Functional imaging is mainly used for clinical research. However, if available, this technique could help the clinical diagnosis. First, because it is possible to confirm the loss of nigrostriatal Dopaminergic neurons using [(18)F]-L-Dopa with PET or [(123)I]-FP-CIT with SPECT. Second, distinguishing idiopathic from atypical parkinsonism might be possible using the assessment of striatal Dopaminergic D2 receptors or the measurement of brain metabolism. However, there has been no prospective study to confirm this hypothesis and functional imaging is only performed to exclude patients with atypical parkinsonism from the waiting list for neurosurgical treatments.