Objective: Investigate if the [¹⁸F]PR04.MZ PET CT is a useful tool in the differential diagnosis of PD and atypical parkinsonian syndromes (AP), mainly MSA and PSP, in the first 5 years of symptoms. 

Background:

As the PET is more available there has been efforts to use it in the differential diagnosis of parkinsonisms (1,2), despite some success finally in clinical settings they are not considered, and there is more consensus about the use of a combination of techniques to help in the differential diagnosis (3).

In the search and development of new biomarkers, we have now the [¹⁸F]PR04.MZ PET CT that use dopamine transporter (DAT) as a ligand and offers higher affinity and selectivity profile for DAT than the previously used tracers (4), by this we expect to know indirectly the density of presynaptic dopaminergic neurons in a more accurate way, in fact this PET CT is the only one that can show the dopaminergic loss in SNpc in PD (5).

The capability of [¹⁸F]PR04.MZ PET CT imaging for differentiating PD and AP has not been tested. 

Method: We performed a retrospective analysis of a cohort of 34 HC and 75 patients with parkinsonian syndroms of less than 5 years of symptoms in which the physician in charge, a movement disorder subspecialist, decided to ask for a [¹⁸F]PR04.MZ PET CT, presumably cases in which the diagnosis was not straightforward. We analyzed the clinical diagnosis and the specific binding ratios (SBRs) for the anterior putamen, posterior putamen, caudate nucleus and substantia nigra. SBRs were calculated as was by Juri et al (5).

Results: Our cohort was composed by 109 individuals, 34 HC, 6 MSA, 4 with an AP that the subspecialist could not classify, 56 PD and 9 PSP. The results of the SBRs in each group are shown in figure 1. We found that HC had higher SBRs in all regions, that PD showed less SBRs than HC with a rostrocaudal gradient (less SBR in posterior putamen). Its is striking that PSP showed a more severe compromise in all regions but specially in the putamen

Conclusion: [18F]PR04.MZ PET CT can shed a light in the differential diagnosis of PD and PSP in the first 5 years of symptoms, in future investigations it would be interesting to look for a threshold easy to use in individual patients exams. With this cohort we cannot conclude that it is useful for the differential with other AP not PSP.

Figure 1

References: References

1. Oh M, Kim JS, Kim JY, et al. Subregional patterns of preferential striatal dopamine transporter loss differ in Parkinson disease, progressive supranuclear palsy, and multiple-system atrophy. J Nucl Med. 2012;53(3):399-406

2. Cheon M, Kim SM, Ha SW, Kang MJ, Yang HE, Yoo J. Diagnostic Performance for Differential Diagnosis of Atypical Parkinsonian Syndromes from Parkinson’s Disease Using Quantitative Indices of 18F-FP-CIT PET/CT. Diagnostics (Basel). 2022;12(6):1402

3. Peralta C, Strafella AP, van Eimeren T, et al. Pragmatic Approach on Neuroimaging Techniques for the Differential Diagnosis of Parkinsonisms. Mov Disord Clin Pract. 2021;9(1):6-19

4. Kramer V, Juri C, Riss PJ, et al. Pharmacokinetic evaluation of [18F]PR04.MZ for PET/CT imaging and quantification of dopamine transporters in the human brain. Eur J Nucl Med Mol Imaging. 2020;47(8):1927-1937

5. Juri C, Kramer V, Riss PJ, et al. [18F]PR04.MZ PET/CT Imaging for Evaluation of Nigrostriatal Neuron Integrity in Patients With Parkinson Disease. Clin Nucl Med. 2021;46(2):119-124

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MDS Abstracts - https://www.mdsabstracts.org/abstract/18fpr04-mz-pet-ct-as-a-clinical-tool-in-the-differential-diagnosis-of-pd-and-other-atypical-parkinsonian-syndromes-in-the-first-5-years-of-symptoms/