[Positron-emission tomography in akinetic rigidity syndrome]. 
Positron emission tomography (PET) is applied to the metabolic evaluation of hypokinetic disorders and particularly to the study of Parkinson's disease.  PET has proved useful for a better understanding of the pathophysiology of these disorders.  Several types of tracers are used for these studies: pre- and post-synaptic markers of the dopaminergic synapse and markers of the global metabolism of brain structures involved in the control of movement.  The latter can be used at rest or in states of motor activation.  These PET tracers have been used to test hypotheses on the aetiology and evolution of Parkinson's disease and on the pathophysiology of drug-induced side effects.  PET also allows quantitative evaluation of new treatment strategies including experimental approaches such as intra-cerebral transplantation.