SPECT and PET in Atypical Parkinsonism

Parkinson disease (PD) is the prototypic movement disorder originally described by James Parkinson, and it accounts for about 80% of a group of related degenerative motor disorders collectively referred to as the parkinsonisms, Parkinson spectrum disorders, or Parkinson plus disorders, terms which are used interchangeably throughout this article. Much work with positron emission tomography (PET) and single-photon emission computed tomography (SPECT) in the movement disorders has focused on the dopamine system. There have been at least 3 different presynaptic dopaminergic targets that are used successfully to interrogate this system. Another approach may be is to assess the dynamics of dopamine release into the synapse by the use of reversible-bound PET tracers or SPECT tracers. Both dopaminergic and nondopaminergic imaging in the diagnosis of movement disorders are discussed in this article.