Single-photon emission computed tomography in diagnosis and differential diagnosis of Parkinson's disease.

The diagnosis of Parkinson's disease is clinical and relies on the presence of characteristic motor symptoms such as bradykinesia, rigidity and resting tremor with non-motor features increasingly recognized among the very early manifestations of the disorder. Functional imaging with tracers targeting specifically the dopamine system and regional brain function may show discrete abnormalities helping the clinician shorten considerably the diagnostic process. In this review, we will discuss the contribution of single-photon emission computed tomography imaging in supporting the clinical diagnosis (motor and pre-motor) of Parkinson's disease and its differential diagnosis with essential tremor and other parkinsonian syndromes.