For many patients with epilepsy, a single spot, or lesion, in their brain is the source of their seizures. When patients don’t find relief with standard antiseizure medication—about one-third of all epilepsy cases—surgically removing the lesion can help. But standard magnetic resonance imaging can’t always identify these seizure focal points. A new study suggests that an MRI method that looks for the neurotransmitter glutamate can detect epileptic lesions when standard MRI fails (Sci. Transl. Med. 2015, DOI: 10.1126/scitranslmed.aaa7095). Kathryn Adamiak Davis, Ravinder Reddy, and colleagues at the University of Pennsylvania investigated glutamate imaging because the neurotransmitter excites neurons to fire and epilepsy is thought to result when neuronal circuits become overexcited. The MRI technique, called glutamate chemical exchange saturation transfer (GluCEST), senses the neurotransmitter through a characteristic signal arising from the proton exchange between glutamate’s amine group and bulk water in the brain. By using GluCEST, the researchers could find epileptic lesions in the brains of four patients who had lesions that were undetectable with standard MRI. One patient later underwent surgery, and the lesion’s location was confirmed.