Positron emission tomography, a new clinical research tool: the example ofneuronal grafts in Parkinson's disease

Functional neuroimagery and more particularly positron emission tomography (PET) has long been restricted to fundamental neuroscientific research, wit h little applications in clinical research mainly because of its high cost. However, in parkinsonian patients treated using fetal neuronal grafts, PET has demonstrated the survival and function of dopaminergic cells implanted into the striatum. By measuring the dopaminergic function using L Dopa lab eled with radioactive fluorine 18, PET has shown an increased uptake of the tracer after transplantation, which parallels the clinical improvement of patients. Since only PET is able to monitor in vivo the degeneration of dop aminergic cells of parkinsonian patients, it a has become a tool in evaluat ing neuroprotective agents. PET is also used for the evaluation of new trea tments in other neurodegenerative diseases such as, for example, Huntington 's disease.