed tomographic image and adjusts the region. I do.

  Next, each process is performed to extract the surface. First, the median processing unit 30 performs median processing to eliminate noise. Specifically, a process is performed in which the central value of the luminance values of 3 × 3 pixels is set to the luminance value of the central pixel. Thereby, a big peak etc. can be removed suddenly. Next, the binarization processing unit 32 binarizes the image. As the threshold value for binarization, a predetermined value can be used, or the examiner may arbitrarily set the threshold value while viewing the image, for example. The noise removing unit 34 removes noise generated in the binarization process.

  The edge detection unit 36 detects an edge, that is, a binary boundary line, from the binarized image from which noise has been removed. Edge detection can be performed using a known filter. The contour line detection unit 38 sets the longest edge among the detected edges as the contour line of the liver margin 12. The longest edge is obtained as follows, for example. First, a labeling process for attaching a common label to consecutive pixels is performed on the edge obtained by the edge detection unit 36. The pixels with the same label are continuous, and the length of the edge can be calculated by counting the number of consecutive pixels. FIG. 6 shows an example of the obtained contour line e.

  Next, with respect to the contour line e, two sides constituting the liver margin are calculated as follows. FIG. 7 shows each pixel constituting the contour line e of FIG. A set of numbers assigned to each pixel is an arithmetic average of the coordinates of the pixel, the preceding and following pixels, and the three pixels. That is, the averaged x and y coordinates of the pixel H are the original coordinates (7, 4) of the pixel H and the coordinates (6, 4), (8, 5) of the pixels G and I before and after, as shown below. ) Is the average value (7, 4.3) of each pixel.

    Hx = (6 + 7 + 8) / 3 = 7

    Hy = (4 + 4 + 5) /3=4.3

  Based on the value of each averaged pixel, the difference from the next pixel is obtained, and the slope of the line segment connecting these pixels is obtained. For example, when this inclination is obtained for the pixel H, the coordinates obtained by the above-mentioned average value for this pixel H and the next pixel I are H (7, 4.3) and I (8, 4.7). The slope a is 0.4 from the equation shown below.

a = (4.7-4.3) / (8-7) = 0.4
FIG. 8 is an example in which the inclination of adjacent pixels obtained in this way is examined for all the pixels constituting the contour line e.

  The straight line calculation unit 40 extracts a straight line portion that remains even after retraction due to hardening of the liver, based on the inclination between adjacent pixels obtained as shown in FIG. Specifically, a section from the upper left point A until the slope reaches a predetermined value is a section related to the upper straight line portion, and thereafter a section from the point where the absolute value is equal to or lower than the predetermined value to the lower left point BB Is a section related to the lower straight line portion. This predetermined value can be set to infinity, for example, and in this case, pixel X is extracted from pixel A in the example of FIG. A range that can be regarded as a straight line is extracted from the slopes belonging to the extracted pixels, and these are defined as straight line portions s1 and s2 (see FIG. 9). For the extraction of the straight line portion, for example, it is possible to select pixels that fall within the standard deviation around the average value of the extracted pixels. In the upper part of FIG. 8, since the average value from pixel A to pixel X is 0.82 and the standard deviation is 0.89, pixels in the range from −0.07 to 1.71 form a straight line portion. Suppose that This is satisfied from pixel B to pixel T, and an approximate straight line is calculated by the method of least squares. In FIG. 9, a straight line approximating the upper straight line portion s1 is m1, and similarly, a straight line approximating the lower straight line portion s2 is m2.

  The blunt portion area measuring unit 42 obtains the area of the portion Φ surrounded by the straight lines m1 and m2 calculated by the straight line calculating unit 40 and the contour line e. This is based on the assumption that the straight lines m1 and m2 are the contours of a normal liver, that is, the two sides constituting the liver margin, and the difference between this and the actual contour is the portion where the liver is retracted due to the lesion.

  The angles of the two straight lines m1 and m2 do not vary greatly depending on the subject, but naturally there are individual differences. Even if the obtained area is the same in the blunt part area measuring unit 42, normalization is preferably performed because the degree of retraction differs if the angle is different. Therefore, the normalizing unit 44 performs normalization by dividing the area of the portion Φ surrounded by the straight lines m1 and m2 and the contour line e by the angle θ (see FIG. 9) at which the straight lines m1 and m2 intersect.

  A value indicating the calculated degree of blunting is displayed on the display unit 46 of the ultrasonic diagnostic apparatus, and a portion that is considered to be retracted, that is, a portion indicated by a symbol Φ in FIG.

  In the above embodiment, the degree of blunting is quantified on the basis of the area of the retracted portion Φ, but it is quantified by the shortest distance f (see FIG. 10) between the intersection of the above approximated lines m1 and m2 and the contour line e. It is also possible to In this case, instead of the blunt portion area measuring unit 42 and the normalizing unit 44 in the block diagram shown in FIG. 4, a retraction distance measuring unit is provided, and the above-mentioned distance f considered to be the length at which the liver margin has retracted due to the hardening of the liver. Measure. This value can be used as an index representing the degree of blunting. This numerical value itself can be displayed on the display unit 46, and the length thereof can be displayed over the ultrasonic tomographic image with an arrow or the like as shown in FIG. Further, a portion surrounded by the approximate straight lines m1 and m2 and the contour line e may be displayed with a color.

It is the figure which showed the external appearance of the human liver. It is the figure which showed the ultrasonic tomographic image of the human liver, and shows the image of the normal liver especially. It is the figure which showed the ultrasonic tomographic image of the human liver, and shows the image of the liver in which especially the liver function fell. It is a functional block diagram of the ultrasonic diagnostic apparatus which concerns on calculation of the retraction degree of a liver margin. It is a figure which shows the example of a setting of a region of interest. It is the figure which showed the region of interest and the outline e of the liver margin. It is explanatory drawing which concerns on calculation of the straight line which shows two sides of a liver margin. It is explanatory drawing which concerns on calculation of the straight line which shows two sides of a liver margin. It is a figure which shows the part which the liver margin retreated. It is a figure which shows the example of the retraction amount of a liver margin.

Explanation of symbols

  10 liver, 12 liver margin, 20 ultrasonic probe, 26 bluntness calculation unit.

Claims (6)

A tomographic image acquisition means for obtaining an ultrasonic tomographic image of the liver;
In the tomographic image, a blunting degree calculating means for calculating a blunting degree that is a value indicating a degree of blunting of the liver margin,
An ultrasonic diagnostic apparatus comprising:   2. The ultrasonic diagnostic apparatus according to claim 1, wherein the blunting degree calculating unit extracts two sides constituting the liver margin, obtains an approximate line for each of them, and calculates the approximate line and the contour of the liver margin. An ultrasonic diagnostic apparatus characterized in that a blunting degree is calculated based on a portion surrounded by a line.   The ultrasonic diagnostic apparatus according to claim 2, wherein the blunting degree calculating unit calculates the blunting degree based on an area of a portion surrounded by the approximate straight line and the contour line.   The ultrasonic diagnostic apparatus according to claim 3, wherein the blunting degree is a value obtained by dividing an area of a portion surrounded by the approximate line and the contour line by an angle at which the approximate line intersects. A characteristic ultrasonic diagnostic apparatus.   2. The ultrasonic diagnostic apparatus according to claim 1, wherein the blunting degree calculating unit extracts two sides constituting a liver margin, obtains an approximate line for each of them, obtains an intersection of the approximate lines, and the contour line An ultrasonic diagnostic apparatus characterized in that the degree of blunting is calculated based on the shortest distance.   6. The ultrasonic diagnostic apparatus according to claim 2, wherein an image is provided in which a color is given to a portion surrounded by the approximate straight line and the contour line.

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