An investigation of multiple time/graphical analysis applied to projection data: theory and validation.

PURPOSE The determination of tissue time-activity course and pharmokinetics in PET is normally performed by region-of-interest analysis of reconstructed images. However, in some cases, the same analysis may equally well be performed on the data in projections before reconstruction, avoiding the reconstruction of large time sequence data sets. This is especially important in 3D mode. METHOD We present a theory that shows why multiple time/graphical analysis can be applied equally well to image or projection data. The method is validated using FDG uptake data from five healthy normal volunteers, by applying the technique to determine regional cerebral metabolic rate for glucose (rCMRglu) and the partition coefficient-related parameter P using various time ranges for the analysis. RESULTS The method is shown to be identical to analysis of image data. Variation with time range of the calculated values for regional cerebral glucose metabolism and the partition coefficient of tissue against plasma is shown to be due to the estimation methodology rather than the choice of analysis on projections or on images. CONCLUSION The theory presented is shown to be valid for FDG determination of regional cerebral glucose metabolism. The absolute values of the rCMRglu and P are similar to those shown previously.