Histopathological analyses and intraoperative magnetic resonance imaging are both used for diagnosis and to define tumour margins during brain tumour surgery, but they have limitations. Eberlin et al. developed a strategy using desorption electrospray ionization mass spectrometry (DESI-MS) to analyse lipid profiles, which may improve brain tumour diagnosis and the definition of tumour margins. This was validated using 32 surgical specimens from five patients.