99mTc-TRODAT-1 SPECT Revealed That Striatal Dopamine Transport Availability Significantly Decreases in Late Mid-Aged Healthy Taiwanese and Then Remains Stable

Objectives: Neuroimaging studies in the past 20 years have documented an age-related decline in striatal dopamine transporters (DATs), which is a marker of dopaminergic neurodegeneration; however, concerns about ethnic variations in the decline in DAT with age have not been addressed. The purpose of this study was to assess the rate of striatal DAT loss in healthy Taiwanese adults using kit-based Tc-99m-TRODAT-1, a radioligand for DAT SPECT. Patients and Methods: Fifty healthy subjects (mean age SD, 63 12 years; range, 30-80 years) were studied. Tc-99m-TRODAT-1 was prepared from a lyophilized kit. Brain DAT SPECT imaging was acquired between 165 and 195 minutes postinjection (similar to 740 MBq or 20 mCi) using a dual-head camera equipped with fan-beam collimators (Helix SPX; GE). Specific uptake in the striatum (ST), caudate nucleus (CA), and putamen (PU) were calculated from reconstructed transaxial slices at the level of maximal striatal activity. Occipital cortices were used as reference areas. Data were presented as specific binding ratios. Results: Age had a significant moderate to large negative effect on striatal DAT, which declined by -25.7% +/- 6.10% between the ages of 30 and 80 years, equivalent to 6.4% loss per decade. The rates of decline in the CA and PU were 6.9% and 7.3% per decade, respectively. Conclusions: This study suggests ethnic variations may not significantly affect the age-related decline in DAT. The data generated in this study could also be used as a reference to estimate DAT loss/occupancy in patients with DAT-related diseases.

Automated summary

This study assessed the rate of striatal dopamine transporter (DAT) loss in healthy Taiwanese adults using Tc-99m-TRODAT-1, and found that age had a significant negative effect on striatal DAT. Ethnic variations may not greatly affect the age-related decline in DAT. These findings are important for estimating DAT loss/occupancy in patients with DAT-related diseases.