A Method for the Continuous Measurement of Cerebral Blood Flow in Man by Means of Radioactive Krypton

The measurement of cerebral blood flow by means of the nitrous oxide method of Kety and Schmidt (1) or the krypton-85 (Kr85) technique of Lassen and Munck (2) requires a steady state of at least ten minutes, for it is not until the end of such a period that the uptake of the gas by the brain can be estimated indirectly from its concentration in cerebral venous blood. These methods are, therefore, not applicable to the study of rapid or transient changes in cerebral blood flow. If, however, a Remitting inert gas such as krypton-79 (Kr79) is employed, its uptake by the brain can be followed by direct measurement of the y-radiation through the intact skull, thus permitting the continuous measurement of cerebral blood flow during transient or rapid changes before equilibration between brain tissue and cerebral venous blood is achieved. The description of the development, evaluation and application of such a method is the subject of this report.