Utility of 18F FDG-PET in Parkinsonism in an African population.

Parkinson's Disease remains a diagnostic challenge. Misdiagnosis during life is approximately 25%. Diseases that resemble PD clinically, such as the Parkinsonianplus disorders usually have a poorer prognosis. A diagnostic biomarker is needed to differentiate PD from PPS. Geographical differences in PD prevalence, genetics and environmental factors may suggest a different pathogenesis of PD in Africa which may affect metabolic changes seen on 18F-FDG-PET. We investigated the utility of 18FFDG-PET in differentiating PD from PPS in a real-life clinical setting. The study was conducted at the Movement Disorder Clinic, South Africa. 81 patients with Parkinsonism had fluorine-18-labelled-fluorodeoxyglucose-PET; 53 PD and 28 PPS. Six persons living with HIV and Parkinsonism were included. Of the 22 Black African patients, 21 had PD and only one had a PPS. Image-based diagnosis was made by visual interpretation aided by statistical parametric mapping (SPM) analysis by a Nuclear Medicine Physician blinded to the clinical diagnosis. This was compared to the final clinical diagnosis made by two Movement disorder Neurologists blinded to the 18F-FDG-PET diagnosis. Patients were followed up for a median of 4 years. 18F-FDGPET diagnosis was in agreement with final clinical diagnosis in 91% of all subjects (90% PD, 93% all PPS). Our paper reports the clinically realistic sample of patients seen with Parkinsonism in Africa. The present data shows that 18F-FDG-PET can distinguish PD from PPS with good accuracy. Few Black Africans present with an Atypical Parkinsonian syndrome. The pattern of metabolism in PLH-PD is similar to PD patients without HIV.