Console Upgrade for 4.7T PET-MRI Preclinical Scanner - Project Summary Funding is requested for an upgrade of an existing 4.7 Tesla Bruker PET-MRI console. The proposed instrument will be a crucial component in facilitating the development of novel PET and MR molecular imaging contrast agents and for diffusion MRI studies of brain structure and neural pathway connectivity. The PET-MRI scanner serves a large NIH-funded user community encompassing a wide variety of biomedical disciplines including fibrosis, cancer, cardialogy, gene expression, and brain structure and function studies. We currently serve users both within the MGH/Harvard/MIT system as well as from around the greater Boston/Cambridge region. The requested MRI console upgrade will replace an old Avance III Bruker console that is nearing the end of its usefull lifetime. Starting in 2024 Bruker Biospin will no longer support or service the Avance III console. Due to the age of the MRI console, we have had numerous equipment failures over the last few years which have caused significant scanner downtime. In the future, such equipment failures will be difficult to address since Bruker will no longer stock spare parts or service such old consoles. The requested console upgrade would therefore allow us to continue to serve the large local NIH-funded user community and offer important molecular imaging and brain structural imaging capabilities to the rapidly expanding user base with molecular and brain imaging interests. In particular, the proposed instrument would allow for integrated PET-MRI workflow with both PET and MRI data acquired in the same software environment with seemless image reconstruction and registration. In addition, the improved 3D dynamic shimming, EPI based diffusion sequences, and gradient coil performance will greatly enhance the brain diffusion MRI studies. Projects requiring MR-PET include the development of Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) contrast agents for molecular imaging of liver fibrogenesis, cardiac fibrosis, pulmnary fibrosis, metastatic breast cancer, gastric cancer, pancreatic adenocarcinoma, inflammatory diseases, Huntington’s Disease, and epigenetic regulation of gene expression. Projects requiring the enhanced MR imaging capabilities include high resolution studies of brain neural tissue microstructure, multimodal studies of brain neurovacular coupling and neurotransmitter receptor trafficking, cardiac fibrosis imaging, and Chemical Exchange Saturation Transfer (CEST) MRI studies of oncolytic virotherapy.