Most of the clinically important cerebral diseases are regional in character. Cerebral vascular disorders and malformations, tumors, and a great many epileptogenic lesions are all of this type. Such cerebral diseases may give rise to an alteration of blood flow in the involved region either directly or via their influence on regional metabolism. Thus it is reasonable to assume that a method measuring the blood flow within circumscribed regions of the human brain should be of considerable clinical value.
The classical techniques for measuring cerebral blood flow in man comprise observations directly involving the extracranial portions of the cerebral arteries and veins in the neck. This is true for the inert gas method of Kety and Schmidt,1 the indicator injection method of Gibbs, Maxwell, and Gibbs,2 and the various electrical flowmeter instruments as applied to the carotid arteries or the internal jugular veins. Owing to the richness