The overall goals is to provide three dimensional (3-D) images of anatomic structure and associated function (e.g., perfusion) at a resolution sufficient for the quantitative description of the packing, perfusion and drainage of organs' Basic Functional Units (BFU-e.g., hepatic lobule) throughout intact rat or mouse organs. This new capability will enable the applicants to address the hypothesis that the pattern of responses of BRUs to pathophysiological stresses must be known if the bulk behavior of organs, in response to those stresses, is to be quantitatively understood. The basis of this application is a recently implemented micro-CT scanner that scans volumes up to 2cm3 made up of 512/3,5-40um on-a-side, cubic voxels. AIM I - Develop and implement a new local tomographic reconstruction algorithms. AIM II - Develop 3-D Image Analysis and Display Techniques - Starting with a wide variety of computer programs, several previously developed for our DSR CT scanner, the applicants proposed to: (a) devise improved 3-D image, display and quantitation processing algorithms to accommodate the more than an order-of-magnitude larger 3-D images, (b) provide image data analysis for quantitation of function by way of: finite element analysis of imaged structure and by, AIM III - Quantitation of Basic Structure-to-Function Relationships in Pathophysiological Processes: (a) The impact of hypertrophy on the myocardial fiber architecture, (b) The role of cortico-medullary vascular architecture on renal function, (c) The remodeling of bile duct branching topology after biliary obstruction, (d) Response of trabecular architectures to (i) mechanical usage and sex steroids or (ii) to fracture. The significance of this facility will be its capability to provide new insights into osteoporosis, microcirculation in atherosclerosis, and hypertension, into renal function of unilateral nephrectomy and into hepatobillary malfunction.