Objective: To compare single-photon emission computed tomography (SPECT) with [123I]FP-CIT and positron emission tomography (PET) with [11C]PE2I as markers of dopamine transporter (DAT) loss in patients early Parkinson’s disease including those who have never been treated.

Background: Although [123I]FP-CIT-SPECT uptake aids the differentiation of non-neurodegenerative parkinsonism from degenerative forms, it has been attached to several limitations, including mild to moderate affinity for serotonin transporter and lack of specificity and sensitivity in differential diagnosis of neurodegenerative parkinsonisms. [11C]PE2I has been shown to have a 30-fold higher affinity and selectivity for DAT over the norepinephrine and serotonin transporter, with a higher specificity for Parkinson’s disease compared to other neurodegenerative parkinsonisms.

Method: We enrolled 48 subjects, of which 16 early de novo, 16 early levodopa-treated patients with Parkinson’s disease, and 16 age- and gender-matched healthy controls. All participants underwent [123I]FP-CIT-SPECT and [11C]PE2I-PET imaging to assess DAT expression.

Results: [123I]FP-CIT-SPECT SBR and [11C]PE2I-PET BPND showed profound loss in caudate and putamen in Parkinson’s disease patients (P<0.001). [123I]FP-CIT-SPECT SBR and [11C]PE2I-PET BPND in the putamen were correlated with disease duration and motor symptoms burden. The loss of [11C]PE2I-PET BPND was greater than the loss of [123I]FP-CIT-SPECT SBR in the putamen (–11%, P<0.01), globus pallidus external (–14%,P<0.01) and internal (–16%, P<0.001), and substantia nigra (–21%, P<0.01) in Parkinson’s disease patients. We then compared early levodopa-treated Parkinson’s disease patients, (who had a longer disease duration of 36 months), with de novo Parkinson’s patients. Early levodopa-treated Parkinson’s disease patients exhibited an additional 30% loss of [11C]PE2I-PET BPND in the putamen (P<0.001; reflecting a 10% mean annual decline), whereas [123I]FP-CIT-SPECT SBR revealed a loss of only 17% in the putamen (P<0.001; reflecting a 5.6% mean annual decline).

Conclusion: Our findings demonstrate that [123I]FP-CIT-SPECT and [11C]PE2I-PET are both robust markers to measure loss of DAT expression in patients with early Parkinson’s disease; however [11C]PE2I-PET shows a superior ability to detect a higher magnitude of DAT expression change.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparison-between-11cpe2i-pet-and-123ifp-cit-spect-as-markers-of-dat-expression-in-early-parkinsons-disease/