18F FDG PET/CT in differential diagnosis of Parkinsonian disorders

Full text: Differential diagnosis of Parkinsonian disorders can be challenging in the early phase of disease course. Positron Emission Tomography (PET) imaging with 18F Fluorodeoxyglucose (FDG) has been used to identify characteristic patterns of glucose metabolism in patients with idiopathic Parkinson's Disease (PD) as well as variant forms of Parkinsonism such as Multisystem Atrophy (MSA), Progressive Supranuclear Palsy (PSP) and cortico basal ganglionic degeneration (CBGD). In this study we assessed the utility of 18F FDG PET/CT in the differential diagnosis Parkinsonian syndromes. 66 Parkinsonian patients with a mean age of 59.6 ± 11.50 years, male: female ratio of 3.12:1, age range of 35-84 years with a disease duration of 2.6 ± .68 years were referred for FDG PET to determine whether their scan patterns could distinguish idiopathic Parkinsons from the Parkinson plus syndromes. Approximately 60 minutes following intravenous injection of 370 MBq of 18F-FDG, PET/CT scan of the brain was acquired in a whole-body Full Ring PET/CT scanner (Discovery STE16 camera). A low dose CT was obtained on the same area without IV contrast for attenuation correction and coregistration. Images were reconstructed using a 3D VUE algorithm and slices were reformatted into transaxial, coronal and sagittal views. Subsequently the images were processed and visually analyzed on Xeleris workstation. Images were classified by visual analysis into the various subgroups, those with normal to increased basal ganglia uptake were classified into Idiopathic Parkinson's (40/45) and when basal ganglia uptake was decreased they were Parkinsons Plus (19/21). The study demonstrates that 18F FDG PET performed at the time of initial referral for parkinsonism could accurately classify patients into Parkinson's disease and Parkinson plus subtypes