No significant correlation of subthalamic nuclei diffusion measures and disease burden: Evidence from 130 Parkinson’s Disease Cases

<h2>Abstract</h2><h3>Background</h3> MRI diffusion measures have been shown to be valuable imaging tools for assessing neuronal degeneration in vivo. In idiopathic Parkinson's disease, diffusion measures of mesencephalic nuclei appeared to correlate with disease manifestations. However, large selective cohorts are lacking to define the clinical relevance of such potential MRI biomarkers. <h3>Method</h3> This study investigates the relevance of 3 Tesla diffusion MRI of the subthalamic nucleus (STN) as a potential imaging biomarker. Experts in deep brain stimulation manually segmented the STN on T2-weighted 3T MRI scans to create templates for measuring mean diffusivity and fractional anisotropy on aligned diffusion-weighted MRI scans. <h3>Results</h3> Demographic data, including age, sex, handedness, and specifications of neurological symptoms such as motor deficit severity, were collected using the Unified Parkinson's Disease Rating Scale in 130 patients at disease onset and progression. Despite a homogeneous study cohort no statistically significant correlations were found between local diffusion measures of the STN and contralateral clinical parameters. <h3>Conclusion</h3> Unlike previous studies that suggested potential correlations between mesencephalic diffusion measures and disease manifestations, this study did not confirm such associations for the subthalamic nucleus at 3T MRI in a large and homogeneous patient cohort. In the future research might focus on patients in earlier stages of the disease and employ higher field strength MRIs with increased spatial resolution to investigate the clinical relevance of MRI diffusion measures of the STN region in Parkinson's disease.