Background: The group of diseases including dementia with Lewy bodies (DLB), Parkinson’s disease (PD), and Parkinson’s disease dementia (PDD) are related to synucleinopathies. In addition to Alzheimer’s disease (AD), these are common neurodegenerative diseases that share clinical features leading to difficulties in diagnosis. Hence, molecular imaging showing correlation with pathogenesis is recognized as a critical tool for improving the efficiency of differential diagnosis.

Objective: To determine characteristic patterns of dopamine transporter (DAT) density using ⁹⁹ᵐTc-TRODAT-1 (TRODAT-1), glucose metabolism using ¹⁸F-fludeoxyglucose (FDG) and amyloid deposition using ¹¹C-Pittsburgh compound B (PiB) among these diseases.

Materials and Methods: Twenty-five individuals participated in the present study and included four healthy controls (HC), eight DLB, two PD, six PDD, and five AD. All subjects underwent FDG and PiB positron emission tomography (PET) and TRODAT-1 single-photon emission computed tomography (SPECT), with visual and semi-quantitative analysis of imaging.

Results: All subjects for synucleinopathy groups (DLB, PD, and PDD) had positive TRODAT-1 SPECT scintigraphy, while the AD and HC groups showed negative results. The positive PiB PET results were 100% in the AD, 33.33% with two of six cases in the PDD group, 37.5% with three of eight cases in the DLB group, and 0% in both the HC and PD groups. The hypometabolism patterns in PDD and AD groups were noted at parietotemporal region and parietotemporal, posterior cingulate, and precuneus regions, respectively. Meanwhile, the DLB hypometabolism pattern was found at parietotemporal, posterior cingulate, precuneus regions, and occipital lobe regions. None of the subjects in the HC or PD groups showed hypometabolism.

Conclusion: Positive TRODAT-1 SPECT provided an informative pattern for differential diagnosis among alpha-synuclein-related diseases, AD, and HC. Remarkably, hypometabolism in the occipital region can be used to differentiate DLB from AD, PDD, and PD. The amyloid deposition pattern in DLB and PDD groups was not significantly different.

Keywords: alpha-synucleinopathies; PET; SPECT; ⁹⁹ᵐTc-TRODAT-1; Alzheimer’s disease

DOI: doi.org/10.35755/jmedassocthai.2021.11.12949

Received 24 May 2021 | Revised 30 July 2021 | Accepted 30 July 2021