The potential for histological screening using a combination of rapid Raman mapping and principal component analysis

Rapid Raman mapping was carried out on 20 microm sections of oesophageal biopsy samples. Contiguous 7 microm sections were stained with haematoxylin and eosin (H&E) with histopathology provided by an expert pathologist. The step size and acquisition times were varied and the resulting spectra, principal component (PC) score maps and loads were compared. Overall mapping times were also compared to traditional Raman point mapping. The principal component loads for each of the maps were seen to be similar despite varying the acquisition time and number of spectra. Gross biochemical information was extracted showing good correlation with the H&E sections even for short overall mapping times (30-90 minutes for a 2 mm biopsy, 0.5 s acquisition time per 25.3 microm Raman pixel). This demonstrates that low signal to noise spectral maps are sufficient for the identification of histologically relevant biochemistry using principal component analysis as long as the spectral dataset is large enough.