FT-Raman spectroscopy was employed to study normal human colorectal tissues in vitro with the aim of evaluating the spectral differences of the complex colon mucous in order to establish a characteristic Raman spectrum. The samples were collected from 39 patients, providing 144 spectra for the statistical analysis. The results enable one to establish three well-defined spectroscopic groups of non-altered colorectal tissues that were consistently checked by statistical (clustering) and biological (histopathology) analyses: group 1 is represented by samples with the presence of epithelial layer, connective tissue papillae, and smooth muscle tissue; group 2 comprises tissues with epithelial layer and connective tissue papillae; group 3 presented mostly fatty and slack conjunctive tissue. The study reveals the existence of an intrinsic spectral variability for each patient that must be considered when sampling tissues fragments to build a spectral database. This is the first step for future studies and applications of Raman spectroscopy to optical biopsy and diagnosis of colorectal cancer.

The algorithm based on PCA has the potential for classifying Raman spectra and can be useful for detection of dysplastic and malign oral lesion.

We employ Fourier-transform Raman spectroscopy to study normal and tumoral human breast tissues, including several subtypes of cancers. We analyzed 194 Raman spectra from breast tissues that were separated into 9 groups according to their corresponding histopathological diagnosis. The assignment of the relevant Raman bands enabled us to connect the several kinds of breast tissues (normal and pathological) to their corresponding biochemical moieties alterations and distinguish among 7 groups: normal breast, fibrocystic condition, duct carcinoma in situ, duct carcinoma in situ with necrosis, infiltrating duct carcinoma not otherwise specified, colloid infiltrating duct carcinoma, and invasive lobular carcinomas. We were able to establish the biochemical basis for each spectrum, relating the observed peaks to specific biomolecules that play a special role in the carcinogenesis process. This work is very useful for the premature optical diagnosis of a broad range of breast pathologies. We noticed that we were not able to differentiate inflammatory and medullary duct carcinomas from infiltrating duct carcinoma not otherwise specified.

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The diagnosis of thyroid pathologies is usually made by cytologic analysis of the fine needle aspiration (FNA) material. However, this procedure has a low sensitivity at times, presenting a variation of 2-37%. The application of optical spectroscopy in the characterization of alterations could result in the development of a minimally invasive and non-destructive method for the diagnosis of thyroid diseases. Thus, the objective of this work was to study the biochemical alterations of tissues and hormones (T3 and T4) of the thyroid gland by means of molecular vibrations probed by FT-Raman spectroscopy. Through the discriminative linear analysis of the Raman spectra of the tissue, it was possible to establish (in percentages) the correct classification index among the groups: goitre adjacent tissue, goitre nodular region, follicular adenoma, follicular carcinoma and papillary carcinoma. As a result of the comparison between the groups goitre adjacent tissue versus goitre nodular region, an index of 58.3% of correct classification was obtained; this percentage was considered low, and it was not possible to distinguish the Raman spectra of these groups. Between goitre (nodular region and adjacent tissue) versus papillary carcinoma, the index of correct classification was 64.9%, which was considered good. A relevant result was obtained in the analysis of the benign tissues (goitre and follicular adenoma) versus malignant tissues (papillary and follicular carcinomas), for which the index was 72.5% and considered good. It was also possible, by means of visual observation, to find similar vibrational modes in the hormones and pathologic tissues. In conclusion, some biochemical alterations, represented by the FT-Raman spectra, were identified that could possibly be used to classify histologic groups of the thyroid. However, more studies are necessary due to the difficulty in setting a standard for pathologic groups.