Measurement of Cerebral Blood Flow by External Collimation Following Intravenous Injection of Radioisotope

A technique is described which studies cerebral circulation by monitoring with external collimated scintillation detectors the passage through each cerebral hemisphere of a bolus of radioisotope injected intravenously. The test is simple, harmless, almost painless, and repeatable at frequent intervals. Radiation of the patient is minimized by use of a rapidly excreted isotope. Theoretical considerations of the test are presented. The clinical applications carried out to date are described. The test appears to give a quick relative determination of the total blood flow to each cerebral hemisphere. The possibilities of obtaining an absolute determination are considered.