PET and SPECT tracers for glutamate receptors

► [11C]ABP688and [18F]SP203 are the most successful PET ligand for imaging mGluR5 in human. ► [11C]JNJ42491293, appears to be a promising PET ligand for imaging mGluR2 in human. ► [18F]MK1312 and [18F]FITM holds promise as a suitable candidate for imaging mGluR1 with PET. ► SPECT ligand guanidine derivative has limited success in imaging NMDAR. Radioligands for PET imaging of glutamate receptors will have the potential for studying neurological and neuropsychiatric disorders and their diagnosis and therapeutic intervention. Glutamate is the major excitatory neurotransmitter in the brain and is implicated in the pathophysiology of many neurodegenerative and neuropsychiatric disorders. Glutamate and its receptors are potential targets in the treatment of these disorders. Glutamate signaling is mediated through ionotropic and metabotropic receptors. The abundant concentration of these receptors can facilitate their in vivo quantification using positron emission tomography (PET). Glutamate receptors are a potentially important set of targets for monitoring disease progression, for evaluating the effect of therapy and for new treatment development based on the quantification of receptor occupancy. Here, we review the PET and single-photon emission computed tomography (SPECT) radioligands that have been developed for imaging glutamate receptors in living brain.