Dopamine transporter imaging in autopsy‐confirmed Parkinson's disease and multiple system atrophy

Abstract

Dopamine transporter single-photon emission computerized tomography can visualize dopaminergic degeneration in Parkinson's disease and multiple system atrophy. Some studies have suggested that dopamine transporter imaging can distinguish these disorders based on a more diffuse and symmetric striatal dopamine transporter binding loss in multiple system atrophy. The present study compared patterns of striatal dopamine transporter distribution in postmortem-confirmed Parkinson's disease and multiple system atrophy. Patients with a postmortem diagnosis of multiple system atrophy (n = 6) or Parkinson's disease (n = 8) who had undergone dopamine transporter imaging were included. Imaging had been performed after a mean disease duration of 3.6 and 4.1 years in multiple system atrophy and Parkinson's disease, respectively. Visual analysis showed bilaterally reduced binding in all patients. Mean overall striatal binding was reduced by 53% in multiple system atrophy and 52% in Parkinson's disease. There was a trend for greater asymmetry of striatal binding in multiple system atrophy compared with Parkinson's disease (23% ± 15% vs 10.5% ± 7%, respectively; P = .071), with 3 multiple system atrophy patients showing more asymmetry of striatal binding than any Parkinson's disease patient. Putamen/caudate binding ratios did not differ between the groups. This is the first study comparing dopamine transporter imaging in autopsy-confirmed multiple system atrophy and Parkinson's disease. Unexpectedly, we found a tendency for greater asymmetry of striatal binding in multiple system atrophy than in Parkinson's disease. Our findings demonstrate that these conditions cannot be differentiated by subregional analysis of striatal dopamine transporter binding.