The overall goal of the proposed animal research is to provide new information relating in vivo 31P-Nuclear Magnetic Resonance (NMR) Spectroscopy to 11C or 18F-2-deoxyglucose (2DG) and 11C-Methionine Positron Emission Tomography (PET) Scanning in the evaluation of tumor metabolism during various stages of tumor growth in both untreated and treated (chemotherapy) animals. More specific aims include quantitating tumor high energy phosphate metabolites and pH using 31P-NMR Spectroscopy (both in vivo and in vitro), glucose uptake and amino acid uptake using PET Scanning, tumor protein synthesis and ATP levels using biochemical techniques and tumor morphology using computerized axial tomography (CT), NMR proton imaging and histology. The above parameters will be compared in two animal tumor models (Rabbit VX-2 hind limb muscle tumor and adult canine brain tumor) during various stages of tumor growth and following either intravenous or intraarterial chemotherapy. Results of the studies should provide important information relating to tumor biology and the potential clinical value of using in vivo imaging and spectroscopy techniques to monitor metabolic changes during the natural history of tumor growth and following therapy. The application of the results could provide a new approach to monitoring cancer therapy and determining prognosis.