Quantitative MRI markers in Parkinson's disease and parkinsonian syndromes

In Parkinson's disease and parkinsonian disorders, the differential diagnosis is still challenging. We aim to review current developments in MRI quantitative markers and their potential in a clinical and neuroscientific setting.There have been efforts to improve MRI acquisition methods and to explore new promising biomarkers. In parallel, technological advances in data analysis (i.e. deep learning) open new ways to use these biomarkers. The MRI markers may differ according to the brain structure investigated. Even if the newly adopted acquisition protocols served mainly the development of brainstem-related biomarkers (neuromelanin MRI, nigrosome sensitive MRI), more established markers (e.g. morphometric values) in basal ganglia, cortex and cerebellum demonstrate their relevance especially to differential diagnosis in parkinsonian syndromes.We provide an overview on recent advances in MRI quantitative markers of Parkinson's disease that we divide for didactic purposes in three anatomical levels - cortical/cerebellum structures, basal ganglia and brainstem. We show the complementarity of new biomarkers sensitive to brain tissue properties to established morphometrics.