New exogenous molecular probes have been used in the optical imaging field. We have already developed a multi-frequency & multispectral optical tomography animal imaging system. The system has been integrated to a magnetic resonance imaging (MRI) system. In this project, we will expand our hybrid system to measure dynamic information from exogenous probes. This system would measure the enhancement kinetics of the bi-functional optical/MR or mono-functional optical contrast agents and the endogenous contrast due to hemoglobin contents and scattering properties. There are two parts of the proposal. In the first part, we will development a novel multi-modality dynamic imaging system. Inthe second part, we will develop polymer based bi-functional and mono-functional optical agents. Such a hybrid system would facilitate the development of new contrast agents for biomedical imaging and that the development of polymer based molecular agents will provide a potential new molecular platform for these new contrast agents. At the end of this project, we will be able to test our hypothesis that “the parameters obtained bymacromolecular optical agent together with total hemoglobin, oxygen saturation and tissue scattering parameters can achieve a higher specificity in differentiating between ENU induced malignant and benign tumors compared to MRI parameters measured by low molecular weight extracellular MRI agents”.