PROJECT SUMMARY/ABSTRACT This application seeks support from the ORIP High-End Instrumentation (HEI) Grant program to fund the latest generation Siemens 7 Tesla (7T) whole-body human MRI system to be used for basic/clinical/translational re- search at the Athinoula A. Martinos Center for Biomedical Imaging at the Massachusetts General Hospital. This system will replace our existing 22-year-old prototype 7T human MRI scanner, which was the second in the world and the first with a clinical console. While this prototype 7T system supported the Martinos Center’s ultra-high field research program for over two decades, the 7T magnet is no longer serviceable by the manufacturer (Agilent) and the scanner is no longer supported for future upgrades by the manufacturer (Siemens). Therefore, usage of this system is winding down as the final projects are completed, and we plan to gracefully retire this historic 7T system in 2024. The new system – a Siemens Terra.X whole-body 7T scanner – will provide a substantial increase in performance for the wide range of NIH-funded research at the Martinos Center and the greater Boston area community, including clinical and neuroradiological studies of the central nervous system (brain and spinal cord), as well as imaging of the throat, knee, and skeletal muscle; cognitive, psychiatric, and basic neuroscience and brain mapping studies; multinuclear spectroscopy; and novel instrumentation development. The features and benefits provided by the Siemens Terra.X include: streamlined and standardized workflows for greater ease of use, enabling a broader user base as well as robustness and consistency across sessions; standardized hardware and software for compatibility with other sites, enabling new, collaborative large-scale multi-site trials; improved manufacturer support and maintenance for a product system moving forward, reduc- ing the burden currently placed on Martinos Center staff; enhanced system performance including 16 parallel transmit channels and 64 radiofrequency (RF) receive channels, stronger and faster gradient coils, higher-order magnetic field shims, increased RF power, a faster image reconstruction computer, high temporal resolution phys- iological monitoring, and new sequence and application packages compatible with the newly released Siemens platform; and an up-to-date testbed for the unique instrumentation and technology research and development performed at the Martinos Center, including advanced imaging sequences and reconstruction, higher-density receive coil arrays, and shim-RF multi-coil arrays to be both shared with our industrial collaborators and freely disseminated to the MRI community. Additionally, this scanner will operate in either “MR only” mode or – after the insertion of a next-generation removable, custom-designed positron emission tomography (PET) camera (funded by U01EB029826) – as a novel 7T PET/MR system with an order of magnitude improvement in PET sensitivity. Therefore, this uni...