Measurement of Total Cerebral Blood Flow in the Monkey by External Monitoring of Cesium-131
A modification of the 42K fractionation technique has been developed which permits rapid, repeated measurement of cerebral blood flow by external isotope monitoring without jugular or carotid puncture. 131Cs, an isotope with distribution characteristics similar to those of 42K, has been used in this study. Cerebral blood flow measurement involves determination of the peak cephalic activity of an intravenously injected bolus of 131Cs by digital rate counting in a well-scintillation crystal that encloses the head. If the entire fraction of the isotopic bolus entering the head appears in the cerebral circulation before significant venous loss of 131Cs begins, the ratio of peak cephalic activity to total injected activity will represent the cephalic portion of the cardiac output. Since cerebral capillaries are not very permeable to 131Cs, activity remaining in the head after decay of peak cephalic activity will represent uptake by noncerebral cephalic tissue, and the peak activity can be corrected to yield only the cerebral cardiac output fraction. Total cerebral blood flow calculated from 131Cs injection was compared with measured bilateral internal jugular flow obtained by cannulation of the jugular veins. In anesthetized rhesus monkeys, the average ratio (calculated flow/measured flow) was 1.05±0.06.
- Accepted October 2, 1967.
- © 1967 American Heart Association, Inc.