Objective: To compare the performance of [¹⁸F]fluorodeoxyglucose (FDG) PET and [¹²³I]metaiodobenzylguanidine (MIBG) scintigraphy in the differential diagnosis of parkinsonism in the same patient sample.

Background: [¹⁸F]fluorodeoxyglucose (FDG) PET and [¹²³I]metaiodobenzylguanidine (MIBG) scintigraphy are recommended in the current consensus criteria for the differential diagnosis of neurodegenerative parkinsonism. A direct comparison of both methods is lacking.

Method: 54 patients of three tertiary referral centers who underwent [¹⁸F]FDG PET and [¹²³I]MIBG scintigraphy in the differential diagnosis of suspected atypical parkinsonian syndrome (APS)  were included in this study. Clinical follow-up diagnoses were made based on case-vignettes by two movement disorder specialists, blinded to imaging results. [¹⁸F]FDG PET scans were evaluated by two raters for disease-specific patterns of Lewy body disease (LBD) or APS. The latter were also assigned to the subgroups of APS. Regions-of-interest analysis on late anterior planar [¹²³I]MIBG images was used to calculate heart-to-mediastinum ratio.

Results: Clinical follow-up diagnoses were n=19 LBD (n = 17 Parkinson’s disease (PD); n=1 PD dementia, N=1 dementia with Lewy bodies), n = 31 APS (n = 28 MSA, n = 3 PSP), n = 3 non-neurodegenerative parkinsonism; n = 1 patient could not be diagnosed and was excluded. For the differentiation of LBD vs. non-LBD the area under the receiver operating characteristic curve (ROC-AUC) was larger for [¹⁸F]FDG PET than for [¹²³I]MIBG scintigraphy at trend level (0.82 vs. 0.69, p = 0.06) (see fig 1a) and reached significance for the more experienced rater (0.83 vs. 0.69, p = 0.04). ROC-AUC for the differentiation of PD vs MSA was greater for [¹⁸F]FDG PET than for [¹²³I]MIBG scintigraphy (0.82 vs. 0.69, p = 0.11) (fig 1b), but failed to reach statistical significance. [¹⁸F]FDG PET and clinical diagnoses matched in 87.1% of APS cases.

Conclusion: The present study suggests that [¹⁸F]FDG PET is superior to [¹²³I]MIBG scintigraphy in the differential diagnosis of neurodegenerative parkinsonism and provides additional information in the delineation of APS subgroups. Therefore, [¹⁸F]FDG PET should be preferred for this purpose.

[figure1]
Figure 1 Receiver operating characteristic (ROC) curves for the A) differentiation of Lewy body diseases from non-Lewy body diseases and B) differentiation of Parkinson’s disease from multiple system atrophy.

References: This abstract has been submitted for presentation at: 58. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, Leipzig, Germany, April 22nd-25th 2020; 64. Jahrestagung der Deutschen Gesellschaft für Klinische Neurophysiologie und Funktionelle Bildgebung, Baden Baden, Germany, March 26th-28th 2020

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MDS Abstracts - https://www.mdsabstracts.org/abstract/fdg-pet-and-mibg-scintigraphy-in-the-differential-diagnosis-of-parkinsonism-a-head-to-head-comparison/