A Head-to-Head Comparison of 18 F-FP-CIT and 18 F-FDOPA PET/CT in Early Parkinson Disease

To compare the diagnostic performance between 18 F-N-3-fluoropropyl-2beta-carbon ethoxy-3beta-4-iodophenyl nortropane ( 18 F-FP-CIT) and 6- 18 F-fluoro-L-dopa ( 18 F-FDOPA) PET/CT in patients with early Parkinson disease (PD).

This study included 42 de novo PD patients who were clinically diagnosed at a university-affiliated tertiary hospital in South Korea and underwent 18 F-FP-CIT and 18 F-FDOPA PET imaging from November 2019 and March 2024. 18 F-FP-CIT and 18 F-FDOPA PET CT images were assessed at the initial diagnosis. The regional standardized uptake value ratios (SUVRs) for each side of the caudate, putamen, and ventral striatum/nucleus accumbens were calculated with the cerebellar cortex as a reference after CT-based or MR-based normalization. The agreement between the paired regional SUVRs of two PET radioligands was assessed by the Bland-Altman method, and the proportional bias between the differences and the average of the matched SUVRs was adjusted by a regression approach.

The median interval between 18 F-FP-CIT PET and 18 F-FDOPA PET was 7.5 months (IQR=8.1). The SUVRs of 18 F-FP-CIT were ∼2-3 times larger than those of 18 F-FDOPA in all the investigated subregions. The Bland-Altman plots revealed that nearly all the dissimilarities fell within the 95% limits of agreement. The performance between 18 F-FP-CIT and 18 F-FDOPA PET CT was comparable in detecting presynaptic dopaminergic deficits at the striatum, regardless of the normalization method. An inverse anteroposterior gradient of nigrostriatal dopaminergic deficit was also observed in both radiotracers.

18 F-FP-CIT and 18 F-FDOPA PET CT images revealed comparable performance in confirming presynaptic dopaminergic degeneration. They were equivalently valuable in discerning the anteroposterior grade of striatopathy in early PD.