Fig. 3

Grade discrimination from fresh serum samples. 3D PCA plot of glioma blood serum samples using the three largest principal components (PC1, PC2, PC3). Control (CTRL) and grade III samples can be discriminated (A) as well as grade III and grade IV (B), grade III and grade IV have a wider distribution in comparison with control samples. (C) Pair-wise comparison between the averaged spectra of control and grade III, and grade III and grade IV. Asterisks indicate the peaks that were significantly different using the t-test, while areas shaded in grey highlight important differences. (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