Evaluation of 99mTc-TRODAT-1 SPECT in the diagnosis of Parkinson’s disease versus other progressive movement disorders

Objective Parkinson disease (PD), parkinsonian syndromes (PS) and essential tremor (ET) are different types of movement disorders which share some symptoms resulting in a difficulty of certain diagnosis. This study was conducted to determine the value of 99m Tc-TRODAT-1 scan to differentiate PD from ET and other PS cases. Methods Totally, 75 patients were studied including 29 PD, 6 possible PD, 22 ET and 18 PS cases. A dual-head SPECT-CT was used to perform basal ganglia (BG) imaging following administration of 99m Tc-TRODAT-1. The BG uptake values were normalized to whole brain and occipital activity. All patients were followed for 2–22 months to reach a certain diagnosis. Results Patients with ET and drug-induced parkinsonism show significantly higher normalized BG uptake as compared to the other subgroups; however, no significant difference was noted between PD and PS patients. The sensitivity and specificity of the findings for the differentiation between patients with the disease associated versus not associated with BG dysfunction were 80 and 83.3 %, respectively. A predictive positive value of 82.6 % was obtained using an additive scaling index defined as asymmetry and unevenness of uptake in putamen and/or caudate contralateral to the dominant side of current symptoms. Conclusions 99m Tc-TRODAT-1 scan is an appropriate method to differentiate PD or PS versus ET. A combination of scan pattern including asymmetry of BG uptake and unevenness of activity in caudate and putamen along with the side of dominant symptoms may be valuable for the differentiation of Parkinson’s disease from the other parkinsonian syndromes.