The discovery of new molecular markers from omics studies enable a more accurate classification of patients in new disease entities that can be targeted by specific treatments. Imaging molecular biomarkers is attractive and can make precision medicine feasible because of the ability to screen patients non-invasively without the risks and sampling bias of biopsies. This is particularly relevant for brain tumors and neurological diseases where biopsies are limited or blood tests may not be conclusive. In this talk I will show how imaging molecular biomarkers by in-vivo MRSI  can inform about genetic mutations in glioma brain tumors and allow to assess the treatment response of patients to novel targeted  inhibitors. In addition, results from metabolic imaging studies of neurodegenerative diseases will be also presented.”