Error analyses in CBF and V0 calculation

Error analyses were performed to investigate the biases of the CBF and V ₀ estimations with simulated delay time shifts. Several small ROIs 10-mm in diameter, including about 30 voxels, were drawn on the brain cortex of parametric images for various values of CBF (30–70 mL/min/100 g) and V ₀ (0.3–2.0 mL/100 g) to obtain tissue TACs from dynamic PET data. The arterial input function after the delay and dispersion correction for the brain tissue TAC (=C _a) was shifted from −3 to 3 s in steps of 0.5 s in the analyses. Using these two TACs of tissue activity and shifted C _a, CBF and V ₀ were recalculated based on a 1-TCM. Percent changes from the original CBF and V ₀ values were calculated and plotted to observe the effect of delay estimation errors on parametric values.