Characterization of SUVmean curve
The SUVmean curves of descending aorta and occipital lobe in the HC and PD groups were depicted in Figure 2A andB , demonstrating negligible difference in curve pattern of both regions between the two groups. As the time went on, the ascending curves of the brain nuclei in the two groups started to separate: while the [11C]CFT uptake of HC group kept increasing, the uptake of PD group tended to reach the “plateau” in advance (Figure 2C , Table 2 ). In putamen, [11C]CFT uptake of the two groups first showed an early distinction (separation time = 2 min), and the statistical significance was found in the highest SUVmean between the two groups (P <0.05).
The SUVmean curve patterns of the pancreas and duodenum could be characterized as “fast-in and slow-out” in both groups, where the peak activities of the HC group in these two organs were higher than the PD group. In the stomach, a relatively faster rising uptake in PD patients was observed in the early stage, yet the final SUVmean of the HC group at 75 min appeared to be higher (Figure 2D and Table 2) .