A method for assessing skin aging using ultrasound images of the inside of the skin

Abstract

To provide a skin aging degree evaluation method capable of highly accurately evaluating a relation between a skin and an age using an easily acquirable ultrasonic image of dermis of a skin.SOLUTION: A skin aging degree evaluation method is characterized by acquiring a ratio and / or difference calculated using an average luminance of an ultrasonic image of a dermis of a skin that can be easily and non-invasively acquired. The method of deriving a skin aging degree, capable of easily evaluating an aging state from structural density inside the dermis of the ultrasonic image of the skin, with due consideration of site differences and individual differences, the method acquires a ratio and / or a difference of the structural density inside the dermis by using a value calculated from two sides, a papillary dermis and a reticular dermis. Thereby, the skin aging degree evaluating method with due consideration of the site differences and individual differences can be provided by just using the ultrasonic image of the dermis of the skin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for evaluating skin aging using internal skin images obtained non-invasively by ultrasound. [Background technology]

[0002] The skin is composed of three layers from the outside: the epidermis, dermis, and subcutaneous tissue. The dermis is layered from the basal layer of the epidermis to the papillary dermis, subpapillary dermis, reticular dermis, and subcutaneous tissue. The dermis is rich in fibrous components such as collagen fibers and elastic elastin, and is greatly involved in the firmness and elasticity of the skin. Therefore, the skin age is estimated using the structural density of these intradermal fibrous components (Patent Documents 1 and 2). In order to meet the interest and desire to know one's own skin condition as a cosmetic treatment, that is, the skin condition, the skin internal structure analysis method has also evolved along with the evolution of the skin internal photography device that can perform non-invasive evaluation (Patent Document 3). Skin evaluation, which allows one to objectively know the condition of one's skin, is important as a means of meeting the desire for beauty.

[0003] The structural density of the dermis is used for evaluating aging skin by analyzing the increase and decrease in brightness of an image obtained non-invasively by each device by selecting an arbitrary part of the dermis. However, since the dermis is affected by multiple factors such as natural aging and photoaging, it is difficult to say that the structural density of the dermis changes uniformly in sync. In the dermis, aging and exposure to ultraviolet rays not only reduce the structural density due to a decrease in fibrous components such as collagen, but also cause the accumulation of thick, short, denatured elastic fiber components such as elastin, which increases the structural density (Patent Document 3, Non-Patent Documents 1 and 2). In addition, since the structural density of the dermis is not uniform depending on the site, this also means that the information on the structural density of the dermis obtained depending on the image acquisition conditions changes significantly. Furthermore, there are individual differences such as differences in the amount of collagen and elastin present in the dermis from birth, which causes differences in the initial state of the structural density of the dermis. Therefore, in the conventional evaluation method, the proposal of an aging index based on an internal skin image obtained by ultrasound was made with high accuracy without considering differences in site and individual differences (Patent Document 3). Furthermore, in order to perform skin evaluation that takes into account differences between regions and individuals, it is necessary to propose a comprehensive skin evaluation that combines internal skin images obtained by ultrasound with other skin property evaluations; it has been difficult to propose aging indexes or skin evaluation that takes into account differences between regions and individuals using only internal skin images obtained by ultrasound (Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 11-290312 [Patent Document 2] Patent Publication No. 2000-83954 [Patent Document 3] Patent Publication No. 2012-235804 [Patent Document 4] Special table 2012-501753 [Non-patent literature]

[0005] [Non-Patent Document 1] Relationship between hyaluronic acid degradation and wrinkle / sagging formation in photoaged skin, Academic Report of the Committee on Solar UV Protection, 9-13 (2018) [Non-Patent Document 2] A new dermis model for elastin fiber formation, Journal of the Japanese Society of Cosmetic Engineers, 44(4), 278-284(2010) Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, in order to solve the above problems, the present invention provides a method for evaluating skin aging that can accurately evaluate the relationship between skin and age using easily obtainable ultrasound images of the dermis inside the skin. [Means for solving the problem]

[0007] The present invention aims to provide a method for evaluating skin aging that can accurately evaluate the relationship between skin and age using an ultrasound image of the dermis of the skin that can be easily obtained non-invasively. A method for easily evaluating the aging state from an ultrasound image of the dermis of the skin while taking into account site differences and individual differences is to process the internal structural density of the dermis of the skin as a ratio and / or difference using values ​​calculated from two sites, the papillary dermis and the reticular dermis. As a result, we have found a method for calculating the degree of skin aging that takes into account site differences and individual differences using only ultrasound images, and have completed the present invention.

[0008] That is, the present invention is as follows. (1) A method for evaluating the degree of skin aging from the internal structure density of the dermis of the skin, comprising: (a) a step of irradiating ultrasonic waves from the surface of the skin toward the inside of the skin, detecting ultrasonic waves reflected from the inside of the skin with an ultrasonic tomography device, and obtaining an ultrasonic image of the inside of the skin; (b) selecting a certain area of ​​the papillary dermis and reticular dermis from the ultrasound image of the dermis portion of the skin obtained in step (a), and calculating an average brightness from the intensity of the reflected ultrasound wave within the certain area; (c) calculating a ratio and / or difference between the average brightness in the papillary dermis and the reticular dermis calculated in the step (b) and using the ratio and / or difference as an aging index; A method for evaluating the degree of skin aging, comprising: (2) The method according to (1), wherein the area of ​​the skin to be evaluated is the face. Effect of the Invention

[0009] The method for evaluating skin aging of the present invention enables quick and easy evaluation of skin aging using non-invasively obtained ultrasound images, and can be used in counseling and skin evaluation, such as beauty advice that takes individual differences into account. [Brief description of the drawings]

[0010] [Figure 1] 1 is an example of an image of the cheek obtained by the ultrasonic tomography device used in the present invention. From the left, it is composed of the epidermis, the dermis, and the subcutaneous tissue. The upper part of the image is the nose side, and the lower part of the image is the ear side.

[0011] [Diagram 2] An experimental graph and correlation coefficient showing the distribution of the average brightness of the papillary dermis / reticular dermis of the cheek using age and ultrasound images of 98 women.

[0012] [Diagram 3] A comparison diagram and correlation coefficient showing the distribution of average brightness in the cheek dermis (from the papillary dermis to the reticular dermis) using ultrasound images and ages of 98 women.

[0013] [Figure 4] A comparison diagram and correlation coefficient showing the distribution of average brightness of the papillary dermis of the cheek using ultrasound images and ages of 98 women.

[0014] [Diagram 5] A comparison diagram and correlation coefficient showing the distribution of average brightness of the reticular dermis of the cheek using ultrasound images and ages of 98 women.

[0015] [Figure 6]A comparison diagram and correlation coefficient showing the distribution of the average brightness of the papillary dermis / reticular dermis of the cheek using ultrasound images and ages of 30 women.

[0016] [Figure 7] A comparison diagram and correlation coefficient showing the distribution of average brightness of the papillary dermis / reticular dermis at the corners of the mouth using ultrasound images and ages of 30 women.

[0017] [Figure 8] A comparison diagram and correlation coefficient showing the distribution of average brightness of the papillary dermis of the cheek using ultrasound images and ages of 30 women.

[0018] [Figure 9] A comparison diagram and correlation coefficient showing the distribution of average brightness of the papillary dermis at the corners of the mouth using ultrasound images and ages of 30 women.

[0019] [Figure 10] A comparison diagram and correlation coefficient showing the distribution of average brightness of the reticular dermis of the cheek using ultrasound images and ages of 30 women.

[0020] [Figure 11] A comparison diagram and correlation coefficient showing the distribution of average brightness of the reticular dermis at the corners of the mouth using ultrasound images and ages of 30 women.

[0021] [Figure 12] An example graph and correlation coefficient showing the distribution of the difference in average brightness between the papillary dermis and reticular dermis of the cheek using ultrasound images and the ages of 98 women.

[0022] [Figure 13] A comparison diagram and correlation coefficient showing the distribution of the difference in average brightness between the papillary dermis and reticular dermis of the cheek using ultrasound images and the ages of 30 women.

[0023] [Figure 14] A comparison diagram and correlation coefficient showing the distribution of the difference in average brightness between the papillary dermis layer at the corners of the mouth and the reticular dermis layer at the cheek using ultrasound images and the ages of 30 women. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will now be described in further detail.

[0025] The images used in the present invention are taken by an ultrasonic tomography device. The ultrasonic waves used in the ultrasonic tomography device are selected from a frequency range of 20 to 75 MHz that can analyze the dermis of the skin. The images of the inside of the skin are taken by irradiating the selected ultrasonic waves perpendicularly to the inside of the skin, and detecting and imaging the ultrasonic waves (reflected waves) reflected from inside the skin by the ultrasonic tomography device.

[0026] The photographed image used in the present invention may be an image of the dermis of the skin, and is preferably an image of an exposed part of the skin. For example, the image may be changed depending on the purpose of measurement, such as the cheek, the corner of the mouth, or the face line.

[0027] The analysis method of the present invention uses the above image to select a certain area of ​​different parts in the depth direction of the dermis of the skin, and calculates the average brightness in the certain area. The different parts in the depth direction of the dermis refer to the papillary dermis, which is the uppermost layer of the dermis, and the reticular dermis, which is the lower part of the papillary dermis. The papillary dermis is located on the dermis side of the part where the papillae stand at the boundary between the epidermis and the dermis, and is located at the uppermost part of the dermis. The reticular dermis is the lower part of the dermis and forms the boundary with the subcutaneous tissue. The dermis has an average thickness of about 2.0 mm, although it varies depending on the part. In order to distinguish the papillary dermis and the reticular dermis from each other so that they are not mixed, the papillary dermis to be analyzed is preferably in the range of up to 0.5 mm deep, with 0 mm directly below the boundary with the epidermis as the reference. Preferably, it is in the range of 0 mm to 0.35 mm deep, directly below the boundary with the epidermis. The reticular dermis to be analyzed, excluding the inclusion of subcutaneous tissue, should be in the range of 0.70 mm to 1.5 mm deep, with 0 mm directly below the boundary with the epidermis as the reference point. Preferably, the range is 0.75 mm to 1.2 mm deep, with 0 mm directly below the boundary with the epidermis as the reference point. The average brightness is calculated using the reflected waves when ultrasound is irradiated into the skin and transmitted or reflected due to differences in structural density within the skin, and the intensity of the reflected waves is divided into multiple gradations and the intensity of the reflected waves within a certain area is averaged. The area for calculating the average brightness is not particularly limited, but is preferably 1 mm 2 ~15mm 2 The range is preferably within the range of 100 to 200 mm. The location to be analyzed is selected from a site located at the depth of the papillary dermis and a site located at the depth of the reticular dermis. The method is characterized in that the ratio of the average brightness of the papillary dermis to the reticular dermis in the dermis, or the difference between the reticular dermis and the papillary dermis, is further calculated using the average brightness calculated from a certain area of ​​the papillary dermis and the reticular dermis. The calculated ratio or difference is taken as the degree of aging. The degree of aging depends on the calculation method, but when expressed as the ratio of the average brightness of the papillary dermis to the reticular dermis, the smaller the value, the higher the degree of aging, and when expressed as the difference between the reticular dermis and the papillary dermis, the larger the value, the higher the degree of aging. In the evaluation of the degree of skin aging, the ratio and / or difference of the average brightness in the papillary dermis and the reticular dermis may be used depending on the purpose.

[0028] In order to effectively explain the present invention, examples are given below, but the present invention is not limited thereto. EXAMPLES

[0029] Images of the inside of the cheek skin were obtained from 98 female subjects using an ultrasound tomography device, DermaScan (manufactured by Cortex Technology). In addition, images of the inside of the skin around the corners of the mouth were obtained from 30 female subjects in order to compare the different areas. The cheek area where the image was obtained refers to the area where two lines drawn from the corners of the eyes and the nostrils intersect, and the corners of the mouth refers to the area directly below the cheek area and beside the corners of the mouth. These two points were used to compare the areas. Each image was analyzed using DermaScan software. For the papillary dermis, a constant area of ​​4.52 mm was obtained in the range of 0 mm to 0.35 mm deep just below the border between the epidermis and dermis in the image. 2 The reticular dermis was also analyzed by dividing the area into 4.52 mm2 and 0.75 mm2 to 1.1 mm2. 2 The area was selected as the analysis region. The average brightness of the entire dermis, which was to be compared with the papillary dermis and reticular dermis, was determined by dividing the area into 13.6 mm2 and 1.1 mm deep, just below the boundary between the epidermis and dermis, so as to include the papillary dermis and reticular dermis. 2 was selected as the analysis area, and the average brightness of the entire dermis was calculated.

[0030] As the first analysis method, the average brightness (%) of each analysis area of ​​the papillary dermis and reticular dermis on the cheek was calculated, and the average brightness was used to calculate the average brightness ratio of the papillary dermis to the reticular dermis. The correlation with age was confirmed using this calculated ratio (Tables 1-2, Figures 2-5). For comparison, the same analysis method was used for 30 women to calculate the average brightness (%) of each analysis area of ​​the papillary dermis and reticular dermis on the cheek and corners of the mouth, and the average brightness was used to calculate the average brightness ratio of the papillary dermis to the reticular dermis. The correlation with age was confirmed using this calculated ratio (Tables 1-2, Figures 6-11).

[0031] As a result, it was confirmed that the average luminance ratio of the papillary dermis to the reticular dermis in the cheeks has a very high correlation with age and can be an index for evaluating the degree of skin aging. When the area where the average luminance was calculated was the entire dermis or the reticular dermis only, no correlation was observed, and it was not an index for evaluating the degree of skin aging (Tables 1-2, Figures 3 and 5). In addition, in the case of the average luminance of the papillary dermis only, a correlation was observed when the number of data subjects increased from 30 to 98 (Tables 1-2, Figures 4 and 8), so it was considered that the average luminance of the papillary dermis only is an index for which the need to improve accuracy should be considered. On the other hand, the average luminance ratio of the papillary dermis to the reticular dermis maintained a high correlation with age in both the cases where the number of data subjects was 30 and 98, and it was confirmed that it is an index for evaluating the degree of aging with high accuracy (Tables 1-2, Figures 2 and 6).

[0032] Additionally, at the corners of the mouth, no correlation was observed between the average luminance of only the papillary dermis or the average luminance of only the reticular dermis and age, but when the average luminance ratio of the papillary dermis to the reticular dermis was used, a weak correlation was observed between age and age (Tables 1-2, Figures 7, 9, and 11). From this, it can be said that calculating the average luminance ratio of the papillary dermis to the reticular dermis from the average luminance of only the papillary dermis and only the reticular dermis is a method for improving the accuracy of indices for evaluating the degree of aging.

[0033] As the second analysis method, the average brightness (%) of each analysis area of ​​the papillary dermis and reticular dermis on the cheek was calculated, and the average brightness was used to calculate the difference in average brightness by subtracting the papillary dermis from the reticular dermis (difference in average brightness = average brightness of reticular dermis - average brightness of papillary dermis). The correlation with age was confirmed using this calculated difference (Tables 1-2, Figures 12-13). For comparison, the same analysis method was used to calculate the average brightness (%) of each analysis area of ​​the papillary dermis and reticular dermis on the cheek and corners of the mouth for 30 women, and the average brightness was used to calculate the difference in average brightness by subtracting the papillary dermis from the reticular dermis. The correlation with age was confirmed using this calculated difference (Tables 1-2, Figures 13-14).

[0034] As a result, it was confirmed that in the cheek, the difference in average brightness when the reticular dermis is subtracted from the papillary dermis has a very high correlation with age and can be used as an index to evaluate the degree of skin aging. The difference in average brightness when the reticular dermis is subtracted from the papillary dermis maintained a high correlation with age in both cases where the data set consisted of 30 and 98 subjects, confirming that it is an index to evaluate the degree of aging with high accuracy (Tables 1-2, Figures 12-13).

[0035] Additionally, at the corners of the mouth, no correlation was observed between the average brightness of only the papillary dermis or the average brightness of only the reticular dermis and age, but a weak correlation was observed between age and age when the difference in average brightness when the reticular dermis is subtracted from the papillary dermis was used (Tables 1-2, Figures 13-14).From this, it can be said that calculating the difference in average brightness by further subtracting the papillary dermis from the reticular dermis from the average brightness of only the papillary dermis or the reticular dermis is a method to improve the accuracy of an index to evaluate the degree of aging.

[0036] [Table 1]

[0037] [Table 2] [Industrial Applicability]

[0038] The present invention makes it possible to evaluate skin aging taking into account regional and individual differences using images obtained from an ultrasound tomography device, which is non-invasive to the skin. This makes it possible to provide accurate information on aging tailored to the individual, for example, through counseling on skin care such as cosmetics and advice through skin checks.

Claims

1. A method for calculating an index for evaluating the degree of skin aging from skin dermis structure density, comprising: (a) applying ultrasonic waves from the surface of the skin toward the inside of the skin, detecting the reflected waves of the ultrasonic waves from the inside of the skin with an ultrasonic tomography device, and obtaining an ultrasonic image of the inside of the skin; (b) selecting a certain area of ​​the papillary dermis and reticular dermis from the ultrasound image of the dermis portion of the skin obtained in (a), and calculating an average brightness from the intensity of the reflected ultrasound wave within the certain area; (c) calculating a ratio and / or difference between the average brightness in the papillary dermis and the reticular dermis calculated in (b) as an aging index; A method for calculating an index for evaluating the degree of skin aging, comprising:

2. 2. The method according to claim 1, wherein the skin site to be evaluated is the face.

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