Investigate changes in white matter (WM) structural integrity and grey matter (GM) volume in Parkinson’s disease (PD) using free-water diffusion tensor imaging (FW-DTI), generalized q-sampling imaging (GQI), and voxel-based morphometry (VBM).

PD is a chronic progressive neurodegenerative disease that leads to significant disability and morbidity. Several different MRI diffusion-related techniques have been used to analyze WM microstructural integrity in PD subjects, but the longitudinal progression has not been assessed using these metrics. Here, we evaluated differences in WM and GM in PD subjects over 12 months (TP1) using GQI, FW-DTI, and VBM.

MRI data from 30 PD subjects (age at baseline: 61.6±5.9 years) and 30 healthy controls (HC) (62.6±5.7 years,) acquired at baseline and after 12 months, were download from the PPMI database. VBM-FSL was used for VBM analysis. DTI were preprocessed using FSL. FW-corrected maps were calculated using an in-house MATLAB script. GQI data were analyzed by DSI Studio. Two-way ANOVA was used for statistical analysis using 3dANOVA3 (AFNI). The main effects for group and time-point (TP) and the interaction term group´TPs were evaluated. Additionally, we analyzed differences for PD and HC between the TPs and the differences between groups of each TP.

Generalized fractional anisotropy (gFA) and FW index showed significant differences (p<0.001, clusters>100 voxels) for the group effect and interaction in several WM areas. At baseline, higher gFA values were found in PD compared with HCs. However, compared with the baseline, PD subjects, showed lower gFA and higher FW in left anterior thalamic radiation, left inferior fronto-occipital fasciculus, and corpus callosum. Lower GM volumes in PD at TP1 were detected in the insula and temporal lobe.

This study demonstrates that GQI, FW-DTI, and VBM can be provide insight into the longitudinal trajectory of WM integrity and GM volumes in PD.