Spectral variations of laser-induced tissue emission during in vivo detection of malignancies in the female genital tract

Trimodal spectroscopy for the detection and characterization of cervical precancers in vivo

OBJECTIVE

The objective of this study was to assess the potential of 3 spectroscopic techniques (intrinsic fluorescence, diffuse reflectance, and light scattering) individually and in combination (trimodal spectroscopy) for the detection of cervical squamous intraepithelial lesions.

STUDY DESIGN

The study was conducted with 44 patients who underwent colposcopy for the evaluation of an abnormal Papanicolaou smear. Fluorescence and reflectance spectra were collected from colposcopically normal and abnormal sites and analyzed to extract quantitative information about tissue biochemistry and morphologic condition. This information was compared with histopathologic classification, and diagnostic algorithms were developed and validated with the use of logistic regression and cross-validation.

RESULTS

Diagnostically significant differences exist in the composition of fluorescing biochemicals, the scattering properties, and the epithelial cell nuclear morphology of cervical squamous intraepithelial lesions and non-squamous intraepithelial lesions. Trimodal spectroscopy is a superior tool for the detection of cervical squamous intraepithelial lesions than any 1 of the techniques alone.

CONCLUSION

Trimodal spectroscopy has the potential to improve the in vivo detection of precancerous cervical changes.

Fluorescence spectroscopy of neoplastic and non-neoplastic tissues

Fast and non-invasive, diagnostic techniques based on fluorescence spectroscopy have the potential to link the biochemical and morphologic properties of tissues to individual patient care. One of the most widely explored applications of fluorescence spectroscopy is the detection of endoscopically invisible, early neoplastic growth in epithelial tissue sites. Currently, there are no effective diagnostic techniques for these early tissue transformations. If fluorescence spectroscopy can be applied successfully as a diagnostic technique in this clinical context, it may increase the potential for curative treatment, and thus, reduce complications and health care costs. Steady-state, fluorescence measurements from small tissue regions as well as relatively large tissue fields have been performed. To a much lesser extent, time-resolved, fluorescence measurements have also been explored for tissue characterization. Furthermore, sources of both intrinsic (endogenous fluorophores) and extrinsic fluorescence (exogenous fluorophores) have been considered. The goal of the current report is to provide a comprehensive review on steady-state and time-resolved, fluorescence measurements of neoplastic and non-neoplastic, biologic systems of varying degrees of complexity. First, the principles and methodology of fluorescence spectroscopy are discussed. Next, the endogenous fluorescence properties of cells, frozen tissue sections and excised and intact bulk tissues are presented; fluorescence measurements from both animal and human tissue models are discussed. This is concluded with future perspectives.