Nuclear Magnetic Resonance (NMR) comes close to being an ideal non-invasive imaging method and an invaluable tool inbiomedical research. The use of non-toxic contrast agents could improve anatomical image detail and in addition provide physiological information. Oxygen-17, a naturally occurring stable isotope with a quadripolar nucleus, has recently been shown to be suitable as an NMR contrast agent by use of the increased T2 relaxation of water protons in exchange with it. This is a new area of NMR contrast agents, which can be used for imaging and biochemical uses. Preliminary work has been done with oxygen-17 water. These studies suggest this technique is feasible. It is unknown if other oxygen-17 compounds would be improved or better specific contrast agents. This proposal is to investigate the use of oxygen- 17 phosphorous containing compounds as a model for oxygen-17 labelled contrast agents in NMR imaging and use in biomedical applications. The possibility of labelling specific compounds with oxygen-17 which can be directed to a specific organ, or disease state will also be investigated. This is the initial effort to use oxygen-17 labelled compounds as MR contrast agents. This work is to determine if this technique can provide improved anatomical detail or information not presently available in the clinical setting. The use of this technique in biochemical applications will also be studied.