Optical biopsy of normal and cacnerous cervical tissues by native fluorescence spectroscopy

Native fluorescence spectra of tissues of both normal and cervical carcinoma were measured at 320 nm excitation. The spectra were normalized with respect to maximum peak intensity and average fluorescence spectra were computed for normal and cancerous cervical tissues. The average fluorescence spectrum of normal cervix is found to be significantly different from that of cancer. Both normal and cancerous cervical tissues show a distinct primary emission peak around 380 nm which may be attributed to the structural proteins, collagen and elastin. In addition, the average spectrum of normal cervix shows a less intense peak around 440 nm, which is red shifted to 460nm and more intense in the case of cancerous cervical tissues, when compared to normal. A ratio parameter I-380/I-460 is introduced and a critical value of 1.9 for this ratio parameter is found to classify cervical cancerous tissues from normal with a sensitivity and specificity of 100% and 85.7% respectively. Also the slope value analysis between 420 to 440nm & 440 to 460nm of the normal and cancerous samples gives 100% accuracy in the classification of normal from the cancerous samples. Further, discriminant analysis together with Principal component analysis (PCA) was performed to determine the statistical significance and to confirm the above two analysis. The potentiality of the ratio parameter and slope values analysis is improved by the support of multivariate statistical analysis.