Measurement of Cerebral Blood Flow by Stable Xenon Contrast Computerized Tomography

Computerized reconstruction techniques have made remarkable progress, providing anatomic resolution in three dimensions by X-ray transmission and positron emission tomography [1–3]. If advantage is taken of these technical advances, localized measurements of cerebral blood flow (LCBF), local tissue: blood partition coefficients (Lλ), and local metabolism are possible with excellent resolution [4–7]. The present communication describes improved methods for measuring LCBF and Lλ, utilizing the CT scanner during 35% stable xenon (Xes) inhalation [6, 7], and their application in normal aged volunteers. Computerized emission tomography has also been used for measuring LCBF during 77Kr or 133Xe inhalation [4, 5]. The latter emission methods have poorer resolution [3] than Xes methods because of technical problems with absorption of isotope emissions, partial volume effects, and Compton scatter.