1 September 2008 Second-harmonic generation in collagen as a potential cancer diagnostic parameter
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J. of Biomedical Optics, 13(5), 054050 (2008). doi:10.1117/1.2983664
Abstract
The fibrillar collagen network in tumor and normal tissues is different due to remodeling of the extracellular matrix during the malignant process. Collagen type I fibers have the crystalline and noncentrosymmetric properties required for generating the second-harmonic signal. The content and structure of collagen were studied by imaging the second-harmonic generation (SHG) signal in frozen sections from three tumor tissues, osteosarcoma, breast carcinoma, and melanoma, and were compared with corresponding normal tissues, bone/femur, breast, and dermis/skin. The collagen density was measured as the percentage of pixels containing SHG signal in tissue images, and material parameters such as the second-order nonlinear optical susceptibility given by the d22 coefficient and an empirical anisotropy parameter were used to characterize the collagen structure. Generally, normal tissues had much more collagen than tumor tissues. In tumor tissues, a cap of collagen was seen at the periphery, and further into the tumors, the distribution of collagen was sparse and heterogeneous. The difference in structure was reflected in the two times higher d22 coefficient and lower anisotropy values in normal tissues compared with tumor tissues. Together, the differences in the collagen content, distribution, and structure show that collagen signature is a promising diagnostic marker.
Tord Hompland, Arne Erikson, Mikael Lindgren, Tore Lindmo, Catharina de Lange Davies, "Second-harmonic generation in collagen as a potential cancer diagnostic parameter," Journal of Biomedical Optics 13(5), 054050 (1 September 2008). http://dx.doi.org/10.1117/1.2983664
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KEYWORDS
Collagen

Tissues

Second-harmonic generation

Optical fibers

Tumors

Anisotropy

Breast

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