A method and system for determining the depth of abnormal melanin deposition based on photoacoustic images

Abstract

This application discloses a method and system for judging the depth of abnormal melanin deposition based on photoacoustic images. Based on the multi-depth melanin signal characteristics of photoacoustic images, this method provides a judgment logic that progressively judges the depth of abnormal melanin deposition according to the thickness of the basal layer and the rate of change of signal intensity in each layer. It breaks through the limitation of the vague definition of deposition depth in traditional classification methods, and achieves precise positioning of the entire layer from the epidermis to the deep dermis, providing quantitative and objective classification basis for clinical practice.

Description

Technical Field

[0001] This invention relates to the field of melanin deposition depth determination technology, specifically to a method and system for determining abnormal melanin deposition depth based on photoacoustic images. Background Technology

[0002] Currently, techniques for obtaining the spatial distribution of melanin at different depths in the skin include traditional optical methods such as multiphoton imaging and confocal microscopy. However, these techniques have limited penetration depth and cannot cover the entire depth distribution of melanin in the dermis. Some studies have also shown that photoacoustic microscopy can achieve imaging of the dermal layer of melanin for corresponding research; however, due to significant individual differences in skin structure, skin color, sun exposure history, and genetics, traditional randomized controlled trials face serious challenges in accurately assessing the depth of melanin deposition.

[0003] In summary, existing technologies lack an effective means to assess the depth of melanin deposition non-invasively, with high resolution and imaging depth reaching the dermis. Summary of the Invention

[0004] To address these issues, this invention proposes a method and system for determining the depth of abnormal melanin deposition based on photoacoustic images.

[0005] According to one aspect of the present invention, a method for determining the depth of abnormal melanin deposition based on photoacoustic images is proposed, comprising the following steps: S1, acquire the target skin area and the normal melanin-deposited skin area, and divide the target skin area and the normal melanin-deposited skin area into the epidermal layer interval, the basal layer interval, the superficial dermal layer interval, and the deep dermal layer interval along the depth direction. S2, calculate the average thickness of the basal layer intervals of the target skin region and the normal melanin-deposited skin region, and the average gray value of the photoacoustic average intensity map of melanin in each interval of the target skin region and the normal melanin-deposited skin region. Then, the ratio of the average gray value of the target skin region to the average gray value of the normal melanin-deposited skin region in each interval is taken as the signal intensity change rate of the corresponding interval, and the ratio of the maximum gray value of the target skin region to the maximum gray value of the normal melanin-deposited skin region is taken as the maximum signal intensity change rate. S3. Based on the average thickness, the signal intensity change rate of each interval, and the maximum signal intensity change rate of the deep dermal interval, determine the abnormal melanin deposition interval of the target skin region. Determine whether the average thickness of the basal layer interval of the target skin region is greater than the normal reference value. If so, when the signal intensity change rate of the basal layer interval of the target skin region is less than a preset threshold, determine that the abnormal melanin deposition interval of the target skin region is the epidermal layer interval. Otherwise, compare the signal intensity change rates of the basal layer interval and the superficial dermal interval of the target skin region, as well as the maximum signal intensity change rate of the deep dermal interval, with the corresponding preset thresholds to obtain multiple judgment results. Based on the combination of the multiple judgment results, determine the abnormal melanin deposition interval.

[0006] Specifically, S3 includes: S301, determine whether the average thickness of the basal layer region of the target skin area is greater than the average thickness of the basal layer region of the normal melanin deposition skin area; S302, if yes, when the signal intensity change rate of the basal layer region is less than 50%, then the melanin abnormal deposition region of the target skin area is determined to be the epidermal layer region; otherwise, S303 is executed. S303, determine whether the intensity change rate of the basal layer interval is greater than or equal to 50% to obtain a first determination result, determine whether the intensity change rate of the superficial dermal layer interval is greater than 50% to obtain a second determination result, and determine whether the maximum intensity change rate of the deep dermal layer interval is greater than 30% to obtain a third determination result. S304, Based on the combination of the first judgment result, the second judgment result and the third judgment result, the abnormal melanin deposition range is determined.

[0007] Specifically, the determination of the abnormal melanin deposition region based on the combination of the first judgment result, the second judgment result, and the third judgment result as described in S304 includes: When (the first judgment result is yes & the second judgment result is no & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin region is determined to be the basal layer area; When (the first judgment result is yes & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area and the superficial dermis area. When (the first judgment result is yes & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area, the superficial dermis area and the deep dermis area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area and the deep dermal area. When (the first judgment result is no & the second judgment result is no & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the deep dermal area.

[0008] Based on the thickness of the basal layer and the rate of change of signal intensity in different skin layers, this application achieves the detection of abnormal melanin deposition depth by combining three judgment results through a preset progressive judgment process.

[0009] Specifically, S1 includes: obtaining the feature points of the first derivative of the photoacoustic intensity distribution curves of the target skin region and the normal melanin-deposited skin region at a specified excitation wavelength, and dividing the target skin region and the normal melanin-deposited skin region into the epidermal layer region, the basal layer region, the superficial dermal layer region, and the deep dermal layer region according to the feature points.

[0010] Based on the distribution characteristics of photoacoustic signal intensity of skin melanin at different depths, this application separates the epidermis, basal layer, superficial dermis, and deep dermis.

[0011] Specifically, the specified excitation wavelength is 650 nm. At this specified excitation wavelength, the difference between melanin and blood vessel imaging is large, which is more advantageous for melanin imaging.

[0012] Specifically, the feature points include maximum and minimum values. The skin depth range from the skin surface to the maximum value is considered as the epidermal layer range. The skin depth range from the maximum value to the minimum value is considered as the basal layer range. The skin depth range extending within 30 micrometers along the depth direction from the basal layer range is considered as the superficial dermal layer range. The skin depth range exceeding the superficial dermal layer range is considered as the deep dermal layer range.

[0013] This application breaks through the limitations of traditional classification methods in defining deposition depth vaguely, and provides specific standards for how to divide the epidermis, basal layer, shallow dermis and deep dermis, so as to achieve precise positioning of the melanin abnormal deposition range from the epidermis to the deep dermis.

[0014] Specifically, the target skin region and the normal melanin-deposited skin region are sampled from the same individual's skin area. By comparing the differences in layering parameters between the target skin region and adjacent normal skin, a single-instance individualized assessment scheme is established, breaking through the limitations of traditional group-based assessment and achieving precise "one person, one type" typing.

[0015] According to one aspect of the present invention, a system for determining the depth of abnormal melanin deposition based on photoacoustic images is proposed, comprising the following modules: The skin region segmentation module is configured to acquire a target skin region and a normal melanin-deposited skin region, and to divide the target skin region and the normal melanin-deposited skin region into epidermal layer intervals, basal layer intervals, superficial dermal layer intervals, and deep dermal layer intervals along the depth direction, respectively. The melanin deposition index calculation module is configured to calculate the average thickness of the basal layer intervals of the target skin region and the normal melanin deposition skin region, and the average gray value of the photoacoustic average intensity map of melanin in each interval of the target skin region and the normal melanin deposition skin region. Then, the ratio of the average gray value of the target skin region to the average gray value of the normal melanin deposition skin region in each interval is used as the signal intensity change rate of the corresponding interval, and the ratio of the maximum gray value of the target skin region to the maximum gray value of the normal melanin deposition skin region is used as the maximum signal intensity change rate. The melanin deposition zone determination module is configured to determine the abnormal melanin deposition zone of the target skin region based on the average thickness, the signal intensity change rate of each zone, and the maximum signal intensity change rate of the deep dermal zone. It determines whether the average thickness of the basal layer zone of the target skin region is greater than a normal reference value. If so, when the signal intensity change rate of the basal layer zone of the target skin region is less than a preset threshold, the abnormal melanin deposition zone of the target skin region is determined to be the epidermal zone. Otherwise, the signal intensity change rates of the basal layer zone and the superficial dermal zone of the target skin region, as well as the maximum signal intensity change rate of the deep dermal zone, are compared with the corresponding preset thresholds to obtain multiple determination results. Based on the combination of these multiple determination results, the abnormal melanin deposition zone is determined.

[0016] The melanin deposition region determination module is specifically configured to perform the following steps: S301, determine whether the average thickness of the basal layer region of the target skin area is greater than the average thickness of the basal layer region of the normal melanin deposition skin area; S302, if yes, when the signal intensity change rate of the basal layer region is less than 50%, then the melanin abnormal deposition region of the target skin area is determined to be the epidermal layer region; otherwise, S303 is executed. S303, determine whether the intensity change rate of the basal layer interval is greater than or equal to 50% to obtain a first determination result, determine whether the intensity change rate of the superficial dermal layer interval is greater than 50% to obtain a second determination result, and determine whether the maximum intensity change rate of the deep dermal layer interval is greater than 30% to obtain a third determination result. S304, Based on the combination of the first judgment result, the second judgment result and the third judgment result, the abnormal melanin deposition range is determined.

[0017] Specifically, in S304, determining the abnormal melanin deposition area based on the combination of the first judgment result, the second judgment result, and the third judgment result specifically includes: when (the first judgment result is yes & the second judgment result is no & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin region is determined to be the basal layer area. When (the first judgment result is yes & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area and the superficial dermis area. When (the first judgment result is yes & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area, the superficial dermis area and the deep dermis area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area and the deep dermal area. When (the first judgment result is no & the second judgment result is no & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the deep dermal area.

[0018] Based on the thickness of the basal layer and the rate of change of signal intensity in different skin layers, this application achieves the detection of abnormal melanin deposition depth by combining three judgment results through a preset progressive judgment process.

[0019] This application breaks through the limitations of traditional classification methods in defining deposition depth vaguely, and provides specific standards for how to divide the epidermis, basal layer, shallow dermis and deep dermis, so as to achieve precise positioning of the melanin abnormal deposition range from the epidermis to the deep dermis.

[0020] The advantages of this invention are: Based on the multi-depth melanin signal characteristics of photoacoustic images, combined with the core judgment logic of basal layer thickness and signal intensity change rate of each layer, it breaks through the limitation of the vague definition of deposition depth in traditional classification methods, and achieves precise positioning of the entire layer from the epidermis to the deep dermis, providing quantitative and objective classification basis for clinical practice. This standardized process, which quantifies skin layering parameters and employs multi-node progressive judgment, replaces the traditional qualitative assessment relying on physician experience, achieving standardized, automated, and reproducible assessment of melanin deposition depth. This method is easy to operate, provides objective results, and enables rapid, full-layer assessment of melanin deposition depth, significantly shortening the classification cycle and improving clinical diagnostic efficiency. Attached Figure Description

[0021] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0022] Figure 1 A flowchart illustrating a method for determining abnormal melanin deposition depth based on photoacoustic images according to the present invention is shown. Figure 2 A comparison diagram of the thickness of the basal layer between the melasma area and the normal skin area is shown; Figure 3 A schematic diagram showing the comparison of the average photoacoustic intensity maps of the epidermal layer, basal layer, and superficial dermis of the melasma area and the normal skin area is presented. Figure 4 A schematic flowchart of the method for classifying melasma according to the present invention is shown; Figure 5 A schematic diagram of a system for determining the depth of abnormal melanin deposition based on photoacoustic images according to the present invention is shown. Figure 6 A schematic diagram of a computer system architecture suitable for implementing the embodiments of this application is shown. Detailed Implementation

[0023] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] Figure 1 A method for determining the depth of abnormal melanin deposition based on photoacoustic images is shown, including the following steps: S1, acquire the target skin area and the normal melanin-deposited skin area, and divide the target skin area and the normal melanin-deposited skin area into the epidermal layer interval, the basal layer interval, the superficial dermal layer interval, and the deep dermal layer interval along the depth direction. S2, calculate the average thickness of the basal layer intervals of the target skin region and the normal melanin-deposited skin region, and the average gray value of the photoacoustic average intensity map of melanin in each interval of the target skin region and the normal melanin-deposited skin region. Then, the ratio of the average gray value of the target skin region to the average gray value of the normal melanin-deposited skin region in each interval is taken as the signal intensity change rate of the corresponding interval, and the ratio of the maximum gray value of the target skin region to the maximum gray value of the normal melanin-deposited skin region is taken as the maximum signal intensity change rate. S3. Based on the average thickness, the signal intensity change rate of each interval, and the maximum signal intensity change rate of the deep dermal interval, determine the abnormal melanin deposition interval of the target skin region. Determine whether the average thickness of the basal layer interval of the target skin region is greater than the normal reference value. If so, when the signal intensity change rate of the basal layer interval of the target skin region is less than a preset threshold, determine that the abnormal melanin deposition interval of the target skin region is the epidermal layer interval. Otherwise, compare the signal intensity change rates of the basal layer interval and the superficial dermal interval of the target skin region, as well as the maximum signal intensity change rate of the deep dermal interval, with the corresponding preset thresholds to obtain multiple judgment results. Based on the combination of the multiple judgment results, determine the abnormal melanin deposition interval.

[0026] In one embodiment, S3 specifically includes: S301, determine whether the average thickness of the basal layer region of the target skin area is greater than the average thickness of the basal layer region of the normal melanin deposition skin area; S302, if yes, when the signal intensity change rate of the basal layer region is less than 50%, then the melanin abnormal deposition region of the target skin area is determined to be the epidermal layer region; otherwise, S303 is executed. S303, determine whether the intensity change rate of the basal layer interval is greater than or equal to 50% to obtain a first determination result, determine whether the intensity change rate of the superficial dermal layer interval is greater than 50% to obtain a second determination result, and determine whether the maximum intensity change rate of the deep dermal layer interval is greater than 30% to obtain a third determination result. S304, Based on the combination of the first judgment result, the second judgment result and the third judgment result, the abnormal melanin deposition range is determined.

[0027] In one embodiment, S1 specifically includes: obtaining feature points of the first derivative of the photoacoustic intensity distribution curves of the target skin region and the normal melanin-deposited skin region at a specified excitation wavelength, and dividing the target skin region and the normal melanin-deposited skin region into the epidermal layer region, the basal layer region, the superficial dermal layer region, and the deep dermal layer region, respectively, based on the feature points.

[0028] In one embodiment, the specified excitation wavelength is 650 nm. At this specified excitation wavelength, the difference between melanin and blood vessel imaging is large, which is more advantageous for melanin imaging.

[0029] In one embodiment, the feature points include maximum and minimum values. The skin depth range from the skin surface to the maximum value is considered as the epidermal layer range, the skin depth range from the maximum value to the minimum value is considered as the basal layer range, the skin depth range extending within 30 micrometers along the depth direction from the basal layer range is considered as the superficial dermal layer range, and the skin depth range exceeding the superficial dermal layer range is considered as the deep dermal layer range.

[0030] In one embodiment, the target skin region and the normal melanin-deposited skin region are sampled from the same individual's skin region.

[0031] In practical applications, the method proposed in this invention can be used for the classification and determination of melasma.

[0032] Melasma is a common acquired skin hyperpigmentation disorder that is directly related to the depth of melanin deposition. Accurate classification is the basis for targeted treatment of melasma, so the method of this application can be used to determine the type of melasma.

[0033] Currently, the clinical classification of melasma is mainly based on Wood's lamp examination combined with histopathological examination, divided into: ① Epidermal type: strong color contrast under Wood's lamp, histopathology reveals pigment deposition in the basal layer and above; ② Dermal type: less contrast under Wood's lamp, histopathology reveals melanophages around blood vessels in the upper and middle dermis; ③ Mixed type: significant contrast in some areas of the same patient under Wood's lamp while other areas are not, with pigmentation in both the epidermis and dermis. Due to significant individual differences in skin structure, skin color, sun exposure history, and genetics, traditional randomized controlled trials face serious challenges in accurately quantifying dermal pigmentation.

[0034] First, the photoacoustic intensity distribution curve along the depth direction of each pixel is obtained based on the cross-sectional photoacoustic image data of the target skin region at an excitation wavelength of 650 nm. Then, the first derivative of the photoacoustic intensity distribution curve of each pixel is calculated to identify feature points that characterize abrupt changes in metabolic activity (such as global maximum points, derivative maxima, and minimum points).

[0035] The depth range between the maximum and minimum values ​​of the first derivative of the photoacoustic intensity distribution curve is considered as the basal layer range. The depth region from the skin surface to the maximum value of the first derivative is considered as the epidermal layer range. The basal layer range extends 30 micrometers deeper into the superficial dermis range, and the range beyond the superficial dermis range is considered as the deep dermis range.

[0036] according to Figure 2 The thickness map of the basal layer region shown is used to calculate the average thickness. Also, as an example, such as... Figure 3 As shown, Figure 3 (a), (b), and (c) in the image are the average photoacoustic intensity maps of the epidermis, basal layer, and superficial dermis of a normal skin area (corresponding to a normal melanin deposition area), respectively. Figure 3 In the diagram, (d), (e), and (f) represent the average photoacoustic intensity maps of the epidermis, basal layer, and superficial dermis of the melasma skin region (corresponding to the target skin region), respectively. The signal intensity change rate is calculated according to the method of this invention. Experimental testing revealed that due to the large variations in photoacoustic signals in the deep dermis, using the average value to determine abnormal melanin deposition would produce inaccurate results. Therefore, after multiple experiments with various indicators, using the maximum intensity change rate yielded accurate results.

[0037] Then, the corresponding method proposed in this application is executed. Figure 4The process for determining the individualized classification type of melasma is as follows. Melasma can be classified into: epidermal type A, basal type B, superficial dermal type C, deep dermal type D, and mixed types I (BC), II (CD), and III (BCD). Dermal melasma includes superficial dermal type C, deep dermal type D, and mixed types I (BC), II (CD), and III (BCD). Melasma containing types C and D (including C / D / BC / CD / BCD) is considered dermal melasma.

[0038] First, an initial screening is conducted by analyzing changes in basal layer thickness: if the thickness of the basal layer region increases relative to the normal melanin deposition area, it indicates that the skin is undergoing a defensive response. At this point, the signal intensity change rate of the basal layer region of the target skin region (i.e., the melasma skin region) is further evaluated.

[0039] If the thickness of the basal layer increases and the rate of change in signal intensity is less than 50%, then the abnormal melanin deposition is determined to be mainly located in the epidermal layer of the melasma skin area (Type A). If the thickness of the substrate layer does not increase, proceed to the next judgment node to evaluate the rate of change of signal intensity in the substrate layer: The determination of the abnormal melanin deposition region based on the combination of the first judgment result, the second judgment result, and the third judgment result as described in S304 specifically includes: When (the first judgment result is yes & the second judgment result is no & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin region is determined to be the basal layer area, i.e., type B. When (the first judgment result is yes & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area and the superficial dermis area, i.e., type BC; When (the first judgment result is yes & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area, the superficial dermis area and the deep dermis area, i.e., BCD type. When (the first judgment result is no & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area, i.e., type C. When (the first judgment result is no & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area and the deep dermal area, i.e., CD mixed type. When (the first judgment result is no & the second judgment result is no & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the deep dermal area, i.e., type D.

[0040] This process, through multi-node, progressive signal feature analysis, achieves precise stratified determination of the depth of abnormal melanin deposition from the epidermis to the dermis, providing a standardized quantitative analysis path for individualized non-invasive assessment of melasma.

[0041] This approach was applied to 42 patients with melasma, and the individualized classification results are shown in Table 1.

[0042] Table 1: Individualized Classification of Melasma ; Therefore, the method proposed in this application achieves precise and non-invasive layered classification of melasma. Based on the multi-depth melanin signal characteristics of photoacoustic images, combined with the core judgment logic of basal layer thickness and signal intensity change rate of each layer, melasma is refined into seven categories: epidermal type A, basal type B, superficial dermal type C, deep dermal type D, and three mixed types of BC / CD / BCD. This method breaks through the limitation of the vague definition of deposition depth in traditional classification methods, and achieves precise positioning of the entire layer from the epidermis to the deep dermis, providing quantitative and objective classification basis for clinical practice. Meanwhile, based on the method for judging the depth of abnormal melanin deposition provided in this application, dermal spots containing superficial dermal features (Type C and mixed subtypes) can be clearly defined, providing targeted guidance for the formulation of phototherapy, drug delivery and other solutions, significantly improving the accuracy of treatment targets and reducing the risk of ineffective treatment or reverse pigmentation due to unclear subtype.

[0043] Furthermore, based on the method for judging the depth of abnormal melanin deposition provided in this application, a standardized judgment process for mixed BC, CD, and BCD melasma is constructed for the first time. Through progressive signal feature analysis, the composite deposition pattern of epidermis-dermis and superficial dermis-deep dermis in mixed melasma is clearly defined, filling the gap in the classification of complex mixed melasma in existing technologies and achieving comprehensive coverage and accurate differentiation of complex cases.

[0044] This invention replaces the traditional qualitative assessment relying on physician experience with a standardized process that quantifies skin layering parameters and uses multi-node progressive judgment, achieving standardization, automation, and replicability of the classification process. This method is convenient to operate, provides objective results, and can quickly complete the full-layer assessment of a single case of melasma, significantly shortening the classification cycle, improving clinical diagnostic efficiency, and providing a unified classification standard for multi-center clinical research, thus promoting the standardization of melasma diagnosis and treatment.

[0045] According to one aspect of the invention, such as Figure 5 As shown, a system for determining the depth of abnormal melanin deposition based on photoacoustic image analysis is proposed, which includes the following modules: The skin region segmentation module 501 is configured to acquire a target skin region and a normal melanin-deposited skin region, and to divide the target skin region and the normal melanin-deposited skin region into an epidermal layer interval, a basal layer interval, a superficial dermal layer interval, and a deep dermal layer interval along the depth direction, respectively. The melanin deposition index calculation module 502 is configured to calculate the average thickness of the basal layer intervals of the target skin region and the normal melanin deposition skin region, and the average gray value of the photoacoustic average intensity map of melanin in each interval of the target skin region and the normal melanin deposition skin region. Then, the ratio of the average gray value of the target skin region to the average gray value of the normal melanin deposition skin region in each interval is used as the signal intensity change rate of the corresponding interval, and the ratio of the maximum gray value of the target skin region to the maximum gray value of the normal melanin deposition skin region is used as the maximum signal intensity change rate. The melanin deposition zone determination module 503 is configured to determine the abnormal melanin deposition zone of the target skin region based on the average thickness, the signal intensity change rate of each zone, and the maximum signal intensity change rate of the deep dermal zone. It determines whether the average thickness of the basal layer zone of the target skin region is greater than a normal reference value. If so, when the signal intensity change rate of the basal layer zone of the target skin region is less than a preset threshold, the abnormal melanin deposition zone of the target skin region is determined to be the epidermal zone. Otherwise, the signal intensity change rates of the basal layer zone and the superficial dermal zone of the target skin region, as well as the maximum signal intensity change rate of the deep dermal zone, are compared with the corresponding preset thresholds to obtain multiple determination results. Based on the combination of these multiple determination results, the abnormal melanin deposition zone is determined.

[0046] In one embodiment, the melanin deposition region determination module is specifically configured to perform the following steps: S301, determine whether the average thickness of the basal layer region of the target skin area is greater than the average thickness of the basal layer region of the normal melanin deposition skin area; S302, if yes, when the signal intensity change rate of the basal layer region is less than 50%, then the melanin abnormal deposition region of the target skin area is determined to be the epidermal layer region; otherwise, S303 is executed. S303, determine whether the intensity change rate of the basal layer interval is greater than or equal to 50% to obtain a first determination result, determine whether the intensity change rate of the superficial dermal layer interval is greater than 50% to obtain a second determination result, and determine whether the maximum intensity change rate of the deep dermal layer interval is greater than 30% to obtain a third determination result. S304, Based on the combination of the first judgment result, the second judgment result and the third judgment result, the abnormal melanin deposition range is determined.

[0047] In one embodiment, the skin region segmentation module is specifically configured to: obtain the feature points of the first derivative of the photoacoustic intensity distribution curves of the target skin region and the normal melanin-deposited skin region at a specified excitation wavelength, and divide the target skin region and the normal melanin-deposited skin region into the epidermal layer region, the basal layer region, the superficial dermal layer region, and the deep dermal layer region, respectively, based on the feature points.

[0048] In one embodiment, the specified excitation wavelength is 650 nm. At this specified excitation wavelength, the difference between melanin and blood vessel imaging is large, which is more advantageous for melanin imaging.

[0049] In one embodiment, the feature points include maximum and minimum values. The skin depth range from the skin surface to the maximum value is considered as the epidermal layer range, the skin depth range from the maximum value to the minimum value is considered as the basal layer range, the skin depth range extending within 30 micrometers along the depth direction from the basal layer range is considered as the superficial dermal layer range, and the skin depth range exceeding the superficial dermal layer range is considered as the deep dermal layer range.

[0050] In one embodiment, the target skin region and the normal melanin-deposited skin region are sampled from the same individual's skin region.

[0051] In practical applications, the system proposed in this invention can be used for the classification and determination of melasma. As mentioned above, the determination of the abnormal melanin deposition region based on the combination of the first judgment result, the second judgment result, and the third judgment result in S304 specifically includes: When (the first judgment result is yes & the second judgment result is no & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin region is determined to be the basal layer area, i.e., type B. When (the first judgment result is yes & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area and the superficial dermis area, i.e., type BC; When (the first judgment result is yes & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area, the superficial dermis area and the deep dermis area, i.e., BCD type. When (the first judgment result is no & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area, i.e., type C. When (the first judgment result is no & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area and the deep dermal area, i.e., CD mixed type. When (the first judgment result is no & the second judgment result is no & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the deep dermal area, i.e., type D.

[0052] The following is for reference. Figure 6 It shows a schematic diagram of the structure of a computer system 600 suitable for implementing electronic devices according to embodiments of the present application. Figure 6 The electronic device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0053] like Figure 6 As shown, the computer system 600 includes a central processing unit (CPU) 601, which performs various appropriate actions and processes based on programs stored in read-only memory (ROM) 602 or programs loaded from storage section 608 into random access memory (RAM) 603. The RAM 603 also stores various programs and data required for the operation of the computer system 600. The CPU 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0054] The following components are connected to I / O interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a liquid crystal display (LCD) and speakers, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card and a modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to I / O interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 610 as needed so that computer programs read from it can be installed into storage section 608 as needed.

[0055] Specifically, according to embodiments of this disclosure, the processes described above with reference to the flowcharts are implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable storage medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program is downloaded and installed from a network via communication section 609, and / or installed from removable medium 611. When the computer program is executed by central processing unit (CPU) 601, it performs the functions defined above in the methods of this application.

[0056] It should be noted that the computer-readable storage medium of this application is a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium is, for example—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium is any tangible medium that contains or stores a program used by or in connection with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium includes a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals take various forms, including, but not limited to, electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable signal medium or any computer-readable storage medium other than a computer-readable storage medium may transmit, propagate, or transfer a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wireless, wireline, optical fiber, RF, etc., or any suitable combination thereof.

[0057] Computer program code for performing the operations of this application is written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code executes entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer is connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or connected to an external computer (e.g., via the Internet using an Internet service provider).

[0058] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram represents a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually execute substantially in parallel, and they may sometimes execute in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, is implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0059] The modules described in the embodiments of this application are implemented in software or hardware.

[0060] In another aspect, this application also provides a computer-readable storage medium included in the electronic device described in the above embodiments; it also exists independently and is not assembled into the electronic device. The computer-readable storage medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the following steps: S1, acquiring a target skin region and a normal melanin-deposited skin region, and dividing the target skin region and the normal melanin-deposited skin region into epidermal intervals, basal intervals, superficial dermal intervals, and deep dermal intervals along the depth direction; S2, calculating the average thickness of the basal interval of the target skin region and the normal melanin-deposited skin region, and the average grayscale value of the photoacoustic average intensity map of melanin in each interval of the target skin region and the normal melanin-deposited skin region, and then using the ratio of the average grayscale value of the target skin region to the average grayscale value of the normal melanin-deposited skin region in each interval as the signal intensity change rate of the corresponding interval, and converting the grayscale value of the target skin region into a signal intensity change rate. The ratio of the maximum grayscale value to the maximum grayscale value of the normal melanin deposition skin area is used as the maximum signal intensity change rate; S3, based on the average thickness, the signal intensity change rate of each interval, and the maximum signal intensity change rate of the deep dermal interval, the abnormal melanin deposition interval of the target skin area is determined, and it is determined whether the average thickness of the basal layer interval of the target skin area is greater than the normal reference value. If so, when the signal intensity change rate of the basal layer interval of the target skin area is less than a preset threshold, the abnormal melanin deposition interval of the target skin area is determined to be the epidermal layer interval. Otherwise, the signal intensity change rates of the basal layer interval and the superficial dermal interval of the target skin area, as well as the maximum signal intensity change rate of the deep dermal interval, are compared with the corresponding preset thresholds to obtain multiple judgment results. Based on the combination of the multiple judgment results, the abnormal melanin deposition interval is determined.

[0061] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for determining the depth of abnormal melanin deposition based on photoacoustic images, characterized in that, Includes the following steps: S1, acquire the target skin area and the normal melanin-deposited skin area, and divide the target skin area and the normal melanin-deposited skin area into the epidermal layer interval, the basal layer interval, the superficial dermal layer interval, and the deep dermal layer interval along the depth direction. S2, calculate the average thickness of the basal layer intervals of the target skin region and the normal melanin-deposited skin region, and the average gray value of the photoacoustic average intensity map of melanin in each interval of the target skin region and the normal melanin-deposited skin region. Then, the ratio of the average gray value of the target skin region to the average gray value of the normal melanin-deposited skin region in each interval is taken as the signal intensity change rate of the corresponding interval, and the ratio of the maximum gray value of the target skin region to the maximum gray value of the normal melanin-deposited skin region is taken as the maximum signal intensity change rate. S3. Based on the average thickness, the signal intensity change rate of each interval, and the maximum signal intensity change rate of the deep dermal interval, determine the abnormal melanin deposition interval of the target skin region. Determine whether the average thickness of the basal layer interval of the target skin region is greater than the normal reference value. If so, when the signal intensity change rate of the basal layer interval of the target skin region is less than a preset threshold, determine that the abnormal melanin deposition interval of the target skin region is the epidermal layer interval. Otherwise, compare the signal intensity change rates of the basal layer interval and the superficial dermal interval of the target skin region, as well as the maximum signal intensity change rate of the deep dermal interval, with the corresponding preset thresholds to obtain multiple judgment results. Based on the combination of the multiple judgment results, determine the abnormal melanin deposition interval.

2. The method for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 1, characterized in that, S3 specifically includes: S301, determine whether the average thickness of the basal layer region of the target skin area is greater than the average thickness of the basal layer region of the normal melanin deposition skin area; S302, if yes, when the signal intensity change rate of the basal layer region is less than 50%, then the melanin abnormal deposition region of the target skin area is determined to be the epidermal layer region; otherwise, S303 is executed. S303, determine whether the intensity change rate of the basal layer interval is greater than or equal to 50% to obtain a first determination result, determine whether the intensity change rate of the superficial dermal layer interval is greater than 50% to obtain a second determination result, and determine whether the maximum intensity change rate of the deep dermal layer interval is greater than 30% to obtain a third determination result. S304, Based on the combination of the first judgment result, the second judgment result and the third judgment result, the abnormal melanin deposition range is determined.

3. The method for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 2, characterized in that, The determination of the abnormal melanin deposition region based on the combination of the first judgment result, the second judgment result, and the third judgment result as described in S304 specifically includes: When (the first judgment result is yes & the second judgment result is no & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin region is determined to be the basal layer area; When (the first judgment result is yes & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area and the superficial dermis area. When (the first judgment result is yes & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area, the superficial dermis area and the deep dermis area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area and the deep dermal area. When (the first judgment result is no & the second judgment result is no & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the deep dermal area.

4. The method for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 1, characterized in that, S1 specifically includes: obtaining the feature points of the first derivative of the photoacoustic intensity distribution curves of the target skin region and the normal melanin-deposited skin region at a specified excitation wavelength, and dividing the target skin region and the normal melanin-deposited skin region into the epidermal layer interval, the basal layer interval, the superficial dermal layer interval, and the deep dermal layer interval according to the feature points.

5. The method for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 4, characterized in that, The specified excitation wavelength is 650 nm.

6. The method for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 4, characterized in that, The feature points include maximum and minimum values. The skin depth range from the skin surface to the maximum value is considered as the epidermal layer range. The skin depth range from the maximum value to the minimum value is considered as the basal layer range. The skin depth range extending within 30 micrometers along the depth direction from the basal layer range is considered as the superficial dermal layer range. The skin depth range exceeding the depth of the superficial dermal layer range is considered as the deep dermal layer range.

7. The method for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 1, characterized in that, The target skin region and the normal melanin-deposited skin region are sampled from the same individual's skin region.

8. A system for determining the depth of abnormal melanin deposition based on photoacoustic images, characterized in that, Includes the following modules: The skin region segmentation module is configured to acquire a target skin region and a normal melanin-deposited skin region, and to divide the target skin region and the normal melanin-deposited skin region into epidermal layer intervals, basal layer intervals, superficial dermal layer intervals, and deep dermal layer intervals along the depth direction, respectively. The melanin deposition index calculation module is configured to calculate the average thickness of the basal layer intervals of the target skin region and the normal melanin deposition skin region, and the average gray value of the photoacoustic average intensity map of melanin in each interval of the target skin region and the normal melanin deposition skin region. Then, the ratio of the average gray value of the target skin region to the average gray value of the normal melanin deposition skin region in each interval is used as the signal intensity change rate of the corresponding interval, and the ratio of the maximum gray value of the target skin region to the maximum gray value of the normal melanin deposition skin region is used as the maximum signal intensity change rate. The melanin deposition zone determination module is configured to determine the abnormal melanin deposition zone of the target skin region based on the average thickness, the signal intensity change rate of each zone, and the maximum signal intensity change rate of the deep dermal zone. It determines whether the average thickness of the basal layer zone of the target skin region is greater than a normal reference value. If so, when the signal intensity change rate of the basal layer zone of the target skin region is less than a preset threshold, the abnormal melanin deposition zone of the target skin region is determined to be the epidermal zone. Otherwise, the signal intensity change rates of the basal layer zone and the superficial dermal zone of the target skin region, as well as the maximum signal intensity change rate of the deep dermal zone, are compared with the corresponding preset thresholds to obtain multiple determination results. Based on the combination of the multiple determination results, the abnormal melanin deposition zone is determined.

9. A system for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 8, characterized in that, The melanin deposition region determination module is specifically configured to perform the following steps: S301, determine whether the average thickness of the basal layer region of the target skin area is greater than the average thickness of the basal layer region of the normal melanin deposition skin area; S302, if yes, when the signal intensity change rate of the basal layer region is less than 50%, then the melanin abnormal deposition region of the target skin area is determined to be the epidermal layer region; otherwise, S303 is executed. S303, determine whether the intensity change rate of the basal layer interval is greater than or equal to 50% to obtain a first determination result, determine whether the intensity change rate of the superficial dermal layer interval is greater than 50% to obtain a second determination result, and determine whether the maximum intensity change rate of the deep dermal layer interval is greater than 30% to obtain a third determination result. S304, Based on the combination of the first judgment result, the second judgment result and the third judgment result, the abnormal melanin deposition range is determined.

10. A system for determining the depth of abnormal melanin deposition based on photoacoustic images according to claim 9, characterized in that, The determination of the abnormal melanin deposition region based on the combination of the first judgment result, the second judgment result, and the third judgment result as described in S304 specifically includes: When (the first judgment result is yes & the second judgment result is no & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin region is determined to be the basal layer area; When (the first judgment result is yes & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area and the superficial dermis area. When (the first judgment result is yes & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the basal layer area, the superficial dermis area and the deep dermis area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is no), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area. When (the first judgment result is no & the second judgment result is yes & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the superficial dermal area and the deep dermal area. When (the first judgment result is no & the second judgment result is no & the third judgment result is yes), the abnormal melanin deposition area of ​​the target skin area is determined to be the deep dermal area.

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