"The introduction of transgenes that express fluorescent proteins (FPs) into cells has revolutionized the ability to visualize many cellular and sub-cellular processes that are otherwise invisible with traditional means of optical imaging. Fluorescent proteins have been widely used in microscopic imaging, however deep tissue imaging has not been possible, before the recent development of fluorescent proteins emitting beyond the 600 nm absorption threshold. In the present proposal the applicant will study and develop a novel optical tomographic method for preclinical research applications with the use of the recently evolved red-shifted fluorescent proteins. The development is going to be based on modifying the existing Fluorescence Molecular Tomography method both in its experimental and theoretical part as necessary. The result will be a tomographic method and system that will be used to reconstruct in 3D the location of the fluorescent proteins deep inside the tissue of small animals (mice) with submillimeter resolution. The proposed method/system will be tested against various of the parameters of its operation and will be used to demonstrate its use in in-vivo biomedical imaging applications. A method/system like the proposed has the potential to become a high capability non invasive monitoring and diagnostic tool in bio-medical research on small animals."