Molecular imaging to track Parkinson's disease and atypical parkinsonisms: New imaging frontiers

Abstract

Molecular imaging has proven to be a powerful tool for investigation of parkinsonian disorders. One current challenge is to identify biomarkers of early changes that may predict the clinical trajectory of parkinsonian disorders. Exciting new tracer developments hold the potential for in vivo markers of underlying pathology. Herein, we provide an overview of molecular imaging advances and how these approaches help us to understand PD and atypical parkinsonisms. © 2016 International Parkinson and Movement Disorder Society.

Brain Magnetic Resonance Imaging (MRI) as a Potential Biomarker for Parkinson’s Disease (PD)

“…To date, researchers have shown the discriminative powers of MRI in separating PD from controls by assessing myelin structure, free water, iron, fiber pathways, or an assortment of other aspects of diseased tissues that define PD [8,9,10]. With atrophy, there is an increase in perivascular space that may allow for a novel imaging approach [11].…”

“…Both MRI and PET imaging have implemented this approach in PD [5,58]. Traditionally 18 F-fluorodopa (Fdopa) radiotracer administration with PET imaging has been employed to evaluate the integrity of the dopaminergic system, and when combined with raclopride (post-synaptic dopamine receptor radiotracer), it is possible to look at dopamine release in response to a variety of tasks [10]. Meanwhile, other PET methods use 15 O-H 2 O to look at cerebral blood flow (CBF) or 18 F-fluorodeoxyglucose (FDG) to assess brain metabolism.…”

“…Meanwhile, other PET methods use 15 O-H 2 O to look at cerebral blood flow (CBF) or 18 F-fluorodeoxyglucose (FDG) to assess brain metabolism. PET imaging has been used to evaluate PD subjects off and on symptomatic PD medications, and at rest or during a task, e.g., joy stick motor task [10]. Resting metabolic changes have been noted in PD using FDG PET methods whereby there is a pattern of reduction, i.e., PD-related pattern (PDRP) in the globus pallidus, putamen, thalamus, premotor and supplementary motor areas [59].…”

Parkinson's Disease Biomarkers: Where Are We and Where Do We Go Next?

“…Reduced binding of presynaptic dopamine transporter (DAT) ligand is well established as a surrogate marker for nigrostriatal degeneration, 67 and dissemination of radioligand measuring DAT binding into the clinical space has been successful. However, DAT binding deficit is not specific to PD 69 and utility as a rate marker is not clear. Emerging data suggest DAT SPECT is also a trait marker for risk of PD in individuals with other prodromal features, 12,70 but in order to maximize its specificity and predictive value it is unlikely that it can be used in isolation.…”

What would Dr. James Parkinson think today? II. Neuroimaging in Parkinson's disease

“…Several papers in this issue of Movement Disorders illustrate the power of contemporary imaging methods. Strafella and colleagues nicely review the impact of molecular (positron emission tomography) imaging on PD research. In a remarkable extension of the clinico‐pathologic correlation method, molecular imaging methods allow in vivo identification of key brain changes underlying specific features of PD.…”