Comparison of perfusion 18F-FP-CIT PET and 99mTc-ECD SPECT in parkinsonian disorders

Early and accurate identification of various conditions that can cause parkinsonian symptoms is important for determining treatment policies. Currently dopamine transporter (DAT) imaging using FP-CIT, glucose metabolism imaging using fluorodeoxyglucose, cerebral blood flow image using ethyl cysteinate dimer (ECD), and others are used for differentiation. However, the use of multiple modalities is inconvenient and costly. In the present retrospective study, we evaluated the correlation between regional brain uptake ratios (URs) in perfusion FP-CIT PET and ECD SPECT images. Twenty patients with Parkinson's symptoms underwent perfusion DAT positron emission tomography (F-18-FP-CIT PET/CT) and cerebral blood flow tomography (Tc-99m-ECD SPECT) within a 2-week period. Perfusion F-18-FP-CIT PET/CT and Tc-99m-ECD SPECT URs of 19 brain regions (bilateral frontal, temporal, parietal and occipital lobes, bilateral caudate nucleus, bilateral putamen, bilateral insula, bilateral cingulate gyrus, bilateral thalamus, and brainstem) were directly compared and correlations were analyzed. Average F-18-FP-CIT PET/CT regional perfusion URs were higher than Tc-99m-ECD SPECT URs. Uptake ratios were well correlated in all 19 regions (except right putamen), and especially in dopamine poor regions (cerebral cortex). In left putamen, URs were significantly correlated, but the correlation coefficient was lower than those of other regions. A single tracer dual phase N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane test seems to be helpful for differential diagnosis of parkinsonian disorders. Large-scale, longitudinal studies on complementary diseases with parkinsonian patterns are required to investigate differences in correlations between perfusion F-18-FP-CIT PET/CT and Tc-99m-ECD SPECT over time.

Automated summary

This study demonstrates a strong correlation between regional brain uptake ratios (URs) in perfusion FP-CIT PET and ECD SPECT images in patients with Parkinson's symptoms, especially in dopamine poor regions. The findings suggest that a single tracer dual phase N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane test may aid in the differential diagnosis of parkinsonian disorders. Further large-scale, longitudinal studies are needed to investigate the changes in correlations between perfusion F-18-FP-CIT PET/CT and Tc-99m-ECD SPECT over time in diseases with parkinsonian patterns.