Simultaneous Positron Emission Tomography (PET) and Magnetic Resonance (MR) imaging (PET-MR) is a novel and promising hybrid modality generating substantial interest in recent years. Individually, these two imaging modalities have complementary advantages and disadvantages in terms of sensitivity, molecular specificity, and spatial and temporal resolution. Their strengths may be integrated and provide new insights in neuroimaging through the concurrent acquisition of synergistic anatomical, functional and biochemical information