Differential diagnosis of Parkinson's disease and vascular parkinsonism by ^99mTc-TRODAT-1

The aim of this study was to use brain SPECT to differentiate vascular parkinsonism (VP) from Parkinson's disease. Methods: Fourteen VP patients (age range, 59-87 y; mean age, 70 ± 7.5 y), 30 Parkinson's disease patients (age range, 54-84 y; mean age, 65 ± 8.8 y), and 26 healthy (control) individuals (age range, 50-85 y; mean age, 60 ± 9 y) were examined. A 925-MBq (25 mCi) dose of ^99mTc-TRODAT-1 was injected intravenously, and brain SPECT images were acquired 4 h after injection. The ratio of specific to nonspecific striatal ^99mTc-TRODAT-1 binding was measured and compared, Results: After a region-of-interest analysis of the images from VP patients, Parkinson's disease patients, and healthy volunteers was performed to obtain ratios of putamen to occipital and striatal to occipital binding as a measurement of specific binding to the dopamine transporters in these regions of the brain, where dopamine neurons are concentrated, the specific binding in the 14 VP patients was slightly lower than but not statistically different from that of the healthy individuals in both putamen and caudate areas. A significant decrease in uptake of ^99mTc-TRO-DAT-1 in the striatum (P < 0.01) was found in Parkinson's disease patients, Reduction of the uptake was more pronounced in the contralateral putamen of Parkinson's disease patients than that of VP patients (P < 0.001). A significant bilateral striatal asymmetry was also observed in Parkinson's disease patients but not in VP patients (P < 0.01). Conclusion: Our findings clearly show that, for VP patients, ^99mTc-TRODAT-1 SPECT is a reliable method to differentiate VP from Parkinson's disease. Further studies, including those to differentiate Parkinson's disease from arteriosclerotic parkinsonism and patients with both VP and Parkinson's disease, are needed to help rule out the possibility of Parkinson's disease as early as possible.