MALDI FT ICR MSI of validation set of prostate tissue specimens, a) H&E image of tissue section post-MALDI analysis with tumor region, as determined by an expert pathologist, outlined in black, b) segmentation map of MALDI MSI data produced via k-means clustering (k = 8), c) m/z 780.5483 which is identified as cardiolipin CL(80:9) (Δppm = 0.18), d) m/z 697.4776 which is identified as phosphatidic acid PA(34:1) (Δppm = 0.43), e) m/z 782.5655 which is identified as phosphatidylcholine PC(34:1) (Δppm = 1.93), f) m/z 943.5682 which is identified as phosphatidylinositol PI(44:9) (Δppm = 1.34).