[Imaging of dopamine transporter with Tc99m-Trodat-SPECT in movement disorders]

Abstract

99mTc-TRODAT-1 is a new, technetium based radiopharmaceutical that selectively binds to the dopamine transporters. The aim of the study was to evaluate the dopamine transporter status in movement disorders.

Methods: In eight healthy volunteers (age range 22-58 years), 28 patients with Parkinson's disease (age range 42-80 years), 10 patients with Parkinsonian syndrome (age range 51-79 years) and 13 patients with essential tremor (age range 43-71 years) were 99mTc-TRODAT-SPECT tests performed. The results were evaluated visually and semiquantitatively.

Results: The visual assessments were concordant with those of the semiquantitative in each case. The 99mTc-TRODAT uptake of the striatum was referenced to the cerebellum, the frontal and occipital cortex. The best deviation was found in aspect of the occipital cortex. The striatum/occipital ratio was the following: healthy volunteers: 2.12 +/- 0.27; Parkinson's disease: 1.52 +/- 0.27; Parkinsonian syndrome: 1.57 +/- 0.26; essential tremor: 2.06 +/- 0.69. The striatal dopamine transporter availability was significantly lower in subjects with Parkinson's disease or Parkinsonian syndrome compared to the control subjects. There was no difference between healthy volunteers and patients with essential tremor. Using discriminant analysis, the discriminant function had significantly different values in the group of Parkinson's disease than in Parkinsonian syndrome: f = -3.675 x caud/occipit + 6.293 x put/occipit -2.548.

Conclusion: 99mTc-TRODAT-SPECT is able to visualise the presynaptic dopaminergic degeneration. This method itself can be useful in differential diagnosis in some type of movement disorders.