Keywords Humans, Diagnostic Imaging, Spectrometry, Mass, Electrospray Ionization, Neoplasms, Metabolomics, Phenotype, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Molecular Imaging Abstract Mass spectrometry imaging (MSI) has gained increasing popularity for tissue-based diagnostics due to its ability to identify and visualize molecular characteristics unique to different phenotypes within heterogeneous samples.