Project Summary (Abstract) We request this high-end instrumentation (HEI) S10 grant to acquire a replacement microPET/CT scanner for the existing Siemens Inveon that was purchased in 2007. There is a great urgency to imminently replace this scanner as the reliability of the scanner has begun to decline significantly especially when the scanner manufacturer discontinued its support of this instrument. The scanner has reached the end of its useful lifetime (14+ years of continuous operation). There is a significant demand for use of the scanner to support a large number of projects that are funded mostly by NIH; thus, combined with the great urgency, we propose to acquire a replacement scanner as soon as possible. There is no other microPET/CT system within the campus core facilities. After a comprehensive comparative study of commercially available scanners, we propose to acquire nanoScan microPET/CT from Mediso USA with GNEXT from Sofie as a backup choice. These two systems have comparable specifications and have been the choice for replacing Siemens Inveon at many other preclinical imaging centers. Both of these systems have depth-of-interaction (DOI) correction technologies that provide more uniform spatial resolution within the field of view than non-DOI detector-based systems like our existing Inveon system. Most members of the technical team including the PI on this S10 grant are the ones who have been supporting microPET/CT operation and research at our institution since 2007, and we have a great degree of technical expertise in small animal imaging using microPET/CT. This expertise includes physics and instrumentation of microPET/CT, PET radiochemistry, small animal imaging procedures, and complex data analysis. At the time of this S10 grant submission, we identified 9 Major and 4 minor users with 30 projects that have specific components that benefit from microPET/CT. The administration of microPET/CT will take advantage of existing technical expertise, local advisory committee, and institutional laboratory animal research resource. The financial administration is through the departmental finance team as well as the institutional research resource program that supports the institution-wide core management software solution. The institutional commitment, in addition to administrative support, includes a significant matching fund against the purchase of the instrument, which was obtained on a highly competitive basis, recognizing our need for microPET/CT replacement over several other resources requested at the same time. The departmental support includes financial backup for recharge operations such as an annual subsidy in case there is a shortfall of revenue over expenses, the upkeep of the infrastructure, funding for pilot projects, and salary support for faculty with the roles of core administration. Finally, one of many impacts of this S10 grant will be to potentially lower the user fee for our microPET/CT users, which could lead to hi...