Abstract

Photodynamic Therapy (PDT) is a technique for destroying tumor cells with little harm to surrounding healthy tissue. However, the light wavelength has limited penetration in the tissue, making the association of a surgical procedure needed for larger lesions. Electrosurgery (ES) is a recommended excision technique, but the optical properties of the tissue damaged by ES and its influence on PDT procedure are unknown. Twelve rats (Wistar) composed the animal model of four groups (ES, PDT, ES+PS+Light, PS+ES+Light), evaluating different orders of conjugation via fluorescence, imaging and necrosis depth. First histopathological analysis has shown a highly modified surface of tissue (integral structure loss and dehydration shrinkage), protein denaturation, accompanied by bleeding and inflammatory damage. Fluorescence imaging showed strong scattering of light at the surface of modified tissue, which may cause higher losses of light on the surface. Fluorescence spectra showed different photosensitizer emissions for distinct operation modes. The different tissue composition can also induce changes on absorption and scattering properties, influencing the light penetration. The study showed significant necrosis formation beyond the limits of electrosurgery damage, making possible the conjugate use of ES and PDT.

© 2011 OSA/SPIE