Fig. 2

Grade discrimination from FFPE tissue samples. (A) Example view of a GBM tissue sample with the Raman microscope after dewaxing, before acquisition. Main structures are visible (vessels, red blood cells, cancer cells) and can be targeted. (B) PCA plot of the 30 glioma FFPE samples. Grade II (in red), grade III (in green), and grade IV (in blue) are easily discriminated by using the two largest principal components. (C) Pair-wise comparison between the averaged spectra of grade II and grade III, and grade III and grade IV. Asterisks indicate the peaks that were significantly different using an unpaired t-test. (D) Scatter plots of individual intensities (and mean ± standard deviation) at peaks showing significant difference using a two-tailed unpaired t-test. Circles drawn on PCA plot highlight trends assessed subjectively by eye