TECHNICAL FIELD

The present invention relates to an endoscope system performing image processing with respect to an image of a biological tissue in a body cavity.

BACKGROUND ART

A lesion portion in a biological tissue has various levels of severity from an inflammation in which a mucosal layer of the biological tissue becomes thin and rough, and exhibits a red color to an ulcer in which a partial loss occurs in the mucosal layer and a lower layer thereof. For example, an ulcer site of a lesion of an ulcerative colitis (UC) that includes tongue fur or mucopus exhibits a white color, and an inflamed site that includes edema or easy bleeding properties exhibits a red color. Such a lesion portion can be observed by being imaged with an endoscope system.

However, in order to enable an operator to identify a normal site and a lesion portion by a color difference in an image of an endoscope, it is necessary to receive long-term training under the guidance of a skilled person. In addition, it is not easy for even a skilled operator to identify the lesion portion from a slight color difference, and a cautious operation is required. Therefore, it is preferable that the endoscope system provides evaluation results in which the degree of lesion in the lesion portion is objectively digitized.

In response, an endoscope system is known in which a stable evaluation value can be calculated by suppressing a variation in an evaluation value of an inflamed site due to the brightness of an image, and a processing load for calculating the evaluation value can be suppressed (Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: WO 2017/057680 A

SUMMARY OF INVENTION

Technical Problem

The endoscope system described above includes a light source device applying illumination light toward an object, an image acquisition unit acquiring a color image including at least three or more color components by receiving and imaging reflection light from the object with an image sensor, and an evaluation unit obtaining an evaluation result relevant to a target illness of each pixel on the basis of an angle between a line segment connecting a predetermined reference point set in a color plane that is defined by at least two color components of at least three or more color components and a pixel corresponding point in a color plane of each of the pixels configuring the color image that is acquired by the image acquisition unit, and a reference axis having a correlation with the target illness. The reference axis is set to pass through the predetermined reference point. The reference axis is at least one of an axis having a correlation with the target illness in which the degree of inflammation in the color plane is less than or equal to a predetermined value and an axis having a correlation with the target illness in which the degree of in lamination is greater than or equal to the predetermined value.

According to such a configuration, a stable inflammation evaluation value can be calculated by suppressing a variation in an inflammation evaluation value due to the brightness of the image, and a processing load for calculating the inflammation evaluation value can be suppressed.

However, a lesion portion that can be evaluated by the endoscope system is an inflamed site in which a mucosal layer of a biological tissue becomes thin and rough, and exhibits a red color, and the degree of inflammation of the inflamed site is evaluated as a color component, and thus, may not sufficiently correspond to a subjective evaluation result of a medical doctor, including an inflammation to an ulcer, or a histological evaluation result. That is, the endoscope system is not capable of evaluating a severity indicating the degree of lesion in the lesion portion including an ulcer in which a partial loss occurs in the mucosal layer and a lower layer thereof.

Therefore, an object of the present invention is to provide an endoscope system that is capable of accurately evaluating the degree of lesion in a lesion portion of a biological tissue.

Solution to Problem

One embodiment of the present invention is an endoscope system. The endoscope system, includes:

an electronic endoscope configured to image a biological tissue in a body cavity;

a processor including an image processing unit configured to obtain a severity of a lesion of the biological tissue in which a degree of lesion is represented as one value by using at least information of a color component of an image of a lesion portion of the biological tissue, from the image that is obtained by the electronic endoscope; and

a monitor configured to display information of the severity. The image processing unit includes

a feature amount calculation unit configured to calculate a plurality of pixel evaluation values corresponding to a plurality of features of an appearance, including at least a first feature and a second feature of an appearance appearing in the lesion portion, which are capable of discriminating each of the plurality of features of the appearance from a feature of a normal portion of the biological tissue by a color component indicated by the lesion portion or a shape of the lesion portion and include a first pixel evaluation value and a second pixel evaluation value respectively indicating a degree of first feature and a degree of second feature, relevant to the color component indicated by the lesion portion or the color component and the shape of the lesion portion, for each pixel from the image,

a representative value calculation unit configured to calculate a plurality of representative evaluation values including a first representative evaluation value of the first feature and a second representative evaluation value of the second feature of the imaged biological tissue by integrating each of the plurality of pixel evaluation values of each of the pixels in the image for each of the plurality of features of the appearance, and

an integration unit configured to calculate one numerical value in which at least two representative evaluation values of the plurality of representative evaluation values are calculated and integrated, as the severity of the lesion.

It is preferable that the integration unit is configured to perform different calculations in accordance with an increase or decrease in at least one representative evaluation value of the plurality of representative evaluation values, in order to calculate the one numerical value.

It is preferable that in the different calculations, a set of at least two representative evaluation values to be used in the calculation is different.

One embodiment of the present invention is an endoscope system. The endoscope system, includes:

an electronic endoscope configured to image a biological tissue in a body cavity;

a processor including an image processing unit configured to obtain a severity of a lesion of the biological tissue in which a degree of lesion is represented as one value by using information of a color component of an image of a lesion portion of the biological tissue, from the image that is obtained by the electronic endoscope; and

a monitor configured to display information of the severity. The image processing unit includes

a feature amount calculation unit configured to calculate two pixel evaluation values of a first pixel evaluation value and a second pixel evaluation value, which are capable of discriminating each of a first feature and a second feature of an appearance appearing in the lesion portion from a normal portion of the biological tissue by a color component indicated by the lesion portion or a shape of the lesion portion and respectively indicate a degree of first feature and a degree of second feature, relevant to the color component indicated by the lesion portion or the color component and the shape of the lesion portion, for each pixel from the image,

a representative value calculation unit configured to calculate a first representative evaluation value of the first feature of the imaged biological tissue by integrating the first pixel evaluation values of each of the pixels in the image and a second representative evaluation value of the second feature of the imaged biological tissue by integrating the second pixel evaluation values of each of the pixels in the image, and

an integration unit configured to calculate one numerical value in which the first representative evaluation value and the second representative evaluation value are calculated and integrated, as the severity of the lesion.

It is preferable that the degree of second feature is a degree of color component included in a portion having a predetermined shape in the image.

It is preferable that the degree of second feature is a degree of feature of a predetermined shape in a portion having the predetermined shape in the image.

It is preferable that the degree of first feature is a degree of color component indicated by the lesion portion of the image.

It is preferable that the first pixel evaluation value is a value indicating a degree of feature relevant to a color component indicating a degree of inflammation of the biological tissue, and

the second pixel evaluation value is a value indicating a degree of color component included in a blood vessel region indicating a blood vessel extending into the shape of a streak in the image.

It is preferable that the color component of the image includes a red component, a green component, and a blue component, and

the feature amount calculation unit is configured to calculate the first pixel evaluation value on the basis of a deviation angle deviating with respect to a reference axis set in advance, in which in a color space that is defined by the red component, the blue component, or the green component, a direction of a line segment connecting a reference point set in the color space and a pixel corresponding point corresponding to the color component of each of the pixels of the image passes through the reference point.

It is preferable that the integration unit is configured to change the calculation of the severity between a case in which the first representative evaluation value or the second representative evaluation value is greater than a threshold value and a case in which the first representative evaluation value or the second representative evaluation value is not greater than the threshold value.

It is preferable that the integration unit is configured to calculate the severity by subtracting the second representative evaluation value from the first representative evaluation value in a case in which the second representative evaluation value is greater than or equal to a threshold value, and by adding the second representative evaluation value to the first representative evaluation value in a case in which the second representative evaluation value is less than the threshold value.

It is preferable that the degree of first feature is a degree of color component indicated by the lesion portion of the image, and

the degree of second feature is a degree of color component included in a portion having a predetermined shape in the image.

It is preferable that the feature amount calculation unit is configured to calculate a third pixel evaluation value indicating a degree of third feature relevant to the color component indicated by the lesion portion, which is different from the first feature and the second feature, for each of the pixels,

the representative value calculation unit is configured to calculate a third representative evaluation value of the third feature of the imaged biological tissue by integrating the third pixel evaluation values of each of the pixels in the image, and

the integration unit is configured to calculate the severity by subtracting the second representative evaluation value from the first representative evaluation value in a case in which the second representative evaluation value is greater than or equal to a threshold value, and by adding the third representative evaluation value to the first representative evaluation value in a case in which the second representative evaluation value is less than the threshold value.

It is preferable that the first pixel evaluation value is a value indicating a degree of feature relevant to a color component indicating a degree of inflammation of the biological tissue,

the second pixel evaluation value is a value indicating a degree of color component included in a blood vessel region indicating a blood vessel extending into the shape of a streak in the image, and

the third pixel evaluation value is a value indicating a degree of feature relevant to a color component indicating a degree of ulcer of the biological tissue.

Advantageous Effects of Invention

According to the endoscope system described above, it is possible to accurately evaluate the degree of lesion in a lesion portion of a biological tissue.

