How PET scans can help find the cause of Parkinson’s disease

Originally published in Insidermedicine

An image-based classification system based on positron emission tomography (PET) scanning can accurately differentiate underlying causes of parkinsonism, according to research published online ahead of print in The Lancet Neurology.

Here are some guidelines for initiating drug therapy in patients with Parkinson’s disease from the American Academy of Neurology

• Consider initial symptomatic treatment of patients with selegiline in order to confer mild, symptomatic benefit prior to the institution of dopaminergic therapy

• Use either levodopa or a dopamine agonist in patients who require the initiation of dopaminergic treatment

• Select dopaminergic treatment base on the relative impact of improving motor disability (better with levodopa) compared with the lessening of motor complications (better with dopamine agonists) for each individual patient

Researchers out of the Feinstein Institute for Medical Research in Manhasset conducted fluorine-18-labelled-fluorodeoxyglucose-PET scanning on the brains of 167 patients with parkinsonism. They used an automated image-based classification procedure of their own design to differentiate patients with idiopathic Parkinson’s disease, multiple system atrophy, and progressive supranuclear palsy. Following imaging, patients were assessed by a blinded movement disorders specialist for a mean of 2-6 years before a final diagnosis was made.

As compared with the diagnoses made by the movement specialists, PET-based diagnosis of idiopathic Parkinson’s disease had a sensitivity of 84%, a specificity of 97%, a positive predictive value of 98%, and a negative predictive value of 82%. Similar accuracy rates were found for the diagnoses of multiple system atrophy and progressive supranuclear palsy.

Today’s research suggests that PET imaging can be used to differentiate underlying pathologies among patients with parkinsonism, providing guidance for appropriate treatment and inclusion in clinical trials.