7. Project Summary/Abstract Funds are being requested to purchase a Super Argus PET/CT 6R small-animal PET (positron emission tomography) and CT (transmission computed tomography) scanner (Scintica, Webster, TX) to replace our Inveon microPET/microCT scanner. Importantly, Siemens Medical Solutions (the manufacturer of the Inveon) has informed us that the support of the Inveon will end within the next 1 to 2 years (i.e., by the end of 2025), meaning that parts and service for needed repairs, software upgrades, and applications support will very likely not be available beyond that end-of-support date. The proposed Super Argus PET/CT 6R will be used in mouse and rat models to non-invasively and longitudinally: monitor cancer and other disease processes; assess trafficking of cancer, immune, and stem cells; evaluate cellular responses to investigational anti-cancer therapies and other interventions; assay genetic pathway expression; and measure tumor targeting and biodistribution of new radiodiagnostic and radiotherapeutic agents. Like the Inveon, the state-of-the-art Super Argus PET/CT 6R, to be installed in our existing Animal Imaging Core Facility, will be a critical, broadly used resource for the pre-clinical and translational oncology research program at Memorial Sloan Kettering Cancer Center (MSK). The Super Argus PET/CT 6R, as noted, will replace the ageing Inveon, installed in 2013 and now over 10 years. With its impending end of support, should the Inveon require service support and replacement parts, they likely will not be available and this heavily used, mission-critical resource would be immediately and permanently disabled - a devastating blow to our entire pre-clinical research program. Funds for a new, fully supported, higher-performance, and more functional small-animal PET/CT system, the Super Argus PET/CT 6R, are therefore urgently requested to maintain, enhance, and expand our PET and CT imaging capabilities. In addition to maintaining manufacturer service and applications support, among the critical advantages of the Super Argus PET/CT 6R over our existing, now-outdated Inveon are: (1) superior spatial resolution – 0.7 mm full-width half-maximum (FWHM) for PET and as low as 15 µm for CT; (2) phoswich detector-based depth-of-interaction (DOI) correction for PET and resulting constant resolution across the 120-mm transaxial field of view (FOV); (3) high PET sensitivity - 12%; and (4) a long axial FOV - 15 cm. The Super Argus PET/CT 6R is a fully integrated multi-modality system providing transparent registration of PET and CT studies or serving as stand-alone PET and CT systems. In addition to numerous new and ongoing funded projects which will use the Super Argus PET/CT 6R, our Facility and MSK have well-established technical and scientific expertise to continue to productively utilize this instrument and an efficient administrative and solvent financial infrastructure in place to support and maintain this instrument and its effec...