Summary Molecular imaging with small animal Positron Emission Tomography/ Computed Tomography (micro-PET/CT) is an established component of preclinical research and drug development which provides in-vivo quantitative molecular imaging in a real-time for disease diagnosis and therapy evaluation, and plays an increasingly crucial role in preclinical precision medicine research. In this proposal, we are requesting funds to acquire a benchtop micro-PET/CT imaging system as a shared research tool to support NIH-funded research of infection diseases. The funds obtained through this grant will be used to acquire a PET/CT scanner for small animal molecular imaging research to be sited within a Biological Safety Level-3 Facility (BSL3). Research in infectious diseases at WUSM stretches across numerous departments with programs addressing every family of pathogen, including bacteria, viruses, fungi and parasites. Molecular imaging (i.e., positron emission tomography, PET) complemented with computed tomography holds great promise for the early, accurate detection of infection and infectious disease, and monitoring of treatment efficacies. The presence of an infectious organism in tissue initiates a complex series of inflammatory responses. We have identified a portable benchtop micro-PET/CT system with advanced preclinical molecular imaging that simplifies workflow, improves siting flexibility, and reduces operational cost. This system will complement our existing real-time and noninvasive molecular imaging equipment that includes small animal MRI and IVIS Spectrum optical imaging. Our long-term goal is to establish a BSL3 Imaging Facility at Washington University to serve the needs of researchers, including other institutions, and more broadly within the community. The requested benchtop micro-PET/CT will be used by NIH funded investigators and will be overseen by a broad-based advisory committee. Strong institutional support and financial commitment will be provided to assure optimal use.