Raman spectroscopy has enabled incredible advances in numerous scientific fields and is a powerful tool for tissue classification and disease recognition, although there have been considerable challenges to using the method in a clinical setting. Scientists have now demonstrated the advantages of wavelength-modulated Raman spectroscopy, opening the door to wider biomedical and clinical applications such as real-time assessment of tissues during surgery. This study is published in Biomedical Spectroscopy and Imaging.
The inelastic scattering of light from any sample is called the Raman effect, named for the Nobel prize-winner C.V. Raman. It yields a molecular fingerprint related to the intrinsic composition of the sample. With the advent of lasers for excitation, this analytical technique has been applied in many disciplines from mineral investigations to protein structure determination and single cell studies. The technique enables cancerous lesions, which are accompanied by changes in chemical composition compared to normal tissue, to be detected as a vibrational spectroscopic fingerprint. However, there are considerable challenges to using the method in a clinical setting because factors such as ambient light, background fluorescence, and 'etaloning' (a phenomenon that degrades the performance of thinned, back-illuminated charge-coupled devices) can hinder the interpretation of images. Pre-processing the data is prone to introduce artefacts and seriously hamper a classification.
Scientists from St. Andrews (UK) and Jena (Germany) have now demonstrated that wavelength-modulated Raman spectroscopy, an alternative to standard Raman spectroscopy with monochromatic excitation, overcomes these key problems. In this study they describe how to record Raman signals against a high auto-fluorescence background by studying liver tissue and record spectra of Paracetamol tablets in ambient light.