Objective: To evaluate the relationship between R1 from ¹⁸PR04.MZ and CBF assessed by ¹⁵O-H2O PET/CT in patients with parkinsonian syndromes.

Background: ¹⁸PR04.MZ is an effective dopamine transporter (DAT) tracer for detecting dopaminergic depletion in degenerative parkinsonisms (DP). R1 images derived from dynamic 18PR04.MZ studies have been proposed as a proxy for cerebral blood flow (CBF), but no study has directly compared R1 with perfusion measured by ¹⁵O-H2O PET/CT, the gold standard for non-invasive CBF assessment.

Method: Fourteen patients with degenerative parkinsonism (11 Parkinson’s disease, two multiple system atrophy, one progressive supranuclear palsy) underwent 18PR04.MZ and ¹⁵O-H2O PET/CT within two weeks. Specific Uptake Ratios (SURs) of caudate, putamen, and substantia nigra were compared with 17 healthy controls (HC). Parametric images of R1 (¹⁸PR04.MZ) and absolute perfusion maps (¹⁵O-H2O) were generated by compartmental analyses. Correlations were assessed across cortical and subcortical regions.

Results: SURs were significantly reduced in patients compared to HC (caudate: 8.7 ± 4.2 vs. 17.9 ± 2.9; putamen: 5.3 ± 4.5 vs. 22.3 ± 3.1; substantia nigra: 0.91 ± 0.71 vs. 4.7 ± 1.4; all p < 0.0001). Significant correlations between R1 and CBF were found in the putamen (correlation coefficient= 0.717, p = 0.0058), parietal (CC= 0.673, p = 0.0117), frontal (CC= 0.631, p = 0.0209), and occipital cortices (CC = 0.573, p = 0.0407).

Conclusion: Dynamic 18PR04.MZ PET with kinetic analysis provides complementary information on CBF and may represent a useful proxy for perfusion imaging in degenerative parkinsonism.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/r1-from-18pr04-mz-as-a-proxy-for-cerebral-blood-flow-in-degenerative-parkinsonism-comparison-with-15o-h2o-pet-ct/