Concepts and clinical utility of the measurement of cerebral blood flow.

Within the past several decades, techniques that accurately measure regional cerebral blood flow have been developed. At the present time, the inert gas washout technique using an intraarterial injection of 133Xe with the Anger scintillation camera or multiple probes as the external detector is the most established of these methods. While quantitative measures of cerebral blood flow have been important in elucidating the physiology of cerebral hemodynamics, the techniques are too invasive for routinely screening patients with cerebrovascular disease. As a result, less invasive methods have been sought for diagnostic screening. Because it requires only an intravenous injection of 99mTc-pertechnetate, the radionuclide cerebral angiogram has achieved some popularity as a semiquantitative measure of cerebral hemodynamics, particularly when coupled with static brain scintigraphy. This review examines our current understanding of cerebral hemodynamics and the advantages and limitations of techniques used to measure cerebral blood flow.