Parkinson's disease in the spinal cord: An exploratory study to establish T2*w, MTR and diffusion-weighted imaging metric values.

Parkinson's disease (PD) is primarily defined by brain pathology, including dopamine neuron degeneration and α-synuclein aggregation. Emerging evidence suggests that the spinal cord is also affected, with ex-vivo studies reporting abnormal α-synuclein protein aggregation within the spinal cord of PD patients. While advanced imaging techniques, such as diffusion tensor imaging (DTI), neurite orientation dispersion and density imaging (NODDI), T2*-weighted (T2*w) imaging, and the magnetization transfer ratio (MTR) have demonstrated potential for detecting PD-related changes in the brain, their application to uncover spinal cord alterations remains unexplored. This study is the first to investigate MRI-derived microstructural metrics in the spinal cord of PD patients, comparing them to healthy controls. Although this study found limited microstructural or structural differences in the spinal cord between PD patients and healthy controls, these findings are consistent with recent results from PD mouse models and complement an earlier functional MRI study using the same cohort, where significant findings were observed. Our lack of significant structural findings may suggest that functional spinal cord changes are more sensitive markers of Parkinson's disease progression-particularly in relation to clinical measures such as the Unified Parkinson's Disease Rating Scale (UPDRS). These results highlight the need for further research to better understand how PD-related alterations in the spinal cord compare to normal aging processes and relate to functional changes.