Development of a clinically feasible [C]PE2I PET method for differential diagnosis of parkinsonism using reduced scan duration and automated reference region extraction.

[C]PE2I is a highly selective dopamine transporter PET ligand. Parametric images based on dynamic [C]PE2I scans, showing dopamine transporter availability (BP) and relative cerebral blood flow (R), can be used in differential diagnosis of parkinsonism. This work aimed to investigate a shortened scan duration and automated generation of parametric images which are two prerequisites for routine clinical application. Twelve subjects with parkinsonism and seventeen healthy controls underwent 80 min dynamic [C]PE2I PET scans. BP and R images were generated using cerebellum reference region defined on a co-registered MRI, as well as a supervised cluster analysis (SVCA)-based reference. Initial 20, 30 and 40 min of the scans were extracted and images of standardized uptake value ratio (SUVR) and R were computed using MRI- and SVCA-based reference. Correlation was high between striatal 80 min MRI-based BP and 40 min SVCA-based SUVR-1 (R=0.95). High correlation was also found between R values in striatal and limbic regions (R≥0.91) whereas correlation was moderate for cortical regions (R=0.71). The results indicate that dynamic [C]PE2I scans can be restricted to 40 min and that SVCA can be used for automatic extraction of a reference region. These outcomes will support routine applications of [C]PE2I PET in clinical settings.