Abstract

The aims of this study were: to quantify near-infrared optical properties of normal cervical tissues and high-grade squamous intra-epithelial lesions ; to assess the feasibility of differentiating normal cervical tissues from H-SIL on the basis of these properties; and to determine how cervical tissue optical properties change following photodynamic therapy of H-SIL in vivo. Using the frequency domain photon migration technique, non-invasive measurements of normal and dysplastic ecto-cervical tissue optical properties, i.e. absorption ) and effective scattering coefficients, and physiological parameters, i.e. tissue water and haemoglobin concentration, percentage oxygen saturation, were performed on 10 patients scheduled for PDT of histologically-proven H-SIL. Cervix absorption and effective scattering parameters were up to 15% lower in H-SIL sites compared with normal cervical tissue for all wavelengths studied. Following PDT, all μ values increased significantly, due to elevated tissue blood and water content associated with PDT-induced hyperaemia and oedema. Tissue total haemoglobin concentration and arterio-venous oxygen saturation measured in H-SIL sites were lower than normal sites.