Abstract We are requesting funds for the purchase of a state-of-the-art in vivo micro Computed Tomography (microCT) scanner for non-invasive, nondestructive, volumetric imaging and analysis of the skeleton from live animals ranging in size from mice to rabbits. The vivaCT80 is manufactured by Scanco Medical AG (Brutisellen, Switzerland) and distributed by Scanco USA, Inc. (King of Prussia, Pennsylvania, USA). The system is capable of acquiring and analyzing three-dimensional images of the skeleton and vasculature of live animals with a voxel size as small as 5µm while maintaining a relatively low radiation dose. The combination of low dose radiation, high speed, and a wide-ranging resolution and field of view in the vivaCT80 are made possible by an 8192 pixel wide detector. The vivaCT80 accommodates a wider range of animal/specimen sizes (90mm bore size with an 80mm field of view) than most competing high-resolution instruments. The x-ray tube is capable of peak energies from 30 kVp to 70 kVp which improves image quality (contrast-to-noise ratio, CNR) and reduces scan time and dose for both high- and low-density specimens The scanner includes an integrated touch display, heating system, animal temperature monitoring, observation camera, respiratory gating,heart beat frequency monitoring, and ports for anesthesia and contrast media, and all software needed for standard and customized volumetric and structural analyses. This instrument will be utilized by five major users, all VA funded with laboratories and animal colonies at the Atlanta VAMC; Drs. George R Beck Jr. (PI) (PhD), Neale Weitzmann (PhD), Hicham Drissi (PhD), Nick Willet (PhD), and Steven Presciutti (MD). In addition to 4 VA merits and 1 VA CDA award, these investigators also are funded by 3 R01s, 3 R21s, DOD, Score, and U54 projects, among others, all focused on musculoskeletal research. The research programs range in focus from diseases of bone homeostasis (i.e. osteoporotic disease), fracture repair, osteoarthritis, biomaterials for bone regeneration and tissue repair, and drug development for improved spine fusion. The equipment will be located in the animal facility on the 4th floor of Building A at the Atlanta VAMC (Decatur GA) where all five major users have animal colonies. The in vivo microCT will signficantly facilitate each of these projects focused on pre-clinical rodent models of bone disease and repair and be a great assest to the rapidly expanding Musculoskeletal group at the Atlanta VAMC. The advantages of having an in vivo microCT are several. 1) All five major users utilize transgenic mouse models It would make possible to expand the ongoing and planned studies with in vivo data about bone structure, a capability which is currently not on hand. 2) The greater sensitivity and precision of in vivo microCT over other methods would results in increased group separation and thus increased ability to interpret the data in a conclusive manner. 3) In many cases it will be ...