Practical approaches for oxygen flow studies in PET

Two simple regional cerebral blood flow (rCBF) models have been proposed and investigated with the ramped infusion injection method: step and scaling. The step model is similar to the Alpert et al.´s (1984) model except that the authors used step-function weights with which they only need to acquire two time frames of images compared to the 18 time frames of images that the authors currently use in their dynamic fitting model. The scaling model is based on the fact that in most patient studies, the rCBF varies around the whole brain CBF. Hence, within a small range of the whole brain CBF, the rCBF can be obtained by linearly scaling the density image corresponding to the whole brain CBF. Both models were evaluated and compared to other conventional models with simulated and patient data. In this study, 10 patients were analyzed. The average percentage errors on rCBF over a large group of regions for the step and the scaling models with respect to the dynamic model are 4.0% and 4.8%, respectively