Raman Spectroscopy of Biological Tissue for Application in Optical Diagnosis of Malignancy

The use of Raman spectroscopy in the detection and classification of malignancy within the human larynx and lymph nodes of the head and neck has been evaluated. Currently histopathology is considered the diagnostic gold standard. The potential for Raman spectroscopy to be used as an in vivo diagnostic tool in the detection of dysplasia and malignancy has been demonstrated. A consensus opinion from three expert histopathologists has been obtained and spectral diagnostic models developed by correlation with these results. The ability of Raman spectroscopy to differentiate between disease entities and normal tissue within the larynx has been shown. Raman spectroscopy was able to identify non-neoplastic vocal cord mucosa (sensitivity 85 %, specificity 95%) from laryngeal mucosa showing neoplastic change (sensitivity 95 %, specificity 85%) with an increase in sensitivity to 89% for the non-neoplastic tissue and a reduction to73% in tissues showing neoplastic changes after cross-validation. For the first time benign changes in the structure of vocal cords such as those exhibiting hyperkeratosis and hyperplasia, where also identified with sensitivity of 97.9% for tissue exhibiting hyperplasia/hyperkeratosis and 100% for normal squamous cell epithelium. Research into the ability of Raman spectroscopy to interrogate lymphoid tissue in order to differentiate reactive nodes (sensitivity 90 %, specificity 88%) from those containing cancer (sensitivity 88 %, specificity 90%) was successful and fully independently validated. This work was further developed and the efficacy of Raman spectroscopy in differentiating between squamous cell carcinoma (sensitivity 76%, specificity 95%), adenocarcinoma (sensitivity 93 %, specificity 99%), Hodgkin‘s lymphoma (sensitivity 80%, specificity 90%) and reactive lymph nodes (sensitivity 81%, specificity 88%) was shown. This model was also independently cross-validated by node producing further improvements to give a spectral performance of sensitivity/specificity for SCC of 75/97%, adenocarcinoma 100/99%, Hodgkin‘s lymphoma 83/92% and reactive lymph nodes 85/86%.