Small animals, particularly genetically engineered mice, are increasingly becoming the preferred laboratory model to gain further understanding of human health and diseases. Major efforts are being made to link the genome to the much more complex phenotypic expression in both form and function ("Physiome"). Also, significant efforts have been directed to studies of large animals and humans, and the knowledge acquired from these need to be associated with imaging of small animals to support the understanding of genomic effects. And finally, small animal imaging offers the opportunity to evaluate pathologic progression in a much-compressed time frame and with a much finer spatial resolution. Over the past several years there has been an explosive growth in the development of micro-imaging technologies, including micro-CT. In this proposal, we request a micro-CT scanner and associated reconstruction hardware to support the ongoing cellular/molecular level research and the integrated, in vivo organ level work funded by the NIH at the University of Iowa (UI). X-ray CT, rather than any one of the other micro imaging modalities, meets the specific needs of the major user group which, to date, is heavily oriented towards lung and bone. Although the UI is strongly funded by the NIH (32ndin terms of the total NIH funding), we have not had local access to any micro-CT imaging system. Recently, there has been an increasingly urgent need for a micro-CT facility from a growing number of NIH funded UI investigators. The system we plan to purchase has been specifically designed based upon the diversified and sophisticated requirements of UI NIH researchers. The system is commercially built by a leading micro- CT Company. The scanner features include: (1) a variable resolution ranging from 7 to 30 microns to correlate low resolution in vivo data to high resolution in vitro anatomy; (2) a high data acquisition speed; (3) a high though-put image reconstruction engine to allow iterative protocol selection according to prior in vivo imaging results. The micro-CT system will be located in an Imaging Center dedicated to x-ray CT-imaging-based research that is currently under construction with a 2.0 million dollar investment from the Ul College of Medicine. The Internal Advisory Committee consists of established investigators and experienced administrators, and will assist the facility director in establishing policy and future directions of the micro-CT facility. The well-qualified staff will provide technical assistance and necessary training.