Multiparametric quantitative MRI uncovers putamen microstructural changes in Parkinson's Disease

Parkinsons disease (PD) is a progressive neurodegenerative disorder dominated by motor and non-motor dysfunction. Despite extensive research, the in vivo characterization of PD-related microstructural brain changes remains an ongoing challenge, limiting advancements in diagnostic and therapeutic strategies. The putamen, a critical structure within the basal ganglia, plays a key role in regulating movement and is profoundly affected in early PD-related neurodegeneration. In this study, we collected multiparametric quantitative MRI (qMRI) brain data of PD patients and healthy controls, to investigate microstructural alterations in the putamen in PD. We utilized a gradient analysis technique to analyze the spatial variations of various qMRI parameters, including relaxation rates (R1, R2, R2*), water fraction (WF), susceptibility, magnetization transfer saturation (MTsat), and diffusion metrics (MD, FA). Our findings reveal significant spatial gradients and interhemispheric asymmetries in these biophysical properties along the anterior-posterior axis of the putamen. Notably, PD patients exhibited increased water fraction and altered transverse relaxation rate R2*, particularly in the posterior putamen, correlated with motor symptom laterality. These microstructural changes suggest underlying tissue atrophy or neuroinflammatory processes associated with PD. The study underscores the importance of the posterior putamen as a focal point for PD pathology and highlights the potential of localized gradient analysis in detecting subtle yet clinically significant brain changes. The new qMRI dataset provides valuable insights into PD pathology, potentially aiding in the development of more precise diagnostic tools and targeted therapies.