In vivo detection of dysplastic tissue by Raman spectroscopy

The detection of dysplasia and early cancer is important because of the imp roved survival rates associated with early treatment of cancer. Raman spect roscopy is sensitive to the changes in molecular composition and molecular conformation that occur in tissue during carcinogenesis, and recent develop ments in fiber-optic probe technology enable its application as an in vivo technique. In this study, the potential of Raman spectroscopy for in vivo c lassification of normal and dysplastic tissue was investigated. A rat model was used for this purpose, in which dysplasia in the epithelium of the pal ate was induced by topical application of the carcinogen 4-nitroquinoline 1 -oxide. High quality in vivo spectra of normal and dysplastic rat palate ti ssue, obtained using signal integration times of 100 s were used to create tissue classification models based on multivariate statistical analysis met hods. These were tested with an independent set of in vivo spectra, obtaine d using signal collection times of 10 s, The best performing model, in whic h signal variance due to signal contributions of the palatal bone was elimi nated, was able to distinguish between normal tissue, low-grade dysplasia, and high-grade dysplasia/carcinoma in situ with a selectivity of 0.93 and a sensitivity of 0.78 for detecting low-grade dysplasia and a specificity of 1 and a sensitivity of 1 for detecting high-grade dysplasia/ carcinoma in situ.