Chapter 42 - A Kinetic Model for Double Injection 18FDG Studies

Abstract

The use of two injections of [18F]fluorodeoxyglucose (18FDG) in a single positron emission tomography positron emission tomography (PET) scanning session allows the examination of relationships between cerebral glucose metabolism and physiological alterations such as functional activation or changes in plasma glucose concentration. This chapter presents a kinetic model for the double injection method in which transfer coefficients are estimated independently for the second injection, allowing the second injection to be administered at a time when the steady state for the second physiological condition has been established. The method is tested using simulated noisy data and is then applied to real PET data in which plasma glucose concentration is changed. The deoxyglucose model is employed with dephosphorylation of FDG-6-phosphate and incorporated biological constraints. PET studies were stimulated to assess the accuracy and precision of parameter estimates. Dynamic FDG PET studies are performed in three healthy volunteers with a Scanditronix PC-2048 15B scanner. Subjects fasted overnight prior to the scan. They were positioned in the scanner so that the uppermost slice was parallel to the orbitomeatal line and contained the high cerebral convexity. Two slow (1 min) injections of FDG were used, the first being 3 mCi at the start of the study and the second being 2 mCi at 70-minute. For the analysis of regional radioactivity, 202 MRI-based cortical regions of interest were drawn on a high-resolution MRI coregistered with the summed PET image.