NEAR-INFRARED RAMAN-SPECTROSCOPY FOR IN-VITRO DETECTION OF CERVICAL PRECANCERS

In this study, we investigate the potential of near-infrared Raman spe ctroscopy to differentiate cervical precancers from normal tissues, in flammation and metaplasia and to differentially diagnose low-grade and high-grade precancers. Near infrared Raman spectra were measured from 36 biopsies from 18 patients in vitro, Detection algorithms were deve loped and evaluated relative to histopathologic examination. Algorithm s based on empirically selected peak intensities, ratios of peak inten sities and a combination of principal component analysis for data redu ction and Fisher discriminant analysis for classification were investi gated. Spectral peaks were tentatively identified from measured spectr a of potential chromophores. Empirically selected normalized intensiti es can differentiate precancers from other tissues with an average sen sitivity and specificity of 88 +/- 4% and 92 +/- 4%, Ratios of unnorma lized intensities can differentiate precancers from other tissues with a sensitivity and specificity of 82% and 88% and high-grade from low- grade lesions with a sensitivity and specificity of 100%. Using multiv ariate methods, intensities at eight frequencies can be used to differ entiate precancers from all other tissues with a sensitivity and speci ficity of 82% and 92% in an unbiased test. Raman algorithms can potent ially separate benign abnormalities such as inflammation and metaplasi a from precancers. Comparison of tissue spectra to published and measu red chromophore spectra indicate that the most likely primary contribu tors to the tissue spectra are collagen, nucleic acids, phospholipids and glucose l-phosphate. These results suggest that near-infrared Rama n spectroscopy can be used for cervical precancer diagnosis and may be able to accurately separate samples with inflammation and metaplasia from precancer.