This grant requests the purchase of a MicroCAT (TM) II Small Animal Imaging System for a multidisciplinary group of investigators at the University of Tennessee Health Science Center. This image analysis system was chosen because of its availability, ease of use, and cost-effective, high-resolution images; distinct advantages over other imaging systems such as MRI systems. This instrument will be shared by several NIH supported researchers and will complement and greatly enhance their current research efforts providing capabilities for data collection that are unavailable by existing techniques. Use of the MicroCAT(TM) II system would greatly facilitate the recognition of murine phenotypic changes associated with known genetic manipulation, thus identification of gene function. It would also allow for more cost effective Longitudinal studies of murine arthritic models and prostate tumor growth in mice, thus greatly facilitating our understanding of the disease and possible treatment modalities. Basically, the instrument will: (1.) facilitate large-scale screening of mutant mice for abnormalities in the central nervous system, the eye, skeleton, and in the internal organs, (2.) provide a reproducible quantitative measurement of the degree and severity of arthritis in the experimental model of collagen induced arthritis in rats and mice, (3.) quantitate the degree of skin, lung, heart, and kidney fibrosis in the Tight Skin 2 mouse model of scleroderma, (4.) assess the rate and amount of bone formation using mesenchymal stem cells and artificial bone matrices in segmental bone defects in compromised hosts, (5.) quantitate bone density changes in a rat osteolysis model, (6.) determine age-related changes in bone density associated with mechanical properties of bone and (7.) quantitate tumor growth in the prostate in tumor susceptible strains of mice undergoing various treatment regimens.