Objective: This study aims to investigate whether early-phase ¹⁸F-N-(3-fluoropropyl)-2β-carboxymethoxy-3β-(4-iodophenyl) nortropane (¹⁸F-FP-CIT) positron emission tomography (PET) images (i.e., images acquired within the first 10 min after ¹⁸F-FP-CIT injection) can be a useful marker for predicting early dementia conversion in patients with newly diagnosed Parkinson’s disease (PD).

Background: Early-phase ¹⁸F-FP-CIT PET images, which are available in a single PET session when diagnosing PD, reflect cerebral perfusion and resemble ¹⁸F-fluorodeoxyglucose PET images.

Method: We retrospectively reviewed the medical records of 187 patients with PD who underwent dual-phase ¹⁸F-FP-CIT PET scans upon initial diagnosis. All patients underwent serial cognitive assessments annually during the follow-up period (>5 years). Patients were classified into either the PD with dementia (PDD) high-risk group (PDD-H, n = 47) or the PDD low-risk group (PDD-L, n = 140), depending on whether they progressed to dementia within 5 years of PD diagnosis. After quantifying the early-phase ¹⁸F-FP-CIT images, statistical parametric mapping analysis was performed to explore the differences in regional uptake between the PDD-H and PDD-L groups. Additionally, a linear discriminant analysis was performed to determine the prediction model for early PDD conversion based on the standard uptake value ratios (SUVRs) of each region of interest on the Desikan–Killiany atlas.

Results: Patients in the PDD-H group were older and had worse baseline cognitive performance than those in the PDD-L group. Compared to the PDD-L group, the PDD-H group exhibited decreased regional uptake mainly in the temporal and posterior cingulate cortices on early-phase ¹⁸F-FP-CIT PET images. The discriminant analysis demonstrated that the prediction model with SUVRs of the entorhinal cortex, amygdala, and isthmus cingulate cortex optimally distinguished the patients in the PDD-H group from those in the PDD-L group.

Conclusion: The present study demonstrated that decreased regional uptake in the medial temporal and posterior cingulate cortices (i.e., Alzheimer’s disease-prone regions) on early-phase ¹⁸F-FP-CIT PET scans was associated with a higher risk of dementia conversion in patients with PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/early-phase-18f-fp-cit-pet-images-a-promising-imaging-biomarker-for-predicting-early-dementia-conversion-in-parkinsons-disease/