Binding of [Tc-99m]TRODAT-1 to dopamine transporters in patients with Parkinson's disease and in healthy volunteers

[Tc-99m]TRODAT-1 is a radiolabeled tropane that binds dopamine transporters . The primary goal of this study was to determine whether its regional cere bral distribution could differentiate between patients with Parkinson's dis ease and healthy human volunteers. Methods: The sample consisted of 42 pati ents with Parkinson's disease, 23 age-matched controls, and 38 healthy adul ts younger than 40 y old. SPECT scans of the brain were acquired on a tripl e-head gamma camera 3-4 h after the intravenous injection of 740 MBq (20 mC i) [99mTc]TRODAT-1, Mean counts per pixel were measured manually in subregi ons of the basal ganglia and normalized to the mean background counts to gi ve specific uptake values ([SUVs] approximate to k3/k4). Patient and contro l groups were also compared with automated statistical parametric mapping t echniques. Logistic discriminant analyses were performed to determine the o ptimum uptake values for differentiating patients from age-matched controls . Results: Quantitative image analysis showed that the group mean SUVs in p atients were less than the mean values in controls for all regions (all Ps < 0.000001). There was overlap in the caudate as well as in the anterior-mo st portion of the putamen, but not in the posterior putamen, even when the asymptomatic sides of 5 patients with clinically defined hemi-Parkinson's d isease were factored in. Conclusion: The findings indicate that Parkinson's disease can be detected with [Tc-99m]TRODAT by simply inspecting the image s for uptake in the posterior putamen, Appropriate asymmetries seem to be v isible with quantification in patients with clinically defined hemi-Parkins on's disease, even though changes in the putamen contralateral to the clini cally unaffected side in these patients appear to precede the development o f symptoms,