The Value of the Dopamine D_2/3 Receptor Ligand ¹⁸F-Desmethoxyfallypride for the Differentiation of Idiopathic and Nonidiopathic Parkinsonian Syndromes

Abstract

We evaluated the utility of the selective dopamine D 2/3 receptor ligand 18 F-desmethoxyfallypride ( 18 F-DMFP) for the differential diagnosis of patients with idiopathic parkinsonian syndrome (IPS) and nonidiopathic parkinsonian syndrome (non-IPS). On the basis of the superior sensitivity of PET, we hypothesized that 18 F-DMFP should have properties for the differential diagnosis of these syndromes superior to what has been reported for the more conventional SPECT procedures. Methods: A series of 81 patients with parkinsonism (26 women, 55 men; mean age 6 SD, 68 6 11 y) were included in this retrospective analysis. A 30-min 18 F-DMFP PET recording was acquired starting 1 h after injection of the tracer (180-200 MBq, intravenously). The specific binding (SB) in divisions of the striatum was calculated relative to the occipital cortex using an observer-independent semiautomatic volume-of-interest-based technique. The optimal SB threshold was defined by means of receiver-operatingcharacteristic analysis, which was also used for the evaluation of the diagnostic performance of SB, ratios between striatal subregions, and absolute asymmetries in SB. Results: Significant differences (P , 0.001) were found in striatal SB between IPS and non-IPS, most notably in the posterior putamen, for which the diagnostic power for discrimination of IPS and non-IPS was the highest (sensitivity, 87%; specificity, 96%; and accuracy, 91%). A further gain of diagnostic power (sensitivity, 92%; specificity, 96%; and accuracy, 94%) was obtained through discriminant analysis combining 3 parameters: SB of the posterior putamen, the posterior-to-anterior putamen ratio, and the posterior putamen-to-caudate ratio. Conclusion: 18 F-DMFP PET is useful for the differential diagnosis of IPS and non-IPS in patients with parkinsonism. The findings are consistent with relative sparing of D 2/3 receptors in the dopamine-denervated putamen of IPS patients, in contrast to a more substantial loss of striatal dopamine receptors in non-IPS patients. The PET procedure for this differential diagnosis was superior to the reported experience with 123 I-iodobenzamide SPECT.

Methylphenidate Effects on Brain Activity as a Function of SLC6A3 Genotype and Striatal Dopamine Transporter Availability

“…The analysis of the different compartment of the striatum, for example, the differentiation of putamen and caudate is performed routinely in the Department of Nuclear Medicine for all DaTSCAN examinations and did not cause an additional effort in our analysis. The rationale for the subsegmentation of the striatum into putamen and caudate stems from previous observations of selective effects of disease (la Fougère et al, 2010) and MPH (Costa et al, 2013b) on putamen but not caudate.…”

Nigrostriatal Dopamine Terminal Imaging with Dopamine Transporter SPECT: An Update

“…1) (39,40). Favorable nuclear medicine imaging techniques for this purpose would be assessment of either postsynaptic D 2 -like receptors or assessment of brain glucose metabolism (41)(42)(43)(44).…”

Diagnostic Accuracy of Combined FP-CIT, IBZM, and MIBG Scintigraphy in the Differential Diagnosis of Degenerative Parkinsonism: A Multidimensional Statistical Approach

“…Molecular imaging techniques using PET or SPECT offer a variety of tools for diagnosing patients with parkinsonian syndromes (6)(7)(8). SPECT of the nigrostriatal dopaminergic system and of the sympathetic innervation of the heart is widely used in this context (4,9).…”