Multimodality imaging plays an increasingly important role in medicine. Combination of PET imaging with other modalities merges the sensitivity and selectivity of PET to target specific biological processes with the high spatial resolution of CT or MR.  PET/MR is particularly useful for in-vivo studies of brain, where is preferred to PET/CT because of its higher contrast for the soft tissues the brain. Simultaneous PET/MR can use information from the MR scan to improve the PET image, improves coregistration, and reduces the overall scanning time, increasing patient's comfort (Catana 2017, Rausch 2017, Lalush 2017).