Purpose: The aims of this study were to evaluate Tc-TRODAT-1 SPECT imaging patterns and to assess their correlation with disease severity in clinically diagnosed patients of Parkinson disease (PD).
Methods: The study included 241 patients with clinically diagnosed idiopathic Parkinson disease who underwent Tc-TRODAT-1 SPECT/CT scan. Binding ratios were calculated for each striatum, caudate, and putamen individually, by drawing region of interest. Occipital cortex region of interest was taken for background correction. Correlation of binding ratio with increasing clinical stage was derived, as described by modified Hoehn and Yahr scale.
Results: Median binding ratio was least in the contralateral putamen for all stages of modified Hoehn and Yahr. A statistically significant negative correlation was found between increasing disease severity and binding ratio in all subregions of striatum. Patients were clinically categorized into postural instability and gait disorder group and tremor-dominant PD group. No significant asymmetry was found between the left and right striatum in patients belonging to postural instability and gait disorder group and in those with bilateral tremors without lateralization.
Conclusions: Tc-TRODAT-1 SPECT is useful in early detection and in assessing disease severity of PD. A significant asymmetry with the contralateral side being affected more than the ipsilateral side can be attributed to tremor-dominant patients. The binding ratio of the ipsilateral striatum may serve useful as a marker of remaining functional dopaminergic neuronal reserve in the striatum.