The in vivo Autoradiographic Measurement of Regional Cerebral Blood Flow Using Stable Xenon and Computerized Tomography: The Effect of Tissue Heterogeneity and Computerized Tomography Noise

Abstract

We have studied the effect of brain tissue (gray matter–white matter) heterogeneity and computerized tomography (CT) noise on the accuracy of xenon CT measurements of regional cerebral blood flow (rCBF) based upon “autoradiographic” and multiple-scan washin protocols, The results of our mathematical analysis indicate that both protocols are associated with a variety of measurement errors that lead to unacceptable and, to a large extent, unpredictable uncertainties in calculated values of rCBF. Brain tissue heterogeneity and high volumetric flow rates may—even in the absence of movement artifact and CT noise—lead to measurement errors in excess of 20%. Moreover, CT noise is additive in regard to these errors, and constitutes the most confounding variable of all.