Cancers are readily visible with positron emission tomography, or PET, an imaging method in which a radioactively labeled tracer accumulates in the tumor. Labeled glucose is often used as a tracer because tumor cells tend to require large amounts of glucose. PET cannot be used to image brain tumors, however, because normal brain cells are also highly dependent on glucose. Now Venneti et al. show that radiolabeled glutamine, which is also taken up by tumor cells, yields clear images of brain tumors in mice and humans. With the glutamine label, cancer cells can be distinguished from normal brain cells and even from tumors that are no longer growing….
