Avaliação do colágeno dérmico no envelhecimento pela ultrassonografia de alta frequência e espectroscopia Raman in vivo e suas correlações com a histologia

• Ano de defesa: 2017
• Autor(a) principal: Caetano, Livia de Vasconcelos Nasser [UNIFESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo (UNIFESP)
• Palavras-chave em Português: Skin aging; Collagen; Ultrasonography; Raman spectral analysis; Histology; Computer assisted image processing; Envelhecimento da pele; Colágeno; Ultrassonografia; Análise espectral raman; Histologia; Processamento de imagem assistida por computador
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=4995871; https://repositorio.unifesp.br/handle/11600/50788

Background: The analysis of the correlation between noninvasive dermal collagen evaluation techniques, such as high frequency ultrasonography and Raman spectroscopy, with skin biopsy – often considered the gold standard - is essential to support the results of dermatological studies. Objectives: to characterize and describe the high frequency ultrasound and the Raman spectroscopy parameters associated to dermal collagen in intrinsically aged and photoaged skin; and to analyze their correlation with histology. Methods: a cross sectional diagnostic assessment intervention study included 23 women between 28 and 82 years from the general outpatient clinic of the department of Dermatology of the Federal University of São Paulo. They were divided into 3 groups according to the right forearm photoaging score as mild (1), moderate (2) or advanced (3). Analysis of the dermis on photoexposed (forearm back) and non-photoexposed area (medial arm) was carried out through three methods: high frequency ultrasound, confocal Raman spectroscopy and skin biopsy for immunohistochemistry (collagen I) and histological assessment using picrosirius-red and Verhöff staining techniques together with digital image analysis of histological and ultrasound pictures. The differences between the photoexposed and non-photoexposed regions were studied and statistic correlations between each of the non-invasive methods and the age, photoaging score and histological parameters were assessed. Results: at the non-photoexposed site, the upper and lower dermis ultrasound parameter ratios better correlated with age. The higher coefficients were for the ratio of the low echogenic pixels between the upper and lower dermis, the ratio of the medium and high echogenic pixels between the upper and lower dermis and the ratio of total intensity between the upper and lower dermis. There was a slight correlation with collagen I area fraction in immunohistochemistry. At the photoexposed area, total and upper dermis parameters demonstrated higher correlations with age and clinical score. The low echogenicity pixels area fraction, medium and high echogenic pixels area fraction and Total Intensity presented the higher coefficients. The correlation coefficients between ultrasound parameters and histology were higher for the photoexposed site compared with the non-photoexposed region. The medium and high echogenic pixels area fraction and Total Intensity presented the higher correlation coefficients with collagen area fraction in the Picrossírius red staining (direct) and with solar elastosis area fraction in Verhöff staining (inverse). Principal Component Analysis of the dermis Raman spectra was able to discriminate the photoexposed region (photoaging) from the non-photoexposed region (intrinsic aging) in group 3; and the non-photoexposed dermis of group 1 from group 3 (intrinsic aging). The peak intensities in 855cm-1 and 938cm-1 showed moderate correlation with age, high-frequency ultrasonography, and immunohistochemistry for Collagen I in the non-exposed region. In the photoexposed region, the ratio between 1275 cm-1 and 1450 cm-1 intensities (I1275/I1450) presented moderate to high correlation with age, photoaging score, dermis echogenicity and histology (immunohistochemistry for collagen I, picrossirius and Verhöff). Conclusion: a moderate to high correlation between histology and ultrasound was found in the photoexposed region. Lower, but significant, correlation coefficients occurred in the non-photoexposed region. Significant correlations were also found between in vivo Raman spectroscopy, histology and ultrasonography. The 938 cm-1 and 855 cm-1 peak intensities may be useful for intrinsic aging assessment, while I1275/I1450 ratio can be used for photoaging measurement.