Usefulness of brain 99mTc-TRODAT-1 SPET for the evaluation of Parkinson's disease

Nigral dopaminergic projections to the striatum are targeted in Parkinson's disease (PD). The extent of the degeneration of the dopaminergic system in PD can be visualised by dopamine transporter imaging using single-photon emission tomography (SPET). In this study in 188 patients with PD, we analysed the image patterns and compared them with the clinical features in order to verify the usefulness of technetium-99m TRODAT-1 brain SPET in the evaluation of patients with PD. Two independent readers visually assessed SPET slices from three brain axes according to a "fine" visual scale; results were also grouped according to a "rough" visual scale. Results of both visual and semi-quantitative analyses were compared among patients with different stages of PD and healthy controls. There was good agreement between the readers in the interpretation of the image patterns [kappa statistic (kappa)=0.85 for the presence of PD; kappa=0.88 for the rough scale and 0.81 for the fine scale]. Good concordance was obtained when visual interpretation was used to evaluate the presence of PD (sensitivity =98%, specificity =86%, kappa=0.85). Semi-quantitative analyses revealed significant negative correlations between both striatal and putaminal uptake and disease severity as assessed using the Hoehn and Yahr scale (rho=-0.89 and -0.93 respectively). An apparent decrease in striatal uptake in early PD, hardly discernible from the uptake level in advanced PD, was commonly found in visual analyses. The results suggest that both visual and semi-quantitative analyses of Tc-99m-TRODAT-1 SPET images reflect neurodegeneration in PD, and that Tc-99m-TRODAT-1 SPET represents an adequate means for evaluation of the status of patients with PD.