Positron emission tomography and its application to the study of cerebrovascular disease in man.

Abstract

THE PATHOPHYSIOLOGY OF STROKE in man has been limited by the lack of accurate, non-invasive techniques for measuring regional cerebral blood flow and metabolism.The development of positron emission tomography (PET) has made it practical to study the local hemodynamic and metabolic changes that occur in human subjects with cerebrovascular disease.Although still in a state of rapid technological and methodological development, PET has already provided important new data about the pathophysiology of stroke and promises to be of even greater value in the future.This article will review the current status of PET for the study of cerebrovascular disease in man.A basic understanding of the advantages and limitations of this technique is necessary to properly interpret these studies.Therefore, we will first briefly discuss some technical and methodologic aspects of PET making specific comments about their importance in the study of cerebrovascular disease.Further details about these aspects of PET can be obtained from recently published reviews. 12 MethodologyIn order to apply PET to the study of cerebral physiology, three things are necessary: (1) a positron emission tomograph for accurate measurement of regional radioactivity in vivo, (2) a positron-emitting radiotracer suitable for human use and (3) a mathematical model of radiotracer kinetics that quantitatively relates regional radioactivity measured by PET to the physiologic variable under study. Positron Emission TomographyThe use of radioactive molecules as tracers to investigate biological function is well established.All quantitative radiotracer methods depend on accurate measurement of tracer radioactivity in tissue or in body fluids.Such measurements are easily accomplished in vitro by a variety of techniques including scintillation

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