Objective: To investigate the utility of 11C-β-CIT PET scan on Parkinson’s disease diagnosis.

Background: The monoamine reuptake sites transport dopamine, noradrenaline and serotonin from the synaptic cleft into the presynaptic nerve terminals. Several ligands were created to study these reuptake sites, as they reflect the integrity of monoaminergic innervation. β-CIT has high affinity for the dopamine transporter and accumulates in the striatum and, in a lesser extent, in the thalamus and midbrain, indicating that there is also affinity for other neurotransmiter systems.

Methods: We used positron emission tomography-computed tomography (PET-CT) and the tracer 11C-β-CIT to measure DAT binding in the caudate nucleus and putamen of 2 patients with inconclusive Parkinsonian features. PET scan was acquired after intravenous administration of 333-370MBq of 11C-β-CIT. Semiquantitative analysis was performed calculating an uptake ratio by dividing putamen and caudate activities by that of the cerebellum (reference region).

Results: Patient 1 is 15 year old adolescent with assimetric parkinsonism since the age of 12, with good response to levodopa. Examination with DATScan showed almost complete deplection of dopamine transporters in the basal ganglia. The PET/CT study showed some DAT activity, more pronounced on the left putamen.. Patient 2 is a 57 years old woman with a psychotic depression following the diagnosis of breast cancer. She developed an akinetic rigid syndrome. The diagnosis of iatrogenic parkinsonism was confirmed on the follow-up. PET examination showed normal bilateral DAT binding.

Conclusions: PET study on patient 1 confirmed the clinical suspicion of dopaminergic degeneration, but with some activity preservation, compared to the DATScan, which is consistent with the patient’s preserved response to levodopa. On patient 2, it predicted a normal activity that proved to be right on follow-up. Our results imply that 11β-CIT is an useful compound for PET examination of the function of the presynaptic monoaminergic neurons. Comparing to the SPECT exams, it has better contrast and higher spatial resolution. Lower half-life has advantages namely shorter scan times, less radiation exposure and the possibility of performing another PET study on the same day, making it a great investigational and diagnostic tool in specialized centers.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/pet-examination-of-the-monoamine-transporter-with-11c-beta-cit/