Quantitative Assessment of Age-dependent Changes in Porphyrins from Fluorescence Images of Ultraviolet Photography by Image Processing.

BACKGROUND: Skin is the first line of defense against harmful external environmental factors. Skin flora living on the skin surface impact skin health and skin disease. Bacteria, form part of the unique and complex skin micro-ecological system. For example, Propionibacterium acnes (P. acnes) is a member of the anaerobic organisms and is involved in the induction of skin acne. It produces porphyrins that absorb ultraviolet light and emit red fluorescence in response. As a result, fluorescence surveillance of the skin can be important in both the diagnosis of skin acne and the evaluation of therapeutic effects. Many different measurement methods for single skin biophysical properties have been reported.. This study focused on the age-dependent changes in porphyrins for normal skin, and developed a novel algorithm to evaluate porphyrins using the fluorescence images by image processing quantitatively. MATERIALS AND METHODS: An extraction algorithm was proposed for the segmentation of porphyrin fluorescence images in OpenCV. The algorithm consisted primarily of preprocessing, conversion from RGB color space to HSV color space, and classification of fluorescence. There are 3595 healthy Japanese aged 16-85 years enrolled in the study and fluorescence images were acquired from their cheek sites under 375 nm UV-LED excitation. Age-related fluorescence variation was conducted applying the algorithm implemented. RESULTS: A new extraction algorithm has been proposed with fluorescence image input and three indexes output, including the number of fluorescence, area of fluorescence, and mean intensity of fluorescence. Proposed algorithm was verified by three parameters, the accuracy, sensitivity, and precision, which refer to the ability of algorithm to detect the number of fluorescence correctly and repeatedly. The verification results were 71%, 72%, and 88% respectively, taking a validly fundamental step for skin health record and analysis. Furthermore, large-scale fluorescence image segmentation results revealed that similar trends were coming out for all three indexes in cheek as people get older. All the fluorescence number, area and mean intensity arrived at the highest at 30 years old and fell off since then. CONCLUSION: The number, area, and fluorescence intensity of porphyrins can be extracted well from fluorescence images with the proposed algorithm in the study, which has the potential to aid in thediagnosis of skin acne and predict skin conditions as an assisted tool. It is implicated that fluorescence status is influenced by age, which rises to the peak around 30 years old for normal cheek's skin.

Objective measurement and comparison of human facial skin color in East Asian females.

BACKGROUND: Skin color is an important physiological index of human skin that has essential significance in cosmetology and dermatological diagnoses and aesthetics, especially in East Asian culture, where the beauty standard is the whiter the skin, the more beautiful a person is. However, there has been a lack of objective comparisons of facial skin color in East Asian females. MATERIALS AND METHODS: Skin color at the cheek site was measured in 445 healthy females, including 362 Chinese women in Beijing and 83 Japanese women in Tokyo, all aged 18-50 years. The parameters consisted of L* , a* , b* , individual typology angle (ITA°), and hue angle and were determined using noninvasive skin measurement instruments. RESULTS: The skin color categories in East Asians ranged from very light (I) to brown (V), and the dark (VI) category was not observed; the main categories were light (II), intermediate (III), and tan (IV). The facial skin color of Chinese individuals was brighter, more reddish, and less yellowish than that of Japanese individuals. With age, L* values decreased, and a* values and hue angle increased in East Asians with significant differences. Chinese women showed the same differences as Japanese women for all parameters in all age groups. CONCLUSIONS: This study provides objective skin color measurements and examines significant differences with respect to geographic location and age.

Photodynamic therapy using direct-current pulsed iontophoresis for 5-aminolevulinic acid application.

In photodynamic therapy (PDT) for skin cancer, 5-aminolevulinic acid (ALA) is applied topically to the affected area to be absorbed percutaneously through passive diffusion, and typically requires 4-6 h before performing PDT. In this study, we attempted to reduce the absorption period in PDT by ionizing ALA using direct-current pulsed iontophoresis to treat actinic keratosis (AK). Twenty percent ALA solution was applied to AK lesions of five patients using direct-current pulsed iontophoresis. ALA-PDT was repeated three times with a total irradiation of 150 J/cm(2) (50 J/cm(2) per irradiation, weekly). One week after the last PDT, therapeutic results were assessed by skin biopsy. In all subjects, protoporphyrin IX (PpIX) production was confirmed after iontophoresis, and its production levels were comparable to the conventional occlusive dressing technique (ODT). Skin biopsies from the treated lesion showed the disappearance of tumour cells. These results indicated that direct-current pulsed iontophoresis for applying ALA before PDT is useful to treat AK.