Evaluation of patients with Clinically Unclear Parkinsonian Syndromes submitted to brain SPECT imaging using the technetium-99m labeled tracer TRODAT-1

Despite its relatively high prevalence Parkinson's Disease (PD) is still misdiagnosed in approximately 25% of cases. In this study our aim was to evaluate patients with Clinically Unclear Parkinsonian Syndromes (CUPS) submitted to brain SPECT imaging using the technetium-99m labeled Dopamine Transporter (DAT) tracer TRODAT-1. We recruited 15 subjects with CUPS and matched them with 13 patients with probable PD and 13 healthy control subjects (HCS). A SPECT with TRODAT-1 was performed at the baseline evaluation and patients from the CUPS were followed-up for 2-years to ensure or not PD diagnosis (“gold-standard”). The mean ± SD results from Right and Left striatum Binding Potential (BP) were, respectively, 1.08 ± 0.20 and 1.04 ± 0.16 in the HCS group, 0.47 ± 0.16 and 0.53 ± 0.17 in the PD group, and 0.68 ± 0.11 and 0.84 ± 0.17 in the CUPS group. The rate of disagreement between baseline SPECT in the CUPS group as compared to the “gold standard” diagnosis (clinical diagnosis of PD on follow-up) was of 20%. The sensitivity of the SPECT with TRODAT-1 was 100%, while specificity was 70%. In conclusion, our data provided further information about the role of the technetium-99m labeled tracer TRODAT-1 as a biomarker of DAT reduction that can also be used in the diagnosis of patients with CUPS.