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Proceedings Paper

Influence of tissue parameters on visual reflectance spectra of port wine stains and normal skin
Author(s): Lill Tove Norvang Nilsen; Elisanne Janne Fiskerstrand; B. Bakken; D. Grini; O. Standahl; Thomas E. Milner; Michael W. Berns; J. Stuart Nelson; Lars Othar Svaasand
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Paper Abstract

The visual appearance of port-wine stain lesions is often a red to purple color due to an enlarged blood volume in the upper dermis. The purpose of the treatment is to re-establish normal skin coloration. Visual reflectance spectra should therefore, in principle, contain all relevant information about the lesion. The influence on the spectra from the different tissue parameters, such as melanin, blood content and scattering, is rather composite. However, a simple mathematical model can give a good understanding of the relevance of the different components. This knowledge can be used to optimize the laser treatment of port-wine stain. In vivo reflectance spectra were obtained using an integrating sphere spectrophotometer. A simple mathematical model based on the diffusion approximation was used to simulate port- wine stain and normal skin reflectance spectra. The absorption coefficients of epidermis and dermis are mainly due to melanin and blood. These parameters were measured in separate in vivo experiments and obtained from skin biopsies. The scattering coefficients were based on reported values. Simulated reflectance spectra show good agreement with the measured ones. Even though the diffusion model has limited validity for wavelengths shorter than 600 nm, the simulated spectra from 450 to 600 nm give a qualitative understanding of the influence of the tissue parameters. The results show that dark red to almost dark grey port-wine stains contain enlarged blood fraction in the entire upper dermis. The red port-wine stains appear when the abnormal density of blood is confined to a thin layer. High amount of epidermal melanin results in reduced reflectance throughout the visible spectrum. The characteristic spectrum due to the blood is suppressed. The reflectance spectra are strongly dependent on the dermal and epidermal scattering coefficient; even minor changes as naturally occurring with age, might have a significant impact. A permanently reduced scattering coefficient might result in a reddish coloration even when a normal blood content is restored. Correlation between measured and simulated spectra give a good understanding of the importance of the parameters determining the visual appearance of port-wine stain.

Paper Details

Date Published: 19 January 1996
PDF: 13 pages
Proc. SPIE 2623, Medical Applications of Lasers III, (19 January 1996); doi: 10.1117/12.230298
Show Author Affiliations
Lill Tove Norvang Nilsen, Norwegian Institute of Technology and Beckman Laser Institute and Medical Clinic (Norway)
Elisanne Janne Fiskerstrand, Univ. Hospital of Trondheim (Norway)
B. Bakken, Norwegian Institute of Technology (Norway)
D. Grini, Norwegian Institute of Technology (Norway)
O. Standahl, Norwegian Institute of Technology (Norway)
Thomas E. Milner, Beckman Laser Institute and Medical Clinic (United States)
Michael W. Berns, Beckman Laser Institute and Medical Clinic (United States)
J. Stuart Nelson, Univ. of California/Irvine (United States)
Lars Othar Svaasand, Norwegian Institute of Technology and Beckman Laser Institute and Medical Clinic (Norway)


Published in SPIE Proceedings Vol. 2623:
Medical Applications of Lasers III
Stephen G. Bown; Herbert J. Geschwind; Raimund Hibst; Frederic Laffitte; Giulio Maira; Roberto Pini; Hans-Dieter Reidenbach; Hans H. Scherer; Pasquale Spinelli, Editor(s)

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