The role of high‐field magnetic resonance imaging in parkinsonian disorders: Pushing the boundaries forward

Abstract

Historically, magnetic resonance imaging (MRI) has contributed little to the study of Parkinson's disease (PD), but modern MRI approaches have unveiled several complementary markers that are useful for research and clinical applications. Iron‐ and neuromelanin‐sensitive MRI detect qualitative changes in the substantia nigra. Quantitative MRI markers can be derived from diffusion weighted and iron‐sensitive imaging or volumetry. Functional brain alterations at rest or during task performance have been captured with functional and arterial spin labeling perfusion MRI. These markers are useful for the diagnosis of PD and atypical parkinsonism, to track disease progression from the premotor stages of these diseases and to better understand the neurobiological basis of clinical deficits. A current research goal using MRI is to generate time‐dependent models of the evolution of PD biomarkers that can help understand neurodegeneration and provide reliable markers for therapeutic trials. This article reviews recent advances in MRI biomarker research at high‐field (3T) and ultra high field‐imaging (7T) in PD and atypical parkinsonism. © 2017 International Parkinson and Movement Disorder Society.

Magnetic resonance imaging and tensor-based morphometry in the MPTP non-human primate model of Parkinson’s disease

“…The development of non-invasive imaging-based biomarkers is essential to further refine the differential diagnosis of PD and to potentially identify prodromal indicators and markers of disease progression [5, 7, 11, 13, 55]. Magnetic Resonance Imaging (MRI) can indicate changes in anatomy based on volumetric changes (T 2 -weighted images).…”

“…The fact that PD-associated cognitive symptoms and non-motor symptoms, are not affected by dopamine replacement [6] also implicates involvement of anatomical structures outside the nigrostriatal axis in the disease process [2]. Ideally, in vivo non-invasive biomarkers of these neuropathological changes should be developed to afford an unequivocal differential diagnosis of PD from other related pathologies, but also to provide a means to monitor and stage the progression of the disease and to therefore assess putative therapeutic interventions [7–11]. …”

“…Magnetic resonance imaging (MRI) and its versatility in assessing a variety of tissue characteristics is potentially well suited to provide non-invasive biomarkers for PD [7, 9, 11–13]. Morphometric structural changes, as indicated by T 2 -weighted images, are thought to provide potential non-invasive biomarkers of PD, but there is considerable variability in these measures [14–19].…”

“…The difficulty in achieving an unequivocal clinical diagnosis of PD is likely to contribute to the heterogeneity of imaging findings [8], as any potential confounds of dopamine-replacement medication have not been systematically addressed [12, 20]. To overcome this issue, modeling of PD-relevant disease mechanisms in animals can potentially provide a reasonably homogenous cohort of subjects that would afford the identification of key inclusion and exclusion criteria to improve the differential diagnosis of PD [11, 21]. These animal models also allow us to validate imaging biomarkers against neuropathological measures at the same time point, which is generally not possible in human subjects.…”

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].…”