At the present time several techniques are available for studying quantitatively global and regional blood flow and metabolism of the human brain. How ever, many scientists working in the clinical and research field who would like to use these tools for their investigations may be less familiar with the indi cations and limitations of the individual methods. The rapid development of both modern imaging techniques and new tracers may have led to some con fusion in answering the question as to which method is appropriate to solve the diagnostic problem of an individuum with brain disease. Scepticism and ignorance as to the methods to be used as tools in differential diagnosis of brain disorders may have prevented their widespread introduction into clinical practice. Thus, the significance of circulatory and metabolic parameters involved in the majority of diseases of the central nervous system may have been overlooked. The contributions compiled in this book describe in detail the individual techniques, outline their indications and limitations and deal in particular with newer methods such as the atraumatic 133Xe technique, stable xenon tomogra phy, three-dimensional techniques such as 133Xe single photon emission tomog raphy and N-isopropyl-P23-iodoamphetamine. Positron emission tomography studies provide information on function and metabolism, particularly that of oxygen and glucose, in regional brain areas of interest. Nuclear magnetic reso nance may be a promising method for studying metabolic parameters; however, accurate circulation measurements can not be performed at present.