 The overall objectives of this study are to establish the clinical feasibility and efficacy of using in vivo electron paramagnetic resonance EPR oximetrya technique related to magnetic resonance imaging MRIto obtain direct and repeated measurements of clinically useful information about tumor tissue oxygenation in specific groups of subjects with the same types of tumors, and to establish the clinical feasibility and efficacy of using inhalation of enriched oxygen to gain additional clinically useful information about responsiveness of tumors to hyper-oxygenation. Two devices are used: a paramagnetic charcoal suspension Carlo Erba India ink and in vivo EPR oximetry to assess oxygen levels. The ink is injected and becomes permanent in the tissue at the site of injection unless removed; thereafter, the in vivo oximetry measurements are noninvasive and can be repeated indefinitely. 