Advanced MRI-based evaluation of gray and white matter changes in Parkinson’s disease

Parkinson’s disease (PD) is the most common movement disorder and the second most common neurodegenerative disease. The aim of our study was to compare gray–white matter changes (GWC) between Parkinson's disease (PD) patients and age-matched healthy control group as well as comparing GWC between different stages of PD (early and complicated). Our study was prospective cross-sectional case–control observational study with analytic component conducted on twenty patients and ten controls without any signs or symptoms of PD or any history of PD in first-degree relatives. All patients and controls were tested for history taking with stress on resting tremors, rigidity, gait abnormalities, postural instability and any symptoms of cognitive impairment, clinical examination including general examination and neurological examination. Also diffusion tensor imaging (DTI) with fiber tracking (tractography) and susceptibility-weighted MR imaging were performed for all cases. As regards DTI and evaluation of fractional anisotropy (FA) and mean diffusivity (MD) values between PD cases and healthy controls, the cases group showed significant decrease in FA values at substantia nigra on both sides and left cingulum as well as significant increase in MD values at substantia nigra on both sides and corpus callosum. Also, there are significant decrease in FA values at substantia nigra on both sides and significant increase in MD values at substantia nigra on both sides and right cingulum in late parkinsonism when compared to early parkinsonism. A cutoff FA value of 0.945 at right substantia nigra and cutoff FA value of 0.585 at left substantia nigra showed significant AUC that could differentiate between cases and controls. Also cutoff MD value of 0.791 at right substantia nigra and cutoff MD value of 0.813 at left substantia nigra showed significant AUC that could differentiate between cases and controls. Diffusion tensor imaging showed valuable role in evaluation of gray–white matter changes in Parkinson's disease. Also, it helps to assess degree of gray–white matter changes when comparing late parkinsonism to early parkinsonism through evaluation of FA and MD values at corpus callosum, substania nigra, and cingulum.