Single photon emission computer tomography of dopamine transporters in monkeys and humans with 99mTc-TRODAT-1

Abstract

Background: The diagnosis of Parkinson's disease is presently based on non-specific symptoms. However, radionuclide dopamine transporters imaging can provide specific diagnostic tool for Parkinson's disease. This study was designed to investigate the effects of imaging of dopamine transporters with 99mTc-TRODAT-1 in early diagnosis or differential diagnosis of Parkinson's disease.

Methods: Nine normal monkeys were used to establish N-methyl-4-phenyl-1, 2, 3, 6-tetra-hydropyridine (MPTP) hemi-Parkinsonian animal models, and they were subjected to imaging. Twenty-nine patients with Parkinson's disease, 12 age-matched healthy volunteers, and 18 age-matched patients with Parkinson's syndrome were investigated. Single photon emission computer tomography (SPECT) was performed 3 hours after intravenous injection of 740 MBq 99mTc-TRODAT-1. Striatum specific uptake of 99mTc-TRODAT-1 was calculated according to the ratio of striatum (ST) to cerebellum (CB) in dopamine transporters uptake.

Results: In normal monkeys, bilateral ratio of ST/CB was 2.34 +/- 0.41. After the injection of MPTP, uptake rate of 99mTc-TRODAT-1 at damaged region was much lower than that at the contralateral region, resulting in a significant difference in the ratio of ST/CB (right: ST/CB = 1.73 +/- 0.35; left: ST/CB = 1.90 +/- 0.30), especially in hemi-Parkinsonian model monkeys (right: ST/CB = 1.29 +/- 0.17; left: ST/CB = 1.80 +/- 0.33). The ratios of ST/CB were 1.57 +/- 0.17 and 1.61 +/- 0.14 for the right and left respectively in the healthy volunteers, 1.04 +/- 0.29 and 1.06 +/- 0.30 in the age-matched patients with Parkinson's disease, and 1.56 +/- 0.17 and 1.59 +/- 0.18 in the age-matched patients with Parkinson's disease syndrome. A significant difference was noted between group of Parkinson's disease, normal controls and Parkinson's disease syndrome.

Conclusion: The results suggest that 99mTc-TRODAT-1 dopamine transporters SPECT has clinical application value in early diagnosis or differential diagnosis of Parkinson's disease.