JPH0710260B2 - Method of displaying tomographic image in ultrasonic diagnostic apparatus - Google Patents

Description

The present invention relates to a method for displaying a tomographic image in an ultrasonic diagnostic apparatus.

(B) Conventional technology and its problems Generally, in an ultrasonic diagnostic apparatus, an ultrasonic wave is transmitted to a subject, and an echo of the ultrasonic wave reflected by each part of the subject is received according to the difference in acoustic impedance. Then, the received echo signal is brightness-modulated to display a tomographic image on the CRT. Therefore, by observing the displayed tomographic image, normality and abnormality of the tissue can be diagnosed to some extent.

However, in the conventional display of a tomographic image, the difference in brightness level is relatively small depending on the tissue, and therefore it may not be possible to easily determine the boundary portion between the abnormal portion and the normal portion of the tissue. For example, in the case of liver tumor, it is difficult to distinguish it from normal liver, and its judgment requires specialized knowledge and experience. In addition, it is necessary to finally cut off the tissue by surgery to determine the quality of the tissue property, which imposes a burden on the patient.

The present invention has been made in view of such circumstances, even when a relatively approximate echo signal intensity is obtained, by easily grasping the region of the abnormal site of the tissue from the tomographic image, The purpose is to enable more accurate diagnosis than ever before.

(C) Means for Solving the Problems A method of displaying a tomographic image of the present invention is to adjust a STC to display a tomographic image having no depth dependence of echo signal intensity, and display the tomographic image from among the displayed tomographic images. Two regions of interest corresponding to the diagnosis target region and the normal region are set, histograms relating to the echo signal intensities existing in each of the set regions of interest are created, and then the difference between the histograms is obtained to obtain the diagnosis target. The width where the frequency of the echo signal intensity of the region is concentrated is set as the window width of the brightness level of the tomographic image, and the region of the abnormal region of the tissue is emphasized on the image by this.

(D) Examples Hereinafter, the present invention will be described in detail based on the examples shown in the drawings.

In this embodiment, as shown in FIG. 1, first, the STC is adjusted on the CRT screen of the ultrasonic diagnostic apparatus to display a tomographic image F having no echo signal intensity depth dependency. Then, in the displayed tomographic image F, for example, regions of interest ROI ₁ and ROI ₂ are respectively included in the diagnosis target site A and the normal site estimated to be tumors.
To set. At that time, the size of each of the regions of interest ROI ₁ and ROI ₂ is adjusted by appropriately enlarging or reducing it according to each part.

Then, the intensity value of the echo signal corresponding to the brightness of the image existing in each of the set regions of interest ROI ₁ and ROI ₂ is stored for each pixel in, for example, the CPU, and based on the stored echo signal intensity value, FIG. As shown in, a histogram is created with the horizontal axis representing the echo signal intensity value and the vertical axis representing the frequency. In this case, the intensity value of the echo signal appearing as the shade of the displayed tomographic image F corresponds to the characteristic of the acoustic impedance of the tissue in the subject. Therefore, the obtained histogram has a distribution shape due to its tissue property. That is, for example, if the region of interest ROI ₁ selected as the diagnosis target region is a tumor, its histogram H
₁ has a distribution shape as shown in FIG. 2 (a), and the histogram H of the normal region of the other region of interest ROI _2
2 has a distribution shape as shown in FIG.

When the respective histograms H ₁ and H ₂ are obtained in this way, then both histograms H ₁ and H ₂ are standardized under a fixed standard. For example, in this embodiment, the two histograms H ₁ and H ₂ are standardized so that the most frequent frequencies p ₁ and p ₂ of the echo signal intensities match.

Then, the difference between both standardized histograms H ₁ and H ₂ is obtained. When the diagnosis target site is a lesion site, the data of this difference has a specific distribution shape in which it is emphasized, as shown in FIG. 2 (c), for example. That is, by subtracting (frequency of echo signal intensity of abnormal portion) from (frequency of echo signal intensity of normal portion), a portion where the frequency of abnormal portion is concentrated is emphasized. Therefore, in FIG. 2 (c),
The width W in which the frequency of the echo signal intensity obtained in the region of interest ROI ₁ of the diagnosis target region is concentrated is set as the window width of the luminance level of the tomographic image.

Then, if the gray scale level is adjusted within the set window width, as shown in FIG. 3, if the site A to be diagnosed is abnormal tissue, the difference in the brightness level of that site is greatly emphasized, and other normal sites are detected. Disappears and is displayed, so that the abnormal region is clearly distinguished from the normal region.
Moreover, the other abnormal parts B and C which could not be observed in the original tomographic image shown in FIG. 1 are also clarified.

The standardization method is not limited to this embodiment, and for example, standardization may be performed so that the total number of pixels is the same, and various processes can be adopted.

(E) Effect As described above, according to the method of the present invention, it is possible to image-enhance and display the diagnosis target site even when the diagnosis target site has an echo signal intensity relatively close to that of the normal site. Therefore, the area of the abnormal site of the tissue can be easily grasped by the noninvasive examination of observing the tomographic image. Therefore, more accurate diagnosis can be made than ever before, and excellent effects such as reduction of the burden on the patient are exhibited.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is an explanatory view showing a display example of a tomographic image of an ultrasonic diagnostic apparatus, and FIG. 2 relates to a frequency obtained from an echo signal intensity value of the tomographic image. FIG. 3 is a diagram showing a histogram, and FIG. 3 is an explanatory diagram showing a display example of an image-enhanced tomographic image. F ... tomographic image, ROI ₁ , ROI ₂ ... region of interest, H ₁ , H ₂ ... histogram, W ... window width.

Claims (1)

[Claims] 1. A STC is adjusted to display a tomographic image having no depth dependence of echo signal intensity, and two regions of interest corresponding to a diagnosis target region and a normal region are displayed from the displayed tomographic image. The histograms relating to the echo signal intensities that exist in each set region of interest are set, and then the difference between the two histograms is obtained to determine the width at which the frequency of the echo signal intensities of the diagnosis target region is concentrated and the brightness of the tomographic image. A method of displaying a tomographic image in an ultrasonic diagnostic apparatus, characterized by setting as a window width of a level.