Noninvasive Estimation of FDG Input Function for Quantification of Cerebral Metabolic Rate of Glucose: Optimization and Multicenter Evaluation

The aims of this study were to determine whether body weight or body surface area (BSA) should be used for noninvasive measure-ment of the cerebral metabolic rate of glucose (CMRGlc) by FDG PET with a standardized input function (SIF) and an autoradio-graphic method and to validate the procedure in a large popula-tion from different PET centers. Methods: Plasma input functions measured by intermittent arterial blood sampling after intrave-nous injection of FDG, in 101 patients from 1 institution who were fasting for at least 4 h, were used to generate the SIF. The SIF was generated by averaging over 101 patients the input function normalized with the net injected dose and initial distribution volume (DV) of FDG estimated by the formula c 3 Ha 3 Wb, where H is body height and W is body weight. To evaluate the estimation of DV by BSA or body weight, the coefficient of variation (CV) of the ratio of Ha 3 Wb to the measured DV wa