A Method for Measuring Cerebral Hemispheric Blood Flow and Metabolism

A new method for measuring cerebral hemispheric blood flow together with metabolism using an injection of a 5 ml bolus of hydrogen-saturated saline into each internal carotid artery is described. This method was extensively evaluated in the monkey prior to being used in man. Under fluoroscopic control, a catheter was inserted into each cerebral transverse sinus via the basilic veins. Hemispheric blood flow was calculated from the clearance curves of hydrogen from the transverse sinus following injection using a formula based upon the Stewart-Hamilton principle. Hemispheric metabolic index for oxygen was estimated using a new formula by assuming that the distribution of hydrogen into each transverse sinus following injection of the bolus indicates the distribution of the blood from each hemisphere into each transverse sinus. This method has certain advantages over the conventional method for measuring cerebral blood flow, since the actual geometry of the brain in which the blood flow measured is known and simultaneous estimations of hemispheric metabolism are possible. Abnormalities of hemispheric blood flow and metabolism have been measured in 30 patients suffering from various neurological disorders including occlusion of one internal carotid artery. The new formula for estimating hemispheric metabolism is applicable to radioisotopic and other indicator injection methods in which blood is sampled from the cerebral transverse sinuses or internal jugular veins. It was also shown that the transverse sinus distribution of blood derived from each cerebral hemisphere varies from one individual to another.