Methods for measurement of blood flow. A current appraisal

Noninvasive measurement of regional blood flow in man

Regional blood flow in man is ideally measured by techniques that are noninvasive, accurate, and can measure flow repetitively with comparative ease. Although numerous noninvasive techniques are available, no single method records blood flow accurately in every location. The neophyte investigator is often faced with a confusing array of methods and can spend considerable time searching for the ideal one. This paper presents current methods available to the clinical or metabolic researcher and comments on the strengths and limitations of each method. It is hoped that this will allow more rapid selection of a flow measurement method that is tailored to each individual's need.

Measurement of total cerebral blood flow in the monkey by external monitoring of cesium-131

A modification of the 42 K fractionation technique has been developed which permits rapid, repeated measurement of cerebral blood flow by external isotope monitoring without jugular or carotid puncture. 131 Cs, an isotope with distribution characteristics similar to those of 42 K, has been used in this study. Cerebral blood flow measurement involves determination of the peak cephalic activity of an intravenously injected bolus of 131 Cs 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 131 Cs 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 131 Cs, 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 131 Cs 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.