Molecular imaging is a powerful tool that has the ability to elucidate biochemical mechanisms and signal the early onset of disease. Overexpression of the peripheral benzodiazepine receptor (PBR) has been observed in a variety disease states, including glioblastoma, breast cancer, and Alzheimer's disease. Thus, the PBR could be an attractive target for molecular imaging. In this paper, the authors report cellular uptake and multimodal (MRI and fluorescence) imaging of PBR-overexpressing C6 glioblastoma (brain cancer) cells using a cocktail administration approach and a new PBR targeted lanthanide chelate molecular imaging agent.