Positron Emission Tomography (PET) has been used for a decade in psychiatric research to study regional brain glucose metabolism, and the results seem to be inconsistent. However, the inconsistency may be explained by differences in methods and clinical protocols. This problem has been recognized by the EEC Concerted Action on PET, which is why a special psychiatric group was convened. Researchers with knowledge in different aspects of PET methodology like mathematical models, cameras, brain atlas, stimulaton studies and psychiatric research organized a meeting to discuss standardization problems and how to minimize errors in PET investigations. This volume will give the reader knowledge about the state of the art, define problems and discuss possible solutions. It gives suggestions for good cinical PET practice. Such a theme has not been published before.