Multimodal Device for Assessment of Skin Malformations
Amina Bekinaa, Valerijs Garancisb, Uldis Rubinsa, Eriks Zaharansa,
Janis Zaharansa , Liene Elstea and Janis Spigulisa
a)Institute of Atomic Physics and Spectroscopy, University of Latvia, Raina Blvd 19,
Riga, LV-1586, Latvia
b)Telemedica SIA, Graudu 68, Riga, LV-1058, Latvia
Many spectral imaging devices are commercially available and used to detect certain skin pathology; however an alternative cost-efficient device can provide an advanced spectral analisys of skin. Multimodal device for diagnosis of pigmented skin lesions was developed and tested. A polarized LED light source illuminates the skin surface at four different wavelengths – blue (450 nm), green (540 nm), red (660 nm) and infrared (940 nm). Spectra of reflected light from the 25 mm wide skin spot is imaged by a CMOS sensor [1]. Four spectral images are obtained for mapping of the main skin chromophores. The specific chromophore distribution differences between different skin malformations were analised and information of subcutaneous structures was consecutively extracted. The chromophore concentration was expressed by from the natural logarithm of relation between two intensities of monochrome light illuminations [2]:
C=A0+A1*1d*loge(I1I2) (1)
where C – respectively hemoglobin, bilirubin, melanin or erythema index map, A0 - first calibration constant, A1- second calibration constant, d – thickness of the measured tissue, I1 and I2– intensities of diffuse reflected light from the skin related for particular chromophore. The distribution of hemoglobin is more pronounced in hemangiomas and angiomas, bilirubin map shows mostly bruises, melanin appears in both malignant and benign skin lesions like melanomas and birthmarks, however erythema index map corresponds to blood perfusion [3]. The software algorithm allows to overlay original image and a map for better monitoring of the skin malformation’s areas with more pronounced chromophore concentration.
Multimodal device as well as chromophore mapping has been successfully tested in the clinic. Computerized image processing allows to observe more detailed structure of skin malformations to avoid the subjectivity of human skin assessment with the naked eye.
References
[1] J. Spigulis, U. Rubins, E. Zaharans, J. Zaharans, L. Elste. A device for multimodal imaging of skin. Proc. SPIE 8574, Multimodal Biomedical Imaging VIII, 85740J (March 13, 2013); doi:10.1117/12.2003510
[2] Non-invasive device and method for measuring bilirubin levels. Patent «0023742 A1» US (2013).
[3] A.Bekina, I.Diebele, U.Rubins, J.Zaharans, A.Derjabo, J.Spigulis. Multispectral assessment of skin malformations by modified video-microscope. Latv. J. Phys. Techn. Sci., v.49, No.5, pp.4-8 (2012)