Separated Source QSM Reveals Dynamic Iron Deposition in Parkinson's Disease: A Longitudinal Study

Motivation: Accurate quantification of brain iron in Parkinson's disease (PD) is crucial for understanding disease progression and developing targeted therapies. Traditional QSM methods are limited by the colocalization of paramagnetic iron and diamagnetic myelin. Goal(s): To investigate longitudinal changes in brain iron levels during PD progression using susceptibility source separation (SSS) to distinguish paramagnetic from diamagnetic contributions. Approach: PD patients underwent MRI and clinical assessments at baseline and 36-month follow-up. SSS was applied to quantify brain iron deposition. Results: Iron deposition began in the substantia nigra pars compacta, spreading to other subcortical nuclei, excluding the putamen and caudate, and correlating with motor symptom severity. Impact: This study applies susceptibility source separation method for quantifying paramagnetic iron deposition in PD, offering insights into disease progression. It enhances our understanding of iron accumulation in specific brain regions, potentially guiding future therapeutic strategies targeting iron dysregulation.