Discrimination between Nontumor Bladder Tissue and Tumor by Raman Spectroscopy.

We have applied Raman spectroscopy to discriminate between nontumor and tumor bladder tissue and to determine the biochemical differences therein. Tissue samples from 15 patients were collected, and frozen sections were made for Raman spectroscopy and histology. Twenty-five pseudocolor Raman maps were created in which each color represents a cluster of spectra measured on tissue areas of similar biochemical composition. For each cluster, the cluster-averaged spectrum (CAS) was calculated and classified as tumor and nontumor in accordance to pathohistology. Unguided hierarchical clustering was applied to display heterogeneity between and within groups of nontumor and tumor CM. A linear discriminant analysis model was developed to discriminate between CM from tumor and nontumor. The model was tested by a leave-one-patient-out validation, 84 of the 90 CM (93%) were correctly classified with 94% sensitivity and 92% specificity. Biochemical differences between tumor and nontumor CM areas were analyzed by fitting spectra of pure compounds to the CM. Nontumor CM showed higher collagen content while tumor CM were characterized by higher lipid, nucleic acid, protein, and glycogen content. Raman spectroscopy enabled effective discrimination between tumor and nontumor bladder tissue based on characterized biochemical differences, despite heterogeneity expressed in both tumor and nontumor CM. [ABSTRACT FROM AUTHOR]