Iam using MR Spectroscopy (1H, 19F, 13C, 31P) for various in vivo animal applications, such as pH and temperature mapping or measurement of brain metabolic rates. Recently I developed a non-invasive method, BIRDS, for in vivo temperature and pH mapping. The method was successfully applied to show that extensive acidic extracellular pH beyond the tumor boundary correlates with tumor cell invasion. BIRDS was also used to measure the effect of the drug MDMA (ecstasy) on the brain temperature. Other recent projects involve the measurement of total brain metabolism by 19F spectroscopy using 2-fluoro-2deoxy-D-glucose (FDG) and measurement of metabolic rates of glucose consumption in brain tumors.