A LTHOUGH the status of regional vascular tone and total cardiac output have been established as important determinants of regional blood flow, the precise role of the physical state of circulating blood has not been extensively explored. A study by Kety' in man has indicated that the increased corpuscular mass of polyeythemia vera can be associated with a reduced cerebral blood flow. The induc...

The nitrous oxide method for regional blood flow determination is based on the assumption that concentration equilibrium for nitrous oxide between the organ and its venous blood is reached. This assumption is examined, and it is shown mathematically that faulty equilibrium is not revealed by presently available criteria. It is shown that quantitatively and qualitatively erroneous results may li...

A tomographic technique has been used recently for cerebral blood flow measurements with inhaled radioxenon. Based on experiments in a specially developed dynamic phantom and on studies in primates in vivo, we have analyzed the validity of this method for measurements of both regional and total blood flow in the brain. We have also examined the errors introduced into flow computations as a func...